Progress and Perspectives of Desalination in China.

In recent decades, the ever-growing demands for clean water in households and industries have urged researchers to take every possible step to deal with the global water crisis. Seawater desalination has turned out to be the most promising and efficient way to provide clean water. Owing to the advancement of synthetic chemistries and technologies, great success has been achieved in the desalination and utilization of seawater worldwide. China, with the world's largest population, has pushed the development of desalination and multipurpose utilization of seawater further in respect of materials, technologies and services, etc. This review reports recent progress of desalination technologies accomplished in China, from the viewpoints of facilities and equipment, collaborations, technologies, applications, research abilities, services, and standard systems. Inspired by the Fourteenth Five-year Plan, it also proposes future perspectives of desalination in China.

The photodegradation of methylene blue in water with PVDF/GO/ZnO composite membrane.

The immobilization of photo-catalyst can effectively avoid the difficulty in recovery of the nano-catalysts after photo-degradation. In this work, PVDF/GO/ZnO composite membranes with photocatalytic performance for organic dyes were prepared by using zinc oxide (ZnO) as photo-catalyst, graphene (GO) as dispersant and poly (vinylidene fluoride) (PVDF) membrane as carrier. The effect ZnO and GO on the structure, surface composition and photocatalytic activity of PVDF/GO/ZnO composite membranes were investigated. Owing to the strong hydrophilicity of the carboxyl group, the addition of GO enhanced the dispersibility of ZnO in PVDF membranes, which was proved by SEM results. Under Xenon irradiation (300 W), the photocatalytic degradation rate of PVDF/GO/ZnO composite membranes for methylene blue (MB) could reach 86.84%. Furthermore, the photocatalytic efficiency of the composites membrane for MB was evaluated with different initial concentrations of MB, pH value of the solution, and electron trapping agent-H2O2 content. And the radical trapping experiments with different active radical scavengers showed that the oxidizing species (O2-) plays an important role in the decolorization process of MB. In summary, this work provides an efficient method to improve the photodegradability of PVDF/GO/ZnO composite membranes and has great potential in the field of water purification.

Polydopamine/cysteine surface modified hemocompatible poly(vinylidene fluoride) hollow fiber membranes for hemodialysis.

Membrane surface design is significant for the development and application of synthetic polymer hemodialysis membranes. In this study, the influence of zwitterionic cysteine on poly(vinylidene fluoride) (PVDF) hollow fiber membrane was investigated. The polydopamine layer was formed through dopamine self-polymerization on PVDF membrane surface, and then cysteine was covalent grafted onto the layer to improve the anti-biofouling property and hemocompatibility. The elementary composition of membrane surfaces was characterized by X-ray photoelectron spectroscopy. The influence of polydopamine and cysteine on modified membrane surface morphologies was studied by field emission scanning electron microscopy. The modified PVDF membranes were confirmed to have excellent hydrophilicity, stable mechanical properties and good hemocompatibility (dynamic and static anti-protein adsorption, hemolysis ratio, plasma coagulation). And these properties were increased with the incorporation of polydopamine and cysteine. The optimized modified membranes exhibited high pure water flux (∼ 195.5 L/m2 h at 0.1 MPa) and selectivity (clearance ratio of urea and lysozyme was 75.1 and 55.4%, and rejection rate of bovine serum albumin was 98.8%). This work provides a surface modification method of PVDF hollow fiber membranes and suggests a potential application of PVDF membranes in hemodialysis field. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2869-2877, 2018.