TiO2 pillared montmorillonite in-situ growth of CeOx/MnOy nanoparticles for effective arsenic (III) adsorption in wastewater.

Compared with As(V), As(III) is a tricky issue worldwide for its higher toxicity and more difficult to remove in aqueous solution. In present study, a novel CeOx/MnOy nanoparticles anchored layered structural TiO2 pillared montmorillonite (TiO2-Mt-Ce-Mn) was fabricated and applied as an efficient absorbent for As(III) removal. Under the condition of the initial As(III) concentration = 20 mg/L and adsorbent dose = 0.4 g/L, TiO2-Mt-Ce-Mn with a high specific surface area (148.099 m2/g) has an outstanding adsorption capacity (46.58 mg/g) for As(III) at pH 4.2, and the effect of oxy-anions on adsorption efficiency is slight except for H2PO4−. Interestingly, the layered structure provides sufficient attachment space for CeOx/MnOy nanoparticles, while CeOx/MnOy nanoparticles in turn endows TiO2-Mt a high redox potential, which further facilitates the oxidation of As(III), and this significantly reduces the toxicity of wastewater. The adsorption mechanism includes the oxidation of As(III) to As(V) by both CeOx/MnOy nanoparticles and TiO2 and effective adsorption of the residual As(III) and the formed As(V) subsequently. In addition, the adsorption efficiency of TiO2-Mt-Ce-Mn can still maintain 79.6% after five cycles through a facile regeneration method. Thus, the nanocomposite with low-cost synthesis process, high adsorption capacity, and regenerability is a promising candidate for As(III) treatment of wastewater.