Hydrophile-lipophile Balance Number Research Articles

Emulsion synthesis of spherical TiO 2SiO 2 colloids from metal alkoxides

A method for synthetizing spherical, submicron titania-silica powders from an oil/water emulsion of metal alkoxides has been developed. The emulsions are formed spontaneously, without the aid of surfactants or other liquids usually associated with emulsion processes. The process capitalizes on immiscibility in the metal alkoxide-water-alcohol ternary system. Control of the hydrophobic nature of partially hydrolized metal alkoxides, minimization of γ o/w and a large ethanol concentration difference between the metal alkoxide solution and the aqueous phase during mixing results in spontaneous emulsification of the metal alkoxide in water. Calculations of the hydrophilic-lipophilic balance number are used successfully to predict metal alkoxide emulsion formation. For the TiO 2SiO 2 system, ammonium hydroxide in the aqueous phase stabilizes the emulsion against coalescence by catalyzing the gelation of the metal alkoxide droplets to porous metal oxide particles. Powders can be synthesized with a high surface area and average particle sizes ranging from 0.05 μm to as large as 1.0 mm diameter.

The HLB number determination of polyoxyethylene surfactants

The Hydrophile-Lipophile-Balance (HLB) numbers were evaluated on the basis of three different, commonly used methods of determination and calculation, in a series of lauric, resp. stearic acids and lauryl alcohol oxyethylenation products prepared by an alkali-catalyzed reaction in a similar scale of hydrophobe: ethylene oxide molar ratios. The results showed that, due to the different principles of the used methods, the HLB numbers were obtained with a great variance, limiting their use as parameters for estimation of the application effectiveness of non-ionic surfactants of the polyoxyethylene type. The HLB concept was not found able to consider the complicated composition of the studied types of surfactants and to provide relevant information in the already mentioned sense.

Effect of surfactant type on selectivity for the separation of 1-methylnaphthalene from dodecane using liquid membranes

The selective removal of aromatics from kerosine for the purposes of smoke-point improvement and to meet the specifications for aviation turbine fuel is an industrially important operation. The present study is part of a programme for developing an energy-efficient aqueous surfactant membrane process with high selectivities for aromatics removal. In the experimental studies, carried out in a batch mixer-settler unit, the kerosine feed was modelled using a synthetic mixture of 1-methylnaphthalene and dodecane. The objective of the experimental study was to study the influence of the surfactant type on the selectivity for removal of l-methylnaphthalene. Eight different types of surfactants were used in the studies, with HLB (hydrophile-lipophile balance) numbers ranging from 12.8 to 17.8. The selectivity β, defined as the ratio of the mass transfer coefficients for transfer of aromatics to that of the non-aromatics, was determined after correcting for nonselective transport due to emulsion breakage. The selectivity thus obtained correlated very well with W, the work of transfer, which reflects the ease of adsorption of the surfactant to form a monolayer relative to the ease of micellization. For high W (i.e., lower ease of micellization) the selectivities are higher, as might be expected because micelle formation leads to non-selective transport through the membrane barrier. The study sheds light on the appropriate choice of surfactant to obtain increased selectivities.

Correlation between the formation of a lamellar liquid crystalline phase and the hydrophile-lipophile balance (HLB) of surfactants

The hydrophile-lipophile balance of nonionic surfactants changes from hydrophilic to lipophilic with the rise in temperature and is considered to be just balanced in a temperature range at which a lamellar liquid crystalline phase forms in the surfactant-water system. The mid-temperature of that range is called the liquid crystal temperature, T LC. It was found that the following relation between the HLB numbers of nonionic surfactants and the LC temperature in an aqueous system is valid: T LC = k H 2 O (∑N HLB (i)W (i) − N H 2 O) where k H 2O = 17°C/HLB unit, N H 2O = 7.4 HLB unit, N HLB ( i) and W ( i) are the HLB number and the weight fraction of ith surfactant in total surfactants. This relationship is similar to that between the HLB number and the HLB temperature in a water/nonionic surfactant/oil system. Since the surfactant ratio to produce a lamellar liquid crystalline phase in a diluted region is almost independent of temperature in an ionicnonionic surfactant system, the condition to produce a lamellar liquid crystal was found at 30°C to be ∑N HLB (i)W (i) = 9.2 . This relation is equivalent to the above equation and is valid for an ionic-nonionic surfactant aqueous system.

Triton solubilization of proteins from pig liver mitochondrial membranes

Various aspects of membrane solubilization by the Triton X-series of nonionic detergents were examined in pig liver mitochondrial membranes. Binding of Triton X-100 to nonsolubilized membranes was saturable with increased concentrations of the detergent. Maximum binding occurred at concentrations exceeding 0.5% Triton X-100 (w/v). Solubilization of both protein and phospholipid increased with increasing Triton X-100 to a plateau which was dependent on the initial membrane protein concentration used. At low detergent concentrations (less than 0.087% Triton X-100, w/v), proteins were preferentially solubilized over phospholipids. At higher Triton X-100 concentrations the opposite was true. Using the well-defined Triton X-series of detergents, the optimal hydrophile-lipophile balance number (HLB) for solubilization of phosphatidylglycerophosphate synthase (EC 2.7.8.5) was 13.5, corresponding to Triton X-100. Activity was solubilized optimally at detergent concentrations between 0.1 and 0.2% (w/v). The optimal protein-to-detergent ratio for solubilization was 3 mg protein/mg Triton X-100. Solubilization of phosphatidylglycerophosphate synthase was generally better at low ionic strength, though total protein solubilization increased at high ionic strength. Solubilization was also dependent on pH. Significantly higher protein solubilization was observed at high pH (i.e., 8.5), as was phosphatidylglycerophosphate synthase solubilization. The manipulation of these variables in improving the recovery and specificity of membrane protein solubilization by detergents was examined.

Evaluation of the hydrophile-lipophile balance (HLB) of nonionic surfactants. I. Multisurfactant systems

Since the hydrophile-lipophile property of nonionic surfactant for a given system is just balanced in a three-phase region of a phase diagram which is a stack of three-phase triangles consisting of an aqueous, a surfactant, and an oil phase, we defined the hydrophile-lipophile balance (HLB) plane on which the three-phase triangle is positioned in the midst of the three-phase region. In a three-component system of nonionic surfactant/water/oil, the HLB plane is located at fixed temperature ( T HLB). Accordingly, the equation of the HLB plane is represented by T = T HLB in this system, and, hence, the phase inversion temperature of emulsion (PIT) is independent of a surfactant concentration. Correlation between T HLB and the Griffin's HLB number was investigated and a linear relationship between them was obtained. In a multisurfactant system, a set of the HLB planes exists in a temperature range between T HLB of the most hydrophilic surfactant and that of the most lipophilic surfactant. The equation of the plane is obtained by a geometrical calculation in a space of temperature and compositions, assuming that the equilibrium concentration of surfactant in the aqueous phase is negligible. The effect of the temperature, the oil/water ratio, the weight ratio between the surfactants, and the surfactant concentration on the phase behavior of a mixed surfactant system is explained very well by the equation. The correlation between the T HLB of the surfactant mixture and Griffin's HLB number is also substantiated.

Evaluation of the hydrophile-lipophile balance (HLB) of nonionic surfactants. II. Commercial-surfactant systems

In order to evaluate the HLB number or the hydrophile-lipophile-balanced temperature, T HLB, of commercial surfactant which is a mixture of unidentified surfactants, the previously described equation of the set of HLB planes is simplified. The effect of temperature, oil/water ratio, and the surfactant concentration on the three-phase region or PIT (phase inversion temperature) is clarified by the equation. The HLB number of a lipophilic commercial surfactant, whose PIT is below 0°C, can also be obtained by mixing with hydrophilic pure surfactant.

The three-phase behavior of a brine/ionic surfactant/nonionic surfactant/oil system: Evaluation of the hydrophile-lipophile balance (HLB) of ionic surfactant

We define the Hydrophile-Lipophile-Balanced plane (HLB plane) as the plane on which the three-phase triangle in the midst of the three-phase region (consisting of water, surfactant, and oil phases) is positioned. The equation of the HLB plane is obtained in the composition tetrahedron of a pseudo-four-component system (the components being brine/ionic surfactant/nonionic surfactant/oil), assuming that the CMC in the aqueous phase is negligible. The effect of the surfactant/cosurfactant ratio, the oil/water ratio, and the surfactant concentration on the three-phase behavior is well predicted by this equation. The effect of salinity and temperature on the three-phase behavior is also discussed. Thus it is shown that a temperature-insensitive microemulsion (surfactant phase) is achieved in a dilute region of ionic-nonionic surfactant pair, by depressing the solubility of the lipophilic surfactant in the oil phase of the three-phase region. Moreover, the equation yields an HLB number of ionic surfactant which is considerably smaller than Griffin's value. It is considered that Griffin's overestimation comes from neglecting the solubility of lipophilic surfactant in the oil phase.

Evaluation of the Hydrophile-Lipophile-Balance (HLB) of Long-chain Nonionic Surfactant

Correlation between hydrophile-lipophile-balance temperature, TcomHLB, and the HLB number of commercial nonionic surfactants (C12C18) was investigated. The empirical formula, Row (1/x-1) = A (T-TcomHLB) is valid for these surfactants. (Row is the weight fraction of oil in water+oil, x, the weight fraction of surfactant in a system, T, the temperature, and A, a constant.) TcomHLB (HLB temperature=Phase Inversion Temperature) is a characteristic temperature related to the NcomHLB (HLB number), i.e., TcomHLB=koil (NcomHLB-Noil), provided the HLB temperature is 1080°C or more. (koil, Noil are constants for a given oil.) Through the application of these equations, an HLB number of a surfactant may be evaluated from the HLB temperature and phase behavior or vice versa.

Principles of attaining very large solubilization (microemulsion): inclusive understanding of the solubilization of oil and water in aqueous and hydrocarbon media

It is intrinsically important to change the hydrophile-lipophile balance (HLB) of a surfactant mixture continuously by various devices in order to attain a large solubilization or ultimately complete mixing of hydrocarbon and water with less surfactant. The maximum solubilization of hydrocarbon (or water) was observed close to the surfactant phase separation at which the hydrophile-lipophile property of a surfactant mixture balances for a given system. The relative solubilities of water and oil in the surfactant phase change with the HLB of a surfactant mixture. Conceptual interpretations on the solubilization of oil and water in surfactant aggregates were embodied on the phase diagrams presented. The devices of cosurfactants, surfactants, and their combinations yielded very large solubilization. The hydrophile-lipophile balance (HLB) of a surfactant is certainly a function of variables such as a surfactant composition, temperature, valence of the counterions, salt concentration, etc. It is argued that the HLB of a surfactant in the system and the HLB number of the surfactant should not be confused.

Activation of C55-isoprenoid alcohol phosphokinase from Staphylococcus aureus. III. Activation by detergents.

The activation of kinase by neutral detergents has been examined. Of those detergents tested, only those with short chain and unsaturated chain hydrophobes were successful activators at 25 degrees. In addition to these structural requirements, a dependence upon hydrophilic-lipophilic balance number was observed when mixing hydrophobic and hydrophilic detergents. Most pairs tested showed an optimal hydrophilic-lipophilic balance number for kinase activation in the hydrophobic range of 6 to 9. Thus, there appears to be both a structural and a relative hydrophobic requirement for activation, and hydrophilic-lipophilic balance number may be a measure of the physical properties of the lipid required for activation.

The HLB dependency for detergent solubilization of hormonally sensitive adenylate cyclase.

The HLB dependency for the solubilization of membrane proteins and adenylate cyclase activity from a plasma membrane-enriched fraction from rat liver has been determined. The HLB (hydrophilic/lipophilic/balance) number of a detergent is an empirical measure of its relative hydrophobicity. Detergent HLB numbers vary systematically with the length of the ethylene oxide chain for a homologous series of detergents such as the Triton X series. These detergents have a constant hydrophobic moiety, octylphenyl, and a variable polar portion, polyethoxyethanol. Basal-NaF-epinephrine-, and glucagon-stimulated adenylate cyclase activities were solubilized in the HLB range of 16.8-17.4. Solubilization was most effective in 0.01 M Tris buffers at pH 7.5 containing 1-5 mM mercaptoethanol, 1 mM MgCl2, and 0.1% Triton X-305. The detergent to membrane protein ratio used in these studies was 3:1. Criteria for solubilization included lack of sedimentation at 100,000 X g, the absence of particulate material in the supernatant when examined by electron microscopy, and inclusion of hormonally sensitive adenylate cyclase activity in Sephadex G-200 gels. The apparent molecular weight of the solubilized enzyme was approximately 200,000 in the presence of Triton X-305. The solubilized enzyme was stimulated 5-fold by NaF, 7-fold by glucagon, and 20-fold by epinephrine compared to the particulate enzyme used in this study which was stimulated 10-fold, 3.4-fold, and 4-fold by NaF, epinephrine, and glucagon, respectively. The solubilized enzyme is stable for several weeks when stored at -60 degrees C.