TY - JOUR
T1 - Effect of magnesium ion on polysaccharide fouling
AU - Wang, Rui
AU - Liang, D.
AU - Liu, Xiaoxing
AU - Fan, Wenhong
AU - Meng, Shujuan
AU - Cai, Weiwei
N1 - Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Polysaccharides have been recognized as a significant type of foulant due to their gelling property which is deeply affected by the existence of divalent cations. However, the effect of magnesium ion on polysaccharides fouling remains largely unknown and results reported by the limited studies are even controversial. In this study, alginate samples were employed to systematically study the effect of Mg2+ on polysaccharides fouling. Four levels of alginates were studied and results led to the same conclusion that the presence of Mg2+ aggravated fouling problems during membrane filtration. Cross-validation of filtration resistances, modelling of filtration data and autopsy of fouled membrane revealed that gel layer formation was the dominant fouling mechanism at the presence of Mg2+. Further analysis showed that the gel layer development strongly depended on the crosslinking of alginate. Moreover, crosslinking of alginate was enhanced by the Mg2+-alginate interaction including Mg2+⋯O(COO−) bonds, Mg2+⋯O(OH) bonds and sharing water molecules from the first coordination shell of Mg2+ with the carboxylate groups of alginate. Increased crosslinking of alginates resulted with the formation of networks with larger effective dimension and more complex three dimension structure, i.e. the transparent exopolymer particles (TEP). TEP promoted the gel layer formation on membrane. Emphasis is given to the link between the Mg2+-polysaccharide interaction and the fouling propensity of polysaccharides. Consequently, understanding the interaction between cations and organic foulants is important, which would provide an insightful guidance for fouling control.
AB - Polysaccharides have been recognized as a significant type of foulant due to their gelling property which is deeply affected by the existence of divalent cations. However, the effect of magnesium ion on polysaccharides fouling remains largely unknown and results reported by the limited studies are even controversial. In this study, alginate samples were employed to systematically study the effect of Mg2+ on polysaccharides fouling. Four levels of alginates were studied and results led to the same conclusion that the presence of Mg2+ aggravated fouling problems during membrane filtration. Cross-validation of filtration resistances, modelling of filtration data and autopsy of fouled membrane revealed that gel layer formation was the dominant fouling mechanism at the presence of Mg2+. Further analysis showed that the gel layer development strongly depended on the crosslinking of alginate. Moreover, crosslinking of alginate was enhanced by the Mg2+-alginate interaction including Mg2+⋯O(COO−) bonds, Mg2+⋯O(OH) bonds and sharing water molecules from the first coordination shell of Mg2+ with the carboxylate groups of alginate. Increased crosslinking of alginates resulted with the formation of networks with larger effective dimension and more complex three dimension structure, i.e. the transparent exopolymer particles (TEP). TEP promoted the gel layer formation on membrane. Emphasis is given to the link between the Mg2+-polysaccharide interaction and the fouling propensity of polysaccharides. Consequently, understanding the interaction between cations and organic foulants is important, which would provide an insightful guidance for fouling control.
KW - Crosslinking of polysaccharides
KW - Gel layer formation
KW - Magnesium ion
KW - Membrane fouling
KW - Transparent exopolymer particles (TEP)
UR - http://www.scopus.com/inward/record.url?scp=85069968519&partnerID=8YFLogxK
U2 - 10.1016/j.cej.2019.122351
DO - 10.1016/j.cej.2019.122351
M3 - Article
AN - SCOPUS:85069968519
SN - 1385-8947
VL - 379
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
M1 - 122351
ER -