Application of stearic acid-modified magnetite in oily wastewater treatment

Key words: 
• stearic acid /
• magnetite /
• oily wastewater

Abstract: The characteristics of oil adsorption by stearic acidmodified magnetite in aqueous solution, and the effect of factors (time, modifier dosage, temperature) on modification and adsorption were presented in this paper. Meanwhile, under analysis of infared spectrum and scanning electron microscope, the mechanism of modification and adsorption was discussed. The results showed that the optimum conditions of stearic acidmodified magnetite were: temperature (20℃), the modified time (45 min), the ratio of modifier dosage to magnetite mass (4%). The physical and chemical properties of magnetite were changed in the process of modification, and stearic acid formed bilayer lipid membranes on the surface of magnetite, thereby decreased the surface wettability of magnetite. In addition, the analysis proved that oil adsorption by stearic acidmodified magnetite conformed to the Langmuir adsorption isotherm. The maximum adsorption capacity and removal rate of stearic acidmodified magnetite were 749.23 mg/g and 93%, respectively. Oil removal rate could keep at 85% after the regeneration treatment of stearic acidmodified magnetite.