Partitioning of clay colloids at air-water interfaces

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:247

Article

Wan, JM ; Tokunaga, TK

关键词: colloids;    air-water interface;    partitioning coefficient;    bubble-column;    kaolinite;    montmorillonite;    illite;    latex microspheres;    pH-dependent charges;   

DOI  :  10.1006/jcis.2001.8132

来源: Elsevier

【 摘 要 】

Colloid sorption onto air-water interfaces in a variety of natural environments has been previously recognized, but better quantification and understanding is still needed. Affinities of clay colloids for the air-water interface were measured using a bubble-column method and reported as partition coefficients (K). Four types of dilute clay suspensions were measured in NaCl solutions under varying pH and ionic strength conditions: kaolinite KGa-1, illite IMt-2, montmorillonite SWy-2, and bentonite. The K values of three types of polystyrene latex particles with different surface-charge properties were also measured for comparison. Kaolinite exhibited extremely high affinity to the air-water interface at pH values below 7. Illite has lower affinity to air-water interfaces than kaolinite, but has similar pH dependence. Na-montmorillonite and bentonite clay were found excluded from the air-water interface at any given pH and ionic strength. Positively and negatively charged latex particles exhibited sorption and exclusion, respectively, at the air-water interface. These results show the importance of electrostatic interactions between the air-water interface and colloids, especially the influence of pH-dependent edge charges, and influence of particle shape. (C) 2002 Elsevier Science (USA).

【 授权许可】

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