啤酒酵母吸附去除水中Cd~(2+)的影响因素

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。本文研究了啤酒酵母对Cd2+吸附效果的主要影响因素,结果表明pH值对Cd2+会产生较大的影响,非固定化和固定化啤酒酵母对Cd2+吸附的最佳pH值都为4,过高和过低均不利于吸附的进行。水中常见的K+、Ca2+、Na+、Mg2+四种离子在低浓度时对Cd2+的吸附无显著影响,但当其浓度高于5mg/L时会影响吸附,其影响顺序为K+Na+Ca2+Mg2+;Zn2+、Fe2+、Cu2+、Pb2+对Cd2+的吸附效果影响顺序为Pb2+Zn2+Fe2+Cu2+;当Cu2+浓度≥50mg/L时,啤酒酵母对Cd2+不产生性吸附,而对Cu2+产生专性吸附。

Influence factors for the biosorption of Cd~(2+) by Saccharomyces cerevisiae

Biosorption is regarded as a cost-effective biotechnology for the treatment of high volume and low concentration complex wastewater containing heavy metal(s). Saccharomyces cerevisiae is one of the promising biosorbents for heavy metal removal. In this paper, the main influence factors for the biosorption of Cd~(2+) by Saccharomyces cerevisiae are discussed. Results indicated that the pH value affects obviously the biosorption performance for Cd~(2+). The maximum biosorption capacity of unit biomass is reached at pH 4 for both the free and immobilized Saccharomyces cerevisiae, and the lower or higher pH values are not beneficial for the biosorption. The coexisting ions K~+, Ca~(2+), Na~+and Mg~(2+)have no obvious impact on the biosorption of Cd~(2+) by statistic analysis at low concentration. While when the concentration of any K~+, Ca~(2+), Na~+or Mg~(2+) ion is higher than 5 mg/L, the removal of Cd~(2+) would be affectted, and the impact sequence is K~+＜Na~+＜Ca~(2+)＜Mg~(2+). The disturbing heavy metal ions Zn~(2+), Fe~(2+), Cu~(2+) and Pb~(2+) affect the biosorption of Cd~(2+), and the impact sequence is Pb~(2+)＜ Zn~(2+)＜Fe~(2+)＞＜Cu~(2+). The competing impact of Cu~(2+) for the Cd~(2+) biosorption is most poignant in all disturbing heavy metal ions because Cd~(2+) ion is nearly not adsorbed at 50mg/L Cu~(2+) or higher.