Efficient removal of anionic dye by constructing thin-film composite membrane with high perm-selectivity and improved anti-dye-deposition property

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/m2 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.