Polymeric anion exchanger supported hydrated Zr(IV) oxide nanoparticles: A reusable hybrid sorbent for selective trace arsenic removal

Natural groundwater contamination by arsenic puts over 100 million people at-risk throughout the world. If arsenic is the primary concern, the most ideal treatment solution would be a regenerable fixed-bed adsorbent: minimal energy requirement, simple operation and low cost. Such an adsorbent should have high arsenic capacity, high physical/chemical durability and high regenerability for several cycles of reuse. Hybrid anion exchange resins impregnated with hydrous zirconium oxide nanoparticles (HAIX-Zr) combine the physical durability and high anion diffusivity of anion exchanger resins with the high arsenic capacity and high chemical durability of zirconium oxides. HAIX-Zr was synthesized using non-hazardous and easy-to-transport pre-calcined zirconium oxide and was tested to be an effective As(V) and As(III) adsorbent over several cycles of exhaustion-regeneration in the presence of high concentrations of competing anions; at high concentrations, phosphate and silica show competition with arsenic. The high regenerability of HAIX-Zr (> 90%) makes it more sustainable to regenerate and reuse the HAIX-Zr for numerous cycles to reduce the volume of arsenic-laden waste. Unlike other iron- or aluminum-based adsorbents, HAIX-Zr is chemically stable at landfill conditions where it could be safely disposed without leaching arsenic.