噻吩磺隆在土壤中的吸附及表面活性剂对吸附的影响

Adsorption of Thifensulfuron in Soils and Influence of Surfactants to Adsorption

采用批量平衡法研究了噻吩磺隆在3种土壤中的吸附行为,并探讨了阴离子表面活性剂SDS、阳离子表面活性剂CTAB和非离子表面活性剂Tween-80对噻吩磺隆在红壤中吸附的影响。结果表明,噻吩磺隆在3种土壤中的吸附可用Freundlich方程来描述,噻吩磺隆在3种土壤中的吸附常数Kf值在0.2483～6.5819之间,这说明噻吩磺隆在土壤中的吸附性较弱。土壤pH值对噻吩磺隆在土壤中的吸附影响较大,土壤pH值越大,其吸附量越小。表面活性剂的加入可明显地改变红壤对噻吩磺隆的吸附能力,其中SDS和CTAB均能够增加红壤对噻吩磺隆的吸附量,但SDS和CTAB对红壤吸附噻吩磺隆的影响情况不尽相同,红壤对噻吩磺隆吸附量的增加程度会随着SDS添加浓度的升高而减少,而随着CTAB的浓度增加,红壤对噻吩磺隆吸附量的增加程度则会增大;非离子表面活性剂Tween-80则可减少红壤对噻吩磺隆的吸附量,而且当Tween-80的添加浓度在其临界胶束浓度左右时,其减少量最小。

Batch equilibrium adsorption was conducted to measure the adsorption of thifensulfuron in three tested soils and the influence of surfactants on adsorption of thifensulfuron was probed in krasnozem. The results showed all of the adsorption isotherms of thifensulfuron in three tested soils could be described by Freundlich equation, adsorption coefficients（Kf） ranged from 0.248 3 to 6.581 9, and the extent of ad- sorption of thifensulfuron in soils as followed： krasnozem〉 fiver cultivated fluviogenie soil〉brown soil. Thifensulfuron was a weak adsorption herbicide in three tested soils, and the pH value of soil was the major effect factor to adsorption of thifensulfuron. It was changed that the ability of adsorption to thifensulfuron in krasnozem after surfactants added. In comparison with the surfactant-free system, anionic surfactant sodium dodecyl sulfate （SDS） and cationic surfactant hexadecyl trimethyl ammonium bromide（CTAB） could increase adsorption of thifensulfuron in krasnozem, at the scope of three added concentrations of SDS, 1 200 mg·L^-1 was the largest one that increased adsorption amount of thifensulfuron, 2 400 mg·L^-1 was the second one and 3 600 mg·L^-1 was the last one, and the orders of influences of CTAB were 500 mg·L^-1〉 300 mg·L^-1〉100 mg·L^-1. Non-ion surfactant Tween-80 could decrease the adsorption of thifensulfuron in krasnozem, and when the added concentrations approached CMC of Tween-80, the adsorption amount of thifensulfuron was higher than others added concentrations.