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Interactions of metal ions with chitosan-based sorbents:a review

机译：金属离子与壳聚糖基吸附剂的相互作用：综述

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Metal cations can be adsorbed by chelation on amine groups of chitosan in near neutral solutions.In the case of metal anions,the sorption proceeds by electrostatic attraction on protonated amine groups in acidic solutions.However,the presence of ligands and the pH strongly control sorption performance(sorption isotherm)and the uptake mechanism(changing the speciation of the metal may result in turning the chelation mechanism into the electrostatic attraction mechanism).Several examples are discussed with precious metals(Pd,Pt),oxo-anions(Mo,V)and heavy metals(Cu,Ag).Sorption performance(equilibrium uptake but also kinetics)is also strictly controlled by other structural parameters of the polymer(degree of deacetylation,crystallinity for example)that control swelling and diffusion properties of chitosan.The identification of the limiting steps of the sorption process helps in designing new derivatives of chitosan.Diffusion properties may be improved by physical modification of chitosan(manufacturing gel beads,decreasing crystallinity).Selectivity can be enhanced by chemical modification(grafting,for example,sulfur compounds).Several examples are discussed to demonstrate the versatility of the material.This versatility allows the polymer to be used under different forms(from water soluble form,to solid form,gels,fibers,hollow fibers...)for polymer-enhanced ultrafiltration and sorption processes.These interactions of metal ions with chitosan can be used for the decontamination of effluents,for the recovery of valuable metals but also for the development of new materials or new processes involving metal-loaded chitosan.Several examples are cited in the design of new sorbing materials,the development of chitosan-supported catalysts,the manufacturing of new materials for opto-electronic applications or agriculture(plant disease treatment...).
机译：金属阳离子可通过螯合在近中性溶液中脱乙酰壳多糖的胺基上而被吸附。对于金属阴离子，其吸附是通过静电吸附在酸性溶液中的质子化胺基上进行的。然而，配体的存在和pH值强烈地控制了吸附性能（吸附等温线）和吸收机理（改变金属的形态可能导致螯合机理转变为静电吸引机理）。讨论了几个有关贵金属（Pd，Pt），氧阴离子（Mo，V）的例子。聚合物的其他结构参数（例如脱乙酰基度，结晶度）也严格控制着壳聚糖的溶胀和扩散特性，因此吸附性能（平衡吸收以及动力学）也得到严格控制。限制吸附过程的步骤有助于设计壳聚糖的新衍生物。通过物理改性壳聚糖可以改善扩散性能（可以通过化学修饰（例如接枝，例如硫化合物）提高选择性。讨论了几个实例来证明材料的多功能性。这种多功能性使聚合物可以以不同的形式使用水溶性形式，固体形式，凝胶，纤维，中空纤维...），用于聚合物增强的超滤和吸附过程。金属离子与壳聚糖的这些相互作用可用于废水的净化，以回收有价值的金属，但是也用于开发涉及金属负载的壳聚糖的新材料或新工艺。在新吸附材料的设计，壳聚糖负载的催化剂的开发，光电应用或农业（工厂）的新材料的制造中列举了几个例子。疾病治疗...）。

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