Sulfhydryl Functionalized Two-Dimensional Ti3C2Tx MXene for Capture of As(III) in Aqueous Solution
A thiol-functionalized Ti3C2Tx (SH-Ti3C2Tx) material was synthesized via chemical bonding of dithiothreitol (DTT) onto Ti3C2Tx MXene for the adsorptive removal of As(III) from water. Characterization by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) confirmed a typical two-dimensional layered structure with DTT covalently attached. The adsorption of As(III) on SH-Ti3C2Tx followed the Langmuir isotherm model, indicating monolayer adsorption. At pH 7, the maximum adsorption capacity reached 55.6 mg·g−1, which is 2.8 times higher than that of pristine Ti3C2Tx (20 mg·g−1). X-ray photoelectron spectroscopy (XPS) revealed that As(III) uptake primarily occurred via formation of As–S bonds. To enable continuous treatment, SH-Ti3C2Tx was loaded onto melamine sponge via electrostatic interactions to fabricate a flow-through adsorption column (SH-Ti3C2Tx@MS). This column achieved removal efficiencies of 99.5% for both high (100 mg·L−1) and low (100 μg·L−1) As(III) concentrations, reducing effluent As(III) to below the World Health Organization guideline of 10 μg·L−1. The spent column could be regenerated using 1 mol·L−1 NaOH solution, retaining over 80% of its initial removal efficiency after five consecutive adsorption–desorption cycles. The SH-Ti3C2Tx material demonstrates significant potential for efficient and reusable removal of As(III) from contaminated waters.