Rapid and efficient oil removal from O/W emulsions by hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions

• Published in: Journal of hazardous materials Vol. 434; p. 128898
• Main Authors: Xie, Xiaomin, Yan, Jingfan, Wu, Qiong, Wang, Tianyu, Chu, Fumin, Yang, Sen
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.07.2022
• Subjects: Absorption; Demulsification; Hydrophilic surface micro-regions; Oil-in-water emulsion; Porous polystyrene microsphere; Porous polystyrene microsphere; Absorption; Oil-in-water emulsion; Hydrophilic surface micro-regions; Demulsification
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.128898

Inspired by Namib Desert beetle’s back which is patterned with different wetting properties, hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions (HPHs) were designed and fabricated by the radical copolymerization in the W1/O/W2 double Pickering emulsions with high internal water phase. The synergistic effect of the hydrophobic surface and the hydrophilic surface micro-regions results in HPHs exhibiting superior performances for separating both surfactant-free and surfactant-stabilized O/W emulsions. After 60 s hand-shaking, the oil was absorbed and stored within HPHs which could be separated from the water using a 600-mesh sieve, and the TOC values of purified water could be reduced to 2.06 ± 0.06–67.38 ± 2.02 ppm when the initial oil content was 1 vol%. Meanwhile, HPHs could be recovered and reused through a simple treatment. The excellent oil removal efficiency was kept even after 50 cycles. High oil removal efficiency, general applicability, easy operation and excellent recyclability endow HPHs with great potential for practical applications. And this work provides a facile and general way to prepare porous polymer microspheres with wettability contrast surfaces. [Display omitted] •Hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions (HPHs) were prepared.•The wettability contrast was the origin of demulsification of O/W emulsion.•HPHs achieved efficient emulsion separation via demulsification and absorption.•HPHs could be recycled at least 50 times.