高岭石-细菌-腐殖酸复合体对铅的吸附机理初探
首发时间:2017-05-11
摘要:本文研究了土壤矿物高岭石、细菌、腐殖酸及其二元、三元复合体对Pb(II)的吸附行为并探讨Pb(II)在复合体表面的吸附机理。静态实验结果表明,高岭石-细菌、高岭石-腐殖酸及高岭石-细菌-腐殖酸复合体对Pb(II)的吸附符合Langmuir方程。腐殖酸的加入促进高岭石、高岭石-细菌复合体对Pb(II)的吸附。EDTA对高岭石-细菌及高岭石-细菌-腐殖酸上Pb(II)的解吸率为60%。腐殖酸的加入,增加了高岭石表面的位点,但降低了高岭石-细菌复合体表面的位点浓度。吸附Pb(II)后,三元复合体中细菌的红外特征吸收峰强度增加,而高岭石的峰强降低。高岭石-细菌-腐殖酸复合体与Pb(II)的相互作用为放热反应,自发过程,反应动力为焓熵双驱动,且主要以氢键力,范德华力相互作用。
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Preliminary study on the adsorption mechanism of Pb(II) on the kaolinite-bacteria-humic acid composite
Abstract:In this study, the adsorption behavior of Pb(II) on kaolinite, bacteria (Pseudomonas putida), humic acid, and its binary/ternary composites were studied. The adsorption mechanism was also discussed. Results of static adsorption experiments revealed that the adsorption isotherms of Pb(II) on kaolinite-P. putida, kaolinite-humic acid, and kaolinite-P. putida-humic acid composites conformed to the Langmuir equation. The introduction of humic acid increased the adsorption of Pb(II) on kaolinite and kaolinite-bacteria composites. 60% of adsorbed Pb(II) can be desorbed by using EDTA as the desorbing agent. The introduction of humic acid increased the adsorption sites of kaolinite and decreased that of kaolinite-P. putida composite. As observed from the infrared absorption spectrum for the ternary composite, the intensity for characteristic absorption peak of bacteria increased and that for kaolinite decreased after the adsorption of Pb(II). Thermodynamics results showed that the adsorption of Pb(II) on kaolinite-P. putida-humic acid composite was a spontaneous and exothermic reaction. According to the estimated values of ?H and ?G, the binding of Pb(II) onto kaolinite-P. putida-humic acid was both enthalpy-driven and entropy-driven.
Keywords: soil science kaolinite bacteria humic acid adsorption mechanism
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