Linear and crosslinked Polyurethanes based catalysts for reduction of methylene blue

Abstract

The large amount of synthetic dyes in effluents is a serious concern to be addressed. The chemicalreduction is one of the potential way to resolve this problem. In this study, linear and crosslinkedpolyurethanes i.e. LPUR & CLPUR were synthesized from toluene diisocyanate (TDI), polyethylene glycol(PEG;1000 g/mole) and tetraethylenepentamine (TEPA). The structure and morphology of synthesizedmaterials were examined by FTIR, SEM and BET. The CLPUR was found stable in aqueous system with0.80 g/cm3density and 16.4998m2g−1surface area. These materials were applied for the reduction ofmethylene blue in presence of NaBH4. Both, polymers catalyzed the process and showed 100% reductionin 16 and 28mins., respectively, while, the reduction rate was significantly low in absence of these mate-rials, even after 120mins. Furthermore, negligible adsorption was observed with only 7% removal of dye.The best reduction rates were observed at low concentration of dye, increasing concentration of NaBH4and with more dosage of polymeric catalyst. The kinetic study of process followed zero order kinetics.