Uptake of chromium by Aspergillus foetidus

Aspergillus foetidus has the ability to take up chromium during the stationary phase of growth and under growth-nonsupportive conditions. We observed a 97% decrease in hexavalent chromium (initial concentration 5 µg/g) at the end of 92 h of growth, which may be due to its reduction to Cr (III) and/or complexation with organic compounds released due to the metabolic activity of the fungus. Replacement culture studies under growth-nonsupportive conditions revealed that the maximum uptake of Cr (VI) at pH 7.0 is 2 mg/g of dry biomass. At low or high pH values, Cr (VI) uptake is significantly reduced. In addition, the initial rate of total chromium uptake is also enhanced by higher biomass concentrations and the presence of glucose. The results obtained through this investigation indicate the possibility of treating waste effluents containing hexavalent chromium using Aspergillus foetidus.     

细菌X07吸附Cr(Ⅵ)的研究

从不同来源的样品中分离出一株吸附Cr(Ⅵ)较强的菌株X07,经鉴定为蜡状芽孢杆菌(Bacillus.cereus)。通过吸附实验探讨了X07死菌体对Cr(Ⅵ)的吸附特性,结果表明,X07死菌体吸附Cr(Ⅵ)的最适pH值为6.0;其吸附Cr(Ⅵ)是一个快速、非温度依赖过程,吸附50min达到饱和,在最初的5min内,吸附量达到最大吸附量的76.8%;菌体浓度的增加有利于对Cr(Ⅵ)的吸附:其吸附等温线符合Langmuir和Freundlich吸附模型,在试验的条件下,对Cr(Ⅵ)的饱和吸附容量为146.9mg/g干菌体。     

Biosorption of Direct Yellow 12 from aqueous solution using green alga Ulva lactuca

The potential of commonly available green alga Ulva lactuca was investigated as viable biomaterials for removal of synthetic azo dye (Direct Yellow 12, DY-12) from aqueous solution. The results obtained from the batch experiments revealed that the ability of the U. lactuca to remove DY-12 from its aqueous solution was dependent on the dye concentration, pH, and algal biomass but less dependent on the particle size of the U. lactuca. The equilibrium conditions and kinetics of adsorption were investigated, and the adsorption kinetic was consistent with the pseudo-second-order model (R ²=1). The adsorption isotherm followed only the Freundlich model with a correlation coefficient R ²=0.99. This study demonstrated that the U. lactuca could be used as an effective biosorbent for the removal of DY-12 from its aqueous solution.     

Biosorption of chromium(VI), nickel(II) and copper(II) ions from aqueous solutions using Pithophora algae

The biosorption of heavy metals is considered to be one of the best alternatives for the treatment of wastewater. The metal binding capacity of algae and acid-treated algae is investigated to find out the removal characteristics of Cr(VI), Ni(II) and Cu(II) ions from single metal solutions. Batch experiments are conducted and the study is extended to investigate the effect of pH, amount of adsorbent and adsorbate concentration on the extent of biosorption. The results indicate that the adsorption capacity of algae depends strongly on pH. The maximum adsorption of Cr(VI), Ni(II) and Cu(II) occurs at pH values of 2, 7 and 4.3, respectively. The adsorption process follows first-order kinetic equation. The data obtained are correlated with Freundlich and Langmuir adsorption isotherms.     

菌株Dyella ginsengisoli LA-4吸附Ni~(2+)的条件优化及特性研究

主要考察了菌株Dyella ginsengisoli LA-4对重金属Ni2+的吸附性能,同时,利用表面响应法对菌株Dyella ginsengisoli LA-4吸附Ni2+的条件(接种量、pH、Ni2+浓度等)进行了优化,并考察了其动力学及吸附等温曲线特性.实验结果表明,菌株Dyella ginsengisoli LA-4吸附Ni2+的最优条件为:接种量10.64 g.L-1,pH为6.50,Ni2+浓度为19.20 mg.L-1,此时的Ni2+最大去除率为99%.动力学分析表明,吸附平衡时间约为30 min,吸附可分为表面快速吸附和缓慢重金属积累两个阶段.利用Langmuir吸附模型能较好地描述菌株Dyella ginsengisoli LA-4对Ni2+的等温吸附行为,最大吸附量为25.81 mg.g-1.     

Biosorption of hexavalent chromium and malachite green from aqueous effluents,using Cladophora sp.

Biosorption potential of green macroalgae Cladophora sp., (GAC) for the removal of hexavalent chromium (Cr(VI)) and malachite green (MG) from aqueous medium was investigated. Optimal conditions for biosorption experiments were determined as a function of initial pH, GAC dosage, temperature and initial concentration of Cr(VI) and MG. The biosorption equilibrium data were fitted with the isotherm models of Langmuir, Freundlich, Kiselev, Frumkin and Jovanovic, while the experimental data were analysed using the kinetic models such as pseudo-first-order, pseudo-second-order, Ritchie's and intraparticle diffusion. The Langmuir maximum biosorption capacity was calculated as 100.00?mg/g (Cr(VI)) and 142.85?mg/g (MG). The biosorption kinetic data showed better agreement with the pseudo-second-order kinetic model. The thermodynamic parameters indicated spontaneous and endothermic nature of the biosorption process for Cr(VI) removal, whereas exothermic in the case of MG removal. Furthermore, the biosorption efficiencies of the GAC reusability were found significant up to five cycles and tested using 0.1, 0.5 and 1.0?M HCl, respectively. The results of the present study indicated that GAC is a suitable biosorbent for the sequestration of Cr(VI) and MG from aqueous solutions.     

基因工程菌E.coli BL21-NiCoT吸附镍的性能研究

以表达Staphylococcus aureus ATCC6538镍钴转运酶NiCoT基因的基因工程菌E.coli BL21-NiCoT作为生物吸附剂处理含镍废水.结果表明:基因工程菌在pH为4～9时有比较好的吸附效果,30 min就达到了吸附平衡;基因工程菌对Ni2 的富集容量比原始宿主菌有很大的提高,最大平衡富集量从3.76 mg/g增加到11.33 mg/g,增幅达3倍多,溶液中Ni2 的最大去除率也从原来的35.62%增加到91.23%;Cu2 、Cr6 、Zn2 等的存在对吸附没有很大的影响.镍进入细胞内后与羟基和酰胺基团发生结合,蛋白类物质和含羟基类物质在细胞内富集镍的过程中起到重要作用;基因工程菌转接10、20、30、40、50次,重组质粒保持良好的结构稳定性,基因工程菌对镍的富集能力也具有较好的稳定性.