Graphene oxide-ZnO nanocomposite: an efficient visible light photocatalyst for degradation of rhodamine B

Lignin-based graphene oxide (L-GO), zinc oxide (ZnO), and modified L-GO-ZnO nanocomposites are prepared to explore the photocatalytic efficiency of the catalysts under UV-visible light irradiation. The absorbance of dye's solution (rhodamine B) at regular intervals has been recorded at lambda(max) = 553 nm using a UV-Vis spectrophotometer. The kinetics parameters, viz. half-life (t(1/2)), time constant tau (Tau), and rate constant (k), have been evaluated by integrated rate expression to predict the order of the reaction. The rate constant for the reactions has been evaluated to be k_(L-GO-ZnO) = 1.46 x 10(-1), k_(ZnO) = 2.23 x 10(-2), and k(_L-GO) = 1.740 x 10(-2) min(-1). The degradation reaction is predicted to follow the first-order kinetics when the data are fitted to the integrated rate expression, kt = -ln(D/D-0). The interactions of the dye and the catalyst have been probed by FTIR spectroscopy. The percent degradation efficiency of ZnO, L-GO, and L-GO-ZnO catalyst is 85.96, 83.15, and 91.75, respectively.