The Photocatalysis-Enhanced TiO₂@HPAN Membrane with High TiO₂ Surface Content for Highly Effective Removal of Cationic Dyes

Abstract

The elimination of dye pollutants from wastewater is a significant concern that has prompted extensive research into the development of highly efficient photocatalytic membranes. A novel method was proposed to prepare photocatalysis-enhanced poly(acrylonitrile-methyl acrylate) (PAN-based) membranes in this study. In detail, the blended membrane containing SiO 2 @TiO 2 nanoparticles with a shell−core structure was first prepared via thermal-induced phase separation. The SiO 2 nanoshells were dissolved, and the released TiO 2 nanoparticles migrated to the membrane surface during a simple hydrolysis process, which prevents the TiO 2 nanoparticles from directly contacting or interacting with the polymer matrix. The hydrogen bonds bind the exposed TiO 2 with the PAN membrane surface, resulting in the formation of the TiO 2 @HPAN hybrid membrane. The photocatalytic efficiency of the TiO 2 @HPAN membrane doubled compared with that of nonhydrolyzed membranes. In the presence of UV light, the hybrid membrane can degrade 99.8% of methylene blue solution in less than 2 h, compared to only 86.1% for the blended membranes. Further, the TiO 2 @HPAN membrane showed excellent photocatalytic activity for cationic dyes due to electrostatic attraction. Moreover, the high-flux recovery rate and recycling stability of the TiO 2 @HPAN membrane lead to an excellent antifouling property. The facile preparation method proposed in this work shows extraordinary potential for the development of highly efficient selective photocatalytic materials for cationic dyes to be used in wastewater treatment applications.

Activated Carbon and Carbon Quantum Dots/Titanium Dioxide Composite Based on Waste Rice Noodles: Simultaneous Synthesis and Application in Water Pollution Control

“…For cost control and resource recycling, a wide variety of AC adsorbents derived from a natural products or organic waste have been reported in recent years, whose sources include coconut shell [ 20 , 21 ], pecan shell [ 22 ], peanut shell [ 23 ], date pit [ 24 ], hazelnut husk [ 25 ], sagowaste [ 26 ], paper mill sludge [ 27 ], polygonum [ 28 ], crassipes root [ 29 ], and so on. On the other hand, nano titanium dioxide (TiO 2 ) is a commercial photocatalyst used in water and air pollution control [ 30 , 31 , 32 ]. However, pure TiO 2 displays a wide band gap whose photogenerated electrons and holes are easy to combine again.…”

Nanochannel-Induced Efficient Water Splitting at the Superhydrophobic Interface

“…For the P 31.9% -TTO sample, the O–H stretching vibration splits into two positive bands at 3447.94 and 3180.69 cm –1 , and the H–O–H bending vibration splits into two peaks at 1670.06 and 1629.04 cm –1 , which directly illustrates the changed H 2 O adsorption configurations on P-TTO. Typically, adsorbed water molecules on the polar surface of metal oxide semiconductors (e.g., TiO 2 ) inevitably render a solid hydrogen-bond network of water clusters, in which the water molecules line up as one-dimensional chains along the metal atoms to form a three-dimensional patterned structure. − For a single semiconductor catalyst, the solid hydrogen-bond network can be destroyed by a few irregular structures, including ravines, edges, boundaries, and surface atom vacancies, serving as reactive sites. − However, for most inert catalyst surfaces, the coverage of hydrogen-bonded water clusters can hardly be destroyed, significantly constraining the reactivity for water splitting . In our system, nanochannels between the nonpolar silane chains are the only space for the contact of water and TTO catalyst at the superhydrophobic water/P-TTO interface, which makes the large-scale hydrogen-bonded water clusters impossible.…”

“…These hydrogen-bonded water clusters were demonstrated to hinder the water-splitting reaction, − contrary to the intuitive perception that the more hydrophilic the material, the better. On the surface of a single semiconductor catalyst, only a few irregular structures, including ravines, edges, boundaries, and surface atom vacancies, can partially destroy the water hydrogen-bond network and modify the local interfacial reaction configuration, thereby promoting the OER as reactive sites. − However, such reactive sites only occupy a small fraction of the catalyst surface, with most of the surface area on semiconductor catalysts covered by the inert hydrogen-bond network . We argue that developing a general strategy to destroy the water hydrogen-bond network at the interface is the key to activating the inert catalyst surface for efficient overall water splitting.…”

Characterization of a Model Bioreactive Membrane for the Simultaneous Separation and Hydrolysis of Lipopolysaccharides

“…In another study, the incorporation of palladium NPs immobilized within an ultrathin hydrogel selective layer achieved up to 98% catalytic conversion to reduce Cr­(VI) to Cr­(III) . Other interesting contributions proposed a photocatalytic membrane by blending SiO 2 /TiO 2 NPs in a poly­(acrylonitrile-methyl acrylate)-based support to degrade dye pollutants from wastewaters …”