啤酒酵母去除水中Cd~(2+)和Cu~(2+)的吸附动力学和解吸特性

生物吸附法是一种经济有效的处理大规模低浓度重金属废水的生物技术,其中啤酒酵母(Saccharomyces cerevisiae)是具有实用潜力的生物吸附剂.通过以实验室培养的啤酒酵母作生物吸附剂,研究了啤酒酵母对Cu~(2+)、Cd~(2+)吸附的动力学解吸特性,结果表明:非固定化啤酒酵母对重金属的吸附是一个快速的、不依赖于生物代谢的过程,经过2h后Cd~(2+)达吸附平衡,Cu~(2+)为3 h.它们的吸附动力学过程均可用Elovich方程、抛物线扩散方程、双常数方程、二级动力学方程、Langmuir动力学方程来拟合,对Cd~(2+)来说,以二级动力学方程的拟合效果最佳,Cu~(2+)以Elovich方程最佳.固定化啤酒酵母吸附Cd~(2+)的平衡时间为60 h,Cu~(2+)为24 h,吸附速率大大降低.固定化啤酒酵母对重金属的吸附动力学也可用Elovich方程、抛物线扩散方程、双常数方程、二级动力学方程、Langmuir动力学方程拟合,但Cd~(2+)以Elovich方程最佳,Cu~(2+)以Langmuir动力学方程最佳.固定化碱处理啤酒酵母可用HC1作为解吸剂进行解吸,使吸附剂得到再生,具有较大的开发应用潜力.

Characteristics of sorption dynamics and desorption of Cd~(2+) and Cu~(2+) by Saccharomyces cerevisiae

Biosorption is regarded as a cost-effective biotechnology for the treatment of high volume and low concentration complex wastewaters containing heavy metal(s). Saccharomyces cerevisiae is one promising biosorbents for heavy metal removal. This paper investigated the characteristics of sorption dynamics and desorption of Cd~(2+) and Cu~(2+) by Saccharomyces cerevisiae. The results presented that the sorption dynamics of free Saccharomyces cerevisiae is quick and independent on metabolic activity. The equilibrium biosorption time for Cd~(2+) and Cu~(2+) is 2 and 3 hours, respectively. The equations including Elovich equation, Parabola diffused equation, Double-invariable equation, Two-stage dynamic equation, and Langmuire dynamic equation, were fitted for simulating the dynamic process of Cd~(2+) and Cu~(2+) biosorption, in which the best equation was Two-stage dynamic equation for Cd~(2+) and Elovich equation for Cu~(2+), respectively, by the evaluation of their correlation coefficients. The equilibrium biosorption time for Cd~(2+) and Cu~2 by caustic-treated yeast immobilized in alginate is 60 and 24 h respectively. The biosorption tempo was decreased greatly. Same as the adsorption dynamics of free yeast, it can be simulated by the equations including Elovich equation, Parabola diffused equation, Double-invariable equation, Two-stage dynamic equation, and Langmuire dynamic equation, but in which the best equation was Elovich equation for Cd~(2+) and Langmuire dynamic equation for Cu~(2+), respectively, by the evaluation of their correlation coefficients. The caustic-treated yeast immobilized in alginate heaving adsorbed Cd~(2+) and Cu~(2+) can be reused by the simple adsorbents HC1.