How to Formulate Biobased Surfactants Through the HLD-NAC Model

Acosta, Edgar; Sundar, Suryavarshini

doi:10.1016/b978-0-12-812705-6.00015-0

Cited by 10 publications

(11 citation statements)

References 46 publications

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“…where L is the surfactant tail length parameter, estimated as 1.4*extended tail length (Acosta, 2008). For a linear C 12 surfactant, L = 23 Å (Acosta & Sundar, 2019). The term ξ is the characteristic length or maximum solubilization capacity of the μE system.…”

Section: Experimental Versus Bifunctional Model σ App For Broad and Narrow Range Aesmentioning

confidence: 99%

Effect of surfactant concentration on the hydrophobicity of polydisperse alkyl ethoxylates

Acosta

Natali

2021

J Surfact & Detergents

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The effect of ethylene oxide number (EON) polydispersity on the phase behavior of alkyl ethoxylates has been well documented in the surfactant literature. These previous studies show that polydisperse alkyl ethoxylates appear more hydrophilic as the surfactant concentration decreases or as the oil-to-water ratio increases. This becomes a troubling issue considering that most surfactant formulations undergo dilution during use, and they experience a wide range of water-to-oil volume ratios. Within the hydrophilic-lipophilic difference framework, the surfactant hydrophobicity is assessed via the sigma (σ) term (also known as the characteristic curvature or Cc). In this work, the effect of surfactant concentration on the apparent value of sigma (σ app ) is evaluated as a function of surfactant concentration. The experimental observations are then explained using a bifunctional model for alkyl ethoxylates that consider the dual nature of polar oils (free alcohol and low EON ethoxymers) as surfactants and as oil components. A segregation-based model and a partition-based model are implemented to account for the distribution of the ethoxymers in the surfactant pseudophase and the oil phase. Combining these distribution models with the bifunctional model and a group contribution model for sigma, one can predict the σ term versus surfactant concentration for a given water/oil ratio, starting from the EON distribution of the surfactant. The practical applications of the model are discussed.

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Section: Experimental Versus Bifunctional Model σ App For Broad and Narrow Range Aesmentioning

confidence: 99%

Effect of surfactant concentration on the hydrophobicity of polydisperse alkyl ethoxylates

Acosta

Natali

2021

J Surfact & Detergents

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“…HLD is correlated to the chemical potential difference when the surfactant is in the oil phase and when the surfactant is in the aqueous phase , Emulsions are most stable for HLD = 0. For ionic surfactants, HLD = ln(S)– k ·EACN+Cc-α T ·( T -25 °C), where k and α T are constants, EACN is the equivalent alkane carbon number of the oil, S is the salinity (g NaCl/100 mL), Cc is the characteristic curvature of the surfactant, and T is the temperature (°C). ,, When emulsions were prepared using lecithin, toluene and 32 g/L NaCl salt, Cc = 5.5, EACN = 1, S = 3.2 g/100 mL, k = 0.13 . The term α T ( T -25 °C) could be neglected because experiments were conducted at T = 23 °C (and this term was therefore small).…”

Section: Resultsmentioning

confidence: 99%

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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“…In order to complete the HLD calculations, we needed the Cc of all the surfactants used in this study. The Cc parameters for Tween 80, Span 20, SDS, and AOT were found in the literature 28 . However, we performed the salinity scan to measure the Cc of the commercial nonionic surfactants such as K3, K6, and AK.…”

Section: Methodsmentioning

confidence: 99%

Design of industrial wastewater demulsifier by HLD-NAC model

Ghasemi

Eslami

2021

Sci Rep

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The chemical method is one of the treatment techniques for the separation of oil–water emulsion systems. The selection of appropriate demulsifiers for each emulsion system is the most challenging issue. Hydrophilic-lipophilic-deviation (HLD) is a powerful semi-empirical model, providing predictive tools to formulate the emulsion and microemulsion systems. This work aims to apply HLD to obtain an optimal condition for demulsification of oil-in-water emulsion system—real industrial wastewater—with different water in oil ratios (WOR). Therefore, the oil parameter of the contaminant oil and surfactant parameter for three types of commercial surfactants were calculated by performing salinity scans. Furthermore, the net-average-curvature (NAC) framework coupled with HLD was used to predict the phase behavior of the synthetic microemulsion systems, incorporating solubilization properties, the shape of droplets, and quality of optimum formulation. The geometrical sizes of non-spherical droplets (Ld, Rd)—as an indicator of how droplet sizes are changing with HLD—were consistent with the separation results. Correlating Ld/Rd at phase transition points with bottle test results validates the hypothesis that NAC-predicted geometries and demulsification behavior are interconnected. Finally, the effect of sec-butanol was examined on both synthetic and real systems, providing reliable insights in terms of the effect of alcohol for WOR ≠ 1.

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How to Formulate Biobased Surfactants Through the HLD-NAC Model

Cited by 10 publications

References 46 publications

Effect of surfactant concentration on the hydrophobicity of polydisperse alkyl ethoxylates

Effect of surfactant concentration on the hydrophobicity of polydisperse alkyl ethoxylates

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

Design of industrial wastewater demulsifier by HLD-NAC model

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