Like Ouyang,Yan Zhang,Yuan Wang,Xinlong Wang,Shaojun Yuan
The coupled adsorption–photocatalytic oxidation process provides a great potential scenario to enhance the removal efficiency of arsenite contaminants by converting As(III) to As(V) and simultaneous adsorption. In this study, the boron-doped black TiO2/g-C3N4 nanocomposite is synthesized by combination of sol–gel and in situ decomposition-thermal polymerization methods as a photocatalyst for the photocatalytic oxidation and adsorption of As(III). Under dark conditions, the boron-doped samples (B-TiO2 and B-TiO2/g-C3N4) display an increase in the As(III) adsorption capacity by one order of magnitude up to circa 3.2 mg g–1 with an initial As(III) concentration of 2 mg L–1 at 298.15 K and pH 5. The adsorption kinetics of As(III) on B-TiO2/g-C3N4 conform to the pseudo-second-order kinetic model, revealing the chemical adsorption mechanism. Under visible light irradiation, the total arsenic removal capacity is substantially improved by 20% with a removal capacity of 3.9 mg g–1. The enhancement of arsenic adsorption is attributed to the chemical complexation and hydrogen bond, in which B–OH bonds play a dominant role. The photocatalytic oxidation mechanism of the as-synthesized B-TiO2/g-C3N4 is attributed to the synergism of superoxide radicals, hydroxyl radicals, and photogenerated holes.
Like Ouyang,Yuan Wang,Ping Zhang,Xinlong Wang,Shaojun Yuan
Arsenite contamination in groundwater seriously impairs human health due to its high mobility and toxicity. Herein, a novel heterostructured MWCNTs@PANI@TiO2 nanocomposite was synthesized via a one-pot polymerization process for the adsorption and photocatalytic oxidation of As(III) from aqueous solution. In the dark, the as-synthesized nanocomposite had a high adsorption capacity of As(III) at about 0.29 mmol·g–1 with an initial As(III) concentration of 0.067–0.801 mmol·L–1 at 298.15 K and exhibited a stable adsorption capacity in a wide pH range of 2–9. The adsorption kinetics of As(III) on MWCNTs@PANI@TiO2 was in accordance with the PSO model and was mainly controlled by chemical adsorption. Under visible light irradiation, the adsorption amount of As(III) on MWCNTs@PANI@TiO2 was substantially enhanced by about 57%, and the photocatalytic conversion of As(III) to As(V) was found to be caused by the photogenerated holes and superoxide free radical (•O2–). The hypothesized adsorption mechanisms of As(III) and As(V) ions on the nanocomposite were possibly ascribed to surface complexation and hydrogen-bonded interactions. The heterostructured MWCNTs@PANI@TiO2 nanocomposite offers a promising candidate for highly efficient removal of As(III) ions from arsenite-polluted groundwater.
危险品化学品经营许可证（带存储）