A research team led by Prof. Wan Yinhua at the Institute of Process Engineering (IPE), Chinese Academy of Sciences, has developed a groundbreaking mix-charged nanofiltration (NF) membrane that promises to revolutionize wastewater treatment, especially for high-salinity organic waste. This novel membrane, featuring a horizontal charge distribution, exhibits exceptional performance in salt permeation, organic matter retention, and antifouling properties, making it an ideal solution for treating complex, high-salinity wastewater.
The findings were published in Environmental Science & Technology on January 7, shedding light on a new approach to overcoming the limitations of traditional NF membranes in wastewater treatment.
Efficient treatment of high-salinity organic wastewater is critical for achieving zero discharge and advancing resource recovery. Conventional NF membranes are effective in separating organic contaminants and monovalent salts but often struggle with the over-rejection of divalent salts. While modifying the charge characteristics of NF membranes has been explored to improve salt permeation, the spatial distribution of charge within these membranes had not been thoroughly understood—until now.
In this new study, the research team designed an NF membrane with horizontal charge distribution, which allows for improved salt transport behavior and optimized filtration performance. The unique design incorporates a combination of interfacial polymerization, polyester template etching, and solvent-induced polyamine intercalation—methods that work together to create a membrane with a near-electroneutral surface. This enables the permeation of divalent salts while maintaining high rejection rates for small organic molecules.
One of the key highlights of this innovative membrane is its antifouling performance. Thanks to its distinctive charge distribution and smooth surface, the membrane shows impressive resistance to fouling from both negatively and positively charged pollutants. This reduces the need for frequent maintenance and ensures consistent performance over time.
When tested on high-salinity organic wastewater, the membrane demonstrated 58.6% salt permeation and 68.7% chemical oxygen demand (COD) rejection—results among the best reported for NF membranes in scientific literature.
Prof. Luo Jianquan, the corresponding author of the study, highlighted the significance of the findings: “Our membrane achieves 58.6% salt permeation and 68.7% COD rejection when treating high-salinity organic wastewater—among the best results reported for NF membranes in the literature.”
This breakthrough represents a significant step forward in the treatment of high-salinity wastewater. By enhancing the membrane’s ability to efficiently remove organic contaminants and salts, the technology holds promise for advancing resource recovery, improving wastewater management practices, and contributing to greater environmental sustainability. With further development and scaling, these mix-charged NF membranes could help pave the way for more efficient, cost-effective solutions in industries dealing with challenging wastewater conditions.
By Impact Lab
