Highly efficient arsenate removal using novel La-GO/B granules: Performance evaluation and mechanistic exploration in simulated real water system

Abstract

This study addresses the primary challenge in arsenate [As(V)] remediation: developing an adsorbent that offers abundant active sites, high affinity, and capacity for As(V) removal while ensuring contaminant levels remain within safe limits. It introduces lanthanum oxide-modified graphene oxide/bentonite (La-GO/B) granules, synthesized in a porous sodium alginate matrix, which exhibit efficient As(V) removal. The granules maintain consistent performance across a pH range of 3–6 and are unaffected by competing ions, demonstrating robustness in complex water environments. With a Langmuir adsorption capacity of 138.45 mg/g at pH 6.0, they retain substantial capacity after five adsorption-desorption cycles. X-ray photoelectron spectroscopy and experimental analysis confirm inner-sphere complexation between As(V) and lanthanum as the main adsorption mechanism. The granules release no detectable lanthanum or by-products, ensuring safety and stability. In fixed-bed column tests, they treat up to 3,800 bed volumes of water, maintaining arsenate concentrations below WHO permissible limits, establishing La-GO/B granules as a promising arsenate adsorbent for water treatment applications.