Hydrophilic Lipophilic Deviation Research Articles

Surfactants produced from carbohydrate derivatives: Part 2. A review on the value chain, synthesis, and the potential role of artificial intelligence within the biorefinery concept

AbstractThis comprehensive and critical review explores the synthesis and applications of carbohydrate‐based surfactants within the biorefinery concept, focusing on biobased sugar‐head molecules suitable for use across several manufacturing sectors, including cosmetics, pharmaceuticals, household products, detergents, and foods. The main focus relies on sustainable alternatives to conventional surfactants, which could reduce the final manufacturing carbon footprint of several industrial feedstocks and products. A thorough analysis of raw materials, highlighting the significance of feedstock sources, and the current biobased surfactants and rhamnolipid biosurfactants production trends, is presented. Key organic reactions for the production of sorbitan esters, sucrose esters, alkyl polyglycosides, and fatty acid glucamines, such as glycosidation, acylation, and etherification, as well as the production of rhamnolipids through fermentation are described. Given the scarce literature on the characterization of these surfactant types within the hydrophilic–lipophilic deviation (HLD) framework, the surfactant contribution parameter (SCP) in the HLD equation for sugar‐head surfactants is critically assessed. The economic landscape is also discussed, noting the significant growth in the biobased surfactants and biosurfactant market, driven by environmental awareness and regulatory changes, with projections indicating a substantial market increase in the forthcoming years. Finally, the promising potential of generative artificial intelligence (AI) in developing customized surfactant molecules, with optimized properties for targeted applications, is emphasized as a promising avenue for future research.

Stability of n‐hexadecane phase change material emulsions using sugar‐based surfactants and the HLD platform

AbstractStoring thermal energy and using renewable energy are some of the most important challenges humanity faces today. Using phase change materials (PCM) is a suitable solution to prevent heat loss. PCM emulsions (PCMEs) have several advantages and are specifically applied in heat exchangers. Here, the formulation of these emulsions, the type of surfactants, and their composition based on freeze–thaw cycle stability are investigated. The Hydrophilic–Lipophilic‐Deviation (HLD) platform is used for this purpose. Considering the importance of stability during temperature changes in PCMEs, three types of surfactants that have different behaviors with respect to temperature are used: ethoxylates, ionics, and sugar‐based surfactants. By performing freeze–thaw cycles on emulsions made by individual surfactants, after 10 freeze–thaw cycles it was observed that the oil separation in each of the samples containing polysorbate80, AOT, lauryl‐myristyl‐alcohol‐polyethylene‐glycol‐ether, SDS, sorbitan‐monooleate, and decylglucoside occurred at the 2nd, 4th, 6th, 7th, 8th, and 10th‐cycle, respectively. Therefore, the sorbitan‐monooleate and decylglucoside had better freeze–thaw cycle stability compared to the others because of their non‐sensitivity to temperature. We also applied the emulsion cycle stability with two combinations of surfactants: (1) polysorbate80 and sorbitan‐monooleate, (2) decylglucoside and sorbitan‐monooleate. The former, despite the effect of temperature, showed no oil phase separation in the nine freeze–thaw cycles, but in the latter, the oil phase separation occurred in the 5th‐cycle. This study shows that synergism of surfactants is the most important factor in the stability of emulsions. To better explore these emulsion systems, the storage stability, freeze–thaw stability, droplet morphology, and viscosity tests were performed on different samples at various HLD values.

Lessons Learned in Interfacial Tension Prediction Using a Mixture of Sulfonate- and Ethoxylate-based Surfactants in a Waxy Oil-brine System

The chemical-enhanced oil recovery (CEOR) method is applied to change reservoir rock or fluid characteristics by injecting alkaline, surfactant, and polymer or a combination of two or three of the compounds. Surfactant flooding improves oil recovery by reducing the interfacial tension between oil and water. Selecting reservoir surfactants, especially microemulsions, requires careful screening. This study predicted waxy oil system interfacial tension using surfactant mixtures at below- and above-optimum salinity. To predict the interfacial tension, microemulsion types, HLB, ideal salinity, and HLD were used. The study predicted oil-surfactant-water interfacial tension using SAE, FEO, and their mixtures. We improved the Huh equation by adding a fitting parameter, β, to accommodate the transition from type III to type II microemulsions as salinity increases. With increasing salinity, anionic surfactant’s hydrophilic-hydrophobic interactions change, affecting the values and surfactant layer thickness. This study improved hydrophilic-lipophilic deviation (HLDN) by establishing a fixed interval for nonionic surfactants. Van der Waals attraction, values and interface surfactant layer thickness are connected, reflecting the fact that lower values reduce interfacial tension better. This study also found that surfactant packing at the oil-water interface increases the order of the oil-solution ratio and the microemulsion values with polarity.

An in-depth investigation of the impact of salt nature on the formulation of microemulsion systems

Electrolytes have a wide range of technological applications. Despite the recent improvements in characterizing and predicting the phase behavior of microemulsion systems by hydrophilic-lipophilic deviation (HLD) and net-average curvature (NAC) frameworks, they are ineffective in the presence of different salts. This work seeks to bridge this gap by investigating the influence of salt nature on the microemulsion phase formulation. First, a one-dimensional salinity scan on different microemulsion systems consisting of sodium dodecyl benzene sulfonate as a surfactant, hexane as an oil and, several brines was carried out, and the effect of each salt on the phase behavior were precisely evaluated. The results for optimum salinity and solubilization parameter of different salts were consistent with the Hofmeister series. In addition, multiple linear regression model is presented to accurately predicting the optimum salinity of different salts using this research data and all the available experimental data. The results revealed that the values estimated by this model is in significant consistency with the experimental data by correlation coefficient of 0.92. Finally, the effect of salt type on the NAC parameters (length parameter, and characteristic length) were evaluated to improve the predicting ability of this equation of state in the presence of various salts. We found that salt nature has a significant impact on both these parameters. It was found that the length parameter is linearly dependent on the optimum ionic strength of salts while the salting-out capacity of each salt was predominant factor affecting the characteristic length.

The effect of HMPAM on performance of nonionic polyether water clarifier from the perspective of HLD theory

Nonionic polyether water clarifier is commonly used in the treatment of produced water from offshore oilfield. At the meantime, hydrophobically modified polyacrylamide (HMPAM) is one of the commonly used polymer oil displacement agents. Predicting the influence of HMPAM on the performance of nonionic polyether water clarifier is of great significance for the treatment of produced water. This work explored the influence of different HMPAMs on the hydrophilic-lipophilic deviation (HLD) equation of a typical nonionic polyether water clarifier AE411 based on the HLD theory, and predicted their influences on the performance of AE411. The results showed that HMPAM had no effect on the parameter K (reflecting the interaction between AE411 hydrophilic groups and oil phase) and ct (reflecting the temperature sensitivity of AE411) in HLD equation of AE411, but reduced the parameter Ccn (reflecting the micelle structure of AE411 in water) and led to an increase in temperature corresponding to AE411′s HLD = 0. It was predicted that higher temperature was needed to ensure the performance of AE411. The experimental results of produced water treatment confirmed this prediction. The results of the paper validated the reliability of HLD application in the field of produced water treatment and provided some guidance for the development of nonionic polyether water clarifier.

Enhanced Oil Recovery by Surfactant Injection was improved during the Last 50 Years Thanks to the Multivariable HLD Formulation Equation

This report reviews the progress in Enhanced Oil Recovery (EOR) through surfactant injection over the past half century from 1974, with a specific focus on the role of the multivariable Hydrophilic-Lipophilic Deviation (HLD) formulation equation in different expressions. This equation has been instrumental in optimizing surfactant formulations for EOR, enabling the fine-tuning of surfactant types and properties to match specific reservoir conditions like brine salinity, crude characteristic, temperature and even pressure. This short assesment discusses the evolution of surfactant types, and their impact on EOR efficiency for a given reservoir specifications. It highlights the role of intramolecular and intermolecular mixing in surfactant performance, and the benefits of using a multivariable HLD equation to predict and optimize the injected formulation. Furthermore, it explores the challenges and solutions related to surfactant adsorption, aggregation, precipitation, and effect on phase behavior and interfacial tension, and how these factors have to be considered when using surfactants for EOR projects. This review aims to address the existing gaps in the literature, such as the complex effects of surfactant mixtures with insensitivity to temperature and injected composition (amphiphilic concentration and water/oil ratio) that make difficult to propose a unified approach for different petroleum reservoirs. It concludes a discussion on the state of the art and future of surfactant EOR, emphasizing the need for continued research and collaboration across academic and industrial sectors

Rational design of O/W nanoemulsions based on the surfactant dodecyldiglyceryl ether using the normalized HLD concept and the formulation-composition map

The 1-O-dodecyl diglycerol ether (C12Gly2) is a well-balanced bio-based surfactant whose amphiphilicity and emulsifying property have been studied within the Normalized Hydrophilic-Lipophilic-Deviation (HLDN) framework. Its Hydrophilic-Lipophilic tendency has been measured in saline and salt-free media by two methods. The classic one, is based on the identification of the optimal formulation (Winsor III) in a series of tubes containing a series of C12Gly2/Alkane/Water systems at equilibrium. The alternative method, much faster and more precise, is based on the phase inversion of the same systems under stirring, the HLDN value of which is gradually modified by changing the temperature or the salinity. C12Gly2 is found to be three times less sensitive to temperature and salinity variations than typical ethoxylated surfactants. By stirring C12Gly2/Alkane/Water systems, O/W or W/O emulsions are obtained depending on whether the alkane is long or short. The finest and the least stable emulsions (1 µm) are obtained with n-octane for which HLDN = 0. By systematically varying the Water-to-Oil Ratio (WOR) and the hydrophobicity of the oil, either direct O/W or reverse W/O emulsions are formed and are represented in a Formulation-Composition map. This map is a powerful tool to guide the formulator about which type of emulsion will be obtained depending on the composition of the SOW system and the emulsification protocol used i.e. the pathway in the map. In particular, it is possible to prepare stable and very fine emulsions (≈ 100 nm) by crossing the inversion border of the map favouring the splitting of the droplets and then moving away from it quickly to prevent the coalescence of the droplets.

The effect of cationic polyamide-amine dendrimer on HLD equation and interface behavior of nonionic polyether water clarifier

Cationic polyamide-amine dendrimer can promote the clarification performance of nonionic block polyether water clarifier for treating produced water from heavy oil field, but the reason is lack of study. In this paper, a cationic polyamide-amine dendrimer TA which can effectively improve the oil removal speed of nonionic polyether DMEA-PE and reduce the onset temperature of DMEA-PE clarification performance was prepared, and the reason was explored from both thermodynamic and dynamic aspects by studying the effect of TA on the hydrophilic-lipophilic deviation (HLD) equation and oil-water interface behavior of DMEA-PE. The research results showed that TA moved up the HLD vs T curve of DMEA-PE and decreased its temperature corresponding HLD = 0, which was a favor of decrease in onset temperature of DMEA-PE clarification performance. TA had no effect on the DMEA-PE's capacity of oil-water interface adsorption and decreasing oil-water interface film strength. However, TA can reduce the electronegativity of oil droplet in water and enhance the oil droplets coalescence, hence the oil removal speed and efficiency of DMEA-PE were enhanced. This is the first time that HLD concept was used to investigate the action mechanism of composite water clarifier and the results are useful for the water clarifier design.

Review: Implementing the hydrophilic–lipophilic deviation model when formulating detergents and other surfactant‐related applications

AbstractWhen designing surfactant formulations using ionic and nonionic surfactants, the hydrophile lipophile balance (HLB) is a generalized surfactant characterization parameter that has shown to be useful when designing surfactant formulations, in the case of both ionic and nonionic surfactants (Davies' and Griffin's methods). Microemulsion phase behavior studies have been extensively used to optimize surfactant formulations, but these studies can cover a very wide phase space and can often encounter troublesome non‐equilibrium issues such as coacervation. Detailed phase behavior studies can be time‐consuming and difficult to apply beyond the specific surfactant‐oil system studied. The hydrophilic–lipophilic deviation (HLD) provides a method to help expedite surfactant formulation research by reducing the number of phase behavior studies required to optimize a given formulation. Detergency experiments have indicated that there is an optimal range of HLD for a given fabric surface. This appears to apply to other applications, as well, for example, surfactant formulations used in enhanced oil recovery have been optimized using the HLD method. These studies found that the HLD can reflect total oil recovery, even if the surfactants were derived from different alcohol feedstocks (e.g., HLD of 0 would describe optimum conditions regardless the type of surfactant). Also with additional parameterization, the HLD method can also be applied to non‐ideal surfactant mixtures, specifically ionic/nonionic blends. Overall, the HLD framework has shown to be an effective screening tool for a wide range of surfactant‐related applications when appropriate experiments, assumptions, and understanding of surfactant and oil interactions are used to generate the HLD parameters.

Microfluidic Study of Oil Droplet Stability in Produced Water with Combinations of Production Chemicals

Discharged produced water contains traces of hydrocarbons after separation that might affect the eco-toxicity. These hydrocarbons can be oil droplets that are stabilized by added production chemicals and their combinations. The chemicals highly affect the treatment of the produced water before either reinjection or discharge to the sea. We apply microfluidic droplet generation for rapid evaluation of the synergistic effects of the combinations of production chemicals on the oil droplet stability. The coalescence frequency of dispersed droplets is calculated on the basis of high-speed camera video acquisition. The dispersed phase is either a model oil or a bottomhole crude oil sample, both in an aqueous medium. The individual and combined effects of a commercial demulsifier and a corrosion inhibitor are evaluated on the basis of the hydrophilic–lipophilic deviation theory. The presence of as low as 4 ppm of the water-in-oil demulsifier is demonstrated to stabilize oil-in-water droplets, while the corrosion inhibitor creates droplets in oil–water slug flow fashion. The presence of the corrosion inhibitor in conjunction with the demulsifier results in the droplet adherence to the channel surface. The importance of the right dosage and the right combination of production chemicals is demonstrated. The microfluidic droplet generation technique is a valuable tool for assessing the effects of production chemicals on oil droplet stability.

Formulation for chemical EOR: Development and evaluation of an ASP formulation In customer field conditions

AbstractAlkali surfactant polymer (ASP) flooding is an enhanced oil recovery (EOR) technology with an impressive potential for increasing incremental oil production from conventional hydrocarbon bearing reservoirs. A challenge to ASP application is the complexity of determining an effective formulation, typically requiring extensive laboratory screening of nearly countless combinations of surfactants and cosolvents. This paper focuses on demonstrating the utility of the hydrophilic–lipophilic deviation (HLD) concept for EOR application to simplify surfactant formulation workstreams seeking an economically viable ASP formulation for field application. In describing work performed for EOR application of ASP under customer conditions using crude oil, the discussion covers the initial evaluation of the promising surfactant formulation (interfacial tension and solubility), the improvement upon the formulation via HLD principles, and the evaluation of the improved surfactant formulation (coreflood studies). The final ASP formulation identified consisted of a 9 to 1 mixture of alkyl propoxy sulfate sodium salt (APS) to alkyl ethoxy sulfate sodium salt (AES) totaling 2000 ppm active surfactant content, 2.0 wt% Na2CO3, and 3000 ppm polyacrylamide polymer (all commercially available products). This formulation had ultra‐low interfacial tension and favorable mixing behavior under reservoir conditions. In coreflood studies, the final formulation reproducibly achieved cumulative oil recovery of 96.4%–98.5% of original oil in place with only 0.3 PV of ASP injection with a chase alkali polymer injection.

Challenges in modeling microemulsion phase behavior

AbstractModeling the complex phase behavior of microemulsions has been the subject of research for decades for hydrocarbon oil and organic contaminant recoveries. The empirical Hand model has been the standard scheme for calculating phase behavior in reservoir simulators. On the other hand, the hydrophilic–lipophilic deviation (HLD) model in conjunction with the net curvature and average curvature models (HLD‐NAC) has provided some theoretical basis for modeling microemulsions. While the HLD‐NAC has been successful in describing salinity scans, only recently an HLD‐NAC approach was devised that could represent binodal curves with physical behavior, resulting in a succession of new microemulsion flash algorithms. While these new algorithms claimed to include the effects of cosolvent, there are only few works in the literature, which give an in‐depth description of the cosolvent modeling. Furthermore, to the best of our knowledge, no work has investigated the capability of HLD‐NAC models for predicting data for different cosolvent concentrations nor did any work present a comprehensive study of the application of HLD‐NAC against Hand model for formulations including cosolvents. This paper aims to contribute in filling such gap. We modify different versions of the new HLD‐NAC approach with physical binodal curves by providing more flexibility into controlling the binodal heights with the cosolvent concentration and investigate how well they can calibrate and predict data. Experimental data sets were considered here. The results suggest that some of the HLD‐NAC approaches produced negative solubilization ratios and the Hand model gave better predictions of the ternary diagram for extreme salinity values.

Modeling of High-Pressure and High-Temperature Microemulsion Experiments using HLD-NAC-Based Equation of State

Summary Surfactant flooding is a promising technique that can reduce interfacial tension (IFT) between oil and water to ultralow values, mobilizing previously trapped oil. For reservoirs at moderate to high pressures, understanding and modeling how pressure affects the phase behavior of a surfactant-brine-oil system is important to the design and implementation of an efficient/cost-effective surfactant flooding project. Typically, however, phase behavior experiments and models of that phase behavior are made only at low pressures. The main objective of this paper is to show how to model experimental data in a unified way for a large range of pressure, temperature, and other parameters, using hydrophilic-lipophilic deviation (HLD) and net-average curvature (NAC)-based equation-of-state (EOS). Pressure and temperature scans show that pressure has a significant effect on the surfactant microemulsion phase behavior, shifting it from an optimal three-phase system at low pressure to a nonoptimal two-phase system at high pressure. Further, multiple scans at different water/oil ratios (WORs) show a shift in the optimum indicating that phase behavior partitioning of the various components is changing with oil saturation. We obtained good fits of all experimental data including all two- and three-phase regions using a single tuned HLD-NAC EOS for a wide range of simultaneous variations in pressure, temperature, salinity, and overall composition. Such a simultaneous match and prediction by a single set of model parameters has never been done before. We also demonstrate the type of data needed for an accurate EOS. When input into a numerical simulator, the tuned EOS improves the predictions of the resulting phase behavior (size and shape of the two-phase lobes and three-phase regions) and IFTs with changing pressure, temperature, salinity, WORs, and surfactant/alcohol concentrations.

Analyzing the surfactant classification confusion through the HLD formulation equation

The qualitative presentation from Winsor on an interfacial balance of interactions between the surfactant and the oil and water phases has been transformed into a multivariable linear equation so-called hydrophilic-lipophilic deviation (HLD). This relation involves at least 6 independent variables (surfactant head and tail specifications, water salinity, oil nature, temperature, and pressure) with a MacLaurin series first order approximation, i.e., a linear multivariable expression. After 40 years of practical experience, it can be said that the HLD relation matches well the experimental data, with only very few exceptions with complex mixtures. Herein, we clear the confusion concerning the meaning and the mathematical handling of the surfactant parameter in the HLD equation. We start with a presentation of simple surfactant systems with only 4 parameters (water salinity, oil nature, surfactant nature, and temperature) as was done 40 years ago. Later, we present a critical discussion on the surfactant term, concerning binary surfactant systems, and on strategies for applications in ternary surfactant mixtures. We have found that the surfactant parameters can only be compared in a series of surfactants with the same head group, where the surfactant parameter is a linear function of the surfactant tail length.

Estimating Preferred Alkane Carbon Numbers of Nonionic Surfactants in Normalized Hydrophilic-Lipophilic Deviation Theory from Dissipative Particle Dynamics Modeling.

The preferred alkane carbon number (PACN) in the normalized hydrophilic-lipophilic deviation (HLDN) theory is a numerical parameter and a transferable scale to characterize the amphiphilicity of surfactants, which is usually measured experimentally using the fish diagram or phase inversion temperature (PIT) methods, and the experimental measurement can only be applied to existing surfactants. Here, for the first time, we propose a procedure to estimate the PACN of CiEj nonionic surfactants directly from dissipative particle dynamics (DPD) simulation. The procedure leverages the method of moment concept to quantitatively evaluate the bending tendency of nonionic surfactant monolayers by calculating the torque density. Seven nonionic surfactants, CiEj (C6E2, C6E3, C8E3, C8E4, C10E4, C12E4, and C12E5), with known PACNs are modeled. Two surfactants, C10E4 and C6E2, were first selected to train and test the interaction parameters, and the relationship between interaction parameters and torque density was mapped for the C10E4-octane-water system using the artificial neural network (ANN) fitting approach to derive the interaction parameters giving zero torque density, then the interaction parameters were tested in the C6E2-dodecane-water system to get the final tuned interaction parameters for PACN estimation. With this procedure, we reproduce the PACN values and their trend of seven nonionic surfactants with reasonable accuracy, which opens the door for quantitative comparison of surfactant amphiphilicity and surfactant classification in silico using the PACN as a transferrable scale.

Formulation in Surfactant Systems: From-Winsor-to-HLDN

Formulation is an ancient concept, although the word has been used only recently. The first formulations made our civilization advance by inventing bronze, steel, and gunpowder; then, it was used in medieval alchemy. When chemistry became a science and with the golden age of organic synthesis, the second formulation period began. This made it possible to create new chemical species and new combinations “à la carte.” However, the research and developments were still carried out by trial and error. Finally, the third period of formulation history began after World War II, when the properties of a system were associated with its ingredients and the way they were assembled or combined. Therefore, the formulation and the systems’ phenomenology were related to the generation of some synergy to obtain a commercial product. Winsor’s formulation studies in the 1950s were enlightening for academy and industries that were studying empirically surfactant-oil-water (SOW) systems. One of its key characteristics was how the interfacial interaction of the adsorbed surfactant with oil and water phases could be equal by varying the physicochemical formulation of the system. Then, Hansen’s solubility parameter in the 1960s helped to reach a further understanding of the affinity of some substances to make them suitable to oil and water phases. In the 1970s, researchers such as Shinoda and Kunieda, and different groups working in Enhanced Oil Recovery (EOR), among them Schechter and Wade’s group at the University of Texas, made formulation become a science by using semiempirical correlations to attain specific characteristics in a system (e.g., low oil-water interfacial tension, formulation of a stable O/W or W/O emulsion, or high-performance solubilization in a bicontinuous microemulsion system at the so-called optimum formulation). Nowadays, over 40 years of studies with the hydrophilic-lipophilic deviation equation (HLD) have made it feasible for formulators to improve products in many different applications using surfactants to attain a target system using HLD in its original or its normalized form, i.e., HLDN. Thus, it can be said that there is still current progress being made towards an interdisciplinary applied science with numerical guidelines. In the present work, the state-of-the-art of formulation in multiphase systems containing two immiscible phases like oil and water, and therefore systems with heterogeneous or micro-heterogeneous interfaces, is discussed. Surfactants, from simple to complex or polymeric, are generally present in such systems to solve a wide variety of problems in many areas. Some significant cases are presented here as examples dealing with petroleum, foods, pharmaceutics, cosmetics, detergency, and other products occurring as dispersions, emulsions, or foams that we find in our everyday lives.

A Normalized HLD (HLDN) Tool for Optimal Salt-Concentration Prediction of Microemulsions

Optimal condition-based microemulsion is key to achieving great efficiency in oil removal. One useful empirical equation to predict an optimal condition is a hydrophilic–lipophilic deviation (HLD). However, the K constants of each surfactant should be the same to combine the HLD equations for the mixed surfactant. Recently, a normalized hydrophilic-lipophilic deviation (HLDN) was presented to avoid this limitation. This work sought to determine the phase behaviors and predict the optimal salt concentrations, using HLDN for the mixed surfactant. Sodium dihexyl sulfosuccinate (SDHS) as an anionic surfactant, and alcohol alkyl polyglycol ether (AAE(6EO4PO)) as a nonionic surfactant, were both investigated. Alkanes and diesel were used as a model oil. The results showed that AAE(6EO4PO) enforced both the hydrophilic and the hydrophobic characteristics. The Winsor Type I-III transition was influenced by the ethylene oxide, while the propylene oxide presence affected the Winsor Type III-II inversion. For the HLDN equation, the average interaction term was 1.82 ± 0.86, which markedly showed a strong correlation with the fraction of nonionic surfactant in the mixed systems. The predicted optimal salt concentrations using HLDN of SDHS-AAE(6EO4PO) in the diesel systems were close to the experimental results, with an error of <10% that is significantly beneficial due to the shorter time required for optimal determination.

The Salinity-Phase-Inversion method (SPI-slope): A straightforward experimental approach to assess the hydrophilic-lipophilic-ratio and the salt-sensitivity of surfactants

HypothesisThe salinity at which the dynamic phase inversion of the reference system C10E4/n-Octane/Water occurs in the presence of increasing amounts of a test surfactant S2 provides quantitative information on the hydrophilic/lipophilic ratio and on the sensitivity to NaClaq of S2. ExperiencesThe Salinities causing the Phase Inversion (SPI) of the reference system mixed with 12 ionic and 10 nonionic well-defined surfactants are determined in order to quantify the contributions of the nature of the polar head and of the alkyl chain length. FindingsThe SPI varies linearly upon the addition of S2. The slope of the straight variation with the molar fraction of S2 is called the “SPI-slope”. It quantifies the hydrophilic/lipophilic ratio of S2 in saline environment and its salt-sensitivity with respect to the reference surfactant C10E4. The SPI-slopes of C12 surfactants bearing different polar heads are found to decrease in the following order: C12NMe3Br > C12E8 > C12E7 ≥C12SO3Na ≈ C12COONa ≥ C12SO4Na > C12E6 > C12E5 > C12E3. This classification is different from that obtained when the phase inversion is caused by a change in temperature (PIT-slope method) because the addition of NaCl in significant amounts (3 to 10 wt%) partially screens the ionic heads and diminishes their apparent hydrophilicities. A simple model, valid for all types of nonionic surfactants, is developed on the basis of the HLDN equation (Normalized Hydrophilic-Lipophilic Deviation) to express the SPI-slope as a function of the hydrophilic/lipophilic ratio (PACN2) and the salinity coefficient (δ2) of S2. All studied surfactants are positioned on a 2D map according to the values of their SPI-slope and their PIT-slope to graphically highlight their hydrophilic/lipophilic ratio and their salt-sensitivity. Finally, a linear model connecting the PIT-slope and the SPI-slope is derived for nonionics, emphasizing that the thermal partitioning of C10E4 towards n-octane is much greater in the PIT-slope than in the SPI-slope experiments.

Characterizing oil mixture and surfactant mixture via hydrophilic-lipophilic deviation (HLD) principle: An insight in consumer products development

Hydrophilic-lipophilic deviation (HLD) concept describes interaction of surfactant, oil, and water in liquid formulations. Within the framework of HLD, this study investigated the behavior of microemulsion consisting of fragrance/essential oil mixtures and surfactants mixture commonly found in consumer products. Strong non-ideal mixing behavior was seen in oil mixtures of fragrance raw materials. A simple non-ideal relationship was proposed to account for the non-ideality of oil mixture of dissimilar properties. With 95% confidence, the error of the predicted optimum salinity (or phase inversion point) is between 0.70 and 1.68 g/100 mL NaCl in mixtures of complex commercial fragrance and octane. Mixing behavior was also evaluated in a ternary surfactants system consisting of sodium laureth sulfate (SLES), cocamidopropyl betaine (CAPB), and decyl glucoside (APG). Within a reasonable tolerance, the ideal mixing rule can be practically applied for such complex surfactant mixtures. Extension of HLD in mixture systems provides practical benefits in product development.

Design of industrial wastewater demulsifier by HLD-NAC model

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.