Enhancing Oily Wastewater Treatment in Petroleum Industry Using Magnetite Nanoparticles

Using magnetic nanoparticles for contaminant removal has received considerable attention for their unique properties. The novelty of this study lies in the integration of electrocoagulation with magnetite nanoparticles for the treatment of oily wastewater, where these processes have been used individually in previous studies. Such combination and enhancement will reduce the requirements for time, power, and cost to reach the allowable limits of oil content. The used commercial magnetite was characterized by XRD, FT-IR, and SEM. Moreover, the experiments were conducted in a batch electrocoagulator with aluminum and iron plates as anode and cathode, respectively. Four parameters were studied, namely pH, current density, time, and magnetite dosage. The results verified that the current density required to obtain 90% oil removal efficiency for the 275-ppm initial oil concentration decreased from 25 to 15 mA/cm 2 after the addition of 0.93 mg/L magnetite to the electrocoagulation process and time decreased from 30 to 10 min, which is an indication of the enhancement of nanoparticles in the electrocoagulation process. Furthermore, the minimum oil content reached by the electrocoagulation + magnetite process was 8.9-ppm at the optimum current density of (20 mA/cm 2 ), while electrocoagulation process provided 22.2-ppm final oil content at the same operating conditions. The adsorption kinetics could be well described by pseudo-second-order model. The Langmuir isotherm model showed a better fit with experimental data compared with Freundlich isotherm model. The treated oily wastewater by the electrocoagulation + magnetite process was found to be feasible for reusing in other processes or reinjection in the oil fields.