Department of Chemistry, Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya, SCSVMV University, Kancheepuram, India.
Environ Sci Pollut Res Int. 2013 Feb;20(2):925-38. doi: 10.1007/s11356-012-0935-8. Epub 2012 May 8.
The influence of clay on the adsorption of heavy metals like copper and cadmium on chitosan from simulated industrial wastewater is evaluated. Chitosan-clay blend with ratio of (1:1), (1:2), and (2:1) have been prepared, and these were used as membranes to remove copper and cadmium ions from synthetic industrial wastewater. The chemical parameters for quantities of adsorption of heavy metal contamination have been done, and the kinetics of adsorption has also been carried out. Clay provides enough absorbable sites to overcome mass transfer limitations. The number of absorbable sites for cadmium is more compared to copper, and thus the rate of recovery of cadmium is faster than copper, and the percentage removal of cadmium is more than copper at all times on clay over nylon 6. This difference indicates the influence of clay in the adsorption of heavy metals in comparison to synthetic polymer nylon 6. Rate constant for first-order kinetics of adsorption, k (1), for copper and cadmium is less than that of clay, which clearly indicates that clay, which is a natural polymer, is more kinetically favored compared to synthetic polymer. The difference in the intraparticle diffusion in both the natural and synthetic polymer is not much, and it suggests that the particle diffusion mechanism is the same in both cases. Copper and cadmium recovery is parallel at all times. The percentage of removal of copper increased with an increase in pH from 3 to 5. In the case of cadmium containing wastewater, the maximum removal of metal occurred at pH 5. The uptake amount of Cu(2+) ions on chitosan increased rapidly with increasing the contact time from 0 to 360 min and then reaches equilibrium after 360 min, and the equilibrium constant for copper and cadmium ions are more or less the same for the adsorption reaction. There are more adsorption sites for cadmium in the presence of clay and mass transfer limitation is avoided without resorting to rotation, which is the highlight of the present work. And more so, this is pronounced in the case of natural polymer compared to synthetic polymer.
评价了粘土对壳聚糖从模拟工业废水中吸附铜和镉等重金属的影响。制备了壳聚糖-粘土比例为（1:1）、（1:2）和（2:1）的混合物，并将其用作从合成工业废水中去除铜和镉离子的膜。进行了吸附重金属污染量的化学参数，并进行了吸附动力学研究。粘土提供了足够的可吸收位点，以克服传质限制。与铜相比，镉的可吸收位点更多，因此镉的回收率比铜快，并且在所有时间内，粘土对尼龙 6 的镉去除率都高于铜。这种差异表明，与合成聚合物尼龙 6 相比，粘土在重金属吸附方面的影响。铜和镉吸附的一级动力学速率常数，k（1），小于粘土的速率常数，这清楚地表明，天然聚合物粘土比合成聚合物更有利于动力学。在天然和合成聚合物中，内扩散的差异不大，这表明在这两种情况下，颗粒扩散机制是相同的。铜和镉的回收在所有时间都是平行的。铜的去除率随着 pH 值从 3 增加到 5 而增加。在含镉废水中，金属的最大去除发生在 pH 值为 5。壳聚糖对 Cu（2+）离子的吸附量随着接触时间从 0 增加到 360 分钟而迅速增加，然后在 360 分钟后达到平衡，铜和镉离子的平衡常数对于吸附反应几乎相同。在存在粘土的情况下，镉具有更多的吸附位点，并且无需旋转即可避免传质限制，这是本工作的重点。而且，与合成聚合物相比，在天然聚合物中更为明显。
