Due to their unique surface characteristics, oil-water separation membranes with superhydrophilic and underwater superoleophobic properties have promising applications in oil-water separation processes. However, the microstructure and chemical composition of the material surfaces are prone to degradation in harsh environments. This article employs nanosecond laser etching to improve the deposition quality of fumed SiO 2 for the fabrication of superhydrophilic and underwater superoleophobic separation membranes. Various analytical methods are used to characterize the separation membranes. Nanosecond laser etching creates rough, ripple-like microstructures on stainless steel mesh, which not only enhances the deposition of fumed SiO 2 but also minimizes the interaction between solids and oil. This results in improved wetting characteristics and underwater oil repellency, significantly boosting both the performance and durability of the membrane. The prepared separation membrane demonstrated an average separation efficiency of 99.4% across five different oil-water mixtures, with all separation fluxes exceeding 58000 L·m⁻²·h⁻¹. After soaking in an acid-base solution for 15 days and undergoing 25 friction tests, the underwater oil contact angle was maintained at 156.3°, demonstrating high separation efficiency and outstanding stability, with significant potential for application, particularly in harsh environments.
The effects of molecular size on SiO 2 deposition regulated surface barriers and zeolite catalysis are probed, taking n -pentane isomerization and benzene alkylation with ethylene as model reactions. Chemical liquid deposition of SiO 2 on the parent ZSM-5 sample only modifies its external surface slightly and passivates a small proportion of Brønsted acid sites. The apparent diffusivities increase significantly at 363–393K after SiO 2 deposition, indicating SiO 2 on ZSM-5 crystals reduces surface barriers at low temperatures. The conversion for n -pentane isomerization increases by up to 26% after SiO 2 deposition, while the conversion for benzene alkylation decreases by up to 19%. Obviously, the positive effect of SiO 2 deposition can be balanced out by the pore confinement effect at high temperatures, which is stronger for a larger molecule. This work provides a unique understanding of molecular size effects on surface barriers, which should serve to guide the design of zeolite catalysts. Graphical Abstract
危险品化学品经营许可证（带存储）