Granular composite of polyvinyl chloride anion exchange resin encapsulated with nano TiO2 for arsenic removal from water

Abstract

Persistently high arsenic levels in drinking water threaten underprivileged areas worldwide. Although nanomaterials exhibit exceptional arsenic removal properties, their implementation presents challenges. We converted N-methylimidazole-modified polyvinyl chloride into a granular anion exchange resin (PNAXRs) using an environmentally friendly and gentle synthesis method. Additionally, a unified approach for embedding nanomaterials within these resins was proposed, yielding a TiO2 composite resin (TiO2@PNAXRs). Structural characterization confirmed the successful grafting of imidazolium cations with anion-exchange properties onto polyvinyl chloride side chains. BET analysis indicates a high specific surface area of 70.31 m2/g for the PNAXRs. TGA curves demonstrate the successful encapsulation of approximately 24.9% TiO2 within the composite resin. The SEM-EDS results show a uniform distribution of TiO2 in the PNAXRs, which facilitates the effective utilization of TiO2. Adsorption experiments in conjunction with XPS analysis provided insights into the dual role of inner-sphere complexation and ion exchange in the adsorption mechanism of As(V) by TiO2@PNAXRs. In dynamic adsorption tests utilizing high-As(V) groundwater from the Datong Basin as the influent, TiO2@PNAXRs demonstrated the ability to produce effluents that meet the World Health Organization's recommended limit for arsenic in drinking water, with a capacity of 1780 bed volumes. These findings support the use of PNAXRs as ideal matrices for TiO2 and their practical application in As(V) removal processes.