Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/16/2006
Publication Date: 11/16/2006
Citation: Aggarwall, V., Lil, H., Teppen, B., Boyd, S., Johnston, C.T., Laird, D.A. 2006. Influence of Smectite Hydration and Interlayer Cation on Substituted Benzenes Sorption [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts, ASA-CSSA-SSSA Annual Meeting, November 12-16, 2006, Indianapolis, IN. 2006 CDROM. Interpretive Summary:
Technical Abstract: Smectite clays demonstrate a high affinity with organic contaminants and pesticides from water. Recent research has shown that the extent of crystalline swelling (or interlayer hydration status) along with surface charge density and exchangeable cations plays a determinant role in controlling the sorption of organic pollutants by smectites. This study was undertaken to determine the effect of clay hydration on the sorption of 1,3-dinitrobenzene (DNB) and dimethyl 1,3-benzenedicarboxylate (DMB) by a reference Wyoming smectite saturated with potassium (K+) and calcium (Ca2+). The results indicate that Ca2+-saturated never-dried clay had higher DNB sorption than Ca2+-saturated freeze-dried clay, while the opposite was observed for DMB. In case of K+-saturated clay, there was no apparent difference between freeze-dried and never-dried clays in sorption of DNB and DMB. For both compounds, K-saturated clays sorbed more than Ca-saturated clays. This can be attributed to the lower hydration energy and hence smaller hydrated radius of K+, which maximizes the siloxane surface available for sorption. The relatively weak hydration of K causes K-saturated clay to swell less in water, thus providing a more favorable sorption domain that may allow the organic substances to compete better with water for coordination sites around the cations.