Chang J S, Huang J C
Department of Chemical Engineering, Feng Chia University, 100 Wen-Hwa Road, Taichung, Taiwan, ROC.
Biotechnol Prog. 1998 Sep-Oct;14(5):735-41. doi: 10.1021/bp980070y.
Fixed-bed columns packed with calcium alginate (CA)-immobilized biomass of Pseudomonas aeruginosa PU21 were utilized to remove lead (Pb), copper (Cu), and cadmium (Cd) from the contaminated water. In the absence of competing metals, saturation capacity of CA-immobilized cells in batch operations was 1.60, 2.42, and 1.06 mmol/g, for Pb, Cu, and Cd, respectively. The Langmuir constants (K) obtained from the Langmuir isotherm were 157.6, 4.2, and 3.7 mM-1 for Pb, Cu, and Cd, respectively. Results from single-metal biosorption with 10-cm immobilized-cell columns show that, for an influent metal concentration of 193 microM, the total capacities for Pb, Cu, and Cd, respectively, were 5.12, 4.03, and 3.48 mmol, which is nearly 25-30% higher than those obtained from columns containing only cell-free CA matrix. With the influent containing ternary mixtures of Pb, Cu, and Cd, columns with immobilized cells exhibited predominant selectivity to Pb, whereas in the cell-free columns, the dominance of Pb adsorption reduced, along with an appreciable increase in the adsorption of Cu. The metal-laden columns were regenerated by elution with HCl solution (pH 2.0). The metal recovery ratios were 80:1, 60:1, and 27:1 for Cu, Cd, and Pb, respectively. Moreover, with a pH gradient elution, the column-trapped metals can be optimally recovered at distinct pH values. Continuous biosorption of Pb, Cu, and Cu with four columns in series was also conducted. Results from the multibed operation demonstrate that Pb ions strongly inhibited the adsorption of Cu and Cd, which only occurred initially, and subsequently, an essential portion of the adsorbed Cu and Cd ions was replaced by Pb ions due to the ion exchange effect. However, since Pb ions were rapidly removed from the bulk at the onset of metal loading, Pb adsorption in columns 2-4 was negligible for the first 10-30 h, leading to an elevation in the breakthrough time (tb) and the capacity for Cu and Cd in columns 2-4. A back-propagation neural network model was shown to be able to predict the breakthrough curves of the three metals in the multicolumn processes with a ternary-metal feed.
利用填充有海藻酸钙（CA）固定化铜绿假单胞菌PU21生物质的固定床柱从受污染水中去除铅（Pb）、铜（Cu）和镉（Cd）。在不存在竞争金属的情况下，分批操作中CA固定化细胞对Pb、Cu和Cd的饱和容量分别为1.60、2.42和1.06 mmol/g。从朗缪尔等温线获得的朗缪尔常数（K）对于Pb、Cu和Cd分别为157.6、4.2和3.7 mM-1。使用10厘米固定化细胞柱进行单金属生物吸附的结果表明，对于193 microM的进水金属浓度，Pb、Cu和Cd的总容量分别为5.12、4.03和3.48 mmol，这比仅含无细胞CA基质的柱所获得的容量高出近25%-30%。对于含有Pb、Cu和Cd三元混合物的进水，固定化细胞柱对Pb表现出主要选择性，而在无细胞柱中，Pb吸附的优势降低，同时Cu的吸附有明显增加。负载金属的柱用HCl溶液（pH 2.0）洗脱进行再生。Cu、Cd和Pb的金属回收率分别为80:1、60:1和27:1。此外，通过pH梯度洗脱，可以在不同的pH值下最佳地回收柱中捕获的金属。还进行了用四个串联柱连续生物吸附Pb、Cu和Cu的实验。多床操作的结果表明，Pb离子强烈抑制Cu和Cd的吸附，这种抑制仅在最初发生，随后，由于离子交换效应，一部分吸附的Cu和Cd离子被Pb离子取代。然而，由于在金属加载开始时Pb离子迅速从主体中去除，在最初的10-30小时内，第2-4柱中Pb的吸附可忽略不计，导致第2-4柱中穿透时间（tb）以及Cu和Cd的容量增加。结果表明，反向传播神经网络模型能够预测在三元金属进料的多柱过程中三种金属的穿透曲线。
