Nano-zirconia modified biochar for efficient removal of arsenite and arsenate from freshwater and seawater.

Abstract

Arsenic (As) pollution in groundwater and seawater represents a major global environmental and public health issue. This study explores the efficacy of nano-zirconium oxide (N-ZrO₂) loaded biochar (BC) for removing inorganic arsenic (iAs), arsenite [As(III)] and arsenate [As(V)], from both freshwater and seawater. Utilizing scanning electron microscopy, flourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, successful loading of N-ZrO₂ onto BC was confirmed, significantly boosting its adsorption capacity to 44.1 mg g^-1 for As(III) and 33.5 mg g^-1 for As(V). The adsorption process, following a pseudo-second-order kinetic model, primarily involved chemisorption, with hydroxyl groups playing a crucial role. The N-ZrO₂-modified BC exhibited minimal pH sensitivity, demonstrating optimal adsorption at a concentration of 0.5 g L^-1, surpassing other materials in efficiency and dosage requirements, and exhibiting potential for recyclability. In practical applications, it achieved high removal efficiencies (95 % in freshwater and 86 % in seawater), establishing 700 °C N-ZrO₂-BC as a proficient adsorbent for simultaneous removal of As(III) and As(V) from contaminated freshwater and seawater. This study offers a promising solution to As contamination, with significant implications for public health and environmental sustainability.