Biohydrogen production from photodecomposition of various cellulosic biomass wastes using metal-TiO2 catalysts

Abstract

Biohydrogen generation from direct photocatalytic decomposition of lignocellulose biomass waste was investigated using TiO2 with metal co-catalysts. The behavior of the photocatalyst was explored by studying the effect of metal co-catalysts (Pd, Cu, Ni, Ce) and the amount of metal loading. The reactivity of TiO2 was found to vary depending on the metal co-catalysts, with the order of reactivity being Pd > Cu > Ni = Ce. Cellulose samples extracted from coconut husk, fern fiber, and cotton linter were characterized using XRD, FTIR, and SEM analysis. Crystallinity index (CI), degree of polymerization (DP), and α-cellulose and hemicellulose concentrations were correlated with hydrogen yield. Cotton linter cellulose with high CI and DP produced 131 μmol of H2 in 3 h followed by cellulose extracted from coconut husk at 38 μmol and fern fibers at 6 μmol. High concentrations of hemicellulose enhanced the rate of H2 production due to the release of acetic acid during photodecomposition and accelerated the hydrolysis. Sugar fractions containing glucose and fructose obtained from hydrothermal treatment of cotton linter cellulose improved H2 yield, which suggests that the rate limiting step of the reaction is the dissociation of β(1→4)-glycosidic bonds to form sugar monomers.