| Mar 11, 2021 |
Novel targeted modification strategy improves separation selectivity of polyamide nanofiltration membranes(Nanowerk News) Recently, a research group led by Prof. WAN Yinhua from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences developed a novel targeted modification strategy to improve the separation selectivity of polyamide nanofiltration (NF) membranes. |
| The study was published in Journal of Membrane Science ("Targeted modification of polyamide nanofiltration membrane for efficient separation of monosaccharides and monovalent salt"). |
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| Diagram of targeted modification of polyamide nanofiltration membrane. (Image: WANG Jingyu) (click on image to enlarge) |
| The low selectivity of commercial NF membranes to monosaccharides and monovalent salts is mainly due to the nonuniform pore size distribution and strong electronegativity. |
| Targeted modification can regulate the pore size distribution and electronegativity of polyamide NF membranes, and thus improve the separation selectivity. |
| In the strategy, carboxyl groups (-COOH) on the surface are activated by N-(3-Dimethylaminopropyl)-N'-ethyl carbodiimide (EDC) and N-Hydroxy succinimide (NHS), and subsequently grafted onto monomer or polymer containing amino groups (-NH2) for more precise separation. |
| The novel targeted modification strategy reduced the effective mean pore size while maintaining the porosity of the NF membrane, due to pore segmentation. This resulted in a remarkable improvement in glucose/fructose rejection (from 67.96% to 84.14%) and separation factor (from 2.20 to 6.78), with only a 4.70% permeability loss. |
| "The outcome of this work not only improves the separation efficiency of small organic and inorganic salts by NF, but also provides a new perspective in regulating pore size distribution and surface charge of NF membranes for precisely separating small molecules,” said Prof. LUO Jianquan from IPE, the corresponding author of the study. |
| The modified membrane also maintained separation performance in crossflow filtration and after alkaline cleaning, which outperformed the pristine NF membrane and those modified by uniform coating and simple physical adsorption. |
| Source: Chinese Academy of Sciences | |
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