2023

Hamedi Hamideh; Zendehboudi Sohrab; Rezaei Nima; Azizi Ali; Shahhoseyni Fereshteh

Using magnetic nanoparticles (MNPs) for emulsified oil separation from wastewater is becoming increasingly widespread. This study aims to synthesize MNPs, using amphiphilic coatings to stabilize the MNPs and prevent their agglomeration for efficiently breaking nano oil-in-water emulsion. We coat two different sizes of Fe3O4 nanoparticles (15–20 nm and 50–100 nm) using cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS) with coating-to-MNP mass ratios of 0.4 and 0.8. We study the effect of various variables on demulsification performance, including the MNP size and concentration, coating materials, and MNP loading. Based on the oil-water separation analysis, smaller size MNPs (MNP1) show a better demulsification performance than the larger ones (MNP2) for 1000 ppm dodecane-in-water emulsion, containing nanosized oil droplets (250–300 nm). Using a low dosage of 0.5 g/L functionalizing MNP1 with a lower coating-to-MNPs mass ratio of 0.4 increases the separation efficiency (SE) from 57.5% for bare MNP1 to 86.1% and 99.8% for MNP1@SDS and MNP1@CTAB, respectively. The highest SE for MNP1@CTAB and the zeta potential measurements imply that electrostatic attraction between negatively charged oil droplets (-55.9±2.44 mV) and positively charged MNP1@CTAB (+35.8±0.34 mV) is the major contributor to high SE. Furthermore, the reusability tests for MNP1@CTAB reveal that after ten cycles, the amount of oil adsorption capacity decreases slightly, from 20 mg/g to 19 mg/g, indicating an excellent stability of synthesized nanoparticles. In conclusion, functionalized MNPs with tailored functional groups feature a high oil SE that could be effectively used in oil separation from emulsified oily wastewater streams.