Into the wonders of surfactant behaviour

In the area of physical chemistry, a topic, which all chemistry undergraduates must encounter, is chemical equilibrium. One very important aspect in this topic and is perhaps surprising, considering its great importance, that little or no attention is given in undergraduate courses is to teaching students the equilibrium between different phases. Even more irony is that the preparation of most commonly used chemical products needs the understanding of phase behavior as an intensified research in priority areas undoubtedly offers vast potential for new, challenging and exciting discoveries. This is more so with the introduction of a group of chemical called surfactant. In the industrial application the surfactants are used either as essential addictives or processing aids or in many cases as only a minor part of a particular system or formulation. Here the surfactant may be regarded as a “performance” or effect chemical, whereby small changes in molecular structure can result in dramatic changes in its phase behavior and performance

Phase Equilibria of a Mixed Alkali Soap/ Carboxylic Acid/Water System

A preliminary investigation was carried out on the phase equilibria in the three component systems, water/sodium caprylate/octanoic acid, water/sodium caprylate and sodium dodecyl sulphate (l:1) / octanoic acid at 30°C. The phases were separated by repeated centrifugation. The birefringence was observed under cross-polarisers and their consistency, texture and optical pattern were examined under the polarizing microscope. On the basis of the results obtained, a phase diagram was drawn that includes two phases of isotropic solution and two mesophases. Results also showed a decreased amount of octanoic acid utilized in obtaining the lamellar liquid crystal phase. The critical micelle concentration was also reduced for the mixed surfactant syste

A Natural Flavour in an Amphiphilic Association Structure

The miscibility ofa banana flavour, amyl acetate, in a water-in-oil microemulsion of water/sodium dodecyl sulphate (SDS): hexan-1-01 (35:65) in n-decane and fJ-xylene system was carried out at 30°e. The systems were tested by a phasestudy and refractometry method. The solubility of the flavour was observed to be connected to the ratio of SDS: hexan-1-D1 and hydrocarbon; a higher solubility of the flavour was observed in a larger ratio. The solubility was, however, inversely proportional to the water content

Micellization in a Mixed Alkali Soap System

The solubility of sodium octanoate and sodium dodecyl sulphate (SDS) in the micelle was investigated by measuring the surface tension of the aqueous solution of surfactant mixture as a function of mole fraction of surfactants. Results indicate that the critical micelle concentration (cmc) of the mixed sU1factant falls between the cmc value of the two surfactants. The results also indicate that the rate of change of cmc value tends to be near the longer hydrocarbon chain molecule (SDS) with lower cmc value. Therefore it was concluded that the longer hydrophobic group of SDS is geometrically favour able for the micelle formation. In addition, the results indicate that SDS and sodium octanoate molecules mix ideally in the micelle solution

Triglyceride Microemulsion Systems with Palm Oil

Microemulsions with refined, bleached and deodorized (RBD) and red palm oil (RPO), and solvents, stabilized by two oppositely charged ionic surfactants and a medium chain alcohol, were investigated. The results showed that only the solvent-in-oil microemulsions were prominent. The maximum solubilization of the both RBD and RPO were higher in the positively charged surfactant containing nitrogen atoms than in the negatively charged one. However, the results did not lend themselves to any decisive factor about the effect of solvents, length of hydrocarbon chain of the fatty acids or the presence of pigment on the microemulsion region in all systems investigated

Kinetic and Equilibrium Studies on the Exchange Process of n-Hexanol and Cetyl Trimethyl Ammonium Bromide (CTAB) Micelles

Kinetic studies using ultrasonic relaxation method in the mixed micellar solutions of n-hexanol dan cetyl trimethyl ammonium bromide have shown a well-defined single relaxation. This is associated with the exchange process involving the partitioning of alcohol with the mixed micelle. The equilibrium measurement which monitors the monomer concentration of n-hexanol was measured using head space analysis involving gas chromatography. The combined relaxation and equilibrium data were analysed using a phenomenological treatment in which the kinetics and thermodynamics parameters were evaluated for the exchange process. The main conclusion from this work is that the association of n-hexanol to the the mixed micelles is almost a diffusion controlled process

A Natural Dye in a Mesophase Region of Cetyltrimethylammonium Bromide/ Octan-l-ol/Water System

A naturally occurring dye, curcumin, was added to a series of lamellar liquidcrystal mesophases consisting of cetyltrimethylammonium bromide (CTAB),octan-1-o1 and water at 30°C. The changes brought about by the addition of the natural dye were followed by optical microscopy and small angle X-ray diffraction techniques. The inter layer spacings of the lamellar liquid crystal mesophases with the natural dye were observed to be lower than the corresponding structure without dye at the equivalent volume ratio of water. The effect of water and the hydrocarbon chain of the lamellar liquid crystal structure were found to be minimal and further inclusion of curcumin prevented the formation of the mesophas

Surfactants And The Stratum Corneum Lipids

A simplified mixture of model stratum corneum lipids was mixed with different surfactants to make a preliminary estimation of the influence of surfactants on the stratum corneum lipid structure. The results revealed differences between cationic and anionic surfactants and between anionic surfactants with different structures. © 1998

The utilisation of palm oil and oil palm residues and the related challenges as a sustainable alternative in biofuel, bioenergy, and transportation sector: a review.

The importance of energy demands that have increased exponentially over the past century has led to the sourcing of other ideal power solutions as the potential replacement alternative to the conventional fossil fuel. However, the utilisation of fossil fuel has created severe environmental issues. The identification of other renewable sources is beneficial to replace the energy utilisation globally. Biomass is a highly favourable sustainable alternative to renewable resources that can produce cleaner, cheaper, and readily available energy sources in the future. The palm oil industry is essentially ideal for the availability of abundant biomass resources, where the multifaceted residues are vital for energy production through the conversion of biomass waste into value-added products simultaneously. This article discusses the utilisation of palm oil and its residues in the energy and transportation sector. Assessment and evaluation on the feasibility of palm oil and its residues were made on the current valorisation methods such as thermochemical and biochemical techniques. Their potential as transportation fuels were concurrently reviewed. This is followed by a discussion on future challenges of palm oil industries that will take place globally, including the prospects from government and nongovernment organisations for the development of palm oil as a sustainable alternative replacement to fossil fuel. Hence, this review aims to provide further insight into the possibilities of palm oil and its residues towards sustainable development with reduced environmental-related issues

Emulsion Properties of Mixed Tween20-Span20 in Non-Aqueous System

Oil-in-glycerol (O/G) emulsion was prepared in the presence of different weight ratios of mixed Tween20-Span20 surfactants. O/G emulsion was observed to form below 50 wt% of oil content at 3 wt% of mixed Tween20Span20 surfactants. Physical properties of the emulsion were determined by using a microscope, particle counting and rheological measurement. An attempt to correlate HLB values of mixed Tween20-Span20 with emulsion stability was also carried out