Oil sludge washing with surfactants and co-solvents: oil recovery from different types of oil sludges

Ramírez, Diego; Shaw, Liz J.; Collins, Chris

doi:10.1007/s11356-020-10591-9

Cited by 27 publications

(14 citation statements)

References 64 publications

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“…There are two moieties of the rhamnolipids, one or two l -rhamnose hydrophilic molecules with a glycosidic linkage to the hydrophobic groups comprising one or multiple β-hydroxylated fatty acids. The diversity in chemical structures of RLs , features their wide-ranging functionalities. , In the past two decades, experimental studies have shown promising results of using RLs for environmental remediation. − By improving the production method, the production cost of RL has become more suitable for massive usage. , Nevertheless, the naturally produced RLs usually contain several RLs homologues and congeners. Understanding the micellar properties and the interfacial behavior of RLs in their pure states or in mixtures, as well as their interactions with hydrocarbons, is the key to advance future development.…”

Section: Introductionmentioning

confidence: 99%

Micellization of Rhamnolipid Biosurfactants and Their Applications in Oil Recovery: Insights from Mesoscale Simulations

Lee

2021

J. Phys. Chem. B

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The dissipative particle dynamics (DPD) mesoscopic method is used to investigate the self-assembly of rhamnolipid congeners and their aggregation behaviors with paraffins including nonane and pentadecane. The coarse-grained force field is parameterized by combining molecular dynamics (MD) simulations, COSMOtherm calculations, and available experimental data. This model reproduces the vesicular formation of α-L-rhamnopyranosylβ-hydroxydecanoyl-β-hydroxydecanoate (Rha-C10-C10) reported by all-atom MD simulations. The vesicle composed of Rha-C10-C10 is found to be most stable at a surfactant concentration of 100−146 mM based on asphericity analysis. The architecture of rhamnolipid congeners affects the morphology of their aggregates. Di-rhamno-di-lipidic dRha-C16-C16 forms vesicles with a thicker unilamellar layer of 3.2 nm. Rha-C16-C16 forms vesicles at a lower concentration of 70 mM, but the enclosed water space collapses when the surfactant concentration increases. dRha-C10-C10 forms wormlike micelles, which agglomerate into a torus and interconnected network at higher concentrations. In the presence of alkane molecules, dRha-C10-C10 maintains its wormlike micellar morphology with alkane molecules wrapped inside the aggregates. For Rha-C10-C10, Rha-C16-C16, and dRha-C16-C16, nonane molecules are distributed in the hydrophobic subdomain formed by rhamnolipid molecules. Spherical vesicles are formed at a surfactant concentration of 50 mM and then develop into ellipsoidal vesicles when the concentration increases to 125 mM. When mixed with pentadecane, the alkane molecules are aggregated and surrounded by surfactants forming a core−shell structure at a low surfactant concentration of 20 mM. At higher alkane and surfactant concentrations, the morphologies develop into disk micelles, wormlike micelles, and vesicles, with pentadecane molecules being distributed and packed with rhamnolipids. The obtained simulation results suggest that these biosurfactants have potential as environmental remediation agents.

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Section: Introductionmentioning

confidence: 99%

Micellization of Rhamnolipid Biosurfactants and Their Applications in Oil Recovery: Insights from Mesoscale Simulations

Lee

2021

J. Phys. Chem. B

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“…The co-solvent used was cyclohexane (high-purity, HPLC grade, Fisher Scientific). Cyclohexane was selected in a previous oil recovery study from OSW processes (Ramirez et al 2020). It was found that the oil recovery rates were not significantly different between cyclohexane and one of the most commonly used solvents, toluene.…”

Section: Surfactants and Co-solventmentioning

confidence: 99%

“…The residuals were obtained at bench scale from the following OSW process. Briefly, the oil sludge (5 g), surfactant [5:1 ratio to oil sludge and at 5CMC, critical micelle concentration; the highest ratio and concentration used in previous oil recovery studies with these oil sludges samples (Ramirez and Collins 2018;Ramirez et al 2020)], and cyclohexane (1:1 ratio to oil sludge) were added to a 40-ml vial. The vial was then agitated at 250 rpm for 60 min and left for 12 h to settle.…”

Section: Oil Sludge Washingmentioning

confidence: 99%

“…First, the sludges and OSW residuals were analysed with the DHA test to have a comprehensive evaluation of the toxicity and to assess the incubation time in this test. All surfactants were added at 5CMC which was the highest concentration used in previous oil recovery studies with these sludges (Ramirez and Collins 2018;Ramirez et al 2020). OSW residual concentrations in soil were taken from Singh and Agrawal (2007) and Mazen et al (2010).…”

Section: Sample Preparationmentioning

confidence: 99%

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Ecotoxicity of oil sludges and residuals from their washing with surfactants: soil dehydrogenase and ryegrass germination tests

Ramírez

Shaw

Collins

2020

Environ Sci Pollut Res

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Oil sludge washing (OSW) with surfactants and co-solvents is used to recover the oil, and this process leaves some residuals (sediments and surfactant solution). Currently, there are no data on the ecotoxicological effects of these OSW residuals from different sludges. This study evaluated the toxicity of OSW residuals from washing four types of oil sludges with five surfactants (Triton X-100 and X-114, Tween 80, sodium dodecyl sulphate (SDS) and rhamnolipid) and a co-solvent (cyclohexane). The toxicity of the residuals was evaluated with the impact on the soil microbial dehydrogenase activity (DHA) and ryegrass (Lolium perenne) seed germination. There was a high DHA detected directly in the sludges and all OSW residual combinations, but this activity could not be attributed to the DHA itself but to some chemical interferences. The DHA was then tested in the soils amended with the OSW residuals to simulate a bioremediation scenario. There were no chemical interferences in this case. In general, the INTF concentrations were significantly higher at low concentrations, 1 and 5% (p < 0.01). There were no significant differences in the DHA at high concentrations of OSW residuals (10, 25 and 50%) which implied that the concentration of the contaminants is not directly proportional to the levels of ecotoxicity. Unexpectedly, the INTF values of the 10, 25 and 50% rhamnolipid-OSW residuals were significantly lower than the Triton X-100 residuals. The ryegrass germination rates were higher than 70% with no apparent phytotoxicity symptoms in the seedlings. Particularly, there was a highly significant negative effect of the residuals on the germination rates at high concentrations (p < 0.01). Given that the extractable petroleum hydrocarbon (EPH) concentrations in the OSW residual-amended soils in both DHA and germination tests were very low (13–21 ppm), other co-contaminants could be contributing to the toxicity. These findings implied that biotreatment techniques can be applied to treat the OSW residuals if necessary.

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“…According to their study, RL has the oil recovery rate among the highest, which is around 40–70%. They have also found that the concentration of the surfactant used has a minimal effect on the oil recovery performance . However, the application ratio of surfactant-to-oil (S/O) does have a great impact on the surfactant’s performance in the presence of hydrocarbon as a cosolvent.…”

Section: Introductionmentioning

confidence: 99%

Rhamnolipid Biosurfactants for Oil Recovery: Salt Effects on the Structural Properties Investigated by Mesoscale Simulations

Chen

Lee

2022

ACS Omega

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Rhamnolipids (RLs) are biosurfactants produced by Pseudomonas. The biodegradability and the variety of their functionality make them suitable for environmental remediation and oil recovery. We use dissipative particle dynamics simulations to investigate the aggregation behaviors of ionic RL congeners with nonane in various operating conditions. Under zero-salinity conditions, all RL congeners studied here form small ellipsoidal clusters with detectable free surfactants. When salt ions are present, the electrostatic repulsion between the ionized heads is overcome, resulting in the formation of larger aggregates of unique structures. RLs with C10-alkyl tails tend to form elongated wormlike micelles, while RLs with C16-alkyl tails tend to form clusters in spherical symmetry, including vesicles. Di-rhamnolipids (dRLs) require stronger solvation than monorhamnolipids (mRLs) to form clusters, and the resulting size of micelles is decreased. The morphology of the mixed dRL/mRL/oil systems is controlled based on the type of the congeners and the oil contents. In addition, the divalent calcium ions are found to be influential to the structure of the micelles through different mechanisms. For 5 wt % salinity, the ionic RLs can form oil-swollen micelles up to a 1:1 surfactant-to-oil ratio, suggesting that ionic RLs are superb to act as cleaning agents for petroleum hydrocarbons in the marine area. These key findings may guide the design for RL-based washing techniques in enhanced oil recovery.

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Oil sludge washing with surfactants and co-solvents: oil recovery from different types of oil sludges

Cited by 27 publications

References 64 publications

Micellization of Rhamnolipid Biosurfactants and Their Applications in Oil Recovery: Insights from Mesoscale Simulations

Micellization of Rhamnolipid Biosurfactants and Their Applications in Oil Recovery: Insights from Mesoscale Simulations

Ecotoxicity of oil sludges and residuals from their washing with surfactants: soil dehydrogenase and ryegrass germination tests

Rhamnolipid Biosurfactants for Oil Recovery: Salt Effects on the Structural Properties Investigated by Mesoscale Simulations

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