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Solution Properties
Published in Thomas J. Bruno, Paris D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, 2020
Thomas J. Bruno, Paris D.N. Svoronos
Where available, the aggregation number is provided [1, 5, 6]. This is the mean number of surfactant molecules present in a micelle after the CMC has been reached. It is measured by use of luminescent probes by varying surfactant concentration and is dependent on temperature and the concentration of any organic or ionic species present. Finally, the hydrophilic lipophilic balance (HLB) is provided where available. This is a fit-for-purpose property rather than a fundamental property which has evolved in definition and determination since being devised, a matter beyond the scope of this chapter. The HLB is a numerical scale between 0 and 20 descriptive of the tendency of a surfactant to be either hydrophilic or hydrophobic. A relatively high HLB (greater than ten) indicates hydrophilicity or good water or polar solvent solubility. A relatively low HLB (lower than ten) indicates lipophilicity or good solubility in nonpolar solvents such as oils or organics. The HLB changes with concentration and mixture composition.
Self-Nanoemulsifying Drug Delivery System: Formulation Development and Quality Attributes
Published in Alexander V. Vakhrushev, Vladimir I. Kodolov, A. K. Haghi, Suresh C. Ameta, Carbon Nanotubes and Nanoparticles, 2019
Pankaj V. Dangre, Shailesh S. Chalikwar
The surfactant is the most essential component of SNEDDS formulation. Surfactant imparts the essential emulsifying characteristics to the SNEDDS. Surfactants of natural origin are preferred because they are safer than the synthetic surfactants. The selection of a particular surfactant for formulation depends upon its HLB value and safety issue. The HLB of surfactant provides important information on potential application in the formulation of SNEDDS. The most widely used are the nonionic surfactants with a relatively high HLB. The nonionic surfactants are nontoxic as compared to the ionic ones.48,49 The most commonly used nonionic surfactant includes Tween 80 and Pluronic F127.49,50 Usually, a stable SNEDDS formulation requires high concentrations of surfactant (30–60%); however, high concentration of surfactant may cause irritation to the gastric mucosa. Furthermore, the droplet size of the emulsion is inversely affected by the concentration of the surfactant.51,52 Surfactant has ability to dissolve relatively large amount of hydrophobic drug molecules and thus prevent the precipitation of the drug within the GIT.53
Enhancing Uptake and Translocation of Systemic Active Ingredients
Published in Chester L. Foy, David W. Pritchard, and Adjuvant Technology, 2018
Roger J. Field, Farhad Dasigheib
The hydrophilic-lipophilic balance (HLB values) for each surfactant is also used to categorize their applicability as emulsifiers, detergents, and/or activators. The HLB value confers a specific surfactant characteristic and can be broadly classified as follows: 130HLB 4–6 water in oil emulsifierHLB 7–9 wetting agentHLB 8–18 oil in water emulsifierHLB 10–18 solubilizer
Optimization of water-emulsified diesel preparation and comparison of mechanical homogenization and ultrasonic dispersion methods to study CI engine performances
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Pijush Kanti Mondal, Bijan Kumar Mandal
In WED, water and diesel are two immiscible liquids, hence the mixture is thermodynamically unstable. A small amount of surface active agents (called surfactants) are added to increase the stability of the emulsion. The surfactant molecule has hydrophobic portion and hydrophilic portion. They accumulate at interface by orienting the hydrophobic portion toward the hydrophobic phase (oil) and hydrophilic portion toward hydrophilic phase (water). This process is called adsorption which reduces the interfacial tension between diesel and water by absorbing at the interface. This alters the free energies at the interface, thus water diesel emulsion is stabilized (Lin and Chen 2008). For example, the interfacial tension of O/W system reduces from 50 mNm−1 before adsorption to 1 to 10 mNm−1 depending on the nature of surfactant (Tadros 2016). Thus the presence of surfactant creates an energy barrier between two phases and the system becomes kinetically stable. An emulsion shows the characteristics of the continuous phase, hence, WED exhibit characteristics of diesel fuel oil and not water. The Hydrophil-Lipophile Balance (HLB) value of a surfactant is the indications of the degree to which it is hydrophilic or lipophilic. Better emulsification effects have been observed when one surfactant having higher HLB value is mixed with a surfactant having lower HLB value and the mixture is used as the surfactant (Ghojel and Honnery 2005; Noor El-Din et al. 2013).
Effect of solid dispersants on the formation of hydrates in W/O emulsion systems: Micron and nanoscale
Published in Journal of Dispersion Science and Technology, 2022
Junwen Bai, Dejun Liu, Liyan Shang, Zhenbo Lv, Jiaqi Zhai, Wenliang Zhao, Jiashun Zhang
The emulsifiers in all W/O emulsions prepared by experiments consist of mixtures of nonionic surfactants. It accounts for 2 wt% of the total liquid phase. The two nonionic surfactants are sorbitol monooleate (Span 80, HLB = 4.3) and polysorbate 80 (Tween 80, HLB = 15). HLB is a measure of hydrophilicity and hydrophobicity of surfactants.[28] Different hydrophobic additives and different types of emulsions could be obtained by mixing two surfactants with different HLB. In addition, the HLB value of the nonionic surfactant mixture could be calculated as follows where and are the values of surfactant A and surfactant B respectively. and represent the mass of surfactant A and surfactant B, respectively.
Experimental investigation of surfactant-stabilized foam stability in the presence of light oil
Published in Journal of Dispersion Science and Technology, 2020
Wanfen Pu, Rui Jiang, Shishi Pang, Tintin Qiu, Ziqi Sun, Chao Shen, Peng Wei
According to W. Griffin and other people's point of view, the greater the HLB value of surfactants, the better the emulsification effect. On the basis of the data in Table 2, the HLB value of the APG is greater than that of the AOS. Nevertheless, the stability of the latter emulsion is better than that of the former. The AOS is an ionic surfactant, the emulsion droplets formed by the van der Waals force caused by the attraction is less than the rejection caused by the charge, so it is difficult to coalescing.[17] Therefore, Ionic surfactants (AOS) has good oil resistance. Finally, based on the current experimental results, the schematic diagram of the principle shown in Figure 11 is drawn.