Thermodynamic mechanism insights into the dynamic evolution of nanofiltration membrane fouling: Effect of calcium ion on organic fouling

• Published in: Desalination 2023-12, Vol.568, p.117036, Article 117036
• Main Authors: Chen, Yunhuan, Zhang, Rui, Wu, Guanxiao, Li, Jiapeng, Ren, Yongsheng, Duan, Xiaoxiao
• Format: Article
• Language: English
• Subjects: Anionic polyacrylamide; Calcium ion; Membrane fouling; Nanofiltration; Thermodynamic mechanism
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2023.117036

To better control nanofiltration (NF) membrane fouling during mine water treatment, an accurate elaboration of the fouling mechanisms of anionic polyacrylamide (APAM) coexisted with Ca2+ and fulvic acid (FA) is vital. An attractive phenomenon was observed during the membrane fouling tests: When Ca2+ and FA coexist with APAM, increasing Ca2+ concentration at high Ca2+ concentration will alleviate membrane fouling. The degree of membrane fouling is determined by the interaction of the foulant with the membrane and is closely related to the Lewis acid-base (AB) interaction energy. At the shortest separation distance, the AB interaction energy decreased from 3608 kT to −17,386 kT when the Ca2+ concentration was increased from 0 mM to 2 mM, then increased to −14,385 kT when the Ca2+ concentration was further increased to 6 mM. The change in AB interaction energy explains the dynamic evolution of the membrane fouling phenomenon. This work elucidates the effects of high Ca2+ concentrations on organic fouling and will benefit the better understanding of the efficient NF processes when multiple pollutants coexist. [Display omitted] •The membrane fouling behavior of single and multiple foulants was investigated.•Experiments showed that high Ca2+ concentration alleviated membrane fouling.•Fouling is determined by the interaction between the initial foulant and membrane.•AB interaction energy is the dominant factor in the evolution of membrane fouling.