Hierarchical Anion Exchange and Reverse Electron Transfer in Layered Double Hydroxides/Peroxymonosulfate System for Roxarsone Elimination.

Roxarsone (ROX) is the main form of arsenic pollution in the world, and developing effective methods for its elimination is beneficial to human health and the ecological environment. Herein, we report glutaraldehyde cross-linked chitosan-encapsulated CoCe-LDH (layered double hydroxides) as an outstanding catalyst for the advanced oxidation of ROX and the efficient adsorption of inorganic arsenic. 100% of ROX and more than 98.5% of As(III)/As(V) were eliminated, and over 99.3% of remaining inorganic arsenic was oxidized to low-toxicity As(V) in the peroxymonosulfate (PMS) activation system, and some specific properties of LDH are considered the main reasons. The hierarchical anion exchange has been confirmed to be beneficial for constructing a high-concentration PMS interlayer microenvironment. The unique reverse electron transfer process induced 100% selective production of singlet oxygen. This work not only develops an advanced ROX removal method but also provides a new understanding of the LDH-based advanced oxidation process.

The Precision Defect Engineering with Nonmetallic Element Refilling Strategy in g-C3 N4 for Enhanced Photocatalytic Hydrogen Production.

Traditional defect engineering and doping strategies are considered effective means for improving H2 evolution, but the uncontrollability of the modification process does not always lead to efficient activity. A defect-induced heteroatom refilling strategy is used here to synthesize heteroatoms introduced carbon nitride by precisely controlling the "introduction" sites on efficient N1 sites. Density functional theory calculations show that the refilling of B, P, and S sites have stronger H2 O adsorption and dissociation capacity than traditional doping, which makes it an optimal H2 production path. The large internal electric field strength of heteroatom-refilled catalysts leads to fast electron transfer and the hydrogen production of the best sample is up to 20.9 mmol g-1  h-1 . This work provides a reliable and clear insight into controlled defect engineering of photocatalysts and a universal modification strategy for typical heteroatom and co-catalyst systems for H2 production.

Integrated photocatalysis-adsorption-membrane separation in rotating reactor for synergistic removal of RhB.

A synergistic system of integrated photocatalysis-adsorption-membrane separation in a rotating reactor was designed. The composite membrane was prepared via filtration process under vacuum, and it was composed of graphene oxide (GO) acted as the separation membrane, activated carbon (AC) as the adsorbent and Ag@BiOBr as the photocatalyst, respectively. In this Ag@BiOBr/AC/GO membrane system, rotation of the membrane could avoid the light-shielding effect from organic color pollutants to achieve the complete removal of pollutants. More importantly, the synergistic effect among photocatalysis, adsorption and membrane separation in rotating reactor was significant for the efficient removal of rhodamine B (RhB). In the Ag@BiOBr/AC/GO composite membrane, GO membrane layer could reject the organic molecular by the assistance of AC layer with efficient adsorption capacity, and Ag@BiOBr at outer layer could photodegrade the organics under visible light irradiation. The photocatalysis process could solve the problem of membrane fouling and adsorption could assist GO membrane for stopping the permeation of pollutants. Meanwhile, GO membrane was not only beneficial for catalyst recovery, but also could concentrate the pollutants via the membrane separation to accelerate the photocatalytic degradation. At the same time, both the photocatalysis degradation and membrane separation could promote the adsorption ability of AC. This synergistic system showed the significant potential for the practical application in the future.

Synergistic Photocatalytic-Photothermal Contribution to Antibacterial Activity in BiOI-Graphene Oxide Nanocomposites.

The threat of environmental microbial contamination to the health of human beings has drawn particular attention. In order to explore the synergistic effect of photocatalytic and photothermal process to the antibacterial property, a stably combined BiOI-graphene oxide (GO) nanocomposite was constructed and prepared through a facile solvothermal method. BiOI crystals were uniformly distributed on the GO nanosheets by the formation of the Bi-C bond. On the basis of various characterizations, the great surface area, the high light harvesting with extension into NIR region, and the efficient transfer of photoinduced electrons by the conductivity of GO were demonstrated, all of which are beneficial for the photocatalytic antibacterial activity. More importantly, the photothermal effect of GO increased the temperature of the BiOI-GO composite with high photothermal conversion efficiency and induced the photogenerated electrons from BiOI crystals to obtain more energy and higher carrier mobility. Conversely, the temperature elevation of BiOI-GO composite improved its capability for light absorption and separation of photoinduced charges. As a result, the BiOI-GO composite enabled the synergistic photocatalytic-photothermal effect for the improvement of the antibacterial property for Acinetobacter baumannii with higher efficiency of TOC removal and leakage of K+ ions, in comparison with the individual photocatalytic process. Thus, the synergistic photocatalytic-photothermal contribution of BiOI-GO composite will provide significance for the potential application of environmental disinfection in the future.