New insights into the humic acid fouling mechanism of ultrafiltration membranes for different Ca2+ dosage ranges: results from micro- and macro-level analyses

Water Science and Technology : a Journal of the International Association on Water Pollution Research
Rui MiaoTingting Liu

Abstract

To reveal the mechanisms of the influence of Ca2+ on membrane fouling with humic acid (HA), the adhesion forces of HA with both other HA molecules and the membrane, the HA fouling layer structure, HA fouling experiments, and the HA rejections at a wide range of Ca2+ dosages were investigated. The results indicated that the effect of Ca2+ on HA fouling can be divided into three stages. At lower ionic strength (IS) of CaCl2, the change in electrostatic forces is the main factor in controlling HA fouling behavior; i.e., increasing Ca2+ dosages resulted in more serious membrane fouling. When the IS of CaCl2 reached 10 mM, HA aggregates became the dominant factor in the fouling process, which could result in a porous fouling layer accompanied by less membrane fouling. Interestingly, much weaker membrane fouling was observed when the IS increased to 100 mM and the HA rejection began to decline. This was because a stronger hydration repulsion force was generated, which could weaken the compactness of the fouling layer and the adhesion forces of HA with both the membrane and HA, while enabling smaller-sized HA to pass more easily into the permeate, which led to less membrane fouling and a lower HA rejection.

References

Mar 23, 2005·Journal of Colloid and Interface Science·Gurdev Singh, Lianfa Song
Aug 30, 2008·Environmental Science & Technology·Hiroshi YamamuraYoshimasa Watanabe
Oct 30, 2010·Colloids and Surfaces. B, Biointerfaces·Yun ShenQingyun Li
Aug 21, 2013·Environmental Science & Technology·Xiaojun Chang, Dermont C Bouchard

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Citations

Sep 23, 2020·Water Science and Technology : a Journal of the International Association on Water Pollution Research·A L CarlsonE Hart

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