去除镉离子固定化生物吸附剂的研制

利用固定化包埋技术,将变形假单胞菌(Pseudomonas plecoglossicida)C-18及生物氧化锰固定在复合载体的网状结构中,制备固定化生物吸附剂,用于处理含高浓度镉的原水.以固定化吸附剂的机械强度、传质性能、镉吸附率为分析指标,对固定化吸附剂的成分配比进行优化.结果显示:将聚乙烯醇和海藻酸钠结合使用,作为包埋剂,可有效提高固定化吸附剂的各项性能;添加生物氧化锰可提高固定化吸附剂的镉吸附率;去除镉离子的固定化吸附剂较为适宜的配方(均为质量分数)为聚乙烯醇4%,海藻酸钠4%,菌体(干重)0.5%,生物氧化锰1.8%.

固定化生物吸附剂处理含铜电镀废水的研究

通过平板涂布法,从电镀污泥中筛选得到1株吸附Cu^(2+)性能优良的菌株,鉴定其为假单胞菌,并将其制成固定化生物吸附剂。研究了包埋比、吸附时间、温度、Cu^(2+)初始质量浓度、pH值、投加量对固定化生物吸附剂去除Cu^(2+)的影响。结果表明:当包埋比为1∶5、吸附时间为60min、温度为35℃、Cu^(2+)初始质量浓度为100mg/L、pH值为6、投加量为10g/L时,固定化生物吸附剂对Cu^(2+)的去除率可达到85.2%。

固定化生物吸附剂对废水中Pb^(2+)和Cd^(2+)的吸附性能

从含重金属废渣堆积区的土壤中筛选分离出一种对重金属Pb^(2+)和Cd^(2+)具有高耐受性的功能菌株,采用包埋法制成固定化生物吸附剂,用于吸附废水中的重金属,考察了重金属的初始浓度、吸附时间、废水pH值及吸附剂添加量等因素对吸附性能的影响.结果表明,筛选出的菌株为短杆菌,对Pb^(2+)和Cd^(2+)的最大耐受浓度分别为2200和700 mg/L;吸附剂投加量为10 g/L、废水pH为6时,Pb^(2+)和Cd^(2+)达最大吸附率,分别为87.77%和57.50%;Pb^(2+)和Cd^(2+)基本可在40 min内被快速吸附达平衡,最大吸附量分别为114.3和82.12 mg/g;废水初始pH为5?7利于吸附;Pb^(2+)和Cd^(2+)初始浓度增加使吸附率降低,且Pb^(2+)初始浓度比Cd^(2+)初始浓度对吸附速率影响更大.Langmuir和Freundlich吸附方程拟合表明,Pb^(2+)和Cd^(2+)的吸附主要为单分子层表面吸附;Pseudo-second order动力学方程拟合表明,吸附过程的限速步骤主要为化学吸附,且Pb^(2+)比Cd^(2+)更易被吸附.

Removal of cadmium from aqueous solution by immobilized Microcystis aeruginosa:Isotherms,kinetics and thermodynamics

The Microcystis aeruginosa(MA) was immobilized on sodium alginate and used as biosorbent for removal of Cd(Ⅱ) ions from aqueous solution.The biosorption process is pH dependent,and the optimum biosorption was observed at pH 6.0 with the biosorption capacity of 98.38 mg/g.Among Langmuir,Freundlich and Temkin isotherm models,the Freundlich and the Temkin isotherm fit well with the experimental data.Cd(Ⅱ) ions biosorption follows the pseudo-second-order kinetic model.The rate controlling mechanism study reveals that film diffusion is the rate-limiting step and intraparticle diffusion is also involved in biosorption.Thermodynamic parameters,such as Gibbs free energy(ΔG°),the enthalpy(ΔH°) and entropy(ΔS°) were calculated,and revealed that the biosorption process is spontaneous,exothermic and random.Furthermore,the immobilized MA can be regenerated using 0.1 mol/L HCl solutions.

Investigation on Adsorption of Lithospermum erythrorhizon onto Fungal Cell Wall Polysaccharides

A culture of Lithospermum erythrorhizon adsorbed on fungal cell wall polysaccharides, a novel bio-adsorbent made from fungal cell wall, has been established in this paper. Three steps were involved in this immobilization. The first step was preparation of suspended plant cells from tightly aggregated plant cell clumps. The disassembled ratio of 0.715g·g-1 (the disassembled cells over total cells) was obtained under optimum condition for the enzymatic reaction. Then, the adsorption of plant cells onto fungal cell wall polysaccharides was conducted and the saturated capacity of 12 g cell per gram of carrier was obtained in adsorption immobilization. Finally, the culture of cells adsorbed on fungal cell wall polysaccharides was compared with that of cells entrapped in alginate or suspension cell culture. While exposed to in situ liquid paraffin extraction coupled with cell culture, the shikonin productivity of immobilized cells by adsorption was 10.67g·L-1, which was 1.8 times of that in suspension culture and 1.5 times of that entrapped in alginate.