Effect Of Solvent Pretreatment Research Articles

Effect of solvent pre-treatment on the physicochemical, thermal profiles and morphological behavior of Mangifera pajang seed fat

In this work, the effect of solvent pre-treatment (hexane, petroleum ether and ethanol) on the physicochemical, thermal and morphology behavior of Mangifera pajang seed fat (MPSF) were investigated. Fat extraction was performed using Soxhlet method, and results showed that the yield, physicochemical, and crystalline structures of the MPSF were significantly (p < 0.05) influenced by the extraction solvents. Hexane gave the highest fat yield (7.67 %) with low unsaturation value (52.13 g iodine/g) compared with petroleum ether and ethanol. Hexane MPSF also had low oxidation rate (peroxide value of 1.1 mEq/g). Both non-stabilized and stabilized hexane MPSF showed a single melting endothermic peak at high temperature with onset, maximum peak and offset temperature of 16.23 ˚C-18.21 °C, 28.22 ˚C-31.25 °C and 34.85 ˚C-39.58 °C, respectively. Hexane MPSF crystallized rapidly at high temperature with single maximum peak starting at 16.51 ˚C-16.68 °C and ending at 0.23 ˚C-1.13 °C. In comparison with ethanol extract, hexane MPSF demonstrated a compact crystalline structure with a large densely packed center. Therefore, MPSF obtained from hexane presented better overall quality than those obtained from other extraction solvents. MPSF exhibited similar melting and morphological behavior to mango kernel fat and commercial cocoa butter. These results suggested that hexane was the best solvent for the extraction of MPSF. This fat also has the potential to be applied as a cocoa butter alternative fat or functional fat.

Effect of Solvent Pre-Treatment on the Physicochemical, Thermal Profiles and Morphological Behavior of &lt;i&gt;Mangifera pajang&lt;/i&gt; Seed Fat

In this work, the effect of solvent pre-treatment (hexane, petroleum ether and ethanol) on the physicochemical, thermal and morphology behavior of Mangifera pajang seed fat (MPSF) were investigated. The results showed that the yield, physicochemical, and crystalline structures of the MPSF were significantly (p<0.05) influenced by the extraction solvents. Hexane gave the highest fat yield (7.67%) with low unsaturation value (52.13 g iodine/g) compared with petroleum ether and ethanol. Hexane MPSF also had low oxidation rate (peroxide value of 1.1 mEq/g). Both non-stabilized and stabilized hexane MPSF showed a single melting endothermic peak at high temperature with onset, maximum peak and offset temperature of 16.23 ˚C-18.21 ˚C, 28.22 ˚C-31.25 ˚C and 34.85 ˚C-39.58 ˚C, respectively. Hexane MPSF crystallized rapidly at high temperature with single maximum peak starting at 16.51 ˚C-16.68 ˚C and ending at 0.23 ˚C-1.13 ˚C. In comparison with ethanol extract, hexane MPSF demonstrated a compact crystalline structure with a large densely packed center. MPSF exhibited similar melting and morphological behavior to mango kernel fat and commercial cocoa butter. These results suggested that hexane was the best solvent for the extraction of MPSF. This fat also has the potential to be applied as a cocoa butter alternative fat.

Effect of solvent pre-treatment on the structures and dissolution of microcrystalline cellulose in lithium chloride/dimethylacetamide

This study systematically investigated the structural changes of cotton-based microcrystalline cellulose (MCC) during solvent treatment in water and dimethylacetamide (DMAc), as well as how solvent exchange affects the dissolution rates of MCC in LiCl/DMAc solution. When MCC is soaked in DMAc or water for 3 days or longer, the surface cellulose layers become exfoliated from the MCC particles and these exfoliated portions are solvable in LiCl/DMAc. DMAc treatment significantly improves the nano-porosity of MCC. Thus, the chloride anions are able to diffuse into cellulose and lead to the final dissolution of cellulose chains via charge repulsion effects. On the other hand, water treatment exhibits strong pore closing effect, especially for nano-pores with a diameter < 30 nm, which prohibits the diffusion of chloride anions and the final dissolution of cellulose chains.

Effect of solvent pretreatment on pyrolysis characteristic of high-sulfur bituminous coal

In this study, high-sulfur bituminous coal was extracted with n-hexane, acetone, carbon disulfide, tetrahydrofuran and pyridine, respectively. The effect of solvent pretreatment on pyrolysis characteristic of high-sulfur coal was studied in a fixed-bed reactor. The heterocyclic aromatic hydrocarbons such as tetrahydrofuran and pyridine got higher extraction yields than other solvents. Oxygenated compounds could be selectively extracted by tetrahydrofuran with a maximum relative content of 9.09%, and nitrogen-containing compounds by pyridine with its content of 5.61%. However, all the solvents did not exhibit the selective extraction ability of sulfur-containing compounds. Compared with raw coal, the phenols content in pyrolysis tar from residues of pyridine and tetrahydrofuran increased significantly, and the sulfur compounds all exhibited lower content tendency. The solvent pretreatment can inhibit the radical condensation reaction effectively, and result in the reduction of high carbon number tar components, which is beneficial to the upgradation of pyrolysis tar. In addition, solvent pretreatment can be able to increase the oil yield, especially pyridine of 17.63%.

COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT, TEMPERATURE, CATALYST AND PRESSURE

ABSTRACT The effect of solvent pretreatment, temperature, a CoMo/Al2O3 catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.

Sarin Transport across excised Human Skin II: Effect of Solvent Pretreatment on Permeability

The effect of pretreating callus membranes with dimethyl sulfoxide, dimethylacetamide, dimethylformamide, formamide, dioxane, or methyl orthoformate on sarin permeability was studied at three temperatures to determine the activation energy for transport. In addition, the effect of membrane pretreatment on permeability through callus membranes from either a sarin-carboxypolymethylene gel or a sarin-polymethyl methacrylate gel was studied.