Multicycle photocatalytic reduction of Cr(VI) over transparent PVA/TiO2 nanocomposite films under visible light

Abstract

Photocatalytic reduction of hexavalent chromium in wastewater has been widely investigated as an attractive treatment method. In this work, we reported an efficient method for photocatalytic reduction of Cr(VI) over transparent polyvinyl alcohol/titanium dioxide (PVA/TiO2) nanocomposite films under sunlight irradiation. The transparent PVA/TiO2 nanocomposite films were prepared by a simple hydrothermal method combined with a solution casting process. The results revealed that the anatase TiO2 nanoparticles with size less than 10 nm were in-situ generated in PVA matrix, which endowed the films with high transparency. Photocatalytic reduction of Cr(VI) over PVA/TiO2 nanocomposite films exhibited superior visible light photocatalytic activity. Mechanism investigation demonstrated that the PVA acted not only as a transparent support for TiO2 nanoparticles, but also as holes scavengers simultaneously to improve the separation of photogenerated holes and electrons. Meanwhile, the transparent PVA/TiO2 nanocomposite films displayed remarkable stability and excellent recyclability during multicycle Cr(VI) photoreduction. Furthermore, the PVA/TiO2 nanocomposite films showed selective adsorption ability for Cr(III), and thus totally removal of Cr(VI) was achieved after photoreduction process.

Molten salt construction of stable oxygen vacancies on TiO2 for enhancement of visible light photocatalytic activity

“…23 Beside the main peak, a shoulder peak at 688.2 eV appears in the B-TiO 2 -2.0, demonstrating the substitution of F atoms for O atoms in TiO 2 lattices. 24,25 Recent research work has reported that uoride anion is efficient for the stabilization of reduced TiO 2 because of its tendency to form a strong bond with the surface Ti atoms. 26 Moreover, uorine-occupied surface oxygen vacancies can maintain the intrinsic nature of the defects.…”

Low Temperature Synthesis of Large‐Size Anatase TiO2 Nanosheets with Enhanced Photocatalytic Activities

“…The pH values of the reacting systems were adjusted with HNO 3 to 2. [25] The typical reactions for photocatalytic reductions of K 2 Cr 2 O 7 by TiO 2 are generally considered as following [26] h response to the light over 400 nm. The reusability of NS for the cyclic photocatalytic reduction of Cr (VI) was tested under FL irradiation.…”

Vortex fluidic mediated one-step fabrication of polyvinyl alcohol hydrogel films with tunable surface morphologies and enhanced self-healing properties

“…A highly crystallized PVA hydrogel has low swelling property, making it desirable for specific biomedical and pharmaceutical applications [4][5][6]. Different studies have shown the notable performance of PVA hydrogel and its composites for wound healing [7], sensors and electrodes [8,9], tissue engineering [10][11][12] and biomedical applications [13][14][15].…”