Investigating the Isotherm, Kinetics and Thermodynamics of Pollutant Adsorption from the Refinery Wastewater by the Rotating Pilot Disc Reactor Covered with Graphene

In this research, the application of adsorption isotherm, kinetic and thermodynamic models in a rotating disk reactor covered with graphene nanoparticles designed to remove aromatic compounds from the wastewater of the refinery located in Sari oil facilities and as a result reducing the chemical oxygen demand (COD) of the wastewater was investigated. Langmuir-Freundlich thermocouple was used to investigate the removal process. Also, adsorption kinetics were investigated by pseudo-first-order, pseudo-second-order and intermolecular diffusion models. The thermodynamics of adsorption was studied by Vant Hoff relation and its results were analyzed. Also, the effect of change in effluent concentration (70,100,150 mg/L) and temperature (20, 30 and 40˚C) and the number of discs containing graphene on the COD removal rate of the effluent was investigated. The results of the experiments showed that the rate of absorption and reduction of effluent COD increased with the increase of initial concentration and the temperature of the process and under optimal conditions was equal to 66%. From the examination of the equations, the applicability of two isothermal equations in the form of Freundlich Langmuir and models Kinetics were determined as pseudo-second order > intermolecular diffusion > pseudo-first order. From the analysis of the data, it was found that increasing the concentration and efficiency of the adsorbent has a positive effect and improves COD removal. At high concentrations, the ratio of effluent to graphene active surfaces and concentration gradients were the leading factors of absorption. The COD reduction percentages for concentrations of 70, 100, and 150 mg/L were 48%, 62%, and 73%, respectively.