Using Box-Behnken experimental design for optimization of gas oil desulfurization by electrochemical oxidation technique

Abstract

Iraqi gas oil with sulfur content 9400 ppm was desulfurized electrochemically at constant current (300 mA), the process consists two steps; first step is electrochemical desulfurization by using electrochemical cell contains two graphite electrodes while the used electrolyte is NaCl to enhance electrolyte electrical conductivity, and hydrogen peroxide as an oxidant agent, second step is extraction with acetonitrile. Optimization of process parameters was done by applying response surface methodology RSM combined with Box -Behnken experimental method, in which the sulfur removal efficiency was acted as response function while the reaction temperature, NaCl concentration and time were selected as controllable (studied) variables. The sulfur removal efficiency was ranged from 55.84 % to 88.07%. The results were analyzed with Design-Expert software by fitting with second order polynomial model and the empirical model was exhibited high correlation factor (R2=0.9966) and the estimated optimization solution stated that maximum sulfur removal efficiency is 88.611% at temperature (57.656 C), NaCl concentration (0.106 M) and, time (51.46 min.).