Applied Mechanics and Materials Vols. 291-294

Abstract: Optimization of culture conditions for lipopeptide production of lipopeptide by Bacillus subtilis NEL-01 was carried out in shaker flask batch fermentations using composite central design of response surface methodology (RSM). A five-level three-factor central composite design was employed to determine the maximum lipopeptide production at optimum levels for culture temperature, initial pH and culture cycle. Culture temperature and culture cycle showed the significant linear main effects, while pH had no significant linear effect. The production was also significantly affected by quadratic effect of culture temperature and initial pH. Optimum fermentation parameters were predicted at temperature, initial pH, and culture cycle of 34.81 °C, 7.33g/l, 49.26 h, respectively. The prediction lipopeptide yield was 1879.56 mg/l. The subsequent experiments confirmed the prediction.

Abstract: A total of 120 D-xylose fermenting yeast strains were isolated from composition soil samples. 6 strains capable of fermenting D-xylose to produce ethanol were obtained by TTC double medium agar method screening and potassium dichromate oxidation method re-screening. All the 6 strains belong to the genera Candida or Pichia by morphology and physiology identification. Candida spp. strains showed rather high efficiency to produce ethanol from D-xylose than the Pichia spp. strains, of which, strain M-105 exhibited a D-xylose consumption rate of 98.28% and the highest ethanol yield (0.465 g/g), with concentration up to 18.58 g/L under the condition of fermenting 40 g/L of this sugar at 28°C and 100 r/min for 72 hours. An average ethanol concentration of 18.35±0.07 g/L was reached from three batches fermentation of M-105 in shaking flask.

Abstract: The catalytic disproportionation of glycerol was investigated over active carbon (AC) supported catalysts. Typically, 1,2-propanediol, acetic acid, and acetaldehyde were found as the major products of the reaction over catalysts Na₂CO₃/AC and K₂CO₃/AC. Other products, such as methanol, ethanol, ethylene glycol, and acetone were also formed as the minor products in the reaction. All of these compounds are defined as oxygenate products (OP). The highest OP yield of 65.3% (carbon mol) was obtained over Na₂CO₃/AC at 593 K.

Abstract: Two renewable and environmentally friendly energy sources, biomass and solar sources, are compounded. It is an integrated thermal power system that avoids their respective shortages based on the principle of cascade utilization of energy according to energy level. The PPSD, a computer aided design tool, models and simulates the whole system and provides important parameters for designers. The calculation results present that the biomass fuel consumption saving is about 35,904 tons if the hybrid solar thermal power system works 2200 hours in a year for the 48tph biomass boiler. The dropping of flue gas emission temperature to 123°Cincreases the boiler efficiency to 91.45%.

Abstract: A lipase gene from sequencing genomic DNA of Bacillus subtilis strain I₄ (I₄-2) was cloned and expressed in E. coli. The deduced amino acid (aa) sequences for the lipase I₄-2 was composed of 31-amino-acid signal sequence and a 181-amino-acid mature part, corresponding to a molecular mass (Mr) of 19.33 kDa. Based on the Mr and the protein sequence, the lipase I₄-2 was belong to the lipase family1.4. The activity of the purified recombinant lipase I₄-2 was apparently optimal at 45°C and pH 7.0. The enzyme was stable at 25°C, and more than 56% of the initial activity after incubation in buffer pH 7.0 for 120 min at 37°C. In addition, lipase I₄-2 was mixed with methanol (50, v/v) for 30 min and residual activity was 45%. lipase I4-2 can catalyzed biodiesel production from soybean oil at methanol : soybean (molar ratio of methanol to oil = 3:1), 10% n-hexane, 3.5% water. The results of GC–MS analysis demonstrated that a 3-stepwise process resulted in a 98% conversion yield after 8 h of reaction at 37°C.

Abstract: Hydrolysis of glucose to produce levulinic acid catalyzed by ZSM-5 loading SO42-/ ZrO2 was studied in this paper. The effects of different factors such as catalyst amount, reaction temperature, reaction time on the yields of levulinic acid and hydroxymethyl furfural were investigated. It was found that the highest yield of levulinic acid was 55.03% (molar percent) under the conditions of catalyst amount 3 g, reaction temperature 180 °C and reaction time 2.5 h. Surface structure of catalyst was analyzed by FT-IR, indicating that crystallinity of catalyst was 0.66.

Abstract: An accurate determination method of fatty acid methyl esters (FAMEs) in biodiesel produced from pistacia chinensis oil by gas chromatography (GC) was developed, with methyl tridecanoate used as an internal standard. The results show that the standard calibration curves for the FAMEs have good linearity over the concentration range, the linearity correlation coefficients (R2) are more than 0.99 for all the components. The average recoveries are from 95.26% to 99.66%. The method has good precision with the RSD ranging from 1.03% to 3.40%.

Abstract: Biodiesel is green and renewable energy ,but producing biodiesel must be based on local conditions to avoid competing with edible oil.China is famous for its food , and it produces several millions of waste frying oils every year, which can offer raw material to produce the biodiesel.The biodiesel produced by waste frying oils is practicable and has been put into commercial application in Japan, and it brings important revelations to China the following :First is to promote the acceptance and the participation of the civilians,second is to formulate supporting policies for biodiesel industry, third is to make good use of the by product glycerin.

Abstract: A native microalgae strain Chlorella vulgaris U3-3from Baimaxueshan Yunnan province has been isolated and identified as a potential feedstock for biodiesel production. The biomass production, lipid productivity, and fatty acid compositions of U3-3 are investigated and compared under phototrophic, heterotrophic and mixotrophic conditions with various media. U3-3 under phototrophic growth on BG11 medium shows higher cellular lipid content (44.6%) than those under heterotrophic and mixotrophic conditions. And U3-3 display its higher biomass production (5.55g/L) than those under phototrophic and heterotrophic conditions growing on optimized medium with supply 35g/L glucose under mixotrophic condition. However, Chlorella vulgaris U3-3 growing under heterotrophic condition with optimized medium of supply 35g/L glucose exhibited more than 7.26-fold and 1.05-fold increase in lipid productivity compared with that under phototrophic and mixotrophic conditions. Moreover, Chlorella vulgaris U3-3 has suitable fatty acid compositions with high saturated acid contents (28.76%) and favorable degree of unsaturation (92.86) growing under heterotrophic condition with optimized medium of supply 35g/L glucose, suggesting its potential as a biodiesel feedstock on this cultivation condition and medium composition.

Abstract: A novel concept and efficient method for producing biodiesel from rapeseed oil deodorizer distillate (RODD) was developed by using compound lipases for one-pot esterification of FFA and transesterification of triglyceride with methanol in a solvent-free system. Compound lipases Novozyme435 and immobilized Pseudomonas cepacia G63 at 1:1(wt/wt) gave FAME about 96% yield under optimal conditions, being better than that with single lipase or other compound lipases. Besides, the loss rate of vitamin E was 18% much lower than that of using chemical catalyst, which shows that the compound lipases Novozyme435 and immobilized P. cepacia G63 can be ideal catalysts for biodiesel production from rapeseed oil deodorizer distillate.