枯草芽孢杆菌对Cu^(2+)的吸附及菌体表面基团分析

Study on adsorption of Cu^(2+) by Bacillus subtilis and quantitative determination of cell surface groups

以枯草芽孢杆菌(Bacillus subtilis)为生物吸附剂,讨论了其对Cu2+的生物吸附规律,并通过酸碱滴定这一表面分析手段,结合相关软件及傅里叶变换红外光谱(FTIR)分析了菌体表面主要的基团种类及数量。结果表明,枯草芽孢杆菌对Cu2+吸附的最佳条件是:pH为6、吸附时间为24h,菌悬液用量和Cu2+初始浓度根据实际情况加以选择,以期达到最佳处理效果并兼顾经济成本;菌体对Cu2+的吸附过程较好地符合Langmuir吸附模型,在设定条件(室温(25℃)、溶液pH为6、吸附时间为24h、Cu2+初始质量浓度为34.52mg/L、菌悬液用量为1.5mL)下,Cu2+的饱和吸附量可达到17.056mg/g;菌体表面带有—COOH、C=O、—OH、—NH、—CONH—、P—O—C等基团,且在酸碱滴定操作过程中,没有掩蔽菌体表面的某种基团,也没有发生细胞溶解而导致基团种类增加;增强溶液酸性可导致菌体表面官能团的质子化效应增加,导致H+与Cu2+竞争官能团,这正是酸度较高不利于菌体与Cu2+结合的原因之一。

The batch removal of Cu2＋ from aqueous solution by adsorption on biosorbents Bacillus subtilis was performed to determine the effect of adsorption time,pH,biosorbent dosage and initial Cu2＋ concentration on the adsorptive capacity for Cu2＋.The acid-base titration and FTIR were employed to analyze the surface properties of Bacillus subtilis.The optimum adsorption conditions were pH of 6 and adsorption time of 24 h;the biosorbent dosage and initial Cu2＋ concentration should be chosen according to the practical fact so as to achieve the best treatment effect and lower economic cost.The adsorption behavior of Cu2＋ by Bacillus subtilis followed Langmuir adsorption isotherm well,and the saturated adsorptive capacity of Cu2＋ was 17.056 mg/g under the conditions of room temperature,pH of 6,initial Cu2＋ concentration of 34.52 mg/L,bacterium suspension 1.5 mL and adsorption time of 24 h.—COOH,C=O,—OH,—NH,—CONH—,P—O—C groups were found on the surface of Bacillus subtilis.In the process of acid-base titration,there was no group increased during cell dissolution.Increasing the acidity of solution could enhance the protonation of surface groups,lead to the competition of H＋ and Cu2＋ for functional group,and further inhibited the Cu2＋ adsorption on Bacillus subtilis.