土壤中磁铁矿对Cr(Ⅵ)还原菌吸附行为的研究

Study on the adsorption behavior of magnetite to Cr(Ⅵ)reducing bacteria in soil

土壤矿物和土壤微生物都是土壤环境的重要组成部分。土壤中存在的Cr(Ⅵ)还原菌在矿物上的吸附行为可能会影响土壤中Cr(Ⅵ)的还原及铬的迁移。研究选取土壤中典型矿物(磁铁矿)为研究对象,探讨了其对Cr(Ⅵ)还原菌QH-2的吸附行为。在试验过程中,测定不同pH值条件下磁铁矿对菌株的吸附量及Zeta电位。使用扫描电镜、傅立叶变换红外光谱仪对吸附菌株后的磁铁矿进行表征。结果表明:磁铁矿可以吸附菌株QH-2,且吸附后晶体结构没有改变;菌株同磁铁矿的吸附在接触1 h后基本达到稳定,且磁铁矿对菌株的最高吸附量能达到129 mg/g。随pH值变化(6~10),磁铁矿对菌株吸附量先上升后下降。傅立叶变换红外光谱图表明磁铁矿吸附菌株后,特征峰位置无明显变化。研究表明磁铁矿能有效地吸附菌株QH-2,且二者吸附以静电作用为主,不涉及价键变化。

Both soil minerals and soil microorganisms are important components of the soil environment.The adsorption behavior of Cr(VI)-reducing bacteria on soil minerals may affect the reduction of Cr(VI)and migration of chromium in the soil environment.The purpose of this paper is to investigate the adsorption behavior of Cr(VI)-reducing bacteria on soil minerals.In this study,the typical mineral(magnetite)in the soil environment was selected as the research object to explore its adsorption behavior on strain QH-2 which belonged to the typical Cr(VI)reducing bacteria and was isolated from the soil contaminated by chromium residue.In the process of the experiment,magnetite and strain QH-2 were incubated together.The adsorption capacity of strain QH-2 by magnetite and the Zeta potential at different pH(6-10)were measured.After incubation,magnetite was characterized by the scanning electron microscope and the Fourier transform infrared spectroscopy(FT-IR).The obtained results demonstrated that magnetite could adsorb strain QH-2,and its crystal structure did not change after adsorption.The adsorption of strain by magnetite reached a rough stability after 1 h of incubation,and the highest adsorption capacity of the strain by magnetite could reach 129 mg/g.When the pH changed from 6 to 10,the adsorption capacity of the magnetite to strain QH-2 increased,and then decreased.The Fourier transform infrared spectrogram showed that there was no obvious change in the position of the characteristic peak after the magnetite adsorbed the strain.This study showed that magnetite could effectively adsorb the strain QH-2,and the adsorption between magnetite and strain QH-2 was mainly electrostatic.This adsorption did not involve changes in valence bonds.This study helps to deepen the understanding of the interaction between minerals,Cr(Ⅵ)reducing bacteria and chromium in the soil environment,and can also provide a theoretical basis for Cr(Ⅵ)reducing bacteria to repair chromium contaminated soil.