EPA-R2-73-058
Match 1973 Environmental Protectian Technology Sartes
A Study of the
Photodegradation of Commercial Dyes
Office of Research sttd
U.S. Environmental Protection Agency
Washington, DC. 204EQ
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RESEARCH REPORTING SERIES
Research reports of the office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
U» Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
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1 1 n Id i. Cri-tif)
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Clemson University, cien,:-on,
Department of Textiles,
6 T""
A STUDSf-OF THE PHOTODEGRADATION OF COMMERCIAL DYES,
10
22
Authorft)
Porter, J»*m J.
Cuaiion
16] r'°':i'^r:'~; 6 / '/i /'w>r/-
'A 17090 EOX
21 A"" Si "">)
,- „ ,^ y -i | \ •> t ] n t • 'J>'n OPO .'Up JOC
ttr-j /^ i**^-*/* it v '* *
^T^'t^^-ty C»^'
, EPA-R2-73-058, March 1973. '/'A, ^
I ) L
22 Deter.plors (Stirred FIISI)
*Dyes, *5henical degradation,
^industrial wastes color,
"^ ^
textiles,
25
photodegradation, Clemaer
27Afcitraci The stability of thirty-six different coirjnercial dyes in water
to visible and ultraviolet light from a carbon arc has been studied.
The dyes were selected on the basis of their importance in the textile
industry from six major classes: basic, acid, direct, vat, disperse
and sulfur dyes. A comparison is made for two of the dyes between
laboratory fading rates and fading rates in natural sunlight. Both
dyes degraded at least 10 times more rapidly in artificial light than
in sunlight. Some previously identified degradation products of Basic
Green 4 were confirmed, and a mechanism of their formation was proposed.
A significant difference in degradation rate was observed b?tveen
water-soluble dyes and pigment dispersions.
This study showed that most commercial colors are resistant to
photodegradation and many weeks would be required to produce
appreciable dye degradation in a natural aquatic environment. (ffrJ
John J. Porter '"-"""'"" Clemson University, Clemson, S.C
TON t) C
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EPA-P2-73-058
March 1973
A STUDY OF THE PHOTODEGRADATION
OF COMMERCIAL DYES
By
John J. Porter
Project 11090 EOX
Project Officer
Dr. Arthur W. Garrison
Southeast Environmental Research Laboratory
College Station Road
Athens, Georgia 30601
Prepared for
OFFICE 01- RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For the Superintendent of Documents, I' ^ C-o\iruniC'it rrhiliiiR Oflu-i, \\ jtlilncton. DO.
I'rlccJI 25 doii.rstlc po«tpild or *1 (-0 Cll'O Idiokstori
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EPA REVIEW NOTICE
This report has bean reviewed by the Environmental Protection
Agency and approved for publication. Approval does not
signify that the contents necessarily reflect the views or
policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products constitute
endorsement or recommendation for use.
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ABSTRACT
The stability of thirty-six different commercial 3yes in
water to visible and ultraviolet light from a carbon arc
has been studied. The dyes were selected on the basis
of tht-ir importance in the textile industry from six
major classes: basic, acid, direct, vat, disperse and
sulfur dyes. A comparison is made for two of the dyes
between laboratory fading rates and fading rates in
natural sunlight. Both dyes degraded at least 10 times
.^ore rapidly in artificial light than in sunlight. Some
previously identified degradation products of Basic
Green 4 were confirmed, and a mechanism of their formation
was proposed. A significant difference in degradation
rate was oi served between water-soluble dyes and pigment
dispersions.
This study showed that most commercial colors are
resistant to photodegradation and many weeks would be
required to produce appreciable dye degradation in a
natural aquatic environment.
This report is submitted in fulfillment of Grant Project
No. 12090 EOX between the Environmental Protection Agency
and the Department of Textiles, Clemson University.
Key Words: Industrial wastes, textiles, color, dyes,
chemical degradation, photodegradation.
10.1
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CONTENTS
Section Page
I Conclusions 1
II Introduction 3
III Experimental Results 5
IV Discussion 33
V Acknowledgements 91
VI References 93
Preceding page blank
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FIGURES
No. Page
1 Pyrex Cell Used for Dye Degradation
Studies 7
2 Structures of Basic Dyes Studied 34
3 Structures of Basic Dyes Studied 35
4 Rate of Photodegradation of Basic
Violet 3 in Water at 50°C *»6
5 Rate of Photodegradati.cn of Basic
Blue 9 in Water at 50°C .......
6 Rate of Photodegradation of Basic
Green 1 in Water at 50°C 38
7 Rate of Photodegradation of Basic
Green 4 in Water at 50°C 39
8 Rate of Photodegradation of Basic
Red 2 in Water at 50°C 40
9 Rate of Photodegradation of Basic
Green 4 in Water Exposed to Sunlight
and Carbon Arc Light 42
10 Degradation Products Isolated from
Basic Green 4 43
11 Mechanism for Degradation of Basic
Green 4 44
12 Structures of Acid Dyes Studied 47
13 Structures of Acid Dyes Studied 48
14 Rate of Photodegradation of Acid
Red 1 in Water at 50°C 49
15 Rate of Photodegradation of Acid
Violet 3 in Water at 50°C 50
16 Rate of Photodegradation of Acid
Orange 10 in Water at 50°C 51
17 Rate of Photodegradation of Acid Red
37 in Water at 50°C 52
18 Rate of Photodegradation of Acid
Black 52 in Water at 50°C 53
19 Rate of Photodegradation of Acid
Violet 43 in Water at 50°C 54
20 Rate of Photodegradation of Acid Blue
40 in Water at 50°C 55
21 Structures of Direct Dyes Studied .... 57
22 Structures of Direct Dyes Studied .... 58
23 Rate of Photodegradation of Direct Red
80 in Water at 50°C 59
24 Rate of Piotodegradation of Direct
Green 6 in Water at 50°c 60
25 Rate of Photodegradation of Direct
Black 80 in Water at 50°C 61
26 Rate of Photodegradation of Direct
Blue 76 in Water at 50°C 62
27 Rate of Photodegradaticn of Direct
Blue 98 in Water at 50°c 63
vi
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FIGURES (continued)
No.
28 Rate of Photodegradation of Direct
Red 83 in Water at 50 C 64
29 Rate of Photodegradation of Direct
Brown 95 in Water at 50°C 65
30 Rate of Photodegradation of Direct
Blue 86 in Water at 50°C 66
31 Rate of Photodegradation of Direct
Blue 76 in Water Exposed to Sunlight
and Carbon Arc Light 68
32 Structures of Vat Dyes Studied 70
33 Rate of Photodegradation of Vat Brown 3
in Water at 50°C 71
34 Rate of Photodegradation of. Vat
Violet 1 in Water at 50°C 72
35 Rate of Photodegradation of Vat Blue 6
in Water at 50°C 73
36 Rate of Photodegradation of Vat
Green 1 in Water at 50°c 74
37 Structures of Disperse Dyes Studied ... 76
38 Structures of Disperse Dyes Studied ... 77
39 Rate of Photodegradation of Disperse
Blue 3 in Water at 50°C 78
40 Rate of Photodegradation of Disperse
Red 17 in Water at 50°C 79
41 Rate of Photodegradation of Disperse
Blue 1 in Water at 50°C 80
42 Rate of Photodegradation of Disperse
Blue 27 in Water at 50°C 81
43 Rate of Photodegradation of Disperse
Red 60 in Water at 50°C 82
44 Rate of Photodegradation of Disperse
Orange 3 in Water at 50°C 83
45 Rate of Photodegradation of Disperse
Blue 7 in Water at 50°C 84
46 Rate of Photodegradation of Disperse
Red 35 in Water at 50°C 85
47 Rate of Photodegradation of Sulfur
Red 5 in Water at 50°C 87
48 Rate of Photodegradation of Sulfur
Blue 7 in Water at 50°C 88
49 Rate of Photodegradation of Sulfur,^.,.
-Blue 13 in Wate* at 50°C 89
50 Rate of Photodegradation of Sulfur
Black 1 in Water at 50°C 90
VII
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TABLES
No. Page
1 Analyses of Commercial Dyes 8
2 Rate of Photodegradation of Basic
Violet 3 in Water at 50°C 11
3 Rate of Photodegradation of Basic Red 2
in Water at 50°C 11
4 Ratr of Photodegradation of Basic
Blue 9 in Water at 50°C 12
5 Rate of Photodegradation of Basic
Green 1 in Water at 50°C 12
6 Rate of Photodegradation of Basic
Green 4 in Water at 50°C 13
7 Photodegradation of Basic Green 4 in
Water Exposed to Sunlight 13
8 Rate of Photodegradation of Acid
Violet 3 in Water at 50°C 14
9 Rate of Photodegradation of Acid
Black 52 in Water at 50°C 14
10 Rate of Photodegradation of Acid Orange
10 in Water at 50°C 15
11 Rate of Photodegradation of Acid
Violet 43 in Water at 50°C 15
12 Rate of Photodegradation of Acid Red 1
in Water at 50°C 16
13 Rate of Photodegradation of Acid Blue 40
in Water at 50P-C 16
14 Rate of Photodegradation of Acid Red 37
in Water at 50°C 17
15 Rate of Photodegradation of Direct
Red 80 in Water at 50°C 17
16 Rate of Photodegradation of Direct
Blue 86 in Water at 50°C 18
17 Rate of Photodegradation of Direct
Brown .95 in Water at 50°C 18
18 Rate of Photodegradation of Direct
Blue 76 in Water at 50°C 19
19 Photodegradation of Direct Blue 76
in Water Exposed to Sunlight 19
20 Rate of Photodegrs.clation of Direct
Green 6 in Water at 50°C 20
21 Rate of Photodegradation of Direct
Blue 98 in Water at 50°C 20
22 Rate of Photodegradaticn of Direct
Red 83 in Water at 50°C 21
23 Rate of Photodegradation of Direct
Black 80 in Water at 50°C 2.1
24 Rate of Photodegradation of Vat Green 1
in Water at 50°C 22
25 Rate of Photodegradation of Vat Blue 6
in Water at 50°C 22
Vlli
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TABLES (continued)
No. Figs
26 Rate of Photodegradation of Vat
Violet 1 in Water at 5C°C 23
27 Rate of Photodegradation of Vat
Brown 3 in Water at 50°C 23
28 Rate of Photodegradation of Disperse
Red 17 in Water at SO^C 24
29 Rate of Photodecradation of Disperse
Blue 3 in Water at SO0'1 i4
30 Rate of Photodegradaticn of Disperse
Blue 1 in Water at 50^-C 25
31 Rate of Photodegradation of Disperse
Orange 3 in Water at 50°C 25
32 Rate of Photodegradation of Disperse
Red 15 in Water at 50°C 26
33 Rate of Photodegradation of Disperse
Red 60 in Water at 50°C 26
34 Rate of Photodegradation of Disperse
Blue 27 in Water at bO°C ....... 27
35 Rate of Photodegradation of Disperse
Blue 7 in Water at 50°C 27
36 Rate of Photodegradot-ion of Sulfur
Black 1 in Water at 5C°C . 28
37 Rite of Photodegradation of Sulfur
Red 5 in Water at 50°C 28
38 Rate of Photodegradation of Sulfur
Blue 7 in Water at 50°C . , 29
39 Rate of Photodegradation of Sulfc.
Blue 13 in Water at 50°C 29
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SBC-TION I
CONCLUSIONS
The thirty-six dyes chosen for this study were selected
from those most used oy the textile industry so that an
accurate assessment could be made of the water pollution
potential of common commercial colors. The results of
the study led to the following conclusions:
1. Most of the dyes are quite resistant to light
degradation showing an average of 40 percent color loss
after 2CC hours exposure co artificial light in water.
2. A comparison of artificial light and natural sunlight
effects on Basic Green 4 and Direct Blue 76 showed that
these dyes degraded at least 10 times slower in natural
sunlight. This means that a minimum of 80 days in a
natural environment would be required to produce
appreciable degradation of the dyes studied.
3, The water soluble dyes—basic, acid, and direct
types—were degraded faster thrn the insoluble pigment
types—vat, disperse and sulfur dyes.
4. The loss of color or degradation of the pigment
dispersion type dyes—vat, disperse, and sulfur dyes—
appeared to be partly due to physical changes in the
dispersion rather than chemical degradation. This is
not unusual for these dyes..
5. A mechanism, proposed in previous research work,
for the degradation of triphenylmethane type basic dyes
was confirmed in this study.
6. The stability of the dyes examined in this study
points to the need for color considerations in
effluents and stream standards. Waste treatment
methods, especially in the textile industry, should
be selected for their ability to remove color as well
as biodegradable chemicals.
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SECTION II
INTRODUCTION
What is the eventual f.)te of natvral and synthetic color-
ing materials that arc discharged into a sewer or indus-
trial v,asto .stream? The total U. S. corunercial color
production currently amounts to almost 0.5 bi31ion pounds
per year.^ What effect will these colors have on the
environment? These questions need qualitative answers
at least. Many discharged dyes and pigments are inert
and non-toxic at their concentrations in natural receiving
waters—some are not so innocuous. In either case, tne
color they impart may be very undesirable to the water
user. This is one of the obvious reasons for research on
the stability of dyes to light ar>C water under conditions
similar to those encountered wheu they are discharged
to natural streams and reservoirs.
This study is limited to some of the more common dyes
used by the textile industry. The total dye consumption
of the textile industry is over 100,000/000 pounds per
year.l Since It has been estimated that a maximum of
90 percent of these dyes end up on fabrics and the
remaining 10 percent goes to the waste stream, approxi-
mately 10,000,000 pounds of dye per year are presently
discharged to waste streams by the textile industry.
Sorr.e of this color can be removed from the waste by the
conventional biological waste treatment systems.2 The
removal occurs when the soluble dye is adsorbed on the
sludge or the insoluble dye pigments settle to the
bottom of a non-agitatsd basin or lagoon. Since the
dyes are designed to resist oxidative degradation by
ozone, bleaches, and oxides of nitrogen it is not likely
that the aerobic biological process would have much
effect on them. This has been shown in previous
research.3
A selection of thirty-six dyes for investigation was
made from six of the common classes: basic, direct,
acid, disperse, vat, and sulfur dyes. The dyes were
chosen on the basis of consumptive use so a realistic
evaluation of the actual textile waste color problem
could be made. Dyes whose structures were not known
because of proprietary reasons were not included in the
study. The photoclegradation in water of the thirty-six
dyes, representing many structural types, was investi-
gated. The kinetics of photodijradacion were compared
to those for sunlight, degradation for two of the more
fugitive dyes. The difficulty of purification of the
dyestuffs and the lack of success in isolating many of
the degradation products prevented the determination of
quantum yields.
Preceding page blank
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The decomposition products of the dyes which degraded
appreciably were analyzed by mass spectral, gas chro-
matographic, and infrared methods. Where sufficient
information was obtained a mechanism was proposed for
the degradation process.
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SECTION III
EXPERIMENTAL RESULTS
Elemental analyses were performed by -Galbraith Laboratories,.
Inc., Knoxville, Tennessee. Gas chromatographic analyses
were performed with a Per kin-Elmer Model 900 instrument
equipped with a flame lor.ization detector. Mass spectra
were determined by a Hitcchi-Perkin-Elmer RM"-7 double
focusing mass spectrometer. Ultraviolet spectra were run
on a Perkin-Elmer Model 202 spectrophotometer and visible
spectra were obtained from a Bausch and Lomb Spectronic 20
spectrophotcmeter as wel] as a recording General Electric
spectrophotometer. Infrcired spectra were run on a Perkin-
Elmer Model Infracord.
Fading Rate Studies
The following commercial dyes were used directly from their
shipping containers without any prior purification:
C.I. Name
Basic Green 1
Basic Violet 3
Basic Red 2
Direct Red 80
Direct Red 83
Direct Black 80
Direct Blue 86
Sulfur Black 1
Sulfur Blue 7
Disperse Red 15
Disperse Red 60
Disperse Blue 7
Disperse Blue 27
Vat Green 1
Vat Blue 6
C.I. Number
Basic Dyes
C.I. Name
42040
4255!5
50240
Basic
Basic
Blue 9
Green 4
Direct Dyes
35780 Direct Blue 98
29225 Direct Blue 76
3160 D Direct %Green 6
74180 Direct Brown 95
Sulfur'Dyes
53185 Sulfur Blue 13
53440 Sulfur Red 5
Disperse Dyes
C.I. Number
52015
42000
23155
24410
30295
30145
53450
53830
60710 Disperse Orange 3 11005
* Disperse Blue 3 61505
62500 Disperse Red 17 11210
60767 Disperse Blue 1 64500
Vat Dyes
59825 Vat Brown 3 69015
69825 Vat Violet 1 60010
*C.I. number not available.
-------
C.I. Name C.J. Number C.I. Nairc; C.I. Number
Acid Dyes
Acid Violet <3 60730 Acid Red 1 18050
Acid Blue 40 62125 Acid Red 37 17045
Acid Violet 3 16580 Acid Orange 10 16230
Acid Black 52 15711
Varied concentrations cf the above dyes in aqueous
solution were exposed to the carbon arc source of an
Atlas Fade-On.eter using a specia] ly constructed cell
shown in Figure 1. The cell was designed to accommodate
a volume of 800 ml. Tre side windows were 1/16" Pyrex
glass transparent down to 280 mp at an absorbence of
1.0 (from UV curve). The top of the cell was covered
with a glass plate to minimize the evaporation of the
liquid but the cell was not sealed so exchange with
oxygen in the air coulc occur. The ambient temperature
in the Fade-Ometer cabinet varied from 100-ilO°F and the
temperatures of the dye solutions varied according to
the intensity of the coloration of the dye solutions.
The glass cell was mounted two inches horizontally from
the glass envelope and centered vertically with the
carbon arc source. Th£' solutions were exposed to the
carbon arc source for £t period of 200 hours. The liquid
was maintained at its original level throughout the
exposure period by frequent additions of ajstilled water.
Little stirring of the dispersions of insoluble dyes was
necessary because of convection currents in the warm cell,
The dye concentrations used in this work were based on
t-ie elemental analysis of the commercial dye as shown
ii. Table 1, except for sulfur dyes which were based on
the dried dye paste and recorded in grams per liter.
One milliliter portion:; of the exposed solutions were
taken at approximately 50-hour intervals and analyzed
for changes in optical density using a Bausch and Lomb
Spectronic 20 spectrophotometer. The results of these
experiments are shown .In Tables 2-39.
In order to correlate i:he fading rate of the dye
solution in the Fade-Ometer with natural sunlight, two
dyes, C.I. Basic Green 4 and C.I. Direct Blue 76, were
exposed to sunlight and Fade-Ometer radiation. A
2-liter Pyrex beaker containing 1.5 liters of dye
solution was placed on the roof to provide maximum day-
light exposure. The top of the beaker was cov&red with
a sheet of the Same 1/L6" Pyrex glass that: was used in
construction of the cells. Samples were taken and
analyzed in the same manner as for the F&de-Ometer
studies.
. 6
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Figure 1 Pyrex Cell Used For Dye
Degradation Studies
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Table 1 Analyses of Commercial Dyes
Calculated
Found
C.T.
Basic
Basic
Basic
Basic
^? ^ 1 C
Direct
Direct
Direct
03 Direct
Direct
Direct
Direct
Direct
Sulfur
Sulfur
Sulfur
Sulfur
Name C.
Green 1
Violet 3
Red 2
Blue 9
nT"Oft»n 4
Red 80
Red 83
Black 80
Blue !*6
Blue 98
Blue 76
Green 6
Brown 95
Black 1
Blue 7
Blue 13
Red 5
I. Number M.W.
42040
42555
50240
52015
42000
35780
29225
31600
74180
23155
24410
30295
30145
53185
53440
53450
53830
482.0
407.5
350.5
319.5
926
134
111.1
806
781.5
923.0
992.0
812.0
759.5
%C
67.20
73.67
68.52
60.12
g-_ 3-7
40.30
36.80
53.51
49.40
49.41
41.13
50.21
49.00
%H
7.05
8.72
5.42
5.63
5. SO
1.94
1.44
2.7C
1.79
2.60
2.42
2.71
2.36
5
iO
16
10
£
30
7
13
14
7
8
13
11
%N j,S
.81 6.64
.31
.03
.01
. O'!
.40 14.31
.60 11.53
.90 7.95
.40 8.19
.59 10.04
.47 12.90
.70 7.88
.07 4.22
unknown
unknown
unknown
unknown
%C
65.29
70.85
51.59
47.80
c. -i ->a
tj i . «^ *
11.26
9.62
20.82
17.42
12.23
9.91
17.40
27.11
40.43
44.16
46,30
44.76
%H
7.16
7.70
6.29
4.92
£ f\ A
V • \J ~*
0.99
1.24
2.37
1.95
0.90
1.04
1.19
1.89
3.38
4.59
5.30
4.20
%N
5.50
9.24
12.36
9.98
e. A A
w • w -*
2.76
2.73
8.08
4.75
2.12
2.50
4.22
5.19
6.59
3.43
2.79
2.35
%S %Activca
97
90
75
80
i n r\
J. \S \J
26
27
37
33
28
30
31
47
18.92
17.70
13.19
17.62
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Table 1 (continued)
Calculated
Found
C.I. Nami C.I.
Disperse Red 15
Disperse R<=d 60
Disperse Blue 7
Disperse Blue 27
Disperse Orange 3
Hicr^o'-co nluc* 1
Disperse Red 17
u> Disperse Clue I
Vat Green 1
Vat Blue 6
Vat Brown 3
Vat Violet 1
Acid Violet 43
Acid Blue 40
Acid Violet 3
Acid Black 52
dumber
60710
62500
60767
11005
c i t;nc
11210
64500
59825
69825
69015
60010
60730
62125
16580
15711
M.W.
239.0
331.0
358
420
242
o*?n
344
268
516
513
663
525
431
473
483
893
70
72
60
62
59
C C
59
62
81
65
76
81
58
55
39
42
%C
.40
.50
.35
.83
.50
"7
« t
.35
.70
.80
.50
.10
.25
.49
.90
.75
.95
%H
3.77
3-93
5.03
3.81
4.14
c r i
•J • ~f A.
5.82
4.45
3.88
2.73
3.17
2.78
3.25
3.48
2.28
1.79
5
4
7
6
23
i r\
JL
-------
Table 1 (continued)
Calculated
Found
C.I.
Acid
Acid
Acid
Name
Red 1
Red 37
Oiange 10
C.I. Number
18050
17045
16230
M.W.
409
524
350
%C
52.80
41.21
54.89
%H
3.18
2.67
3.14
%N
10.28
10.69
S.OO
%S
15.66
12.21
9.15
%C
30.88
21.03
34.45
%H
3.32
2.29
2.39
%N %S
7.42
4.35
5.C9
lActive3
72
45
64
Based on the analyses of the commercial dye as received. All dye pastes were dried to constant
weight at 105°C before elemental analyses were determined. The limiting element in the analyses
t- was used for %Active calculation for all dyes except sulfur dyes which have no known molecular
0 structure. % Activity for the sulfur dyes was based on the solids obtained after drying the
commercial dye paste.
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TABLE 2
RATE OF riiOTODEGRADATlON OF
BASIC VIOLET 3 IN WATER AT 50°C
Tiirc, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 30.0 0.520 8.80
56 42.0 0.377 6.38
115 55.6 0.254 4.30
lt'1 67.0 0.172 2.91
200 79.5 0.100 1.69
For Transmission and absorbency measurements a 1 milli-
?.itor sample ot the dye solution was removed and diluted
to 150 milliliters with 95% ethanol. (wavelength = 585m ).)
Based en % activity of commercial dye given in Table 1
7 ABT.E 3
RATE OF PHOTODEGRADATION OF
BASIC RED 2 IN WATER AT 50°C
Time, n Concentration i<
Hours %Transmission Absorbency1"' moles/lit<=r x 10
0 21.0 0.680 10.75
56 34.8 0.460 7.27
115 43.8 0.360 5.69
161 59.0 0.230 3.63
200 65.3 0.185 2.92
For Transmission and absorbency measurements a l milli-
litcr sample of the dye siolution was removed and dilated
fco 150 railliliters with 95% ethanol. (wavelength = 530m)_)
Based on % activity of commercial dye given in Table 1
11
-------
TABLE 4
RATE OF PHOTODEGRADATION OF
BASIC BLUE 9 IN WATER AT 50°C
Time, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 20.5 0.690 11.81
56 29.8 0.530 9.07
115 33.7 0.475 8.13
161 39.0 0.410 7.02
200 52.0 0.300 5.13
For Transmission and ab:sorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 150 milliliters with 95% ethanol. (wavelength = 650m v)
Based on % activity of commercial dye given in Table l
TABLE 5
RATE OF PHOTODEGRADATION OF
BASIC GREEN 3 IN WATER AT 50°C
Time, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 31.0 0.510 9.82
56 40.0 0.400 7.70
115 64.7 0.190 3.66
161 75.5 0.122 2.35
200 88.8 0.051 0.98
a For Transmission and absorbency measurements as 1 milli-
liter sample of the dye solution was removed and diluted
to 150 milliliters with 95% ethanol. (wavelength = 637m v)
Based on % activity of commercial dye given in Table 1
.12
-------
TABLE 6
RATE OF PHOTODEGRADATIQW OF
BASIC GREEN 4 IN WATER AT 50°C
Time,
Hours
0
47
89
200
%Transmission
23.0
65.5
72.1
89.0
Absorbency
0.640
0.182
0.139
0.05C
Concentration >
moles/liter x 10
6.38
1.81
1.39
0.50
aFor Transmission and absorbency measurements a 1 milli-
liter sample of the dye isolution was removed and diluted
to 90 milliliters with 915% ethanol. (wavelength = 625 m
Based on % activity of commercial dye given in Table 1
TABLE 7
PHOTODEGRADATION OF BASIC GREEN 4
IN WATER EXPOSED TO SUNLIGHT
0
13
24
36
42
69
0
312
576
864
1008
1656
%Transmiss:.onc
25.0
26.0
26.0
29.8
33.1
44.0
Absorbency'
0.600
0.590
0.590
0.530
0.479
0.355
Concentration
i,
x 10
7.91
7.79
7.79
6.99
6.32
4.68
For Transmission and absorbency measurements a 1 milli-
liter sample of the c> ™ s;olution was removed and diluted
tc 120 milliliters w: . T? ethanol. (wavelength = 625 mi)
Based on % activity of commercial dye given in Table 1.
13
-------
TABLE 8
RATE OF PHOTODEGRADATIOH OF
ACID VIOLET i IN WATER AT 50°C
Time, Concentration .,
Hours %Transmission Absorbency moles/liter x 10
0 28.2 O.bSO 6.29
61 69.0 0.160 1.83
103 84.0 0.075 0.85
156 9C.O 0.047 0.53
200 94.0 0.025 0.28
aFor Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 40 milliliters with 30t, by volume dimethylfcrmamide
in distilled water. (wave-length = 705 m u)
b
Based on % activity of commercial dye given in Table l
TABLE 9
RATE OF PHOTODEGRADATION OF
ACID BLACK 52 IN WATER AT 59-° C
Time, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 52.5 0.280 6.65
61 54.0 0.268 6.36
103 53.5 0.270 6.41
156 53.5 0.270 6.41
200 55.C 0.260 6.17
For Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 40 milliliters with 30% by volume dimethylformamide
in distilled water. (wavelength = 650 my)
Based on % activity of comnercial dye given in Table 1
14
-------
TABLE 10
RATE OF PHOTODEGRADATION OF
ACID ORANGE 1C IN WATER AT 50°C
Time, Concentration i
Hours %Transmission Absorbency3 mo]es/liter x 10
0 27.8 0.560 10,37
61 36.5 0.440 6.15
103 53.7 0.270 5.00
156 94.0 0.025 0.46
200 96.5 0.015 0.28
aFor Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 40 milliliters with 30% by volume dimethylformamide
in distilled water, (wavelength = 480 mr)
Based on % activity of commercial dye given in Table 1
TABLE 11
RATE OF PHOTODEGRADATION oF
ACID VIOLET 43 IN WATER AT 50°C
Time, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 67.5 0.180 8.00
61 73.2 0.130 5.78
103 77.0 0.11L 5.11
156 80.5 0.093 4.13
200 83.0 0.080 3.56
aFor Transmission and absoroency measuremsnts a 1 milli-
liter sample of the dye solution was removed and diluted
to 20 miliiliters with 30% by volume dir^thylformatiide
in distilled water. (wavelength = 70b my)
Based on % activity of commercial dye given in Table 1
15
-------
TABLE 12
RATE OF PHOTODEGRADATION OF
ACID RED ] IN WATER AT 50°C
Time, Concentration /,
Hourr, %Transmission Ahsorbency molos/litcr x iC
r> 23.0 0.640 11.37
47 65.5 0.182 10.85
89 72.1 0.139 10.51
200 89.0 0.050 3.18
aFor Transmission and c,bsorbency measurements a 1 milli-
sample of the dye solution was removed ard diluted
to 40 milliliters with 30% by volume dimethylformamide
in distilled water, (wavelength = 532 mp)
Basec on % activity of corronercial dye given in Table 1
TABLE 13
RATE OF PHOTODEGRADATION OF
ACID BLUE 40 IN WATEP AT 50°C
Tine, Concentration
Hours %Transmission • Absorbencya moles/liter x 10
0 55.5 0.255 2.90
47 56.0 0.250 2.85
89 56.5 0.248 2.83
200 • 60.0 0.223 2.54
For Transmission and absorbency rdeasurements a 1 milli-
liter sample of the' dye solution was removed and diluted
to 20 Milliliters with 30% by volume dimethylformamide
in distilled water. (wavelength = 705 m v.)
DBased on % activity Df commercial dye gjven in Table 1
16
-------
TABLE 14
RATS OF PHOTODEGRADATION OF
ACID RED 37 IN WATER AT 50°C
Time, Concentration t,
Hours %Transmission Absorbency moles/liter x 10
0 21.5 0.670 6.56
47 65.5 0.182 1.78
89 89.5 0.047 0.46
200 95.0 0.022 0.22
aFor Transmission and absorbency measurements a 1 milliliter
sample of the dye solution was removed and diluted to 20
milliliters with 30% by volume dimethylformamide in dis-
tilled water, (wavelength = 525 my)
Based on % activity of commercial dye given in Table 1
TABLE 15
RATE OI? PHOTODEGRADATION OF
DIRECT RED 80 IN WATER AT 50°C
Time, , Concentration
Hours %Transmission Absorbency0 mo] >s/liter x ]0
0 23 0.640 2.50
56 23.5 0.630 2.46
111 24.0 0.620 2.42
157 24.5 0.614 2.39
200 26.2 0.580 2.26
*a
For Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 50 milliliters with 30% by volume diniethylformamicle
in distilled water, (wavelength = 530 m v)
Based on % activity of commercial dye given in Table 1
17
-------
TABLF 16
RATE OF PHOTODEGRADATION OF
DIRECT BLUE 86 IN WATER AT 50°C
Time,
Hours
%Transmissionc
Absorbency
,
Concentration
!
moles/]iter x 10
0
56
111
157
200
23.0
24.5
24.0
26.5
26.2
0.640
0.612
0.620
0.580
0.580
5.89
5.63
5.70
5.33
5.33
For Transmission and absorbency measurements a 1 milli-
liter sample of the d"f solution was removed and diluted
to 75 milliliters with 30% by volume dimethylformamide
in distilled water, (wavelength = 670 mu)
Based on % activity of. commercial dye given in Table 1
TABLE 17
RATE OF PI1OIODEGRADATION OF
DIRECT BROWN 95 IN WATER AT 50 C
Time,
Hours
0
68
112
154
200
%Transmissionc
18.9
25.0
29.0
30.2
36.0
Absorbency'
0.730
0.600
0.540
0.510
0.441
Concentration L
moles/liter x 10
9.77
8.04
7.24
6.82
5.92
For Transmission and absorbency measurement!; a 1 milli-
liter sample of the dye solution was removed and diluted
to 100 milliliters with 30% by volume dimethylf ornwnude
in distilled water. (wavelength - 470 my)
JBased on % activity of cormercial dye given in Table j.
18
-------
TABLE 18
RATE OF PKOTODEGRADATION OF
DIRECT BLUE 76 IN WATER AT 50°C
Time,
Hours
0
68
112
154
200
%Transmission
32.8
73.4
84.0
83.0
89.0
Absorbency
0.490
0.133
0.072
0.080
0.050
Concentration
moles/liter x 10
3.95
1.07
0.58
0.64
0.40
*°or Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with 3D% by volume dimethylformamide
in distilled water (wavelength = 665 mv)
bBased on % activity of commercial dye given in Table I
TABLE 19
PHOTODEGRADATION OF DIRECT BLUE 76
IN WATER EXPOSED TO SUNLIGHT
Time
Days Hours
0
13
24
36
42
69
0
312
576
864
1008
1656
%Transmis5ion Absorbency1
62.7
71.0
75.5
76.0
77.8
80.1
0.205
0.150
0.125
0.120
0.110
0.095
Concentration t
moles/liter x 10
5.03
3,
3.
2.
2,
68
07
94
70
2.33
For Transmission and absorbency measurements a I milli-
liter sample of the dye solution was removed and diluted
to 100 milliliters with 30% by volume dimethylformamide
in distilled water, (wavelength = 665 m u)
Based on % activity of commercial dye given in Table 1
19
-------
TABLE 20
RATE OF PHOTODEGRADATIGN OF
DIRECT GREEN (. IN WATER AT 50 C
Time,
Hours
0
68
112
154
200
%Transmission
22.0
26.0
29.0
30.0
35.0
Absorbency
0.660
0.590
0.540
0.510
0.459
Concentration
moles/liter x 10
5.54
4.95
4.53
4.28
3.85
For Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with 30\> by volume uimethylformamide
in distilled water. (wavelength = 650 my)
Based on % activity of commercial dye given in Table 1
TABLE 21
RATE OF PHOTODEGRADATION OF
DIRECT BLUE 98 IN WATER AT 50 °C
Time,
Hours
0
68
112
154
200
%Transmission
65.0
71.8
/3.0
73.0
76.7
Absorbency
0.190
0.145
0.137
0.137
0.116
Concentration i
moles/liter x 10
4.01
3.06
2.89
2.89
2.45
a
For Transmission and absorbency maasurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with 30% by volume dimethylformamide
in diotilled water, (wavelength = 650 my)
DBased on % activity of commercial dye given in Table 1
20
-------
TABLE 22
RATE OF PHOTODEGRADATION OF
DIRECT RED 83 IN WATER AT 50°C
Time, Concentration i
Hours %Transmissiona Absorbency3 moles/liter x 10
0 28.5 0.545 3.11
56 29.8 0.530 3.0?
Ill 34.2 0.464 2.65
157 43.5 0.360 2.05
200 52.8 0.278 1.58
For Transmission and abso^bency measurements a 1 milli-
liter sample of the dy; solution was removed and diluted
to 50 nillilitsrs with 30% by volume dimethylformamide
in distilled water. (wavelength = 537 m ji)
Based on % activity of commercial dye given in Table 1
TABLE 23
RATE OF PHOTODEGRADATION OF
DIRECT BLACK 80 IN WATER AT 50°C
Time, Concentration
Hours %Transmission Absorbency moles/liter x 10
0 45.0 0.348 6.84
56 47.8 0.320 6.29
111 52.0 0.282 5.54
157 55.0 0.260 5.11
200 57.7 0.240 4.72
a
For Transmission and absorbency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to JOO milliliters with 30% by volume dimethylformamide
in distilled water. (wavelength = 660 m v)
b
Based on %activity of coiranercial dye given in Table 1
21
-------
TABLE 24
RATE OF PHOTODEG.XADATION OF
VAT GREEN 1 IN WATER AT 50°C
Time, Concentration
Hours ^Transmission Absorbency moles/liter x 10
0 25.0 0.600 - 4.06
60 27.5 0.560 3.79
110 31.0 0.510 3.46
146 35.7 0.450 -£v&5
200 43.0 0.367 2.48
For Transmission and absorbency measurements a one milli-
liter sample of the dye solution was removed and diluted
to 20 tniliiliters with diiriethylformanude. (wavelength =
6b'0 m u)
Based on % activity of commercial dye given in Table i
TABLE 25
RATE OF PHOTODEGRADATION OF
VAT BLUE 6 IN WATER AT 50°C
Time, Concentration
Hours %Transmission Absorbency moles/liter x 10
0 71.0 0.150 1.91
60 72.5 . 0.140 1.79
110 76.0 0.120 1.53
146 77.8 0.110 1.44
200 82.0 0.086 1.10
aFor Transmission and absorbency measurements a one milli-
liter sample of the dye solution was removed and diluted
to 20 milliliters with dimethylformamide. (wavelength =
695 mu)
Based on % activity of commarcial dye given in Table 1
-------
TABLE 26
RATE OF PHOTODEGRADATION OF
VAT VIOLET 1 IN WATER AT 50°C
Time, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 41.0 0.390 4.20
60 44.0 0.353 3.81
110 49.0 0.310 3.34
M6 52.2 0.280 3.02
200 58.0 0.237 2.55
For Transmission and abso::bency measurements a one milli-
liter sample of the dye solution was removed and diluted
to 20 milliliters with dimethylformamide. (wavelength =
550 m U)
t>.
Based on * activity of cornr^ercial dye given in Table 1
TABLE 27
RATE OF PHOTODEGRADATION OF
VAT BROWN 3 iCN WATER AT 50 °C
t,.
Time,. Concentration
Hours %Vransmission Absorbencya moles/liter x 10
0 29.5 0.530 9.33
60 32.3 0.490 8.62
110 37.5 0.425 7.48
146 41,0 0.388 6.82
200 49.0 0.310 5.46
aFor Transmission and absorbency measurements a one milli
liter sample of the dye solution was removed and diluted
to 20 milliliters with dimethylformamide. (wavelength =
550 my)
Based on % activity of commercial dye given in Table i
23
-------
TABLE 28
RATE OF FHOTODEGRADATION OF
DISPERSE RED 17 IN WATER AT 50°C
Time,
Hoars
0
70
103
157
200
%Transmissionc
28.5
33.0
34.0
37.8
41.8
Absorbency'
0.545
0.480
0.465
0.423
0.380
Concentration
moles/liter x 10
10.29
9.06
8.78
7.98
7.17
For Transmission and absorbency measurements a one milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with dimethylformamide. (wavelength =
505 in y)
Based on % activity of commercial dye given in Table 1
TABLE 29
RATE OF PHOTODEGRADATION OF
DISPERSE BLUE 3 IN WATER AT 50°C
Time,
Hours
0
70
103
157
200
%Transmission
47.5
56.0
60.5
67.0
74.0
a
Absorbency'
0.320
0.251
0.220
0.173
0 330
Concentration j
moles/liter x 10
3.
2.
59
82
2.47
1.94
1.46
For Transmission and absorbency measurements a one milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with dimethylformamide. (wavelength =
650 mp)
""Based on % activity of cotmiercidl dye given in Table 1
-------
TABLE 30
RATE OF PHOTODEGRADATION OF
DISPERSE BLUE 1 IN WATER AT 50°c
Time, Concentration i
Hours %Transmission Absorbency * moles/liter x 10
0 26.3 0.580 19.45
70 34.8 0.460 15.42
103 39.0 0.410 13.75
157 41.0 0.388 13.01
200 39.0 0.410 13.75
aFor Transmission and absorbency measurements a one milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with dimethylformamide. (wavelength =
650 mv)
Based on % activity of commercial dye given in Table 1
TABLE 31
RATE OF PHOTODEGRADATION OF
DISPERSE ORANGE 3 IN WATER AT 50°C
Time, Concentration i
Hours %Transmission Absorbency moles/liter x 10
0 21.0 0.680 22.53
70 22.0' 0.660 21.87
103 23.0 0.640 21.20
157 24.1 0.620 20.o4
200 23.5 0.630 20.87
For Transmission and absorbency measurements a one m\lli-
liter sample of the dye solution was removed and diluted
to 100 milliliters with dimethylformamide. (wavelength =
v 4 5 m v)
Based on % activity of commercial dye given in Table i
25
-------
TABLE 32
RATE OF PH DTODEGRADATTON OF
DISPERSE RED 15 IN WATER AT 50 °C
Time ,
Hours
0
60
105
151
200
%Transmission
23.8
26.0
25.8
27.5
26.2
Absorbency
0.624
0.590
0.555
0.560
U.500
Concentrat
moles/lite
24.71
23.36
23.56
22.18
22.97
For Transmission and absotbeiicy measurements a one milli
liter sample of the dye solution was removed and diluted
to 70 milliliters with dimethylf ormamide. (wavelength =
537 my)
Based on % activity of co-jjnercial dye given in Table 1
TABLE 33
RATE OF PHOTODEGRADATION OF
DISPERSE RED 60 IN WATER AT 50 °C
Time,
f
Hours
0
60
105
151
200
%Transmissiona
40.0
42.3
43.6
45.3
44.8
Absorbency
0.400
0.370
0.360
0.341
0.346
Concentrat
moles/lite
12.16
• 41.25
10.94
10.36
10.52
aFor Transmission and absorlsency measurements a 1 milli-
liter sample of the dye solution was removed and diluted
to 70 milliliters with dimethylformamide. (wavelength =
555 mv)
Based on % activity of comriercial dye qiven in Table 1
-------
r.'/\DLh; 34
RATE OF PIOTODEGUADATION OF
Time ,
Hours
0
60
105
153
200
%Tram;mj
33.
36.
35.
37.
36.
;s:iona
0
"j
0
1,
0
Absorbancv'"
0.4?0
0 . 4 t, 0
u . i 5'0
> . * 7 :
0.441
Concent
moles/1
10
11
11
10
11
rat
ite
.71
.?2
.47
.51
.24
clFor Transmission and abscrbency meiasurtments a 1 milli-
liter cu'nplc of the d\ o ^olution \-f.~: rfncveci and diluted
to 20 miJliliterd wiu a^.oth^ J Lorr.a.aiue. (wavelength =
537 m y)
Based on % activity of cor-'Crcici! dve aiven in Table 1
'j./\BLE 3b
RATii OF PJiOVOL'LC.KAuAV;Oi\ Of
DISPENSE L-U.E / K; \«.:^'< AT ^0 ~C
Time,
Hours
0
GO
105
151
200
%Trannmi
24.
?6 .
28.
30.
31.
s-.i0na
2
&
0
1
b
.v=..
0
0
0
0
(t
crbency'"
.f)lG
r O f \
, '^} _j \J
,5?0
. S k u
Concent
no lor,/ 1
10
15
14
33
33
r?t
lie
.06
,12
. 3 4
.55
.03
aFor Transiiiission and rib&orbi;:icy i.i^-aT.rt .T.onts a i i.iillo-
litor sample o? tho dye aoI1'"ion v .-, j-'"noved and dilxitad
to 50 miliiiiteri. v.-j r.h d: .i.tr.y ''-'jir. 1:51. ^ :. (wave] unq'. ii -
650 my)
Based on % actrtvJty of cor.nercial dye g:ven in Table 1
27
-------
TABLE 36
RATE OF PHOTODEGRADATION OF
SULFUR BLACK 1 IN WATER AT 50°C
Time, . Concentration
Hours ITransmission Absorbencyd grams/liter
0 57.8 0.240 1.92
70 63.0 0.200 1.60
159 65.0 0.190 1.52
200 67.3 0.175 1.40
For Transmission and absorbency measurements a 2 milli-
liter sample of th^ dye solution was diluted to twenty
milliliters with a solution containing 5% Na?S_0. and
3% NaOH. (wavelength = 400 mp)
^Based on the analyses of i-he commercial dye paste for
total solids.
TABLE 37
RATE OF PHOTODEGRADATION OF
SULFL'n RED !> IN WATER AT 50°C
Time, Concentration
Hours %Transraission Absorbency grams/liter
0 32.?, 0.490 1.98
70 34.a 0.460 1.86
159 39.0 0.410 1.65
200 40.0 0.400 1.61
aFor Transmission and absorbency measurements a 2 milli-
liter sample of the dye solution was diluted to twenty
milliliters with a solution containing 5% Na.S^O. and
3% NaOH. (wavelength = 4CO mu5
Based on the analyses of the commercial dye paste for
total solids.
20
-------
TABLE 38
RATE OF PIIOTODEGHADATION OF
SULFUR BLUE 7 IN WATER AT 50°C
Time, a . Concentration
Hours %Transmission Absorbency grams/liter
0 22.0 0.660 2.16
70 24.8 0.510 2.00
159 23.0 O.G40 2.10
200 25.0 0.600 1.96
transmission and absorbenoy measurements a 2 rcilli-
liter sample of the dye solution was diluted to twenty
uilliliters for a solution containing 5% Na?S90. and
31 NciOH. (wavelength = 400 nip)
°Based on the analyses of the commercial dya paste for
total solids.
TABLE 39
RATE OF PHOTODEGRADATION 0?
SULFUR BLUE lit IN WATER AT 50°C
Time, Concentration
Hours ^.Transmission Absorbency grams/litei
0 52.2 0.280 1.27
70 54.8 - - 0.260 1.18
159 54.8 0.260 1.18
200 60.5 0.220 1.08
For Transmission and absorbency measurements a 2 milli-
liter sample of the £ye solution was diluted to twenty
milliliters with a solution containing 5% Na-S^G, and
3% NaOH. (wavelength = 400 my)
Based on the analyses of the commercial dye paste for
total solids.
29
-------
The following dyes showed greater than 50% loss in optical
density after 200 hours Fade-Ometer radiation and were
analyzed for identification of degradation products:
Basic Green 1 C.I. 42040 Direct Red 83 C.I. 29225
Basic Red 2 C.I. 50240 Direct Blue 76 C.I. 24410
Basic Violet 3 C.I. 42555 Vat Blue 6 C.I. 69C25
Basic Green 4 C.I. 42000 Acid Red 37 C.I. 17045
Basic Blue 9 C.I. 50215 »cid Orange 10 C.I. 16230
Disperse Blue 3 C.I. 62505 Acid Violet 3 C.I. 16580
Ac the completion ol the exposure period, the faded samples'
were removed from the cells, placed in polyethylene bottles
and stored at -20oe in a freezer to prevent further re-
actions which may have been initiated in the Fade-Ometer.
The samples were removed several times from thjs freezer,
allowed to thaw anc, immediately replaced in the freezer.
This was done to separate decomposition products from the
aqueous solution wjthout promoting further decomposition.
After this approximately 250 ml of the faded solution was
filtered in a gravity funnel. The collected precipitate
was allowed to air dry and then rinsed from the filter
paper with spectro c.rade acetone.
For those dyes from which no precipitate was collected,
the water solution of the dye was placed en a watch
glass and allowed to evaporate at room temperature. The
samples were covered to prevent atmospheric contami-
nation.
Solid residues isolated by both methods were analyzed
by mass spectrometry using the solids probe or gas-
chromatograph inlet system, and by gas chromatography
when volatile residues were obtained.
The conditions generally used fee the gas chromatograph
were:
Helium Flow 30 ml/rain
Injection Port. Tr-mp. 325°C
Column Temp. 100-275°C (Isothermal at 275°)
Manifold Temp. 320°C
Column: 1/8", 6 foot stainless steel, SE 30
silicone oil
30
-------
Chemical Preparations
The leuco carbinol forms of Basic Green .1, Basic Green 4,
and Basic Violet 3 were prepared to provide knowns for
degradation product identification.
To approximately 3 grains of commercial dye in 100 ml of
distilled water, 5 ml of concentrated ammcnium hydroxide
was added. The resulting precipitate was filtered,
washed and dried. After drying, the residue was dissolved
in benzene to remove inorganic impurities, filtered and
the benzene evaporated. The isolated crystals were used
as knowns.
Other reference compounds were purchased from commercial
suppliers.
31
-------
SECTION IV
DISCUSSION
Commercial dyes may be considered to oe either relatively
inert or unstable. To most the term inert would de-
scribe stable behavior upon exposure to near-ultraviolet
and visible light. However, sirce most dyes are applied
to fibers from aqueous solution, the part that water
plays in the degradation process cannot be neglected.
All results reported in this study were obtained from
water solutions or suspensions. The data, therefore,
reflect the combined effects of light and water. The
basic dyes showed the most degradation and will be the
first class discussed.
Basic Dyes
Basic dyes are cationic organic nolecules capable of
dyeing wool, polyester, acrylic and other fibers that
have been prepared to contain anionic sites whicn
attract and interact with cationic molecules.4 These
dyes were first discovered in 1859 by Verguin^ in
France and some of the original dyes are still in use.
These dyes are applied from an aqueous solution con-
taining enough acetic acid to adjust the pH to 4-6.
The weight of the dyebath will generally be 20 times
the weight of fabric being dyed. The solution is
carefully heated to L90°F and held there for one to
two hours. The bath is then cooled, discharged and
fresh water added to rinse surface dye from the .fibers.
Basic dyes are the brightest class of soluble dyes
used by the textile industry. Their tinctorial value
is very high causing less than 1 ppm of the dye to
produce an obvious water coloration. This factor would
cause these dyes to have the greatest potential threat
of coloration to a natural water supply. Fortunately
these dyes are adsorbed by many minerals and organic
matter so natural processes can generally remove them
from a stream without the help of sunlight if given
sufficient time.
The structures of the basic dyes used in this study
are shown in Figures 2 and 3. These structures
represent the triphenylmethane, phenazine and thiazine
types.
The fading rate curves for the basic dyes are shown in
Figures 4 to 8. The basic dyes all showed appreciable
degradation during their 200-hour exposure to visible
and ultraviolet light. To compare the effect of
sunlight and artificial light Basic Green 4 was exposed
Preceding page blank 33
-------
N(C2H5)2
.P
S0
4
i!
N(C2Hb)2
Basic Croon I C.I. 42040
NCCHJ,
"
r
C+ C!
Pasic
r?"
N (Ch-^)o
^, * ^"
3 C.T. 42555
N
BasJc I
Piguro 2 Structursj; oj '
2 C.] . 50240
Doh. Studied
34
-------
Basic Blue 9 C. I. 52015
HN(CH3)2
HNCCH3)2
Basic Green 4 C.I. 42000
Figure 3 Structuces of Basic Dyes Studied
35
-------
1
50
100 .150
Time, hours
- L
200
Figure 4 Rate oE Phofcodegradation of Basic Violet 3
in Water at 50°C.
36
-------
c
GJ
o
c
o
u
3 t-
o
50
100 150
Time, hours
200
Figure 5 Rate of Photodegradation of Basic Blue 9
in Water at 50UC.
37
-------
M
(0
4-)
•H
H
\
W
-------
M
OJ
4J
•H
10
o
iH
O
c
0
•r-t
4J
IS
Vl
4J
C
a)
o
c
o
o
o
—o
50
100
150
200
Tine, hours
Figure 7 Rate of Photodegrc Nation of Basic Green 4
in Water at 50°C.
-------
12
0)
4J
•M
,—I
\
in
O 6
e
c
O
•i-t
4J
(0
V4
4J
C
QJ
O
C
O
u
O
O
--..O
50
100 150
Time, hours
200
Figure 8
Rate of Photodegradation of Basic 3ed 2
in Water at 50°C.
40
-------
to sunlight on the roof of 1:he building. The degradation
rate curve for natural light is shown in Figure 9 with
the data from Figure 7 plotted on this figure for com-
parison. The fading rate in artificial light is much
faster as expected—the data indicate that the fading
rate is at least 10 times as fast. This check was
repeated vvith one of the direct dyes and is reported
later.
The degradation products that could be identified by
mass spectrcmetry and gas chromatography from Basic
Green 4 are shown in Figure 10. The products isolated
show some correlation with data obtained previously by
other researchers. ^ The reisults of this study and
other studies7 show that these dyes may decompose by
two principal paths. A proposed mechanism for the
degradation of the triphenylmethane dyes is shown in
Figure 11.
The carbinol form of the dye is converted to the
excited state (possibly trjplet) by absorption of
ultraviolet light. The excited molecule is converted
into products by: (1) fragmentation into radicals and
rapid reaction of the radic.il moieties with oxygen and
water to give the products Isolated, or (2) concerted
reaction of the excited carbinol form with oxygen and
water to give degradation products directly. Oxygen
seems to be necessary for the formation of the products
obtained, which is in agreement with the results of
previous studies.6
Evidence for the degradation of the carbinol form and
not the cation is seen in the work reported by Bitzer
and Brielmaier.7 They found the rate of decomposition
to be inversely proportional to the hydrogen ion
concentration in a pH range between 1 and 5.
By adding phloroacetophenone to an alcohol solution of
CI Basic Green 4, Bitzer7 found that the time required
for bleaching the solution was increased from two days
to several weeks. He attributed this to the fact that
the adsorption region of the ketone and the dye were
similar, so both compounds would be absorbing the same
degradative radiation.8
Most covalent bonds have dissociation energies which
are well within the energy range of natural and
artificial daylight. The enclosed carbon arc light
source produces a spectral wavelength range of 279 rim
to 12,000 nm^ which corresponds to energies, of 95.3
to 40.9 kcal/mole, respectively. Since most dyes have
adsorption maxima within this region, ±t ;.s under-
standable that a number of them are vulnerable tc
photochemical degradation.
41
-------
O
rH
X
r-l
O
C
O
•H
c
arc
500
1000
1500
Time, hours
Figure 9 Rate of Fhotodegradation of Basic Green 4 in Water Exposed to
Sunlight and Carbon Arc Light
-------
N(CH3)2
HN CH,
OH
N(CH3)2
Leuco base p-MPthylaminobenzopher.one
0
OH
NCCH,)-
o-DimethylaminobenzophenDne ' p-Dimethylaminophenol
Figv\re 10 Degradation Products Isolated from Basic Green 4
43
-------
NCCHO;
f Vc+ cr .=
>
NCCHJ
3'2
NCCHO
3'*
•COM
N(CH3)2
I H20 or 02
HO
f~\
•COM
N(CH3)2
UV
V
EXCITED
STATE
H?0 or 02
Figure 11 Mechanism for Degradation of Basic Green 4
-------
Basic Green 4 has two adsorption bands in the visible
region. The band at 422 nm represents an energy of
67.8 kcai/mole, while the adsorption at 619 nm corres-
ponds to an energy va3.ue of 46.2 kcal/mole. A third
band exists in the nefr ultraviolet at 318 nra and is
equivalent to 89.9 kc<:i I/mole. The leuco carbinol form
in Figure 10 which hd£i been shown to be the fugitive
species dees not absorb visible light and therefore
requires ultraviolet ] ight for degradation. Visible
light can degrade dyes; — McLarenlO founa in a study of
over one hundred dyes that the most fugitive examples
were readily degraded by visible and ultraviolet
light, with wavelengths longer than 600 nm being
responsible for degradation in somf instances.
The possibility of nor -light-catalyzed hydrolysis was
eliminated when an aqueous solution of CI Basic Green 4
was shown to undergo ro significant change over an
eight-day period at 65Cv,"^ in the absence of light.
7he evidence for the triphenylmethane dyes shows that
their rate of degradation is clearly pH dependent and
inversely proportional to the hydronium ion concen-
tration. ' Since the dyes would comnonly be found in
natural water supplies or receiving streams at or
near a neutral pH, th" degradations were conducted at
neutral pH.
One point worth noting is the stability of seme of
the degradation products to ultraviolet light as
evidenced by their isolation. The toxic properties
of these products should be determined since they would
remain in the environment for much longer periods than
the dye nolecule.
Acid Dyes
Acid dyes have an ancient origin, dating back many
centuries to the first use of natural dyes on wool
fibers. The first recorded preparation of a synthetic
acid dye was in 1771.12 woulfe synthesized picric
acid from indigo with nitric acid. Because of their
bright colors the dyes still have widespread use today.
Acid dyes are used for nylon, wool and acrylic fibers.
The nylon or wool fiber is dyed from a bath having a
weight of 20 to 30 times that of the fabric. The fiber
is placed into the war.n dyebath and the dye is then
added. The temperatura is raised slowly to 200°F and
if necessary acetic or sulfuric acid is added to
exhaust the dye onto trie fiber. If the dye tends to
go onto the fiber tcto rapTdly it may be necessary to
add a retarding agent such as sodium sulfate. Several
retarding or leveling agents are used with acid dyes.
45
-------
These dyes are comparatively small molecules with one
or more sulfonic acid groups attached to the organic
substrate. They have good water solubility and mey or
may not be removed from a waste stream by a conventional
biological waste treatment plant. Because of this und
their high tinctorial color value it is important to
be able to estimate their light stability in a natural
water supply.
The acid dyes as a class have poor light fastness on
textile fibers compared to vat or disperse dyes. This
suggests that their photodegradation in water would be
quite significant. Structures of acid dyes used ir;
this study are shown in Figures 12 and 13. The curves
for their fading rate's are shown in Figures 14 to 20.
Of the seven dyes studied, three showed drastic photo-
induced degradation.
One generalization indicated here is that the acici azo
dyes are more fugitive to light than the acid anthra-
guinone dyes (Violet 43 and Blue 40). An exception
is the Acid Black 52 which is really a premetalized
azo acid dye and is not comparable because of the known
stability metal coordination adds to any dyestuff.14
A detailed interpretation of the data is difficult.
Acid Red 1, Figure 14, was stable and Acid Violet 3/
Figure 15, and Acid Red 37, Figure 17, were completely
degraded. This may be explained by the susceptibility
of the primary amine group to oxidative attack. Why
Acid Orange 10, Figure 16, was also degraded cannot
be explained on this basis because it has no vulnerable
amine group. The primary amine appears to be less
labile when it is attached r.o the anthraquinor.e •
structure as is illustrated by the curve for Acid
Blue 40 shown in Figure 20.
Thp basic reason for the degradation of the acid dyes
seems to be their susceptibility to electrophil.i7
attack. This has bear demonstrated with the basjic
dyes and shown to be applicable to the reactions of
oxidizing reagents with other dyes.15 The more
electron attracting groups that are present on the
dye molecule generally the more stable it is to
light.16
Acid dyes should r>e one of the best classes for which
to interpret a fading mechanism because ttosy*sn«e
water soluble and give homogenous solutions. This is
not true for the disperse, vat and sulfur dye classes
which can undergo physical changes which affect the
-------
OH OH
NaO-iS'
Acid"Violet 3 C.I. 16580
Acid Black !»2 C.I. 15711
OH NHCOCH
Aci4,S
-------
S03Na
HO* C.I. 60730
NHCOCH:
Acid Blue 40 C.I. 62125
Figure 13 Structures of Acid Dyes Studied
48
-------
12
i
c
O
C
O
O
O
0
10
O
O
rH
X
0)
4J
•H
O
50
100
Time, hours
150
200
Figure 14 Rate of Photodegradation of Acid Red 1
in water at 50°C.
-------
o
r->
X
W
Q)
rH
O
c
o
-r-1
•P
•M
C
0)
U
C
O
o
50
100
Time, hours
O
150
200
Figure 15 Rate of Photodegradation of Acid Violet 3
in water at 50°C.
50
-------
12 .
a;
4J
W
OJ
r-\
§
c
o
H
-P
c
0)
o
o
u
10
6 r
4 .
2 '
50
100
Time, hours
150
200
Figure 1C Rate of Photodegradation of Acid Orange 10
in Water at 50°C.
51
-------
2 5
VJ
(U
-p
•H
W
O
rH
o
e
c
•H
4J
C
(U
u
c
0
o
50 100 150 200
Time, hours
Figure 17 Rate of ^hotodegradation of Acid Red 37
in Water at 50°C.
52
-------
X
w
0)
•H
O
O
•H
4J
(0
M
-P
C
-------
12
10
o
iH
X
0)
-M
o
c
o
•H
JJ
10
n
4J
c
o
u
o
o
50
100
Time, hours
150
200
Figure 19
Ratt> of Photodegradation of Acid Violet 43
in Water at 50°c.
-------
M
r-t
o
G
O
•H
4J
0)
u
c
o
u
50
100
Time, hours
150
200
Figure 20 Rate of Photodegradation of Acid Blue 40
in Water at 5U°c.
55
-------
absorption of light w.Lthout undergoing any chemical
degradation. These dyes are discussed later.
Attempts to isolate degradation products from the acid
dyes were unsuccessful. Degradation products such as
phenol or aniline were either volatilized from the
reaction cell during the study or were degraded them-
selves since no low molecular weight products were
detected by gas chromatographic or mass spectral analyses
of the final concentrated solutions. Evidently the ionic
degradation products were not volatile enough for
analysis by GC or MS, and preparation of their diazo-
methane derivatives was unsuccessful. Additional work
in this area might lead to characterization of some of
the degradation products.
Direct Dyes
The direct dyes are one of the major classes of dyes
used on cellulose fibers. The dyes are applied from a
water bath about 30 times the weight of the fabric
being dyed. After the fabric and dyes are placed in
the bath, it is heated to near boiling and a salt is
added to exhaust the dye onto the fiber. The amount
of s<.<]t required varies from dye to dye but is approxi-
mately 10 percent of the weight of fabric being dyed.
The dyes were chosen on the basis of use by the textile
industry—their structares are shown in Figures 21 and
22. They are more resistant to light degradation than
the basic or acid dyes previously discussed as can be
seen by the fading rate curve? shown in Figures 23 to
30.
Only two of the direct dyes, Direct Blue 76 «nd Direct
Red 83, lost greater than 50 percent of their optical
density after 200 hours exposure to artificial light.
This is rot unusual -as the direct dyes have better
light fastness propert-.es on textile fibers than the
acii or basic colors. After exposure, no volatile
degradation products could be dtcected in the con-
centrated d} e solutions; by gas chromatographic or mass
spectral analyses. Attempts to prepare methyl ester
.-•.derivatives of the expected ionic degradation products
by treatment with diazomex.hane yielded nothing
detectable by mass spectral or gas chromatographic
analyses. As was the case with the acid dyes, the low
molecular weight products were destroyed or volatilized
during exposure and the high molecular weight products
had too low a vapor pressure to allow separation and
identification.
56
-------
Na03S
OH H C.I. 24410
HO N=M
'N-iOsS^As^SOjNa-
Direct Green 6 C.I. 30295
Direct Brown 95 C.I. 30145
Figure 21 Structures of Direct Dyes Studied
-------
S03IVa
.. Cu
MaO,S
\ M-
. v 11
Direct Red 83 C.I. 29225
OH
NaO,S
Direct B .ack 80 C.I. 31600
N
C
c i
V-^M
C^
C
I!
N
CO
J2
OH
WjS03Na
NH2
Direct Blue 36 C.I. 74180
S03Na
NH-
Direct RUG 80 C.I. 35780
CO
Figure? 22 Structures of Direct Dyes Studied
58
-------
r H
o
0 O
-o-
-o o
0
u
100 150
Time, hours
200
Figure-- 23
59
-------
0)
-P
•rH
r-H
O
e
c
o
•H
4J
(C
14
4J
C
(U
o
c
o
U
50
100
Time, hours
150
200
Figure 24 Rate of Photodegradation of Direct Green 6
in Water at 50"C.
60
-------
10
X
M
•H
r-l
\
VI
Q)
t-I
O
e
c
o
•H
4J
C
-------
o
H
X
-P
•H
r4
W
0)
rH
O
6
c.
O
•H
4J
c
-------
O
i-4
X
•P 4
•H
(0
0)
iH
O
c
O
•H
4J
4J
C
(1)
8
0
u
50
103
150
200
Time, hours
Figure 27 Rate of Photodegradation of Direct Blue 98
in Water at 50 C.
63
-------
o
i-H
X
•P
•H
M
Q)
i—t
O
e
c
o
c
(1)
o
vJ
o
u
50
100
Time, hours
150
200
Figure 28
Rate of Photodegradation of Direct Red 83 i
Water at 50°G.
•64
-------
12
o
r-l
X
10
-------
O
O
-P
W
-------
Some of the direct dyer would have sufficient affinity
for the sludge in a biological waste treatm3nt plant to
be adsorbed and removed from the wastewater. Others
would require chemical or physical treatment for their
removal. In any case the data show that most direct
dyes would be stable and resist photochemical degradation
in a treatment plant or receiving water.
The comparison between degradation by natural and
artificial light can be seen in Figure 31. The data
show that the rate of degradation is at least 10 times
as slow in natural daylight as in artificial light.
This indicates that the direct dyes are very stable in
natural waters.
67
-------
CO
o
iH
X
o
£
O
•H
•P
4J
C
O
U
C
O
o
1 -
sunlight
500
1000
Time, hours
15 CO
Figure 31
Rate of Photodegradation of Direct Blue 76 in Water Exposed to
Sunlight and Carbon Arc light
-------
Vat Dyes
Vat dyes are applied to cellulose fibers by batch and
continuous processes. The vat dye is a nonionic water
insoluble pigment that must be reduced to a soluble
anionic leuco form with sodium hydrosulfite. The bath
from which the dye is applied varies in volume, is alka-
line and contains dispersing agents, sodium sulfite and
excess sodium hydrosulfite. After the dye is adsorbed
on the fiber it is oxidized to the insoluble form with
a common oxidizing agent. If the dyes are applied by
continuous processes the chemicals which are used are
the same but require much less water.
The structures of the vat dyes used for this study are
shown in Figure 32. Vat dyes are applied almost exclus-
ively on cellulose fibers. They are noted for their
resistance to light degradation,1^ and were found to
be fairly staole in this study as the curves in
Figures 33 to 36 show. The dyes did show up to 40
percent color loss after 200 hoars exposure to
artificial light. This was not completely due to
decomposition of the dye, but partly to aggregation
of the dispersion.18 This is supported by the fact
that the absorbency of all four dyes decreased to about
the same extent in 200 hours—more difference would be
expected if photochemical degradation was the only
factor responsible. Vat dyes are sold as a pigment
dispersion. The pigment particl.es are near one
micron or less in size.19 When the dispersion is
warmed or heated over a period of time the small
particles can coalesce into larger particles, causing
the dispersion to have a lower optical censity.18
This may hava occurred to some degree during exposure
to the carbon arc and accounted for some of the
tinctorial loss of the dye dispersions. Aliqucts of
the dispersion were taken and dissolved in dimethyl
formamide for measurement. Complete solution of the
dyes may not have occurred with dimethyl foimamide and would
become more difficult as the pigment particles grew
larger during exposure, resulting in lower absorbency.
This point is speculative, but pigment aggregation is
a well established phenomenon with vat dyes.18
The residue remaining after degradation of Vat Blue 6,
which is noted in the industry for its instability
when compared to other vat dyes, was analyzed for
chlorine to check for cnemical changes upon ultraviolet
exposure. The elemental analysis showed a 25 percent
loss of chlorine which would account for at least 25
percent decomposition of the dye. The low volatility-
and solubility of the residues prevented successful
mass spectral and chromatographic analyses of the
degradation products.
69
-------
0
0
Vat Brown 3 C.I. 69015
CH30 OCH3
Vat Green 1 C.I. 59825
Vat Blue 6 C.I. 69825
Vat Violet 1 C.I. 600.10
Figure 32 Structures of Vat Dyes Studied
70
Ch
-------
0)
4-1
•H
•H
\
Ul
QJ
r-l
o
c
o
•rH
4J
(0
M
4J
C
O
c
o
o
10
50
:ioo
Tine, hours
150
200
Figure 33
Rate of Photodegradation of Vac Brown 3
in Water at
71
-------
Vl
OJ
4J
VI
o
l-»
o
c
o
.(J
c
(U
u
c
o
0
50
100
Time, hours
150
200
Figure 34
Rate of Photodegradation of Vat Violet 1
in Water at 50°C.
72
-------
o
4J
W
0)
r-4
O
c
o
•H
4.'
fi>
M
•P
4)
O
c
o
o
50
100
150
200
Time, hours
Figure 35 Rate of Photodegradation of Vat Blue 6
in Water at 50°C.
73
-------
50
100
Time, hours
150
200
Figure 36 Rate of Photodegradation of Vat Green 1
in Water at 50°C.
74
-------
Because of their inherent light stability, this study
of the vat dyes can give us an idea of the effect of
physical changes on the fading of all pigmented i.ypes
of dyes;. The color changes that occurred with the vat
dyes are mostly caused by changes in physical proper-
ties of the pigment dispersions. Obviously the dis-
persions arc stable enough to color a waste stream for
a long^period of time. If biodegradable dispersing
agents^1" are used in the commercially prepared dye,
then the dispersion nay be more easily destroyed in
a biological waste tieatment plant and some of the dye
may be removed by adsorption on the sludge. Since
the pigment is fairly inert the best method of removal
is possibly by chemical coagulation.21
Disperse Dyes
The disperse dyes were originally prepared for dyeing
acetate fibers that were introduced to the textile
markets alter World War 1.22 These dyes are neutral
organic r.olecules and have very low solubilities in
water. Because of this they are ground with a dis-
persing agent in a similar manner to that used for
vat dyes, and dispersed in water for use by the textile
industry. These dyes are applied to polyester, nylon,
acrylic aad acetate fibers by batch operations and on
continuous ranges. The batch operation uses a bath
with a weight of approximately 30 times the fabric
weight. The dye bath is heated to near boiling for
one to three hours, then drained and the fabric
rinsed. For some fibers, such as polyester, either
carriers or pressure vessel:: are required to speed up
the dyeing process. The carriers are organic compounds
which swell the fiber, allowing the dye to penetrate.
In the continuous process the dye solution is paddad
onto the fabric and dried and then heated at 20QOC for
one or two minutes. The dye penetrates the synthetic
fiber at these high temperatures and excess dye is
removed in a subsequent washing operation.
Because of the wide use of disperse dyes today,
several of then were chosen for study—their structures
are shown in Figures 37 and 33.
Disperse dyes, being in pignent form, are more
resistant to light degradation than if they were dis-
solved in the water. This can be seen by the fading
rate curves shown in Figures; 39 to 46. The only dye
that gave greater than 50% optical density decrease
was Disperse Blue 3. The residue isolated from this
dye solution after exposure could not be separated
into identifiable fractions and no degradation products
could be detected by mass spectral analyses.
-------
OH 9 OH
NC2 5 NH(J>CH2CH2OH
Disperse Blue 27 C.I. 60767
Disperse Blue 1 C.I. 64500
Disperse Orange 3 C.I. 11005
OH 9 NHC2H4OH
KTHC2H4OH
Disperse Blue 7 C.I. 62500
Figure 37 Structures of Disperse Dyes Studied
76
-------
Disperse Rud 60
CH
Disperse Red :,.? C.I. 11210
Disperse Red 15 C.I. 60710
Disperse Blue 3 C.I. 61505
Figure 38 Structures of Dispeise Dyes Studied
77
-------
o
iH
X
o
•rl
in
0)
r-i
o
c
o
•H
4J
10
H
4->
C
0)
u
c
0
u
50
100
Time, hours
150
200
Figure 39 Rate of Photodegradation of Disperse Blue 3
in Water at 50°C.
78
-------
15
M
0)
10
W
CD
iH
o
c
o
•H
4J
C
0)
o
c
o
u
o
50
J.OO
Tim
-------
20
V-l
(U
•P
•H
in
Q)
r-l
O
o
-H
•p
c
QJ
O
C
o
o
15
10
50 100 150 200
Time, hours
Figure 41 Rate of Photodegradation of Disperse Blue 1
in water at 50°C.
80
-------
12
o
o 10
0)
+J
•H
O
E
O
•H
-P
«J
J-l
4J
c
-------
12
X
M
-M
•H
Ifl
0)
,H
O
c
o
C
QJ
U
C
O
o
10
50
100
150
200
Time, hours
Figure 43 Rate of Photodegradation of Disperse Rea 6
in Water at 50CC.
82
-------
30
25
20
-o
15
10
50
100
Tiire, hours
150
200-
Figure 44 Rate of Photodegraclat.icn of Disperse Oranae 3
in water at 50°C.
83
-------
15
10
50 100
Time, hours
150
200
Figure 45 Rate of Photodegradation of Disperse Blue 7
in Water at 50°C.
84
-------
20
o
t-t
X
(0
-------
Since the disperse dyes are more soluble in water than
the vat dyes^j it was expected that they would degrade
faster than the vat dyes when they were exposed to
artificial light. This was not the case, as the data
show. Disperse dyes are very resistant to degradation
by the quantity of light that reaches natural streams
and reservoirs.
Sulfur Dyes
Most sulfur dyes have complex structures that have not
been completely characterized.24 This is understandable
when we consider that some of the first dyes of this
class were synthesized from sawdust, bran or manure
and sulfur. The newer dyes in t-his class utilize nitro
aromatic systems as starting material. Their structures
are less complex than the original dyes but still complex
enough to prevent complete characterization.
These dyes are used exclusively on cellulose fibers
and are applied from a bath containing sodium poiy-
sulfide and sodium hydroxide. The dye is solubl-. in
this solution and can penetrate1 the fiber. Th-» bath
to fiber weight ratio is 30 to one and dyeing time is
one to three hours. The dyes are also applied on a
continuous range. The dye solution is padd.ed onto the
fabric and steamed. After the batch or^continuous
dyeing operation the dye is oxidized with air or
sodium dichromate to the insoluble form which remains
in the fiber.
Most of the sulfur dyes are mixtures containing several
aromatic sulfur and nitrogen systems linked by a series
of disulfice groups. These dye.s thus '~.ve large mole-
cular weights and very low water solubilities which
no doubt account for their stability to light
degradation. Sulfur dyes have good ;ijht and wash
fastness on textile fibers so tfeir stability in this
study is expected. Because of the low extent of
degradation of the sulfur dyet and their unknown
structures no attempt was made to identify degradation
products.
The degradation curves in Figures 47 to 50 show that
these dyes cou3d exist for a lorg period of time in a
natural stream.
-------
M
0)
4J
-H
M
tn
c
o
•H
•P
ro
U
4J
C
QJ
U
C
O
O
o
50
100
Time, hours
150
200
Figure 47 Rate of Photode'dradation of Sulfur Red 5
in Water at 50fC.
87
-------
4)
4J
• H
rH
V.
cr>
C
o
•H
iJ
C
CJ
o
C
o
o
o
50
]00
Time, hours
150
200
Figure 48 Rate of Photodogracation of Sulfur Blue 7
in WaLer at 50 °C.
88
-------
Vl
0)
••H
r-l
V.
in
M
C
O
•H
4-1
(0
u
4J
c
-------
0)
4J
U)
E
o
o
c:
o
•H
O
c
o
o
50
100
Time, hours
150
200
Figure 50 Rate of Photodcgradation of Sulfur Black 1
in Water at 50°C.
90
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AUCTION
"ho investigator expresses .ii.; appreciation to Scott M.
Spjar^D jnd .Marsha i^ r\'h...te, Jr., who assisted in thi^
work. Thanhs are also given to Dr. Arthur W. G?.mH«»!
"of the Southonst Water Labo.atory, 7ithens, Georgia,
E?A, lor his assistance with t.he analytical work and
lelpful discussions over the course of the study.
^'ir.al.ly, appreciation is cxpresseu for the cooperation
^nr. H.niancial rsv-pport of the- Office of Research and
,'!or.it c; .xiii_. of t!u: Lnv..iO!r...eiiCc-j. i'i'>tection Agency.
91
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SECTION VI
REFERENCES
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3. Michelsen, D. L. Textile Chemist and Colorist, 1,
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4. Trotman. F. R. Dyeing and Chemical Technology of
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Preceding page blank 93
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15. Kerr, N., M. A. Morris and S.H. Zeronian. "The Effect
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94 H)S OOVtRNk't'tT fRINTlNS OFf ICI
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