Evaluation of Collagen-Polyurethane-Chitosan Hydrogels for Lead Ions Removal from Water

Abstract

Collagen-polyurethane-chitosan hydrogels were synthesized by modifying the chemical structure of the crosslinking agent, with the aim to test which one plays a better role in removing of lead ions from water through adsorption process. In the first instance, two chemical crosslinkers based on aqueous polyurethane prepolymers (PPU) were used, where the type of aliphatic diisocyanate: hexamethylene diisocyanate P(HDI) or isophoronadiisocyanate P(IPDI) was varied. Hydrogels were subsequently designed using type I collagen (C) and chitosan (Q) varying the type of crosslinker: CQ-P(HDI) and CQ-P(IPDI), respectively. Hydrogels were characterized by means of crosslinking index, infrared spectroscopy (FTIR), thermogravimetric behavior (TGA) and swelling/degradation kinetics. Finally, tests were performed to determine the removal rate of Pb (II) ions in model waters. The results indicate that CQ-P(HDI) hydrogels have a higher degree of crosslinking, improving its resistance to the both thermal and hydrolytic degradation, and higher swelling capacity at acidic pH; compared to those derived from CQ-P(IPDI); however, these hydrogels do not show a decrement in the removal rate of Pb (II) ions from water, compared to the CQ hydrogel (without crosslinking), thus these innovative materials could be used as an alternative with potential use in the remediation of waters contaminated with lead ions.