A Porous Material Made from Curdlan by EDTAD Functionalization Shows High Adsorption Capacity on Removal of Cu~(2+) and Zn~(2+) from Water

摘要

A linear bacterial beta-1,3-glucan, curdlan, was functionalized by ethylenediamine tetraacetic dianhydride (EDTAD) to form a porous insoluble material (Curd-E) in this study. Various technics, including FTIR, solid state C-13 NMR, XRD, TGA, and SEM, were combined to determine the chemical and microscopic structure of the resultant. It's suggested that EDTAD esterified and cross-linked C6-hydroxyl groups of curdlan molecules to form the porous Curd-E. Moreover, Curd-E showed high adsorption capacity on Cu2+ (224.97 mg/g, pH 6.0) and Zn2+ (255.64 mg/g, pH 4.5) in comparison with the biomaterial and mineral based adsorbents. Data also indicated that the site affinity of Curd-E for cations was in the order of chelation > coordination/complexation > ion exchange. Besides, 2-site Langmuir and 2-step Freundlich isotherms gave the best interpretation for Cu2+ adsorption and Zn2+ adsorption, respectively. Since the adsorption capacity maintained 91.8% +/- 0.8% after five cycles of adsorption/desorption, it is believed that Curd-E is suitable for removal of divalent cations in wastewater as a novel candidate.