Intelligent light-driven polystyrene foams for water purification and research into their functionality: superhydrophobic, self-cleaning, oil-water separation, and photothermal conversion

Abstract

Frequent oil spills and discharges of oily wastewater have seriously jeopardized the sustainability of the ecosystem while causing irreversible damage to marine ecosystems, which urgently need to be dealt with through effective measures. In this study, the organic monomers styrene (St) and divinylbenzene (DVB) were used as the continuous phase, and the Fe₃O₄ nanoparticles encapsulated in polydopamine (PDA) were dispersed in water as the dispersed phase. Novel superhydrophobic P(St-DVB)/Fe₃O₄@PDA foams with photothermal effect were successfully constructed based on the high internal phase emulsion template method. Fe₃O₄@PDA nanoparticles were composited with the foams so that the material could be rapidly heated up to 119.7 °C under simulated solar irradiation. Moreover, the contact angle (WCA) of the P(St-DVB)/Fe₃O₄@PDA foam was 154° and the oil contact angle (OCA) was 0°. The P(St-DVB)/Fe₃O₄@PDA foam's adsorption of many types of oil/organic solvents ranged from 50.50 to 114.6 g/g. Furthermore, the foam had a separation efficiency of not less than 99% for a wide range of emulsions stabilized by Span80, and the separation efficiency was maintained at about 99% for the continuous treatment of oil-water mixtures. Finally, it was worth mentioning that the foams also had excellent self-cleaning properties and showed good chemical stability in harsh environments such as strong acids and alkalis. Given these unique performance advantages, P(St-DVB)/Fe₃O₄@PDA foams promised to be both an ideal and practical solution for oil-water separation, especially in the case of high-viscosity crude oil spills.