Preparation and antifouling performance of thin inorganic ultrafiltration membrane via assisted sol-gel method with different composition of dual additives

A novel TiO₂ thin film was prepared on the ceramic hollow fiber by the sol-gel method using poly(vinylpyrrolidone) (PVP) and polyvinyl alcohol (PVA) as additives. SEM images verified the formation of TiO₂ layer with various thickness using different composition of titania sols. The effect of the PVP and PVA contents on the TiO₂ sol properties, the separation and the antifouling performance of the ultrafiltration membranes were investigated thoroughly. When the contents of PVP and PVA were 1.0 wt% and 0.8 wt%, respectively, the resultant membrane showed a thickness of 0.55 μm with a pure water flux of 255 L m^?2 h^?1. In addition, the adherent foulant bovine serum albumin was applied to evaluate the antifouling performance. During the three fouling-recovery cycles, the flux recovery ratio and the flux decay ratio maintained about 99% and 30%. The BSA flux and rejection were still 169 L m^?2 h^?1 and 96.9% after the cycles, indicating a superior antifouling property.     

Performance of surface ionic conduction single chamber fuel cell prepared by the sol gel method

The performance of surface ionic conduction single chamber fuel cell (SIC‐SCFC) prepared by the sol gel method was studied on electric characteristics due to the differences of the operating temperature and humidity, the electrode distance and electrolyte film depth, and multiple cells with the series and parallel connections. The SIC–SCFC was arranged the both anode of Pt and cathode of Au on the boehmite electrolyte. The open circuit voltage (OCV) of single cell achieved a maximum of 530mV in the dry gas mixtures of O₂/H₂=50% in room temperature operation, and but it became decrease as over 60%. The OCV was maintained the constant value between operating temperatures of 30°C to 80°C, and but it was decreased sharply at over 90°C because a humidity on the cell became lower as increasing operating temperature. Then, the cell property was improved to 120°C by adding to the humidity of 70% using a humidifier. The electrode distance and the electrolyte film depth of SIC‐SCFC found to be contributed to the reductions of the cell resistance and the surface roughness on the electrode, respectively. Moreover, the power property of SIC‐SCFC was significantly improved by cell stacks comprised of the series or parallel connection of a cell.     

Surface sedimentation and adherence of Nano‐SiO2 to improve thermal stability and flame resistance of melamine‐formaldehyde foam via sol‐gel method

Melamine‐formaldehyde foam possesses intrinsic flame retardance; however, relative poor thermal stability and a certain amount of heat release rate restrict its applications in heated environment to a degree. In the present research, sol‐gel method has been adopted to precipitate nano‐SiO₂ particles on the surface of the melamine‐formaldehyde foam's fibers to construct a protective inorganic gel layer. Taking advantages of the shielding effects of the gel layer, the thermal‐oxygen degradation of the foam can be greatly retarded during heating; hence, the thermal stability is remarkably improved, and the flame retardance is further enhanced. In addition, introducing a small amount of membrane‐forming agent in the sol‐gel system can make the depositional nano‐SiO₂ particles well adhered to avoid dusting.     

UHMWPE/HDPE/纳米SiO2共混体系的毛细管挤出流变行为

采用毛细管流变仪,研究了超高分子量聚乙烯(UHMWPE)/高密度聚乙烯(HDPE)/纳米二氧化硅(SiO2)共混体系,及其对照组的流变行为和挤出过程中的不稳定流动现象,分析了共混物发生鲨鱼皮畸变和整体破裂的临界剪切应力和临界剪切速率的变化情况。结果表明,经过偶联剂改性的纳米SiO2粒子,在PE基质的共混体系中存在一定的界面黏附作用,降低了纳米共混体系的挤出胀大比,弹性特征减轻。这种界面相互作用限制了纳米共混材料在口模区域的黏性流动以及分子链离开口模后的构象恢复,降低了发生流动不稳定现象的临界剪切速率,发生鲨鱼皮畸变的临界剪切应力增大,整体破裂后,形成交替出现"鲨鱼皮-破裂"的振荡性变化外观。     

Polymers dynamics of the nonfluoro,nano-brush repelling agent with self-stratifying property in water-based coatings

While perfluoroalkyl acids (PFAAs), also known as C8s, are used extensively in textile repellent coatings, concerns have arisen for their carcinogenicity and hazardous effects on the environment. In this study, a novel water-based, nonfluoro, and nanobrush textile repelling agent was prepared by conventional sol–gel chemistry using amorphous fumed silica and n-octyltriethoxysilane as the starting materials. Minimal interaction between the designed repelling agent and marketed water-based resins was confirmed using linear viscosity region (LVR) analysis and asymmetric-flow field-flow fractionation (AF4), suggesting the self-stratification potential of the repelling agent. More specifically, the repelling agent exhibited excellent compatibility and self-stratifying ability with a force-emulsified acrylic-based resin, affording a water contact angle of 104.3° when incorporated at 7% solid content. Performance tests carried out on thermoplastic polyurethane (TPU) revealed excellent adhesion (100/100) of a final formulation, and a significant increase in water contact angle from 80.1° to 103.8° after treatment. In addition, the fouling area after the removal of a submerged sample from a mixture of slurry, polymer, and oil decreased from 48 to 1% when the repelling agent was added. Moreover, the sludge-fouling property remained unchanged after 1000 cycles of abrasion. These findings demonstrate the potential of the described nonfluoro, nanobrush repelling agent as an environmentally safe alternative for use with commercial resins, in turn realizing a fully water-based hydrophobic coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48003.     

Toward a continuous synthesis of porous carbon xerogel beads

A continuous process for producing porous carbon xerogel beads has been developed. It consists in injecting a pre‐cured aqueous solution of resorcinol and formaldehyde on top of a column filled with hot oleic acid. The latter is pumped on the top of the column and fed at the bottom, generating an upward flow that can be adjusted to match the terminal velocity of the settling beads. Thus, the bead residence time in the column can be adjusted to match the gelation time, allowing the beads to solidify before reaching the bottom of the vessel. The obtained beads are subsequently dried and pyrolyzed. The developed experimental setup proved the continuous synthesis of porous carbon beads is possible. Nevertheless, the shaping process caused various texture changes of the porous carbon, which mainly yields macropores instead of micro and mesopores. This process also leads to the build‐up of a denser skin around the beads. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1049–1058, 2018     

Preparation and characterization of novel addition cured polydimethylsiloxane nanocomposites using nano‐silica sol as reinforcing filler

A series of novel addition cured polydimethylsiloxane (PDMS) nanocomposites with various amounts of nano‐silica sol were prepared via hydrosilylation for the first time. The influence of various amounts of nano‐silica sol on the morphology, thermal behavior, mechanical and optical properties of these PDMS nanocomposites was studied in detail. It was found that with an increment in the amount of nano‐silica sol the reinforcing effect of the nano‐silica sol on the thermal and mechanical properties of the PDMS nanocomposites was very noticeable compared with the reference material. The prominent improvements in resistance to thermal degradation and mechanical properties can probably be attributed to the strong interaction of PDMS chains and uniformly dispersed particles resulting from the nano‐silica sol. However, the transparency of the PDMS nanocomposites slightly decreased with an increment in weight fraction of nano‐silica, compared with that of PDMS composite without nano‐silica (Sol‐0), which can probably be ascribed to an increasing size of the aggregated particles in the PDMS nanocomposites. The optimum amount of nano‐silica sol for preparing novel addition curing PDMS nanocomposites was about 15 wt%. © 2015 Society of Chemical Industry     

Preparation and characterization of ZrO2/PES hybrid ultrafiltration membrane with uniform ZrO2 nanoparticles

In current or next-generation reuse systems, the development of new classes of antifouling membranes is needed before viable membrane-based approaches for wastewater reclamation can be achieved. In this study, ZrO₂/PES hybrid ultrafiltration membranes with uniform ZrO₂ nanoparticles were prepared by combining an ion-exchange process with a traditional immersion precipitation process. Hydrous ZrO₂ sol was synthesized by addition of anion-exchange resin in N,N-dimethylformamide solvent containing zirconyl chloride. Homogeneous ZrO₂/PES casting solution was then obtained by dissolving PES polymer in the ZrO₂ sol. The existence and dispersion states of ZrO₂ nanoparticles in the resultant membrane matrix were examined by X-ray photoelectron spectrometer, thermogravimetric analysis, scanning electron microscope and transmission electron microscope. The results indicate that the ZrO₂ nanoparticles were well dispersed throughout the PES matrix and the diameter of the formed nanoparticles was about 5–10 nm. The hydrophilicity of the membranes was determined by measuring the contact angles. The antifouling property was determined by antifouling experiments and atomic force microscopy. The results confirm that the existence of ZrO₂ nanoparticles improves the hydrophilicity and reduces protein adsorption of membranes.