聚酰胺纳滤膜表面羧基密度调控及其抗污染性能

Regulation of carboxyl density in polyamide nanofiltration membranes and study of anti-fouling performances

采用均苯三甲酰氯(TMC)、对苯二甲酰氯(IPC)与哌嗪进行界面聚合反应,制备了不同羧基密度的聚酰胺纳滤膜.研究了羧基密度对膜污染的影响,并对纳滤膜的镁-锂分离选择效果进行评估.结果表明,TMC纳滤膜的羧基密度是IPC纳滤膜的3倍,水通量分别为81.9 L/(m^(2)·h·MPa)和56.5 L/(m^(2)·h·MPa).TMC纳滤膜对硫酸镁、氯化钠的截留效果优于IPC纳滤膜,对卤水镁的截留率达82.66%,对锂的截留率为-27.82%,具有较好的镁-锂分离选择效果.膜污染结果显示,TMC纳滤膜的不可逆通量衰减指数是IPC纳滤膜的3倍,抗污染能力与膜面羧基密度成反比.结果证实了膜面羧基官能团在膜污染中的关键作用,为制备具备抗污染性和高镁-锂分离比的纳滤膜提供了新思路.

This study employed trimesoyl chloride,isophthaloyl chloride,and piperazine to conduct interfacial polymerization,resulting in polyamide nanofiltration membranes with varying carboxyl group densities.The impact of carboxyl group density on membrane fouling and separation performance of magnesium and lithium were thoroughly investigated.The results revealed that the carboxyl group density in trimesoyl chloride-based membrane(TMC)was three times higher than that in isophthaloyl chloride-based membrane(IPC).Furthermore,the flux of TMC,IPC membranes were 81.9 L/(m^(2)·h·MPa)and 56.5 L/(m^(2)·h·MPa),respectively.Notably,the TMC membrane exhibited superior retention for magnesium sulfate and sodium chloride compared to the IPC membrane,achieving a retention rate of 82.66%for magnesium in brine and-27.82%for lithium.Moreover,the membrane fouling indicated that the irreversible flux reduction rates of the TMC membrane was three times higher than that of the IPC membrane,suggesting an inverse correlation between anti-fouling capability and carboxyl group density on membrane surfaces.These results validate the pivotal role of surface carboxyl functional groups in membrane fouling,providing critical insights for the development of anti-fouling and highly selective nanofiltration membranes.