Papers by Author: Verawat Champreda

Abstract: Lignocellulosic biomass is a renewable source for sustainable production of fuels, chemicals, and other materials with the advantages on its carbon-neutral nature. Fractionation of lignocellulosic materials is a pre-requisite in the biorefinery process in order to convert the cellulose, hemicellulose, and lignin to valuable products with maximized economics prospective. In this work, a modified clean fractionation (CF) process using ternary mixture system of ethyl acetate/methanol/water was studied with the use of acid promoters. H₂SO₄ was found to be the efficient promoter due to low cost compare to other acid promoters. The optimal fractionation conditions operated in the solvent mixture containing 0.025 M H₂SO₄ at 160°C for 50 min led to 63.72% recovery of the cellulose in the solid pulp while 90% and 59.94% of hemicellulose-derived products and lignin were recovered in the aqueous-alcohol and organic fractions, respectively. The enzymatic digestibility of the cellulose-enriched pulp was increased, resulting increasing glucose yield from 38.32% of the native biomass to 70.04% using the hydrolysis reaction with Cellic Ctech2^® at 15 FPU/g. The work demonstrated the applicability of the modified CF process for fractionation of lignocellulose components for integrated biorefinery process.

Abstract: The composite polydimethylsiloxane PERVAPTM 4060 was used for separation of methanol/water solutions by using pervaporation technique. The effect of feed concentration, feed temperature, and feed flow rate were investigated for the separation performance. The experimental data showed that increasing of the feed methanol concentration from 0.5 to 10 wt% resulted in an increase in total permeation flux up for to 35 % whilst the separation factor (α) decreased by 85%. The results also showed that increasing operating temperature from 40 to 60 °C caused an increases in methanol permeance up to 130%.

Abstract: The layer formation of bovine serum albumin (BSA) on a poly(styrene-co-maleic acid) (PSMA) surface was investigated by using quartz crystal microbalance (QCM) technique at various pH values. The formation of a BSA surface was examined by atomic force microscopy (AFM). To study the effect on the layer formation, the pH of solution was varied from 2 to 7.4 while the concentration of BSA was in the range of 0.01 to 5 mg/ml during the layer absorption. It was found that the BSA adsorption strongly depends on the pH of solution, and the concentration of BSA. The absorption layer occurred maximum at the pH value of 3.5 which resulted from the charge of PSMA and BSA molecules. The layer formation reached the saturate value at the concentration higher than 3 mg/ml. The molecular packing of the BSA layer at different pH values was determined by AFM and total mass change of QCM.