Yoke-Leng Sim

Kinetics and mechanism of large rate enhancement in an acidic aqueous cleavage of the tertiary amide bond of N-(2-methoxyphenyl)-N'-morpholinophthalamide (1).

The rate of conversion of 1 to N-(2-methoxyphenyl)phthalimide (2) within [HCl] range 5.0x10(-3)-1.0 M at 1.0M ionic strength (by NaCl) reveals the presence of both uncatalyzed and specific acid-catalyzed kinetic terms in the rate law. Intramolecular carboxamide group-assisted cleavage of amide bond of 1 reveals rate enhancement of much larger than 10(6)-fold compared to the expected rate of analogous intermolecular reaction.

Urea adsorption by activated carbon prepared from palm kernel shell

Dialysis treatment is crucial for patients suffer from renal failure. The dialysis system removes the uremic toxin to a safe level in a patient’s body. One of the major limitations of the current hemodialysis system is the capability to efficiently remove uremic toxins from patient’s body. Nanoporous materials can be applied to improve the treatment. Palm kernel shell (PKS) biomass generated from palm oil mills can be utilized to prepare high quality nanoporous activated carbon (AC) and applied for urea adsorption in the dialysis system. In this study, AC was prepared from PKS via different carbonization temperatures and followed by carbon dioxide gas activation processes. The physical and chemical properties of the samples were studied. The results show that the porous AC with BET surface areas ranging from 541 to 622 m2g−1 and with total pore volumes varying from 0.254 to 0.297 cm3g−1, are formed with different carbonization temperatures. The equilibrium constant for urea adsorption by AC samples carbonized at 400, 500 and 600 °C are 0.091, 0.287 and 0.334, respectively. The increase of carbonization temperatures from 400 to 600 °C resulted in the increase in urea adsorption by AC predominantly due to increase in surface area. The present study reveals the feasibility of preparing AC with good porosity from PKS and potentially applied in urea adsorption application.Dialysis treatment is crucial for patients suffer from renal failure. The dialysis system removes the uremic toxin to a safe level in a patient’s body. One of the major limitations of the current hemodialysis system is the capability to efficiently remove uremic toxins from patient’s body. Nanoporous materials can be applied to improve the treatment. Palm kernel shell (PKS) biomass generated from palm oil mills can be utilized to prepare high quality nanoporous activated carbon (AC) and applied for urea adsorption in the dialysis system. In this study, AC was prepared from PKS via different carbonization temperatures and followed by carbon dioxide gas activation processes. The physical and chemical properties of the samples were studied. The results show that the porous AC with BET surface areas ranging from 541 to 622 m2g−1 and with total pore volumes varying from 0.254 to 0.297 cm3g−1, are formed with different carbonization temperatures. The equilibrium constant for urea adsorption by AC samples carbon...

Liquid fuels from food waste: An alternative process to co-digestion

Waste from uneaten, spoiled, or otherwise unusable food is an untapped source of material for biofuels. A process is described to recover the oil from mixed food waste, together with a solid residue. This process includes grinding the food waste to an aqueous slurry, skimming off the oil, a combined steam treatment of the remaining solids concurrent with extrusion through a porous cylinder to release the remaining oil, a second oil skimming step, and centrifuging the solids to obtain a moist solid cake for fermentation. The water, together with any resulting oil from the centrifuging step, is recycled back to the grinding step, and the cycle is repeated. The efficiency of oil extraction increases with the oil content of the waste, and greater than 90% of the oil was collected from waste containing at least 3% oil based on the wet mass. Fermentation was performed on the solid cake to obtain ethanol, and the dried solid fermentation residue was a nearly odorless material with potential uses of biochar, gasi...

Hydrocarbon fuels from brown grease: Moving from the research laboratory toward an industrial process

Brown grease is a generic term for the oily solids and semi-solids that accumulate in the sewer system and in sewage treatment plants. It has previously been shown that brown grease undergoes pyrolysis to form a homologous series of alkanes and 1-alkenes between 7 and 17 carbon atoms, with smaller amounts of higher hydrocarbons and ketones up to about 30 carbon atoms. The initial study was performed in batch mode on a scale of up to 50 grams of starting material. However, continuous processes are usually more efficient for large scale production of fuels and commodity chemicals. This work describes the research and development of a continuous process. The first step was to determine the required reactor temperature. Brown grease consists largely of saturated and unsaturated fatty acids, and they react at different rates, and produce different products and intermediates. Intermediates include ketones, alcohols, and aldehydes, and Fe(III) ion catalyzes at least some of the reactions. By monitoring the pyrol...

Kinetic Evidence for Near Irreversible Nonionic Micellar Entrapment of N-(2′-Methoxyphenyl)phthalimide (1) under the Typical Alkaline Reaction Conditions

The values of pseudo-first-order rate constants (k obs) for alkaline hydrolysis of 1, obtained at 1.0 mM NaOH and within [ CmEnT] (total concentration of CmEn) range of 3.0–5.0 mM for C12E23 and 10–20 mM for C18E20, fail to obey pseudophase micellar (PM) model. The values of the fraction of near irreversible CmEn micellar trapped 1 molecules (F IT1) vary in the range ~0–0.75 for C12E23 and ~0–0.83 for C18E20 under such conditions. The values of F IT1 become 1.0 at ≥10 mM C12E23 and 50 mM C18E20. Kinetic analysis of the observed data at ≥10 mM C12E23 shows near irreversible micellar entrapment of 1 molecules under such conditions.