Department of Bioengineering, Marmara University, 34722 Istanbul, Turkey.
Bioprocess Biosyst Eng. 2011 Oct;34(8):997-1005. doi: 10.1007/s00449-011-0550-y. Epub 2011 May 21.
The potential of the dried yeast, wild-type Schizosaccharomyces pombe, to remove Ni(II) ion was investigated in batch mode under varying experimental conditions including pH, temperature, initial metal ion concentration and biosorbent dose. Optimum pH for biosorption was determined as 5.0. The highest equilibrium uptake of Ni(II) on S. pombe, q (e), was obtained at 25 °C as 33.8 mg g(-1). It decreased with increasing temperature within a range of 25-50 °C denoting an exothermic behaviour. Increasing initial Ni(II) concentration up to 400 mg L(-1) also elevated equilibrium uptake. No more adsorption took place beyond 400 mg L(-1). Equilibrium data fitted better to Langmuir model rather than Freundlich model. Sips, Redlich-Peterson, and Kahn isotherm equations modelled the investigated system with a performance not better than Langmuir. Kinetic model evaluations showed that Ni(II) biosorption process followed the pseudo-second order rate model while rate constants decreased with increasing temperature. Gibbs free energy changes (ΔG°) of the system at 25, 30, 35 and 50 °C were found as -1.47E + 4, -1.49E + 4, -1.51E + 4, and -1.58E + 4 J mol(-1), respectively. Enthalpy change (ΔH°) was determined as -2.57E + 3 J mol(-1) which also supports the observed exothermic behaviour of the biosorption process. Entropy change (ΔS°) had a positive value (40.75 J mol(-1) K(-1)) indicating an increase in randomness during biosorption process. Consequently, S. pombe was found to be a potential low-cost agent for Ni(II) in slightly acidic aqueous medium. In parallel, it has been assumed to act as a separating agent for Ni(II) recovery from its aqueous solution.
在不同的实验条件下，包括 pH 值、温度、初始金属离子浓度和生物吸附剂剂量，研究了干酵母、野生型裂殖酵母去除 Ni(II)离子的潜力。确定了生物吸附的最佳 pH 值为 5.0。在 25°C 下，S. pombe 对 Ni(II)的最大平衡吸附量 q(e)为 33.8mg g(-1)。在 25-50°C 的范围内，随着温度的升高，它会降低，这表明是一个放热行为。增加初始 Ni(II)浓度至 400mg L(-1)也会提高平衡吸附量。超过 400mg L(-1)，就不会再发生吸附。平衡数据更符合 Langmuir 模型，而不是 Freundlich 模型。Sips、Redlich-Peterson 和 Kahn 等温方程对所研究的体系进行了建模，但性能并不优于 Langmuir。动力学模型评价表明，Ni(II)的生物吸附过程遵循伪二级速率模型，而速率常数随温度的升高而降低。在 25、30、35 和 50°C 下，系统的吉布斯自由能变化(ΔG°)分别为-1.47E + 4、-1.49E + 4、-1.51E + 4 和-1.58E + 4 J mol(-1)。焓变(ΔH°)为-2.57E + 3 J mol(-1)，这也支持了生物吸附过程中观察到的放热行为。熵变(ΔS°)为正值(40.75 J mol(-1) K(-1))，表明生物吸附过程中随机性增加。因此，裂殖酵母被认为是一种在弱酸性水溶液中去除 Ni(II)的潜在低成本剂。同时，它也被认为是从水溶液中回收 Ni(II)的分离剂。
