United States Environmental Protection Agency Water Engineering Research Laboratory Cincinnati OH 45268 Research and Development EPA/600/S2-86/063 Sept. 1986 &ERA Project Summary Evaluation of Alternatives to Toxic Organic Paint Strippers Wilfred J. Hahn and P. O. Werschulz A study was undertaken to survey commercially available paint stripping formulations and identify those whose use would result in lower total toxic or- ganics (TTO) loading in stripping opera- tion wastewaters without decreasing the effectiveness or efficiency of the stripping operation. Data were gath- ered by means of a literature review, a survey of potential suppliers, and bench scale tests of alternative strip- ping formulations identified as having potential for reducing the level of re- leased TTO. The chemical composition of an epoxy stripper (MS-111)* used ex- tensively in military installations was compared with commercially available alternatives having the potential to re- duce TTO in stripping wastewaters. The paint stripping operation at the Sacramento Army Depot (SAAD) was studied to establish a basis for design- ing bench scale tests that would com- pare the performance characteristics. The bench scale tests of SAAD- supplied samples and the selected al- ternative formulations identified three stripping formulations that met the performance standards experienced by MS-111 and that were expected to sig- nificantly reduce TTO levels in stripping operation wastewaters. This Project Summary was devel- oped by EPA's Water Engineering Re- search Laboratory, Cincinnati, OH, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). •Mention of trade names or commercial products does not constitute endorsement or recommenda- tion ior use. Introduction Background This study was undertaken to identify commercially available paint strippers that would reduce TTO (as defined in 40 CFR Part 413) levels in stripping opera- tion wastewaters. A review of industry literature identified alternatives that had potential for reducing TTO. Bench scale tests were performed to identify each alternative's performance characteris- tics and potential for reducing TTO in stripping operation wastewaters. Total Toxic Organics in Stripping Operations Wastewaters Contributors to TTO enter stripping operation wastewaters principally through "dragout," a term applied to material that adheres to metal parts as they are removed from the stripping tank. This material is deposited in the rinse water or removed in the hot water/ steam lancing operation and is dis- charged to the floor drain system. Two substances present in most stripping formulations contribute to TTO levels: methylene chloride and phenol. SAAD Paint Stripping Operation SAAD refurbishes communication and other electronic equipment and the enclosures used to house the equip- ment. The majority of the equipment encountered at SAAD is fabricated from aluminum, and exposure to hot caustic liquid would cause severe corrosion. Accordingly, cold, acidic, organic, solvent-based stripping formulations are used. The primary formulation used ------- at SAAD is MS-111, the trade name of an epoxy stripper produced by Miller- Stephenson Chemical Company, Inc. The formulation contains (by volume) 85% methylene chloride, 10% phenol, 5% formic acid, and less than 1% surfac- tant. The substance of greatest concern is methylene chloride, a major contribu- tor to the TTO found in stripping opera- tion wastewaters. Of lesser concern is phenol, which also contributes to TTO but in far smaller amounts. Materials to be stripped are loaded into a large wire mesh basket and low- ered into the cold strip (MS-111) tank for approximately 20 minutes. The exact submergence time in the stripper is left to the operator's judgement, since strip- ping efficiency is often affected by the shape of the pieces and the way they are packed in the basket. After a short drainage period, the basket is dipped briefly into a hot (170°F) caustic solution to neutralize the acidity of the stripping solution. After draning the caustic solu- tion, the basket is submerged in a water rinse tank. Finally, the parts are individ- ually cleaned with a high pressure steam/hot water lance. Methods Identification of Alternative Paint Strippers Materials safety data sheets (MSDS) or other literature describing the chemi- cal composition of stripping products was solicited from 68 potential suppli- ers. A review of this information yielded a listing of formulations judged to have the potential to meet performance re- quirements and reduce TTO levels in stripping operation wastewaters pri- marily because these formulations con- tained less methylene chloride than did the MS-111. The chemical composition of the formulations selected for study are presented in Table 1. Bench Scale Test Program The bench scale test program was de- signed to simulate operation conditions at SAAD and to provide performance data on alternative stripping formula- tions for comparison with MS-111. Test procedures were prepared to obtain data on the efficiency of removal of the paint finishes typically encountered in the SAAD refurbishing operation. Per- sonnel conducting the tests were in- structed to note any abnormal precau- tions required in the handling of strippers, to record weight loss data on the coupons tested, and to provide de- Table 1. Chemical Composition of Candidate Strippers Supplier Nalco Chemical Co. GAP Enthone, Inc. Savogran Co. Savogran Co. Trade Name 84TB-227 140641 S-26 Stripeeze Kutzit Composition* Chemical Cyclic amide N-methyl-2-pyrrolidone Methylene chloride Phenol Formic acid Methylene chloride Toluene Methanol Acetone Paraffin wax Methylene chloride Methanol Toluene Acetone Paraffin wax Percent 100 100 <50 <20 <5 <20 <40 <30 <25 <2 <30 <30 <30 <30 <2 Mitchell-Bradford Chemical Company Miller-Stephenson Chemical Company Oakite Products Oakite Products Quick Strip-8 MS-111 ALM (Ambient) FHS Methylene chloride An acid Methylene chloride Phenol Formic acid Surfactant Monoethyl amine Furfuryl alcohol Tributyl phosphate Sodium hydroxide Butyl cellosolve Formic acid Mixed Aromatics Diisobutyl ketone Dodecylbemene sulfonic acid Hydrofluoric acid Oakite Products Enthone, Inc. ALM (180°) S-26 Diluted 1:1 With Water 60 85 10 5 10 10 <5 35 15 10 10 <5 *From materials safety data sheets or updated information from suppliers. tailed comments on the results of a visual inspection following the stripping and stream lansing operations. Results Test Evaluation Procedures Performance of each candidate for- mulation was evaluated against re- quirements of SAAD for surface prepa- ration before applying new coatings and was compared with the perform- ance of MS-111 on similar paint sam- ples specifically prepared for the bench scale tests. Only stripping formulations demonstrating the capability to remove all types of SAAD-provided paint sam- ples were considered viable alternatives to MS-111. Summary Comparison of Alternative Formulations Comparisons were based primarily on visual examination of the sample coupons in accordance with stripping operation evaluation procedures at SAAD; however, physical data were also analyzed. Before and after the strip- ping operation, each paint sample cou- pon was weighed and its thickness was measured. Although these data did not provide a precise measurement of strip- ping efficiency, they did tend to support ------- the conclusion reached through visual inspection. Stripping efficiency for all of the formulations tested is summarized in Table 2. Overall Evaluation and Ranking of Alternative Strippers Viable alternatives to MS-1 1 1 must be available commercially and must have demonstrated the capability of remov- ing all types of paint encountered in re- furbishing equipment at the SAAD. Can- didate strippers satisfying these criteria must next be judged on their potential for eliminating or reducing the TTO in the stripping operation wastewaters. Based on the concentration of methylene chloride and phenol, as re- ported in the MSDS or provided by the supplier, the three acceptable alterna- tives are ranked as follows: • Enthone S-26 diluted 1 : 1 with water— 60% reduction in TTO expected; • Mitchell-Bradford Quick Strip No. 8— 33% reduction in TTO expected and • Enthone S-26 (undiluted)— 22% re- duction in TTO expected. Table 2. Effectiveness of Commercial Paint Strippers Percent of Top Coat Removed After 20-Minute Submergence Paint Type Paint Stripper MS-111 MC* MC 100 S-26 MC /Hi/ 1 \Lfli. / QS No. 8 MC ALM (Hot)* FHS GAF 140641* Nalco 84TB227 Stripeeze MC Kutzit MC ALM** Enamel on Zinc 100 100 100 100 100 100 100 100 100 100 100 Enamel on Zinc Chro- mate 100 100 100 100 100 100 100 100 100 100 100 Enamel on Zinc Chro- mate 100 100 100 99 100 100 50 20 75 50 25 Epoxy on Primer 100 100 100 3 0 0 0 0 0 0 0 Poly- amide on Epoxy 100 100 100 100 100 50 0 0 0 0 0 Poly- amide on Water Reduce 100 100 100 100 100 95 0 0 0 0 0 Poly- amide on Zinc Chro- mate 100 100 100 100 100 20 0 0 0 0 0 Poly- amide on Epoxy 100 100 100 100 0 0 0 0 0 0 'Contains methylene chloride. +Stripper heated to 82°C (180°F) as recommended by supplier. #Pure chemical compound; no commercial formulations available. Also recommended to be used hot, although not known prior to the test. **Same formulation as "X" tested at room temperature. ------- Wilfred J. Hahn and P. P. Werschulzare with Carltech Associates, Inc. Columbia, MD2W45. Thomas J. Powers is the EPA Project Officer (see below). The complete report, entitled "Evaluation of Alternatives to Toxic Organic Paint Strippers," (Order No. PB86-219 177/AS; Cost: $16.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Water Engineering Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 - - „ L. ,3. C (~ i- X" - ">. •- F-A#v«J Official Business Penalty for Private Use $300 EPA/600/S2-86/063 0000329 PS ------- |