Woranart Jonglertjunya

Gold Recovery from Aqueous Solutions Using Bioadsorbent Synthesized from Rambutan Peel

The recovery of gold from chloride solutions using bioadsorbent synthesized from waste rambutan peel was studied. The initial gold concentration 25-900 mg/L, solution pH 1-4, temperature 25-60 °C and the amount of adsorbent 1-25 mg were found to affect the efficiency for gold recovery as well as loading capacity. The 99.8 % gold recovery was accomplished in 1 h with loading capacity of 100 mg Au/g adsorbent at the following conditions: adsorbent 25 mg, initial gold concentration 100 mg/L, pH 2 and temperature 60 °C. The decrease of adsorbent from 25 to 1 mg resulted in the highest loading capacity of 2530 mg Au/g adsorbent and 100 % gold recovery within 100 h. The adsorption isotherm as well as mechanism were also elucidated. The Langmuir isotherm and the pseudo second-order kinetic model were fitted well with the experimental results. The activation energy of reaction was calculated to be 31.07 kJ/mol. The mechanism of adsorption is clarified to be the oxidation of hydroxyl groups and reduction of trivalent gold ions to metallic gold on the adsorbent surface which were supported by FT-IR, XRF and SEM.

Saccharification of Delignified Sugarcane Bagasse for Lactic Acid Fermentation using Lactobacillus sp.

Delignified sugarcane bagasse (SCB) by solvent extraction was carried out at moderate condition (90°C, 4 h) in the presence of acid catalyst. To investigate the dissolution of lignin into solvent, different solvents were utilized during lignin extraction process. Delignified SCB was further hydrolyzed by cell wall degrading enzyme complexes prior to sugar determination. The results showed that n-butanol was the most promising solvent enhancing lignin dissolution which in turn led to highest yield of glucose (63.1% based on treated SCB) and no xylose was detected in hydrolysate. The lignin extraction by n-butanol in the presence of H2SO4 and subsequent saccharification process were then scaled up for lactic acid production. The maximum lactic acid was obtained at 25.7 ± 0.2 g/l from L. casei fermentation after 96 hours when sugarcane bagasse hydrolysate containing 25.6±1.4 g/l initial glucose concentration was used as substrate.

Butanol, Ethanol and Acetone Production from Sugarcane Bagasses by Acid Hydrolysis and Fermentation Using Clostridium sp.

Utilization of sugarcane bagasses for butanol, ethanol and acetone production was studied by acid hydrolysis and bacterial fermentation. Glucose, xylose and arabinose contents of sugarcane bagasse hydrolyzed in 5% (v/v) sulfuric acid solution were investigated in respective range of 5 to 60 min. Results showed glucose and xylose released during hydrolysis at 121 C and long treatment time of 60 minutes had high concentrations of 18.7 and 19.8 g/l, respectively. The sugarcane bagasse hydrolysate was then used for butanol, ethanol and acetone production by anaerobic fermentation using C.butyricum, C. sporogenes, C.beijerinckii and C.acetobutylicum. The maximum production based on solvent yield was 4.7 g/l butanol, 6.3 g/l ethanol and 9.7 g/l acetone obtained from fermentation of sugarcane bagasse hydrolysate using C. beijerinckii for 48 hours in the presence of 0.5% (w/v) sugarcane bagasse.

Modeling Keeping Quality of Pasteurized Milk

The quality attributes of pasteurized milk such as total viable count (TVC), pH, conductivity and titratable acidity (TA) were determined during storage at 6, 15 and 25°C. The quality deterioration was indicated by an increase in initial TVC, conductivity and TA, and decrease in pH. The TVC increased from initial 103.6 CFU/ml to about 106-107 CFU/ml indicating spoilage of milk. The milk could be kept without spoilage for about 4, 1 and 0.35 day during storage at 6, 15 and 25°C, respectively. Changes in pH and TA could only be detected after TVC reached a level of about 106 CFU/ml.). Results showed that both multiple regression and Gompertz models could be used for shelf-life prediction of pasteurized milk. However, the Gompertz model resulted in superior fitting to experimental data (r2 = 0.98) compared to the multiple regression model (r2 = 0.76).