A hybrid anion exchanger with nanoscale zero valent iron for trace hexavalent chromium removal from drinking water

• Published in: Environmental science. Advances Vol. 3; no. 11; pp. 1598 - 1615
• Main Authors: Mungan, Annabel L., Hjelvik, Elizabeth A., Straub, Anthony P., Korak, Julie A.
• Format: Journal Article
• Language: English
• Published: 28.10.2024
• ISSN: 2754-7000; 2754-7000
• DOI: 10.1039/D4VA00246F

Hexavalent chromium, Cr( vi ), is a human carcinogen that occurs in groundwater worldwide. While not federally regulated in the USA, the State of California has approved a new Cr( vi ) maximum contaminant level at 10 μg L −1 , expected to go into effect fall 2024. This study synthesizes, characterizes, and verifies performance of a hybrid strong base anion exchanger with nanoscale zero valent iron (NZVI-resin) for trace Cr( vi ) removal from drinking water. NZVI-resin was synthesized by exchanging tetrachloroferrate ion (FeCl 4 − ) onto the resin prior to sodium borohydride (NaBH 4 ) reduction. The impact of important synthesis variables was identified, including reagent concentrations and molar ratios, solvent selection, temperature, and drying procedure. Material characterization techniques ( e.g. SEM-EDS and XPS) determined NZVI presence and elemental distribution on the resin surface. Our work showed a 360% increase in treated water throughput using NZVI-resin compared to unmodified resin for trace Cr( vi ) removal in column experiments. This work presents a broad assessment of the material characteristics of NZVI-resin, discusses the limitations of batch tests, and describes operational challenges for Cr( vi ) treatment.