Preparation of Hydrophobic Octadecylphosphonic Acid-Coated Magnetite Nanoparticles for the Demulsification of n-Hexane-in-Water Nanoemulsions

• Published in: Materials Vol. 16; no. 15; p. 5367
• Main Authors: Liang, Jiling, Han, Tingting, Wang, Wenwu, Zhang, Lunqiu, Zhang, Yan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 31.07.2023; MDPI
• Subjects: Biochemical oxygen demand; Calcium chloride; Chemical oxygen demand; Contact angle; demulsification; Efficiency; Electrolytes; Electron microscopy; Energy consumption; Ethanol; Fourier transforms; Hazardous substances; Hexanes; Hydrocarbons; Hydrophobicity; Hydroxyl groups; Infrared analysis; Iron oxides; Magnetite; magnetite nanoparticle; Membrane separation; Microscopy; Nanoemulsions; Nanoparticles; O/W nanoemulsion; octadecylphosphonic acid; Operating costs; Pollutants; Purification; Sewage; Stability analysis; Wastewater; Wastewater treatment; Water treatment; China; Sudan; demulsification; octadecylphosphonic acid; O/W nanoemulsion; magnetite nanoparticle
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16155367

To design more environmentally friendly, economical, and efficient demulsifiers for oily wastewater treatment, hydrophobic octadecylphosphonic acid (ODPA)-modified Fe O nanoparticles (referred to as Fe O @ODPA) were prepared by condensation of hydroxyl groups between ODPA and Fe O nanoparticles using the co-precipitation method. The prepared magnetite nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric/differential thermogravimetric (TG/DTG) analysis. The water contact angles ( ) of Fe O @ODPA nanoparticles were more than 120°, indicating hydrophobic nature, and the diameter of the obtained spherical-shaped magnetite nanoparticles was 12-15 nm. The ODPA coating amount ( ) (coating weight per gram Fe O ) and specific surface area ( ) of Fe O @ODPA were 0.124-0.144 g·g and 78.65-91.01 m ·g , respectively. To evaluate the demulsification ability, stability, and reusability, the magnetite nanoparticles were used to demulsify an n-hexane-in-water nanoemulsion. The effects of the magnetite nanoparticle dosage ( ), pH value of nanoemulsion, and NaCl or CaCl electrolytes on the demulsification efficiency ( ) were investigated. The of Fe O @ODPA samples was found to be higher than that of bare Fe O samples (S0, ST, and SN) under all values. With the increase in , the of Fe O @ODPA samples initially increased and then approached equilibrium value at Cs = 80.0 g·L . A maximum of ~93% was achieved at = 100.0 g·L for the Fe O @ODPA sample S2. The pH and two electrolytes had a minor effect on The Fe O @ODPA nanoparticles maintained high even after being reused for demulsification 11 times. This indicates that the hydrophobic Fe O @ODPA samples can be used as an effective magnetite demulsifer for oil-in-water nanoemulsions.