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In recent years, a temperature-sensitive hydrogel was reported as a promising draw agent in forward osmosis (FO) technology. PEG, acts as porogen, as an enabler to improve the swelling property of hydrogels. From FO test, the addition of porogen to the hydrogel can improve the water flux of FO by increasing the swelling properties of the hydrogel. And the hydrogel modified with porogen improves the concentration efficiency of wastewater from 1.09 to 1.124 times, indicating that the modification of the hydrogel by the porogen has positive significance for FO technology. In this study, an advanced hydrogel was synthesized via physical copolymerization by using N-isopropylacrylamide and sodium acrylate. The internal structure was investigated by SEM test where it was found that that porogens have different mechanisms of action on hydrogel performance: Porogen affects the swelling property of hydrogel by changing the internal network structure through physical “occupation”. The effect of porogen concentration is to act on the porosity of hydrogel, while the main effect of the molecular weight of porogen on the hydrogel structure is by altering the pore size.

In order to further improve its photocatalytic activity, the BiOI microspheres were activated by a synchronous coupling of Bi metal and graphene under solvothermal conditions. The effects of the synthesis temperature (160–200 °C) on crystallinity, morphology, and photocatalytic activity were studied in particular. As expected, the ternary Bi-BiOI/graphene photocatalyst synthesized at 180 °C exhibited higher photocatalytic activity for NO oxidation removal under visible light irradiation than individual BiOI, and binary Bi-BiOI and BiOI/graphene composites. The photocatalytic efficiency for the NO removal of the ternary Bi-BiOI/graphene photocatalyst synthesized at 180 °C reached 51.8% within 30 min of visible light irradiation. The enhanced photocatalytic activity of the ternary Bi-BiOI/graphene photocatalyst is attributed to (I) the efficient transfer of photo-generated electrons from BiOI and Bi to graphene, leading to the effective separation of the photo-generated electron-hole pairs and (II) the surface plasmon resonance effect of Bi nanoparticles in the composite photocatalyst. Furthermore, the results of the scavenger experiments and DMPO-ESR spin-trapping measurements reveal that O2− radical species play the most critical role and holes serve as a secondary active species in the oxidative removal process of NO by 180BOI/GR composite under visible light irradiation.

The efficient removal of antibiotics in water is essential to protect aquatic environment as antibiotics are some of the most hazardous pollutants in water. Herein, we report the synthesis of a novel N-GNDs/Ag/BiVO4 ternary photocatalyst consisting of BiVO4 coupled with Ag nanoparticles (Ag-NPs) and nitrogen-doped graphene nanodots (N-GNDs) to degrade and mineralize tetracycline hydrochloride (TC•HCl) in water. The ternary photocatalyst shows higher photocatalytic degradation of TC•HCl under full spectrum light than pure BiVO4. Based on the morphology, crystalline structure, physicochemical properties, and photoelectrochemical behavior of the ternary photocatalyst, the enhanced photocatalytic performance is attributed to the upconversion effect of N-GNDs and the localized surface plasmon resonance (LSPR) effect of Ag-NPs. Thus, the synergetic effects expand the absorption range of light and significantly promotes the separation of photoexcited carriers. Further, a possible photocatalytic reaction mechanism of TC•HCl degradation over N-GNDs/Ag/BiVO4 is discussed via through investigation of the charge carrier migration, active species, and intermediates in the degradation processes.

The two key factors such as light adsorption and separation of charge carriers in photocatalysts play crucial roles in determining the overall photocatalytic efficiency. Herein, we report synergetic effects of Fe-doping and Au nanoparticles (Au-NPs) deposition on the photocatalytic activity of the modified Bi4O5Br2 (BOB) nanosheets photocatalyst for Bisphenol A degradation and gaseous NO oxidative removal. Fe-doped BOB nanosheets decorated with Au-NPs are synthesized by a two-step chemical method. It was found that the Fe-doped BOB sample decorated with Au-NPs (Au-Fe-BOB) exhibits higher photocatalytic activity than the BOB, Fe-doped BOB, and Au-NPs-loaded BOB samples. Internal Fe-doping in the BOB enhanced the visible light absorption and the separation efficiency of photogenerated charge carriers acting as a scavenger. Moreover, the decorated Au-NPs in the composite photocatalyst extended the light adsorption in the range of visible and near- infrared light due to surface plasmon resonance effect of Au-NPs. The spin trapping measurements of Au-Fe-BOB composite photocatalyst show that the •O2− is a main reactive species during the photocatalytic reaction under visible-light irradiation. The excellent photocatalytic efficiency and stability of Au-Fe-BOB with visible-light response allow to be readily constructed and applied for practical removal of various pollutants using solar light in the future.