Semi-interpenetrating networks of biopolymer chitosan/acrylic acid and thiourea hydrogels: synthesis, characterization and their potential for removal of cadmium

摘要

The present manuscript deals with the synthesis of novel chitosan-based semi-interpenetrating networks (semi-CIPNs) and explores their potential for removal of Cd2+ ions from solution. Microwave radiation-induced polymerization was carried out using biopolymer chitosan (CS) and acrylic acid (AA) monomer, in the presence of initiator (K2S2O8) and cross-linker thiourea (CH4N2S). The effect of polymerization variables such as the amount of solvent, concentrations of initiator, monomer and cross-linker and the reaction time were optimized as a function of percentage grafting (Pg). Under optimized conditions, the liquid uptake potential of the synthesized semi-CIPN was studied in terms of percentage swelling (Ps). The semi-CIPN showed the maximum percentage grafting (3845%) and percentage swelling (311%) under the optimized conditions. The physico-chemical techniques such as Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA/DTG/DTA), scanning electron microscopy (SEM), and X-ray diffractometry (XRD) provided the evidence for formation of semi-CIPN from chitosan. Semi-CIPN was found to be an efficient device for facile sequestering of Cd2+ ions on the basis of batch experimental studies as 98.1% efficiency was observed for removal of Cd2+ from 100mg/L solution. Reusability of polymeric material was evaluated for its sorption performance in consecutive adsorption and desorption cycle and it was observed that the regeneration efficiency decreases slowly up to eighth adsorption/desorption cycles, thereafter, it decreases significantly in the 9th and 10th cycles and 40% efficiency has been observed after 12th cycle. Regeneration of the synthesized semi-CIPN explores the reusability and economic feasibility of biopolymer material.