Cellulose Acetate-Based Polyamide Nanofiltration Membranes by Diethylenetriamine-Assisted Interfacial Polymerization for Effective Removal of Dyes and Salt Ions
Yaling Lin, Minfu Mo, Junkang Lin, Xiaojuan Ma, Yubin Hong, Lihui Chen, Dong Wang, Lili Huang
Abstract
In this study, cellulose acetate (CA)-based polyamide (PA) nanofiltration membranes (CA-NF-2/0.4) with enhanced antifouling and separation performance were prepared through the interfacial polymerization of diethylenetriamine (DETA) and 1,3,5-benzenetricarbonyl chloride (TMC) for the effective removal of dyes and salt ions. Benefiting from the three reaction sites (primary and secondary amino groups) of DETA, a PA layer with a three-dimensional network structure formed on the CA substrate, imparting the CA-NF-2/0.4 membranes with a strong negative charge (−24.8 mV at pH 7) and a defect-free morphological feature. Consequently, the CA-NF-2/0.4 membranes exhibited high removal efficiencies for various dyes (99% for Rose Bengal and Congo Red, 95.5% for Methyl Orange, and 96.1% for Methylene Blue), as well as various monovalent and divalent salts, including MgCl 2 (84.2%), Na 2 SO 4 (92.7%), MgSO 4 (91.8%), and NaCl (54.1%). Additionally, the CA-NF-2/0.4 membranes demonstrated excellent antifouling properties [the flux recovery ratio (flux recovery rate > 98.5%), long-term durability, and stability under high operational pressures and salt concentrations] due to their good hydrophilicity (water contact angle of 39.8°) and the hydrogen bonding interaction between the active amine groups of DETA and the –OH groups of the CA support layer. This study presents an effective method for fabricating cellulose-based NF membranes with high separation and antifouling performance, offering insights into the high-value utilization of cellulose-based materials.