Terrestrial environment

Sorption of Triton X-100 on soil organic matter fractions:Kinetics and isotherms


ZHANG Guangzhi , HU Hao , SUN Weiling , NI Jinren

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Received June 29, 2008,Revised October 28, 2008, Accepted , Available online

Volume 21,2009,Pages 795-800

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Kinetics and isotherms of Triton X-100 sorption on soil, base-extracted soil (BE), humic acid (HA) and humin (HM) were investigated respectively to get better understanding on characteristics of the surfactant sorption onto di erent soil organic matters (SOMs). It was demonstrated that the kinetics results could be satisfactorily described by the pseudo-second order model. The half of the time to reach equilibrium (t1=2) for di erent sorbents followed the sequence of soil > HA > BE > HM. Furthermore, the calculated equilibrium sorption capacity (Ceq) was found in the sequence of HA > BE > HM > soil, which agreed well with the experimental results. The isotherms of Triton X-100 sorption on soil and HA could be well described by the S-type isotherm, but BE and HM by the L-type. The isotherms of all the four sorbents were found reasonably fitted to the Langmuir equation. The Kd value, defined as the ratio of Triton X-100 in sorbent and in the equilibrium solution for given concentrations, generally followed the order of HM > HA > soil > BE. Separated HM and HA showed high a nity for Triton X-100, but the HA and HM in soil and BE were tightly bounded by the minerals. Thus, the HA on the soil surface might dominate the sorption, whereas the bounded HM would play a key role upon the surfactants being penetrated inside the soil.

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