Natural emulsion gels and lecithin-based sorbents: A potential treatment method for organic spills on surface waters

Safieh, Peter; Pensini, Erica; Marangoni, Alejandro G.; Lamont, Kristine; Ghazani, Saeed M.; Callaghan-Patrachar, Nukhalu; Strüder‐Kypke, Michaela C.; Peyronel, Fernanda; Chen, Jay; Rodriguez, Braulio Macias

doi:10.1016/j.colsurfa.2019.04.090

Cited by 13 publications

(10 citation statements)

References 43 publications

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“…Biosurfactants (natural surfactants) were used with the purpose of emulsifying toluene, to promote its mobility and facilitate its removal using electrokinetic remediation (as highlighted earlier and as further discussed in the section titled “Hydrocarbon Removal”). Saponin is a natural surfactant present in diverse plants, and lecithin is also a natural emulsifier, , derived for instance from soy . The stability of emulsions stabilized by lecithin, saponin, or lecithin and saponin mixtures is shown in Figures and , in either DI water or 32 g/L NaCl.…”

Section: Resultsmentioning

confidence: 99%

“…Each experiment was replicated three times. The interfacial tension was estimated using a Biolin Scientific Theta Lite optical tensiometer, Attension software (Bioling Scientific, Gothenburg, Sweden) and the Young–Laplace model (1) []: where R 0 is the radius of curvature at the drop apex where y = 0, Δρ is the difference in density between the two liquids, g is the gravity constant, σ is the interfacial tension, and R 1 and R 2 are the principal radii of curvature (note that at the apex, R = R 1  R 2 ).…”

Section: Methodsmentioning

confidence: 99%

“…Indeed, a limitation of electrokinetic remediation is that it can treat exclusively contaminants that are dissolved and mobile in groundwater, and capillary forces impede NAPL transport. , This limitation can be overcome by using surfactants, which can dissolve NAPL sorbed onto the soil and decrease interfacial tension, enhancing NAPL mobility . The use of biobased surfactants is desirable in the context of soil remediation, because synthetic surfactants can be toxic to autochthonous microorganisms. , Diverse natural compounds are effective emulsifiers, including humic acids, lecithin, , extracts from fungi, and saponin . Specifically, lecithin has been proposed as a safe stabilizer of oil–water emulsions, with a broad range of oils (either petroleum-derived or natural) .…”

Section: Introductionmentioning

confidence: 99%

“…21 The use of biobased surfactants is desirable in the context of soil remediation, because synthetic surfactants can be toxic to autochthonous microorganisms. 8,24 Diverse natural compounds are effective emulsifiers, including humic acids, 25 lecithin, 26,27 extracts from fungi, 2 and saponin. 28 Specifically, lecithin has been proposed as a safe stabilizer of oil−water emulsions, with a broad range of oils (either petroleum-derived or natural).…”

Section: ■ Introductionmentioning

confidence: 99%

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Zein-Bonded Graphene and Biosurfactants Enable the Electrokinetic Clean-Up of Hydrocarbons

et al. 2021

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Nonaqueous phase liquids (NAPL, e.g., hydrocarbons and chlorinated compounds) are common groundwater pollutants. Electrokinetic remediation of NAPLs uses electric fields to draw them toward electrodes and remove them from groundwater. The treatment requires NAPL mobility. Emulsification increases mobility, but at a risk for downstream receptors. We propose using alkaline aqueous solutions of zein and graphene nanoparticles (GNP) to form conductive materials, which could also act as barriers to control NAPL migration. Alkaline zein−GNP solutions can be injected in the polluted soil and solidified by neutralizing the pH (e.g., with glacial acetic acid, GAA). Shear rheology experiments showed that zein−GNP composites were cohesive, and voltammetry showed that GNP increased electrical conductivity of zein-based materials by 3.5 times. Gas chromatography−mass spectroscopy (GC−MS) demonstrated that the electrokinetic treatment of model sandy aquifers yielded >60% and ∼47% removal of emulsified toluene in freshwater and in salt solutions, respectively (with 30 min treatment using a 10 V differential voltage between a zein−GNP and an aluminum electrode. NaCl was used as model salt contaminant. The conductivity of surfactant solutions was lower in saline water than in freshwater, explaining differences in toluene removal. Toluene−water emulsions were stabilized using the natural surfactants lecithin and saponin. These surfactants acted synergistically in stabilizing emulsions in either freshwater or salt solutions. Lecithin and saponin likely interacted at toluene−water interfaces, as indicated by the morphology, interfacial tension and compressional rigidity of toluene−water interfaces with both components (relative to interfaces of either lecithin or saponin alone). The compressional behavior of interfacial films was well-described by the Marczak model. Electrokinetic treatment of saturated model sandy aquifers also decreased the turbidity of emulsions of water and either tricholoroethylene (TCE, by ∼41%) or diesel (by ∼75%), in the presence of a bacterial biosurfactant. This decrease was used as semiquantitative indicator of NAPL removal from water.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Zein-Bonded Graphene and Biosurfactants Enable the Electrokinetic Clean-Up of Hydrocarbons

et al. 2021

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“…In addition to sorbents 11 , 12 , separation sponges have been developed to clean-up oil spills in surface waters. Separation sponges can be attached onto suction ports on boats, to selectively extract oil from surface waters 13 .…”

Section: Introductionmentioning

confidence: 99%

Selective solvent filters for non-aqueous phase liquid separation from water

Marshall

Estepa

Corradini

et al. 2020

Sci Rep

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Injectable filters permeable to water but impermeable to non-polar solvents were developed to contain non-aqueous phase liquids (NAPL) in contaminated aquifers, hence protecting downstream receptors during NAPL remediation. Filters were produced by injecting aqueous solutions of 0.01% chitosan, hydroxyethylcellulose and quaternized hydroxyethylcellulose into sand columns, followed by rinsing with water. Polymer sorption onto silica was verified using a quartz-crystal microbalance with dissipation monitoring. Fluorescence and gas chromatography mass spectroscopy showed low ppm range concentrations of non-polar solvents (e.g., hexane and toluene) in water eluted from the filters (in the absence of emulsifiers). The contact angles between polymer-coated surfaces and hexane or toluene were > 90°, indicating surface oleophobicity. Organic, polar solvents (e.g. tetrahydrofuran and tetrachloroethylene, TCE) were not separated from water. The contact angles between polymercoated surfaces and TCE was also > 90°. However, the contact area with polymer coated surfaces was greater for TCE than non-polar solvents, suggesting higher affinity between TCE and the surfaces. Emulsifiers can be used to facilitate NAPL extraction from aquifers. Emulsion separation efficiency depended on the emulsifier used. Emulsions were not separated with classical surfactants (e.g. Tween 20 and oleic acid) or alkaline zein solutions. Partial emulsion separation was achieved with humic acids and zein particles. Petroleum hydrocarbons (e.g. toluene) are common soil and groundwater contaminants because of their historical and current use in industry 1. Oil spills in surface waters can also occur during transport by boat, threatening surface water bodies and ecosystems in their proximity 2-4. In 1969, the oil well blowout in Santa Barbara, California released 4.1-4.6 million barrels of oil 5,6. Since then, American waters have been contaminated by more than 44 oil spills (each over 420,000 US gallons) 7. Spills have also occurred in Greece (where the Agia Zoni II released over 2,500 tonnes of oil in 2017 8), in India (where the Ennore spill released 160 tonnes of oil 9) and in east China (where the Sanchi oil tanker released 136,000 tonnes of natural-gas condensate in 2018 10). In addition to sorbents 11,12 , separation sponges have been developed to clean-up oil spills in surface waters. Separation sponges can be attached onto suction ports on boats, to selectively extract oil from surface waters 13. Oil-water separation sponges are produced using different methods, including dip coating, chemical vapor deposition, in situ chemical reaction, wet chemical reaction, thermal treatment, polymerization, electroless deposition, or carbonization 13. Different materials have been used to produce sponges for oil-water separation. For instance, graphene/polyurethane sponges have been obtained by in situ polymerization of N-methylpyrrolidone in the presence of graphene 14. These sponges have been used to selectively extract hexane, crude oil and engine oil flo...

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