Chitosan-based ion-imprinted cryo-composites with excellent selectivity for copper ions

• Published in: Carbohydrate polymers 2018-04, Vol.186, p.140-149
• Main Authors: Dinu, Maria Valentina, Dinu, Ionel Adrian, Lazar, Maria Marinela, Dragan, Ecaterina Stela
• Format: Article
• Language: English
• Subjects: Chitosan; Cryo-composites; Ion-imprinting; Selectivity; Unidirectional freezing
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2018.01.033

An original strategy is proposed here to design chitosan-based ion-imprinted cryo-composites (II-CCs) with pre-organized recognition sites and tailored porous structure by combining ion-imprinting and ice-templating techniques. The cryo-composites showed a tube-like porous morphology with interconnected parallel micro-channels, the distance between the channel walls being around 15 μm. Both the entrapment of a natural zeolite and the presence of carboxylate groups, generated by partial hydrolysis of amide moieties, led to II-CCs with controlled swelling ratios (25–40 g/g, depending on pH) and enhanced overall chelating efficiency (260 mg Cu2+/g composite). To point out the importance of introducing Cu2+ recognition sites, sorption experiments using mixtures of Cu2+ and other competing ions (Co2+, Ni2+, Zn2+ or/and Pb2+) were also carried out. The higher values of selectivity coefficients obtained for the II-CCs compared to those of non-imprinted ones highlight the remarkable potential of our sorbents for decontamination of wastewaters and recycling of Cu2+ ions.