In this work, nanofiltration membrane with an asymmetric selective separation layer and improved surface negative charge was designed and fabricated to efficient remove anionic dyes from aqueous solution. Firstly, loose polyester selective separation layer was formed through interfacial polymerization of triethanolamine and trimesoyl chloride. Surface carboxylation was then implemented via esterification using poly(acrylic acid) to generate a dense skin. Membrane characterizations verified the asymmetric structure and enrichment of surface carboxyl group, which endowed the carboxylated membrane with improved perm-selectivity and anti-dye-deposition property to anionic dye aqueous solutions. The desired surface carboxylated membrane exhibited 99.6% methyl blue removal, 8.05 l/m 2 h bar steady-state water permeability and 14.3% relative flux decline ratio under 5.0 bar. The water permeability of carboxylated membrane to methyl blue aqueous solution was higher than those of most reported membranes and even at least two times higher than that of the polyester-based membrane having nearly the same dye removal ability. The attractive results indicate that surface carboxylated polyester based thin-film composite membrane is a promising material for high-efficiency nanofiltration of anionic dye aqueous solution. This study provides valuable insights into the construction and fabrication of high performance nanofiltration membrane for efficient treatment of anionic dye aqueous solution.
The development of high performance membrane is crucial for enhanced separation efficiency of nanofiltration process in treating wastewaters from dye and textile industries. In this work, a novel thin-film composite nanofiltration membrane with an asymmetric separation layer composed of relatively compact skin and loose body was designed and fabricated for improved perm-selectivity and antifouling property. Nascent composite membrane with loose poly(piperazine amide) (PA) separation layer was interfacially synthesized and performed with secondary surface reaction using an aqueous tannic acid (TA) solution. Membrane characterizations verified the formation of compact TA skin on top of the loose PA layer through forming covalent bonds via esterification reaction. Compared with the composite nanofiltration membrane with PA symmetric separation layer having the same glucose rejection of about 82.0%, the permeability to pure water of the composite membrane with PA/TA asymmetric separation layer was higher by 28.0%, the water fluxes to aqueous solutions dissolved with model anionic dyes of alizarin yellow R, sunset yellow and Congo red under steady state were higher by 50.3, 43.9 and 36.1%, and the steady-state flux declines were lowered by 27.8, 43.4 and 23.5%, respectively. Furthermore, the PA/TA-based membrane also exhibited better antifouling property and rejection ability to alizarin yellow R.
危险品化学品经营许可证（带存储）