Oxidant-free aqueous arsenic removal over few-layer Ti3C2Tx MXene via coupled As(III) photooxidation and As(V) adsorption

Coupling arsenite oxidation with arsenate capture may reduce the need for separately dosed oxidants in water treatment, but the roles of the active phase and adsorption sites require careful evaluation. Here, Ti 3 C 2 T x -based nanosheets were prepared by NH 4 F-assisted electrochemical etching and tetramethylammonium hydroxide (TMAH)-mediated delamination without directly adding HF. The material exhibited a BET surface area of 80.37 m 2 /g and expanded basal spacing. Batch experiments under simulated solar irradiation showed light-dependent arsenic transformation and As(V) uptake without an added chemical oxidant. Under simulated solar irradiation, the material achieved efficient oxidant-free arsenic removal through coupled As(III) photooxidation and As(V) adsorption, enabling nearly complete oxidation of 10 mg/L As(III) within 3 h and a high maximum As(V) adsorption capacity of 349.1 mg/g. The system also showed good environmental adaptability and reusability, maintaining over 85% arsenic removal efficiency across pH 3–9 in the presence of common coexisting ions, with negligible performance decay after four regeneration cycles. Mechanistic analysis reveals that the enlarged interlayer spacing and exposed terminal groups provide abundant binding sites for As(V), while the ultrathin Few-Layer structure and favorable interfacial charge transfer promote As(III) photooxidation. This work demonstrates an oxidant-free MXene-based strategy for efficient remediation of arsenic-contaminated water.