Development of porous materials based on styrene-ethylene-butylene-styrene for oil spill remediation

Abstract

Marine oil spills, resulting from catastrophic equipment failure during oil transportation or the release of oily wastewater from industrial operations, can lead to economic losses and severe environmental damage to marine life. The urgent need for polluted water remediation has prompted scientists and technocrats to develop oil spill cleanup methods, and Oil sorbents have emerged as one of the most effective solutions, as they cause minimal harm to the marine environment and quickly remove pollutants with high oil uptake efficiency. Hydrophobic polymeric foams and fibers, in particular, have gained recognition for their porous structures and large surface areas, which grant them enhanced sorption capacity and separation efficiency. Styrene-ethylene-butylene-styrene (SEBS) is a hydrophobic and oleophilic thermoplastic elastomer, consisting of rubbery midblock (ethylene-butylene) and glassy end blocks (styrene). The midblock is soluble in hydrocarbon oil, while the end blocks are not, allowing the polymer to selectively capture oil while maintaining its elasticity. SEBS's unique features make it an excellent candidate for an oil sorbent with high oil absorption capacity, efficient oil/water separation, and selective oil congealing properties. However, creating a porous SEBS material is challenging due to its poor melt strength and low melt flow index. In this thesis, the development of porous structures based on SEBS as mitigation approaches to address the oil spill challenge are investigated and presented. In the first part, the fabrication of a novel and highly effective elastomer foam based on a styrene-ethylene-butylene-styrene (SEBS) and ethylene propylene diene monomer (EPDM) blend was studied. Dicumyl peroxide served as a radical initiator for the elastomer blend's crosslinking. This crosslinking significantly improved the melt strength of the SEBS/EPDM blend, allowing for extensive expansion and the creation of well-defined porous structures. Consequently, the material exhibited exceptional oil absorption capabilities due to the increased surface. The later section focuses on developing melt-blown SEBS. To overcome the inherent low melt flow index (MFI) of SEBS, which hinders the melt-blowing process, high MFI polypropylene (PP) was incorporated as a blending additive. The impact of blending polypropylene with SEBS on melt-blowing processability and fiber quality was then examined. Notably, adding 10 wt% PP to SEBS significantly enhances fiber melt-blowing processability, resulting in a more extensive and evenly dispersed fiber stream. Further analysis revealed superior oil uptake capacity and increased surface area, enabling effective interaction between SEBS-based fibers and oil. This interaction led to the formation of a semi-solid gel that creates a barrier, limiting further oil dispersion even at saturation point, demonstrating a markedly superior oil immobilization performance compared to conventional polypropylene melt-blown fibers. Overall, this study showed that the rational design of porous structures from SEBS allows the selective sorption of oil from water.