嗜麦芽窄食单胞菌对铜镉的吸附特性与离子交换

研究了投菌量、金属浓度和戊二醛浓度对嗜麦芽窄食单胞菌吸附水体中Cu2+和Cd2+特性的影响,分析了重金属生物吸附、NO3-去除与菌体离子释放的关联,从离子吸附、交换、转化与释放的角度探讨了重金属生物吸附机制.结果表明嗜麦芽窄食单胞菌对Cu2+和Cd2+吸附性能良好,0.2 g·L-1干重菌体处理浓度为0.05 mmol·L-1的Cu(NO3)2和Cd(NO3)2溶液120 min后,Cu2+和Cd2+的吸附率分别达96.3%和83.9%.菌体对Cu(NO3)2和Cd(NO3)2溶液的吸附过程存在Cu2+和Cd2+的表面吸附与胞内运输、NO3-胞内积累、NO3-还原为NO2-等行为,而且Cu2+和Cd2+的胞内运输、NO3-积累和还原需要消耗能量,并会促进Cl-、PO43-、SO42-、Na+、NH4+、K+和Ca2+等离子的释放.红外光谱分析表明菌体酰胺基、羟基与羧基均参与了Cu2+和Cd2+的吸附.X-光电子能谱分析显示吸附后Cu2+和Cd2+的价态不发生变化.

Characteristic and Ion Exchanges During Cu2+and Cd2+ Biosorption by Stenotrophomonas maltophilia

The characteristics of Cu²⁺and Cd²⁺ biosorption by Stenotrophomonas maltophilia (S. maltophilia) under different biomass, metal concentration and glutaraldehyde content were studied and the correlations among metal biosorption, NO₃^- removal and ion release were analyzed. The mechanism was explored through ion biosorption, exchange, conversion and release. The experimental results demonstrated that S. maltophilia was an efficient strain to remove Cu²⁺ and Cd²⁺. The biosorption efficiencies of Cu²⁺ and Cd²⁺ achieved 96.3% and 83.9%, respectively after dealing with 0.05 mmol·L^-1 aqueous solutions for 120 min with dry biosorbent dosage of 0.2 g·L^-1. Cu²⁺ and Cd²⁺ biosorption by S. maltophilia included surface adsorption, transmembrane active transportation, bioaccumulation of NO₃^- and reduction of NO₃^- to NO₂^-. The intracellular transfer and reduction of NO₃^- to NO₂^- during biosorption by S. maltophilia were energy-consuming biological processes. It could also promote the release of Cl^-, PO₄^3-, SO₄^2-, Na⁺, NH₄⁺, K⁺ and Ca²⁺. From FTIR investigation, involvement of various functional groups like acetylamino, hydroxyl and carboxyl in the binding of Cu²⁺ and Cd²⁺was evident. Moreover, XPS results proved that the valence state of Cu²⁺ and Cd²⁺ did not changed by biosorption.