酱油曲霉对水中微量Cd^(2+)的吸附

Biosorption of low level Cd^(2+) in water by Aspergillus sojae

以酱油曲霉(Aspergillus sojae)为吸附剂,对水溶液中微量Cd2+进行了吸附研究.实验考察了预处理方法、菌体用量、pH、温度和吸附时间对吸附的影响,同时分析了其吸附动力学和吸附等温线特性,并对酱油曲霉菌体吸附Cd2+的可能作用机理进行了探讨.结果表明,碱预处理的菌体吸附效果最好.在菌体用量为0.08 g时,对Cd2+的吸附量达到最大,为0.095 mg.g-1.pH值在3.4—8之间,酱油曲霉菌体对Cd2+的吸附效果比较稳定,其最大吸附率出现在pH 3.4.温度在15℃—30℃之间时,菌体对Cd2+的吸附率差异很小,吸附率在88.3%—94.4%之间.二级动力学方程能很好地表征酱油曲霉吸附微量Cd2+的过程,R2在0.99以上,其吸附平衡时间大约2.5 h,线性模型更适于描述该吸附平衡过程.SEM、FTIR分析得出,Cd2+可能是与酱油曲霉菌体表面的羟基、酰胺基、羧基、磷酸基和胺基等基团相络合而被吸附,也可能是形成颗粒沉淀而附着在菌丝上.

The influence of pretreatment methods,biomass dose,pH,temperature and time on the adsorption of low-level in aqueous solution Cd2＋ by Aspergillus sojae was investigated.The biosorption kinetics,equilibrium and mechanisms were also discussed.The results showed that NaOH-pretreated mycelium was the best among several pretreatment methods.The adsorption capacity of Cd2＋ reached a maximum of 0.095 mg · g-1 when biomass dosage was 0.08 g.Cd2＋ adsorption rate was relatively stable at pH 3.4—8 and the maximum adsorption rate was reached at pH 3.4.The adsorption efficiency was in the range of 88.3%— 94.4% at 15 ℃—30 ℃.The biosorption process followed second-order kinetics and the biosorption equilibrium time was about 2.5 h.The Linear model was more suitable to describe the adsorption equilibrium process.FTIR and SEM observations indicated that Cd2＋ was likely to bind with the activated groups on the cell surfaces including hydroxyl,carboxyl,amide,phosphate group and amido,or to form particle precipitates attached to the mycelium.