Sub-4 nanometer porous membrane enables highly efficient electrodialytic fractionation of dyes and inorganic salts
Jiuyang Lin, Zijian Yu, Tianci Chen, Junming Huang, Lianxin Chen, Jiangjing Li, Xuewei Li, Xiaolei Huang, Jianquan Luo, Elisa Y.M. Ang, William Toh, Peng Cheng Wang, Teng Yong Ng, Dong Han Seo, Shuaifei Zhao, Kuo Zhong, Ming Xie, Wenyuan Ye, Bart Van der Bruggen, Yinhua Wan
Abstract
During the synthesis of dyes, desalination of high-salinity dye-containing waste liquor is a critical premise for high-quality, clean dye production. Conventional membrane processes, such as electrodialysis, nanofiltration and ultrafiltration, are inevitably subjected to serious membrane fouling, deteriorating the dye/salt fractionation efficacy. Integrating the technical merits of electrodialysis and pressure-driven membrane separation, we devise an electro-driven filtration process using a tight ultrafiltration membrane as alternative to conventional anion exchange membrane for rapid anion transfer, in view of dye desalination and purification. By employing a sub-4 nanometer tight ultrafiltration membrane as anion conducting membrane, the electro-driven filtration process achieves 98.15% desalination efficiency and 99.66% dye recovery for one-step fractionation of reactive dye and NaCl salt, markedly outperforming the system using commercial anion exchange membranes. Notably, the electro-driven filtration system displays a consistently high and stable fractionation performance for dyes and salts with unprecedentedly low membrane fouling through an eight-cycle continuous operation. Our results demonstrate that the electro-driven filtration process using nanoporous membranes as high-performance anion conducting membranes shows a critical potential in fractionation of organic dyes and inorganic salts, unlocking the proof of concept of nanoporous membranes in electro-driven application.