Solvent Crystallization of Palm-Based Dihydroxystearic Acid

Palm based 9,lO-threo dihydroxystearic acid (DHSA) was produced from epoxidation of oleic acid with performic acid, followed by hydrolysis of the epoxide. It is widely used as ingredient in cosmetic industries. However, it is a requirement for low purity crude DHSA to undergo a purification stage in order to fulfil the stringent quality requirement in this field. Solvent crystallization has been employed with detailed examination to produce good quality crystallized product. The objective of this research work is to carry out a preliminary and detailed study on the solvent crystallization of palm based DHSA. Preliminary study was done using two different solvents, ethanol and hexane, at several concentratipns and cooling conditions. The chemical and physical product properties of the crystallized product are evaluated using gas chromatography (GC), crystal size distribution (CSD) and scanning electron microscopy (SEM). The preliminary studies suggested that crystallization of DHSA using ethanol has been successfully achieved and natural cooling mode gives better performance compared to rapid cooling mode, almost in all aspects. However, crystallization of DHSA using hexane as solvent was unable to shape DHSA into crystal. It produced bulk solid DHSA with low purity percentage (79%). Based on preliminary studies, an investigation on controlled cooling crystallization using a fabricated crystallizer has been conducted. This study focuses on various operating conditions, namely temperature (24"C, 26"C, 28"C), time (1 - 12 hours), seeding process (2.5, 5, lograms) and cooling modes (natural and controlled crystallization). Effect of these parameters on crystal size distribution (CSD), purity and yield of crystallized product has been examined. Quality and quantity of crystals produced via the controlled cooling crystallizer are greatly influenced by the operating temperature. Higher working temperature produced crystals with higher purity and larger average crystal size. However, the yield is lower. Controlled crystallization process results in a better crystal properties compared to natural cooling crystallization, generally in almost all aspects. Furthermore, the addition of DHSA seed into the solution could reduce the purity of product and at the same time, as it could retard the crystal growth

Production of biodiesel from used cooking oil (UCO) using ion exchange resins as catalysts

This study focuses on the development of novel two-stage esterification-transesterification synthesis of biodiesel from used cooking oil (UCO) using novel heterogeneous catalysts. The esterification of the UCO was investigated using three types of ion exchange resins catalysts including Purolite D5081, Purolite D5082 and Amberlyst 15. Of all the catalysts investigated, Purolite D5081 resin showed the best catalytic performance and was selected for further optimisation studies. From the optimisation study, it was found that the external and internal mass transfer resistance has negligible effect on the esterification reaction. At the optimum reaction conditions, Purolite D5081 achieved 92% conversion of FFA. During reusability study, the conversion of FFA dropped by 10% after each cycle and it was found that progressive pore blockage and sulphur leaching were dominant factors that decreased the catalytic performance of the Purolite D5081 catalyst. A kinetic modelling for FFA esterification was carried out using Purolite D5081 as a catalyst. Three types of kinetic models were investigated i.e. pseudo homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHHW). Experimental data obtained from the batch kinetic studies was successfully represented by the PH model and a good agreement between experimental and calculated values was obtained. The activation energy for esterification and hydrolysis reaction was found to be 53 and 107 kJ/moL. The transesterification of pre-treated cooking oil (P-UCO) was investigated using various types of heterogeneous catalysts including Purolite CT-122, Purolite CT-169, Purolite CT-175, Purolite CT-275, Purolite D5081, Diaion PA306s and Cs-supported heteropolyacids catalysts. Of all the catalysts investigated, Diaion PA306s catalyst showed the highest conversion of triglycerides and was selected for further optimisation studies. At the optimum reaction conditions, Diaion PA306s achieved ca. 75% of triglycerides conversion. During the reusability study, Diaion PA306s catalyst gave a similar conversion of triglycerides after being reused once. Therefore, it was concluded that the resin can be used several times without losing catalytic activity. Several purification methods have been investigated and dry washing method was chosen as the best alternative for biodiesel purification

Habit and morphology study on the palm-based 9,10-dihydroxystearic acid (DHSA) crystals

Dihydroxystearic acid (DHSA) and its derivatives are hydroxyl fatty acids suitable to be used as multipurpose intermediates in the synthesis of personal care products and decorative cosmetics. In Malaysia, DHSA has been successfully produced from palm-based oleic acid, via epoxidation with per-formic acid followed with hydrolysis of the epoxide. The objective of this paper is to study the crystals of DHSA produced under different crystallization conditions. The crystal habit and morphology were observed in terms of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that solvent type, solvent concentration and cooling mode affect the crystal habit but not the morphology. The DHSA crystals agglomerated into either sphere-like or plate-like habit structure while always maintaining the triclinic crystal system

Effect of solvent concentration and cooling modes on morphology, particle size distribution, and yield of dihydroxystearic acid (DHSA) crystals

Palm-based dihydroxystearic acid was purified by employing solvent crystallization using ethanol and ethanol/water mixture as solvents. Two different cooling modes, rapid and natural cooling, were employed for the crystallization process. In this study, the cooling effects on morphology, habit, particle size distribution, and yield of dihydroxystearic acid crystals were investigated. The dihydroxystearic acid crystals appeared to agglomerate into sphere-like and plate-like structures, depending on the cooling modes and the presence of water. By manipulating the solvent and cooling modes, the crystal yield ranged from 0.8% to 42.1%, while the crystal purity ranged from 73.3% to 91.4%. Solvent crystallization using ethanol was best achieved through natural cooling with the dihydroxystearic acid to ethanol ratio of 1.0:1.0, which produced the narrowest particle size distribution curve with the largest average particle size

Development, characterization and commercial application of palm based dihydroxystearic acid and its derivatives: an overview

Hydroxyl fatty acids and their derivatives are of high value due to their wide range of industrial application, including cosmetic, food, personal care and pharmaceutical products. Realizing the importance of hydroxyl fatty acids, and yet due to the absence of the conventional starting raw materials, Malaysia has developed 9,10-dihydroxystearic acid (9,10-DHSA) and its derivatives from locally abundant palm based oils. The aim of this article is to provide a general description of the works that have thus far being done on palm based 9,10-DHSA: starting from its conception and production from commercial grade palm based crude oleic acid via epoxidation and hydrolysis, purification through solvent crystallization and characterization through wet and analytical chemistry, moving on to developmental works done on producing its derivatives through blending, esterification, amidation and polymerization, and completing with applications of 9,10-DHSA and its derivatives, e.g. DHSA-stearates and DHSA-estolides, in commercial products such as soaps, deodorant sticks and shampoos. This article incorporates some of the patent filed technological knowhow on 9,10-DHSA and its derivatives, and will also point out some of the shortcomings in previously published documents and provide some recommendations for future research works in mitigating these shortcomings

Solvent crystallization of palm based dihydroxystearic acid with isopropyl alcohol: effects of solvent quantity and concentration on particle size distribution, crystal habit and morphology, and resultant crystal purity

Crude dihydroxystearic acid was prepared from palm based oleic acid and was then solvent purified with isopropyl alcohol in a custom fabricated simultaneous batch crystallizer unit. The crystallized dihydroxystearic acid was a functional ingredient that acted as multipurpose intermediate for synthesis of various fine chemicals, cosmetics and personal care products. The effects of solvent quantity and concentration on particle size distribution, crystal habit and morphology, and resultant crystal purity were studied. The crystals were purer but smaller and the span of the distribution curve was wider at higher solvent quantity and concentration. Through scanning electron microscopy and X-ray diffraction, it was observed that the crystals agglomerated into plate-like (flaky) habit with triclinic crystal structure. Solvent crystallization with 80% IPA at 20°C and solute:solvent ratio of 1.0:1.0 was the most optimized and efficient, producing β-DHSA crystals that has high resistance against fat exudation during vacuum filtration process

Development of a reactive distillation column prototype to convert acrylic acid in the petrochemical wastewater to valuable butyl acrylate through esterification

Wastewater containing 2-20wt% of acrylic acid (AA) is currently burned using incinerator which is neither economical feasible nor environmental friendly. Esterification in a reactive distillation column (RDC) is a promising method to recover AA from wastewater. AA could be converted to a valuable ester product while purifying water. A RDC prototype was developed and tested for the recovery of AA from the wastewater. A maximum AA conversion of 99.5% was achieved when the BuOH to AA molar ratio and reflux ratio were 4 and 5 respectively. The data was used to validate the simulation results generated using equilibrium stage model in ASPEN PLUS program. A technically optimized RD process was then proposed

A short review on production of syngas via glycerol dry reforming

Glycerol. a by-product from biodiesel production, has been widely investigated as one of the alternative feedstocks for production of synthesis gas (syngas). The production of syngas through glycerol pyrolysis, gasification, and steam reforming has been well established. However, to date, there were only a few literatures focusing on the use of glycerol dry reforming (GDR) to produce syngas. GDR offers a better pathway for the production of syngas as it converts carbon dioxide, a greenhouse gas, into a value-added product and converts the biodiesel by-product, glycerol, into an alternative source of energy. Nickel (Ni) is extensively used as a catalyst in many reforming processes due to its excellent capacity for carbon-carbon bond cleavage and because it is easily available and economically cheap. The major challenge faced by the application of Ni as a catalyst in GDR is mainly due to the deactivation of catalyst through carbon formation. This review focuses on the performance of potential catalysts and operating conditions that exhibit high catalytic activity and stability in GDR. Few perspectives of catalyst properties such as catalyst dispersion, basicity and acidity, reducibility, oxygen storage capability, and interaction between support and catalyst have been included in the review, and their catalytic performances have been deliberated. Effects of reaction parameters such as reaction temperature, gas hourly space velocity, and reactants partial pressure were discussed in detail, followed by the thermodynamics study. This short review is expected to create a clear understanding on the correlation between catalytic properties and their performance in glycerol dry reforming