Continuous preparation of polyHIPE monoliths from ionomer-stabilized high internal phase emulsions (HIPEs) for efficient recovery of spilled oils
Graphical abstract
Introduction
Oil spills have attracted considerable attention, as they are one of the major issues in the current world and cause serious damages to environment, transportation and even our health [1]. Several kinds of technologies have been developed to remove the spilled oils [2]. They are bioremediation with microorganisms [3], [4] or biological agents, in situ combust [5], [6], chemical treatment with demulsifies [7] or dispersants [8], [9] and mechanical treatment with oil–water gelators [10], [11], [12], [13] or absorbents [14], [15], [16], [17], [18], [19]. Among those technologies, mechanical treatment using absorbents is the most promising, since it can remove the pollutants and reclaim the spilled oils at the same time. Therefore, the manufacture and application of absorbent are important for efficient reclamation of spilled oils.
A variety of absorbents have been investigated and fabricated for oil spill recovery [14], [15], [20], [21], [22], [23], and porous materials from emulsion templating (termed as polyHIPEs) have attracted considerable attention [16], [24], because they usually exhibit interconnected macro-porous structures which facilitate the absorption of viscous liquids such as crude oil [23], [25].
To produce polyHIPEs, stable HIPEs are required. HIPEs are traditionally stabilized by surfactants and particles. However, a careful choice of surfactant is required to avoid phase inversion of emulsions at a high volume fraction of internal phase [26] and a high concentration (up to 50% of the continuous phase) is usually needed [27], [28], [29]. Surfactants are usually removed once polyHIPEs are produced, and these used surfactant can be a new pollutant to environment. Although surfactant can be incorporated into polyHIPEs covalently, specific monomers and surfactant are needed [30]. Surface modified particle have also been reported to stabilize HIPEs and they are known as Pickering HIPEs [31], [32], but the corresponding polyHIPEs usually have closed-cell structures [32]. Moreover, the toxicity of these nanoparticles are still in dispute [33], [34]. Recently, various amphiphilic soft particles and block copolymers have been developed to stabilize HIPEs [35], [36], [37], [38]. It has demonstrated that block copolymer (as HIPE stabilizer) is not removed during the purifying process as the entanglement of block copolymer in the polyHIPEs prevents leaching of the HIPE stabilizer [38].
We focus on the preparation of HIPEs and their applications in petroleum fields [20], [21], [39], [40], [41], [42]. An ionomer, sulfonated polystyrene has been reported previously as an efficient HIPE stabilizer [41]. Herein, we report a continuous approach to prepare polyHIPEs for oil spill recovery. The polyHIPEs (SPS-polyHIPEs) was prepared by light induced polymerization of sulfonated polystyrene stabilized HIPEs (SPS-HIPEs). The sulfonated polystyrene was obtained by sulfonation of waste polystyrene, realizing a transition from trash into treasure. SPS-polyHIPEs can be produced in a few minutes, providing a possibility to manufacture them continuously. The as-prepared SPS-polyHIPE monoliths are hydrophobic with controlled morphology, and they exhibit high absorption rate, recovery rate, high reusability and recycle. Therefore, this paper shows an environment-friendly and efficient approach to prepare and apply SPS-polyHIPE monoliths for oil spill reclamation.
Section snippets
Chemicals and reagents
Waste polystyrene foams were collected from packing materials of vacuum cleaner (Homemake®). Ethylene glycol dimethacrylate, tetraethyl orthosilicate (TEOS) and 2-Hydroxy-2-methylpropiophenone (Darocur 1173) were used as received. Butyl acrylate was purified by passing a neutral aluminium oxide column before use. All the chemicals mentioned above were purchased from Sigma-Aldrich. Seawater was collected from Anglesea, Australia. The other reagents and solvents were analytical grade and used
SPS-polyHIPEs from SPS-stabilized HIPEs
SPS with a sulfonation degree of 9.8 mol% was obtained by the sulfonation of used polystyrene foams. Polystyrene foams are commonly used as packing material and thermal insulation material, and used polystyrene foams are usually deposed into landfill because polystyrene is completed decomposed into toxic gases instead of carbonization at moderate temperature. As an amphiphilic macromolecule, SPS was has reported as an efficient water-in-oil HIPE stabilizer [41]. Here, a low concentration (0.5
Conclusions
SPS-polyHIPEs has been successfully fabricated from light induced polymerization of SPS-stabilized HIPEs. The SPS was prepared from waste foams, realizing a sustainable method to deal with waste polystyrene. SPS-polyHIPEs with a high gel fraction of 93% can be obtained in 5 min, and they can be used directly without a purification process. These monoliths are hydrophobic with controllable interconnected macro-porous structures, which facilitate the reclamation of spilled oils. These monoliths
Acknowledgements
SAXS measurements were conducted on the SAXS/WAXS beam-line at the Australian Synchrotron, Victoria, Australia.
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