Modeling of adsorption isotherms of oil content through the electrocoagulation treatment of real oily wastewater

Abstract

The adsorption equilibrium isotherms of oil content via the electrocoagulation treatment of real oily wastewater were studied and modeled. Ten isotherm models (Langmuir, Freundlish, Temkin, Dubinin–Radushkevich, Kiselev, Fowler–Guggenheim, Elovich, Hurkins-Jura, Jovanovic and Hill–de Boer models) were selected to predict the adsorption equilibrium isotherms and their characteristics parameters. A triple aluminum tubes was manufactured in a monopolar-concentric arrangement to investigate the purpose of treating real oily wastewater (523.11 ppm of oil content) produced from crude oil wells location (West Qurna 1 /Basra-Iraq) under the impacts of the operational variables; the electrolysis time (2-20 min.), the current density (4.4 mA/cm2), the initial pH equaling 6.5, and the agitation speed fixed as 200 rpm. The results showed that the studied models fitted the data in the order as: Freundlish (R2=0.9991) > Langmuir (R2=0.9960) > Hurkins-Jura (R2=0.9926) > Temkin (R2=0.9922) > Elovich (R2=0.9906) > Jovanovic (R2=0.9573) > Fowler–Guggenheim (R2=0.8676) > Hill–de Boer (R2=0.8294) > Dubinin–Radushkevich (R2=0.7928) > Kiselev (R2=0.7366) isotherms. The modeling of adsorption isotherm revealed that the interaction of oil content with the electro-coagulant is characterized as physical adsorption process. There is no formation of complex between the adsorbed molecules due to the repulsion among them. Additionally, the heat of adsorption will decrease with loading via the electrocoagulation treatment of real oily wastewater.