Strength and sorption capacity modulation of carboxymethylcellulose hydrogels in presence of ester-bonded gemini surfactants

Abstract

The present work describes strength modulation of carboxymethylcellulose (CMC) hydrogel on addition of biodegradable diester-bonded gemini surfactants. These CMC-surfactant hybrid hydrogels were prepared using carboxymethylcellulose sodium salt and gemini surfactants in urea solution. The structure and morphology of the synthesized hybrid hydrogels were characterised using FT-IR spectroscopy and scanning electron microscopy. The gelling behaviour of synthesized hybrid hydrogels were investigated in distilled water in presence of different salts and differing pH's. The swelling capacity of these hydrogels were found to decrease with an increase in the charge of the metal cation ions (Al3+<Ca2+<Na+). The rheometric observations reveal an increase in the elastic modulus (G) of the CMC hydrogel on addition of surfactant, indicating an increase in the mechanical strength of the hydrogel. However, at higher surfactant concentrations the G value progressively decreased. The effect of added surfactants on gelation temperature of CMC was investigated through oscillating temperature sweep. The gelation temperature of CMC-urea+16-E2-16 surfactant was found to be higher than that of CMC-urea+14-E2-14 gemini surfactant. The encapsulation capacity of synthesized CMC-urea+surfactant hybrid hydrogel systems were explored for sorption capacity of various hazardous polynuclear aromatic hydrocarbons (PAHs) from their aqueous solutions. The observed results suggest that sorption of PAHs using CMC-urea+surfactant hydrogel systems can be a valuable approach towards safer remediation of groundwater contaminated by toxic organic compounds.