Enhanced As(iii) removal from water using an oxidative UiO-66-Cl anchored carbon framework: oxidation and adsorption

Abstract

Millions of people around the world are affected by the consumption of arsenic-contaminated groundwater, particularly the frequently detected As(III). Adsorption-based treatment is well suited to domestic water purification but is less efficient for the easily migrated As(III). Herein, an oxidative UiO-66-Cl anchored dopamine-modified carbon framework (UiO-66-Cl/DCF) was fabricated for single-step As(III) removal. The in situ anchored oxidative UiO-66-Cl provides both oxidative and adsorptive active sites, while the macroporous structure of the carbon framework ensures their high utilization. By oxidizing As(III) to higher-adsorbing As(V), UiO-66-Cl/DCF (1 g L⁻¹) could reduce the As(III) level (∼950 μg L⁻¹) to below 10 μg L⁻¹ within 10 min. Similar results were achieved over a wide pH range of 3–11. UiO-66-Cl/DCF could remove more than 99.0% of As(III) in the coexistence of some ubiquitous anions, excluding 50 mg L⁻¹ phosphate. Its removal capacity for As(III) was higher than 19.45 mg g⁻¹ at pH 7. The used UiO-66-Cl/DCF was easily regenerated by desorption followed by chlorination, with As(III) removal efficiency exceeding 99% in the sixth cycle. Furthermore, UiO-66-Cl/DCF could reduce As(III) levels (∼1000 μg L⁻¹) in natural groundwater, river water, and tap water to less than 10 μg L⁻¹. Therefore, the proposed UiO-66-Cl/DCF could work as a reliable candidate for single-step purification of As(III)-contaminated water.