pH-responsive modified magnetic nanoparticles for treatment of oily wastewater

Unfortunately, with the expansion of oil industries, the damage caused by oil-in-water emulsions on the environment and people’s lives has increased. In this study, using different ratios of iron oxide nanoparticles and modified aniline (4:1 (Fe41), 1:1 (Fe11), and 1:4(Fe14)), demulsifiers were fabricated that could destabilize oil-in-water emulsions in three acidic, alkaline, and neutral environments. The characteristics of the made magnetic demulsifiers were evaluated by X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), etc. tests. The turbidity results, Fe41, indicate that the pH = 7 demulsifier can be reduced to below 100 NTU. Also, changing nanoparticles to modify the aniline ratio can improve the efficiency of demulsifiers in different environments. While, in pH = 4, the turbidity result for Fe41 is 153 NTU, the turbidity result for Fe14 is 114 NTU. Moreover, zeta potential, contact angle, and optical microscope tests were used to understand the demulsification mechanism better. These evaluations showed that in the neutral environment (pH = 7), electrostatic interactions play the most crucial role in the performance of the demulsifier. but in acidic conditions other parameters (such as pi-pi interaction) are also involved. Moreover, the magnetic property of the demulsifier made it possible to use this demulsifier up to four times.