Green dispersants for oil spill response: A comprehensive review of recent advances

Plant biomass extracted eco-friendly natural surfactant enhanced bio-electrokinetic remediation of crude oil contaminated soil

The current work investigates bioremediation (BIO) and electrokinetic (EK) remediation of crude oil hydrocarbons utilizing the biomass-electrokinetic (BIO-EK) approaches. The use of natural surfactants derived from plant biomass may improve remediation capacity by enhancing the solubility of organic pollutants. Sapindus mukorossi, a natural surfactant producer, was extracted from plant biomass in this study. The crude oil biodegradation efficiency was reported to be 98 %. In nature, FTIR confirms that plant biomass is lipopeptide. GCMS revealed that the crude oil (C7 - C23) was efficiently bio-degraded from lower to higher molecular weight. The application of natural surfactants in electokinetic remediation increased the plant biomass degradation of crude oil polluted soil by 98% compared to electrokinetic 55% in 2 days. Natural surfactant improves hydrocarbon solubilization and accelerates hydrocarbon electro migration to the anodic compartment, as confirmed by the presence of greater total organic content than the electrokinetic. This study proves that BIO-EK compared with a natural surfactant derived from plant biomass may be utilized to improve in situ bioremediation of crude oil polluted soils.

A Novel Biosurfactant-Based Oil Spill Response Dispersant for Efficient Application under Temperate and Arctic Conditions

Synthetic oil spill dispersants have become essential in offshore oil spill response strategies. However, their use raises significant concerns regarding toxicity to phyto- and zooplankton and other marine organisms, especially in isolated and vulnerable areas such as the Arctic and shorelines. Sustainable alternatives may be developed by replacing the major active components of commercial dispersants with their natural counterparts. During this study, interfacial properties of different types of glycolipid-based biosurfactants (rhamnolipids, mannosylerythritol lipids, and trehalose lipids) were explored in a crude oil-seawater system. The best-performing biosurfactant was further mixed with different nontoxic components of Corexit 9500A, and the interfacial properties of the most promising dispersant blend were further explored with various types of crude oils, weathered oil, bunker, and diesel fuel in natural seawater. Our findings indicate that the most efficient dispersant formulation was achieved when mannosylerythritol lipids (MELs) were mixed with Tween 80 (T). The MELs-T dispersant blend significantly reduced the interfacial tension (IFT) of various crude oils in seawater with results comparable to those obtained with Corexit 9500A. Importantly, no leaching or desorption of MELs-T components from the crude oil-water interface was observed. Furthermore, for weathered and more viscous asphaltenic bunker fuel oil, IFT results with the MELs-T dispersant blend surpassed those obtained with Corexit 9500A. This dispersant blend also demonstrated effectiveness at different dosages (dispersant-to-oil ratio (DOR)) and under various temperature conditions. The efficacy of the MELs-T dispersant was further confirmed by standard baffled flask tests (BFTs) and Mackay-Nadeau-Steelman (MNS) tests. Overall, our study provides promising data for the development of effective biobased dispersants, particularly in the context of petroleum exploitation in subsea resources and transportation in the Arctic.

Modified silica-based double-layered hydrophobic-coated stainless steel mesh and its application for oil/seawater separation

A double-layered hydrophobic-coated stainless steel mesh (CSSM) was successfully prepared by vapor deposition of polydimethylsiloxane (PDMS) to form aerosol silica (SiO2) particles on SSM followed by coating with the in situ modified SiO2 generated in the natural rubber (NR) latex for use in oil/seawater separation. The in situ SiO2 particles were modified with octyltriethoxysilane (OTES) or hexadecyltrimethoxysilane (HDTMS). Transmission electron microscopy, 29Si solid-state nuclear magnetic resonance, and Fourier transform infrared spectroscopy were used to determine the structure of the in situ modified SiO2 generated in the NR latex. Scanning electron microscopy and water contact angle analyses were applied to characterize the morphology and hydrophobicity of the CSSM, respectively. The presence of aerosol SiO2 particles from PDMS and in situ modified SiO2 by OTES (MSi-O) or HDTMS (MSi-H) generated in the NR could enhance the surface roughness and hydrophobicity of the CSSM. The hydrophobic CSSM was then applied for the separation of chloroform/seawater and crude oil/seawater mixtures. A high separation efficiency (up to 99.3%) with the PDMS/NR/MSi-H CSSM was obtained and the mesh was reusable for up to 20 cycles.