An asymmetric alumina ceramic membrane was prepared by secondary dip coating. The influence of different dispersants and dip coating parameters on the microstructure of the membrane separation layer was explored. Meanwhile, the pure water fluxes of the membranes with various microstructures were also studied. The results show that a separation layer with a defect-free thickness of 16.5 μm and high surface flatness can be obtained when using polycarboxylate as a dispersant and twice dip coating within 2 s + 1 s and the pure water flux of an asymmetric membrane up to 1153 L × m-2 × h-1 × bar-1. The present work provides a simple and effective method for controlling the morphology and permeation performance of an asymmetric alumina membrane.

In order to solve the poor structural stability of graphene oxide (GO) membrane, a facile and effective cross-linking technology was employed to create a high-performance GO membrane. Herein, DL-Tyrosine/amidinothiourea and (3-Aminopropyl) triethoxysilane were used to crosslink GO nanosheets and porous alumina substrate, respectively. The group evolution of GO with different cross-linking agents was detected via FTIR. Ultrasonic treatment and soaking experiment were conducted to explore the structural stability of the different membranes. The GO membrane cross-linked with amidinothiourea exhibits exceptional structural stability. Meanwhile, the membrane has superior separation performance, with the pure water flux reaching approximately 109.6 L∙m-2∙h-1∙bar-1. During the treatment of 0.1 g/L NaCl solution, its permeation flux and rejection for NaCl are about 86.8 L∙m-2∙h-1∙bar-1 and 50.8%, respectively. The long-term filtration experiment also demonstrates that the membrane exhibits great operational stability. All these indicate the cross-linking graphene oxide membrane has promising potential applications in water treatment.