Wang Yanhua,Du Yingchao,Yan Jingmin,Wang Yongliang,Yu Bo,Zhang Xiaomeng,Ye Shufeng
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 CeO x /MnO y nanoparticles anchored layered structural TiO 2 pillared montmorillonite (TiO 2 -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, TiO 2 -Mt-Ce-Mn with a high specific surface area (148.099 m 2 /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 H 2 PO 4 − . Interestingly, the layered structure provides sufficient attachment space for CeO x /MnO y nanoparticles, while CeO x /MnO y nanoparticles in turn endows TiO 2 -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 CeO x /MnO y nanoparticles and TiO 2 and effective adsorption of the residual As(III) and the formed As(V) subsequently. In addition, the adsorption efficiency of TiO 2 -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.
A series of BiOCl/TiO 2 /montmorillonite photocatalytic material (BTM) were prepared by sol-gel method combined with calcination process, and were used for the degradation of Congo red. The phase composition, morphology, and optical properties of the as-prepared materials were characterized by XRD, SEM, BET and UV–vis DRS. Compared with BiOCl and TiO 2 , BTM has a better removal effect on Congo red, in which BTM-20 has the highest photocatalytic activity. After 120 min of illumination, the degradation rate of Congo red by BTM-20 reached 94.04 %. The photocatalytic degradation process of Congo red by BTM-20 conformed to the pseudo-first-order kinetic model with a reaction constant of 0.00803 min −1 . The type-Ⅱ heterojunction between BiOCl and TiO 2 promotes the separation of photogenerated electron-hole pairs of BTM-20 and enhances the absorption for visible light. The experiment of the free radical capture indicated that superoxide radical played a leading role in photocatalytic degradation of Congo red, followed by hydroxyl radical. This study provides a new treatment ideas for environmental remediation, and provides an efficient photocatalytic material for the degradation of pollutant.
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