Ceria–graphite composite for arsenate removal from groundwater: strategic surface anchoring for enhanced performance

Abstract

Groundwater is a vital drinking water source worldwide, yet its purity is increasingly threatened by geogenic and anthropogenic pollutants. Among these, arsenic (As) contamination poses severe environmental and health risks. To address this, a novel ceria-decorated graphite (CDG) composite was synthesized via a micelle-mediated route, designed to combine the high surface area of graphite with the active sites of ceria for enhanced As(V) adsorption. CDG achieved removal, decreasing slightly from 100% to 97.3% as the As(V) concentration increased from 2 to 10 mg L⁻¹ under optimized conditions (pH 7, 25 °C, 30 min). Co-existing ions had negligible effect. Adsorption kinetics followed a pseudo-second-order mechanism (R² = 0.99), indicating chemisorption, while equilibrium data fit the Freundlich model (R² = 0.94), suggesting multilayer adsorption on a heterogeneous surface. CDG exhibited a mesoporous structure with a BET surface area of 31.087 m² g⁻¹, supporting efficient adsorption, with a maximum adsorption capacity of 19.5 mg g⁻¹. Application to real groundwater from Punjab (Ferozpur, Bhadru) reduced As(V) from 0.05 mg L⁻¹ to 0.001 mg L⁻¹ (98% removal), demonstrating both practical applicability and potential for scalable water treatment.