United States Environmental Protection Agency CTEgjHHEEZ I ¦¦ ii ill 11 T ¦ Microwave Irradiation-enabled Household On-site Regeneration of Activated Carbon for Sustainable Point-of-Use Removal of PFAS in Drinking Water !| Qiufeng Lin (Engineering), Zepei Tang (Engineering), Junkui Cui (Science), " Lisitai Yang (Engineering), Yang Deng* (PhD, PE; PI) a Dept. of Earth and Environmental Studies, Montclair State University (Montclair, NJ USA) Dr. Yang Deng I denqy@mail.montc PROSPERITY PLANET mail.montclair.edu I 973-655-6678 BACKGROUND & OBJECTIVES METHODOLOGY (CONT.) RESULTS (CONT.) Millions of the U.S. people across this country rely on household water treatment (HWT), accomplished by deploying point-of-use (POU) or point-of-entiy (POE) devices, for drinking water. However, per- and polyfluoroalkyl substances (PFAS) broadly found in the U.S. drinking water are challenging established HWT technologies. Some of them (e.g., ceramic filters) poorly alleviate PFAS, while others (e.g., RO filtration and granular activated carbon (GAC)), though effective, remained challenged due to inherent technical and economical restrictions. Particularly, they cannot destruct toxic PFAS to provide an ultimate solution to PFAS pollution. Challenges for POU removals of PFAS in drinking water include: 1) trace concentrations; 2) low lifetime health advisory or maximum contaminant levels; 3) persistence; 4) prevalence; and 5) fewer technology options available for the POU scenario. Therefore, the lone-ranee eoal is to develop sustainable POU technologies for surmounting emerging and persistent contaminants in drinking water. The primary objective of this proposal is to validate, optimize, and demonstrate microwave (MW) irradiation- enabled thermal destruction of PFAS sorbed on activated carbon, thereby enabling a design capable of demonstrating long-term performance for cost-effective POU removal of PFAS in drinking water. The central hypothesis is that household microwave ovens can effectively destruct PFAS on exhausted activated carbon for adsorbent regeneration and PFAS detoxification, thus achieving a cyclic adsorption - regeneration approach to PFAS in drinking water. METHODOLOGY PFOA contaminated natural water GAC PFOA-free water U vj u Adsorption phase PFOA/NOM-Iaden GAC Household microwave oven as an on-site GAC regeneration process for PFOA-laden GAC in the presence ofNOM Regeneration phase Fig. 1 The overall treatment scheme for PFOA mitigation and GAC regeneration Fig. 2 The selected GAC Fig. 3 PFOA adsorption by GAC in the presence ofNOM www.epa.gov/research 200 mM NaOH in 90% MeOH solution I 1 PFOA-laden ~" GAC treated — by MW Agilent 6460C High-performance Liquid Chromatography-triple Quadrupole Mass Spectrometer (HPLC-MS/MS) Fig. 4 The treatment scheme for PFOA extraction from GAC and PFOA detection by HPLC-MS/MS RESULTS Table 1. The optimization of PFOA extraction from GAC NO. Extraction methods 10%NaCl 100% Methanol 90% Methanol 80% Methanol 70% Methanol 60% Methanol PFOA extraction rate(%) 0.62 7.71 75.02 68.61 57.42 20.25 8 74 8 200 mM NaOH in 90% Methanol 95.93 9 200 mM NaOH in 80% Methanol 88.64 10 100 mM NaOH in 90% Methanol 87.02 ll 100 mM NaOH in 80% Methanol 81.40 o .Q 60.00 d) 0.20 GAC dosage (g) Fig. 5 Effect of GAC dosage on PFOA adsorption (Experimental condition: PFOAmm= 20 jtig/L; DOC = 4 mg/L; pHwnai = 7.00; _ * i—~ . —,3 a- in al PFOA concentration 0.00 5 40.00 E 2 < o Heating Time (min) Fig. 6 Effect of heating time on PFOA destruction from GAC by microwave (Experimental condition: GAC = 0.50 g) Fig. 7 Comparison of energy dispersive X-Ray spectroscopy (EDS) spectra of GAC under different conditions: (a) fresh GAC, (b) PFOA-laden GAC, and (c) PFOA-laden GAC treated by MW (Experimental condition: GAC = 0.50 g; PFOAm»«i= 20 jUg/L; DOC = 4 mg/L; pFLnuw = 7.00; adsorption time = 24 hrs; and MW heating time = 10 min) IMPLICATIONS Treatment capability - MW thermal regeneration permits recurring GAC adsorption of PFAS, while chemically destructing toxic PFAS. Environmental friendliness - Low energy footprint due to rapid MW regeneration; less GAC wastes; and minimal leaching from GAC. User experience - Household MW ovens makes the operation easy. Economic viability - No financial needs for additional equipment except MW ovens (a common kitchen appliance), repeated use of GAC, and lower expenses for less waste disposal. Social acceptance - The above-stated merits foster public acceptance and market adoption. CONCLUSIONS Household microwave oven can serve as an on-site PFOA- laden GAC regeneration process. A 5-min heating time achieved a remarkable 99.48% removal rate of PFOA, while extending the heating time to 10 min resulted in a complete elimination of PFOA. FUTURE WORK Implement microwave irradiation of multiple PFAS-sorbed GAC (e.g., PFOS, PFNA, PFBS, PFBA, and GenX). Examine performance of the repeated adsorption - regeneration cycles. Lifecycle analysis. ACKNOWLEDMENT This project is supported by EPA P3 Program (Grant No. SU840408). ------- |