Photo-degradation, thermodynamic and kinetic study of carcinogenic dyes via zinc oxide/graphene oxide nanocomposites

Pollution problem increases with the same face as the industrial development. One of the toxic ingredients of these industrial effluents is the organic dyes. Zinc oxide/Graphene oxide nanocomposite (ZnO-GNc) was synthesized in aqueous solution by mixing ultrasonically various compositions. The prepared ZnO-GNc nanocomposite was characterized by XRD, FTIR, FE-SEM, EDX and TEM. XRD of Graphene oxide (GO) showed their crystalline nature and the average size was 3.54, 18.98 and 15.47 nm for GO, ZnO, and ZnO-GNc respectively. An active toxic and stable dye, Methyl red (MR) was employed as the target pollutant to evaluate the photocatalytic activity of ZnO-GNc. The photocatalytic performance of ZnO-GNc nanocomposite was compared with that of zinc oxide (ZnO) and GO. The effect of some parameters, dye concentration, pH and temperature of dye solution were studied. The kinetic studies show that the process of MR photocatalytic discoloration by ZnO-GNc followed first-order reaction kinetics under different conditions with the rate constant of 2.2 × 10−2 s−1. The possible reasons for the high values of photocatalytic efficiency of the ZnO-GNc may be due to the improved charge passage and separation.