Selective removal of Pb from lead-acid battery wastewater using hybrid gel cation exchanger loaded with hydrated iron oxide nanoparticles: Fabrication, characterization, and pilot-scale validation

Abstract

In this study, a strong acid gel cation exchanger (C100) impregnated with hydrated ferric hydroxide (HFO) nanoparticles (C100-Fe) was synthesized, characterized, and validated for application as a novel adsorbent to remove lead (Pb2+) from industrial lead-acid battery wastewater. Analysis with a SEM-EDS showed high concentrations of iron doped and distributed within the gel phase of the parent cation exchanger up to 8.60 wt%. HFO nanoparticles were 20–100 nm in size according to transmission electron microscopy. The C100-Fe adsorbent was applied to remove trace Pb2+(150 µg/L) using NSF/ANSI standard 53 challenge that included competing ions. The results demonstrated that C100-Fe could remove Pb2+ up to 15,000 bed volumes (BVs) at a breakthrough cutoff of 50 µg/L, whereas the granular activated carbon (GAC), GAC impregnated with HFO nanoparticles (GAC-Fe), and the parent cation exchanger (C100) were able to treat only 1200, 1700, and 3500 BVs before breakthrough, respectively. Due to amphoteric behavior of hydrated ferric hydroxide, C100-Fe could be regenerated and reused with 10 BVs of 0.5% HNO3 solution. Wastewater from a battery manufacturing plant containing 5.0 mg Pb2+/L along with 250 mg Ca2+/L was also used to test the performance of C100-Fe in both lab scale and onsite pilot scale. C100-Fe selectively removed Pb2+ for approximately 6500 BVs (breakthrough at 0.2 mg/L), while the C100, GAC, and GAC-Fe treated the same wastewater for only 400, 900, and 1500 BVs, respectively. The results confirmed that C100-Fe can be efficaciously applied for lead removal and achieve both drinking and industrial wastewater standards. The results from the onsite pilot scale test conducted over 30 consecutive days confirmed the robust material can be used to supplement the traditional coprecipitation method.