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Double-shelled hollow hybrid spheres consisting of plasmonic Ag and TiO2 nanoparticles were successfully synthesized through a simple reaction process. The analysis reveals that Ag nanoparticles were dispersed uniformly in the TiO2 nanoparticle shell. The plasmonic Ag-TiO2 hollow sphere proves to greatly enhance the photocatalytic activity toward reduction of CO2 into renewable hydrocarbon fuel (CH4) in the presence of water vapor under visible-light irradiation. The possible formation mechanism of the hollow sphere and related plasmon-enhanced photocatalytic performance were also briefly discussed.

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Here we report multilayer hollow spheres consisting of alternating ultrathin Ti0.91O2 nanosheets and CdS nanoparticles via exquisite layer-by-layer self-assembly to achieve an all solid-state Z-scheme system with 7-times enhancement of the CH4-production rate relative to pure Ti0.91O2 hollow spheres, due to a greatly prolonged lifetime of charge carriers.

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Loose nanofiltration (NF) membranes with diverse selectivity can meet the great demands in various bioseparation applications. Thus, a facile strategy to tune the properties such as pore size, surface charge, and hydrophilicity of the NF membrane is required to produce tailor-made loose NF membranes without changing the existing production line. Herein, we systematically investigated the post-treatment of the nascent poly(piperazine amide) NF membranes using different reagents (organic acids, weak bases, organic solvents and ionic liquid (IL)). Various characterizations revealed that the skin/separation layer became looser and permeance was promoted with the decrease of salt rejection in varying degrees. It was found that the O/N ratio did not rigorously represent the cross-linking degree of the skin layer, because besides the hydrolysis of the residual acyl chloride impeding the amido bond formation, the breaking of existing amido bonds and the grafting of free trimesoyl chloride molecules on the nascent membranes could also increase the O/N ratio during post-treatments. Then three mechanisms including hydrolysis, swelling rearrangement and capping reaction effects were proposed to better understand the membrane properties variations. All these effects resulted in larger pore size of the NF membrane, and the hydrolysis/capping effect might increase negative charge and hydrophilicity on the membrane, while the swelling rearrangement could produce less defective skin structure. These three effects might be involved together during a single treatment. Finally, the NF membrane post-treated by N-hexane could efficiently separate antibiotics and NaCl with the highest permeate flux, whereas the one post-treated by ionic liquid outperformed others for the decoloration of cane molasses (much more efficient than NF270, DL, and NTR7450 membranes). The long-term operating stability of the post-treated membranes selected was also confirmed by a continuous crossflow filtration for 15 h with regular alkaline cleaning.

Nanofiltration (NF) membranes, especially polyamide (PA) ones, are widely applied in water treatment, food processing, and resource recovery thanks to their excellent separation selectivity to small solutes and high water permeability. However, membrane fouling is inevitable during the long-term operation and limits the large-scale applications of NF technology. Chemical cleaning is considered the most effective way to avoid fouling aggravation and quickly restore membrane permeability on site. However, frequent chemical cleaning would cause reversible/ irreversible changes in the physical and chemical properties of NF membranes, resulting in membrane damage and deterioration of separation performance. Moreover, the PA NF membrane with high selectivity and a relatively low cross-linking degree is more sensitive to chemical cleaning. Many efforts, therefore, have been dedicated to clarifying the effect of chemical cleaning on the NF membrane properties and its separation performance. This review summarizes recent developments in the field and epitomizes the synergistic/inhibitory effect among the chemical cleaning agents on the fouling removal. Besides the practical guides for chemical cleaning of the PA NF membrane, many opportunities to advance the field are also pointed out.