Equilibrium and Kinetics Behavior of Oil Spill Process onto Synthesized Nano-Activated Carbon

Abstract

Oil spills were removed from polluted wastewater using synthetic nano-activated carbon that prepared through the alkaline activation of water hyacinth roots followed by zinc chloride treatment prior to its carbonization. The prepared nano-activated carbon attains high oil sorption capacity of 28.31 g oil/ g sorbent and no water pickup. The SEM examination of the prepared activated carbon investigates its spherical morphological structure with average diameter of 60nm. The different processing parameters affecting on the oil sorption onto the prepared nano-activated carbon were optimized. The maximum oil sorption capacity of 30.2 g oil/g activated carbon has been recorded after 60 min sorption time using 10 g from the prepared nano-activated carbon at initial oil film thickness of 1 mm. The oil sorption data recorded at equilibrium conditions have been analyzed using the linear forms of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm models and the applicability of these isotherm equations to the sorption system was compared by judging the correlation coefficients, R 2. It was established that the equilibrium isotherm models applicability follows the order of: Freundlich> Langmuir> Dubinin-Radushkevich for the oil sorption onto activated carbon. Accordingly, the oil sorption process at equilibrium may be described mainly using both Freundlich and Langmuir isotherms. These results give prediction that the oil sorption process takes place onto nano-activated carbon as mono-layer coverage with some degree of heterogeneity. The kinetics of the oil sorption process was modeled using four kinetic models namely pseudo first-order, pseudo second-order, Elovich, and intraparticle diffusion kinetic models. The pseudo second-order model yielded the highest R 2 value of 0.9933. So, the kinetics of the oil sorption process onto the prepared nano-activated carbon may be described as second-order, which reveals that the main oil adsorption mechanism is probably chemisorption reaction.