柠檬酸替代EDTA清洗对反渗透膜海藻酸钙污染的研究

Study on Calcium Alginate Fouling of Reverse Osmosis Membrane by Citric Acid Replacing EDTA Cleaning

反渗透膜在工业水处理过程中会被水中杂质污染,EDTA作为有效的清洗剂之一,因成本高、环境危害程度大等原因,在工业大规模使用具有一定局限性。选用海藻酸钙为特征污染物对反渗透膜进行快速污染,以EDTA和柠檬酸作为清洗剂进行清洗,并对比清洗效果。研究发现,EDTA溶液在pH为11.5、柠檬酸盐在pH高于4.5的情况下,均对膜通量恢复有明显作用,并且高浓度的柠檬酸清洗效果更好。从实验结果推测,柠檬酸在合适的pH条件下,与海藻酸钙中的钙离子结合,破坏有机-无机大分子的紧密结构,引起污染层松动,实现污染物(海藻酸钙)的去除,为工业上替代EDTA清洗被有机-无机络合物污染的反渗透膜提供借鉴和参考。

The reverse osmosis membrane will be polluted by impurities in water during industrial water treatment.EDTA,one of the effective cleaning agent,is limited in the large-scale use in industry membrane cleaning field because of the high cost and harm to the environment.Alginate-calcium was selected as the characteristic pollutant to quickly pollute the RO membrane.EDTA and citric acid were used as cleaning agents to clean the RO membrane,and the cleaning effect was compared.The results showed EDTA solution at pH=11.5 and citric acid at pH>4.5 had a high contribute to membrane flux recovery,and higher concentration of citric acid solution corresponded higher cleaning efficiency.From the experimental results,it is speculated that citric acid can combine with calcium ions in calcium alginate under appropriate pH conditions to destroy the tight structure of organic and inorganic macromolecules,cause the loosening of pollution layer,and realize the removal of pollutants(calcium alginate).This research provides the references for industrial cleaning of RO membranes contaminated by organic-inorganic complex instead of EDTA.