Influence of ionic strength and pH on the limitation of latex microsphere deposition sites on iron-oxide coated sand by humic acid

Author(s)

Thilo Hofmann, Frank von der Kammer, Xingyao Yang, Ray Flynn

Abstract

This study, for the first time, investigates and quantifies the influence of slight changes in solution pH and

ionic strength (IS) on colloidal microsphere deposition site coverage by Suwannee River Humic Acid

(SRHA) in a column matrix packed with saturated iron-oxide coated sand.

Triple pulse experimental (TPE) results show adsorbed SRHA enhances microsphere mobility more at

higher pH and lower IS and covers more sites than at higher IS and lower pH. Random sequential

adsorption (RSA) modelling of experimental data suggests 1 mg of adsorbed SRHA occupied

9.28 0.03 109 sites at pH7.6 and IS of 1.6 mMol but covered 2.75 0.2 109 sites at pH6.3 and IS of

20 mMol. Experimental responses are suspected to arise from molecular conformation changes whereby

SRHA extends more at higher pH and lower ionic strength but is more compact at lower pH and higher IS.

Results suggest effects of pH and IS on regulating SRHA conformation were additive.

Organisation(s)

External organisation(s)

Queen's University Belfast

Journal

Environmental Pollution

Volume

159

Pages

1896-1904

No. of pages

9

ISSN

0269-7491

Publication date

2011

Peer reviewed

Yes

Austrian Fields of Science 2012

105303 Hydrogeology, 104023 Environmental chemistry, 105105 Geochemistry, 105904 Environmental research

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