| Cotton plays an important role in our national economy and the cotton production in the world. Cottonseed is the main by-product of cotton. It is significant to exploit the cottonseed for the stable production and comprehensive utilization of cotton in our country. Therefore, it is meaningful for us to research on the cottonseed meal and cottonseed oil with the purpose of raising utilizing efficiency and economic benefit of cottonseed. Results can be used to guide producing of biodiesel for the other plant oil.Cottonseed meal and cottonseed oil was selected as raw material in this paper. The cottonseed meals were treated by microorganism fermentation. The appropriate strain, optimum fermentation conditions and the comparison of microbial, chemical and physical detoxification techniques were researched in this study. The method and parameters of detoxification were obtained. The process parameters about the biodiesel prepared from cottonseed oil by esterification which is catalyzed by alkali were optimized through single factor test and orthogonal test. In addition the product quality of biodiesel prepared from cottonseed oil was evaluated. The results and conclusions are as follows:The yeast Y3 could reduce the gossypol most effectively among the five yeast strains. Influencing factors of gossypol detoxification such as the ratio of material and water, fermentation temperature and time was studied when using cottonseed meal as fermentation substrate. The effects of microbial , chemical and physical techniques on gossypol detoxification were compared in this study. The optimum fermentation conditions were obtained: incubation temperature 25℃, ratio of material to water 1:0.8, incubation period of 36 h. The yield and gossypol content was 84.2% and 131mg/kg, respectively. In addition, after two grade fermentation, the yield and gossypol content could reach 93.3% and 56mg/kg, respectively, with inoculum concentration 2.5% and incubation time 48 h. The protein content of cottonseed meal increased 4.6%. Fermentation substrate had the balm of yeast which could improve palatability of feed. Degrading gossypol by chemical reagents of 1%FeSO4,2%NaOH and 2.5%CaO,inoculum concentration 2.5% and ratio of material to water 3:1 showed the highest effective in detoxification. Cottonseed meal mixed with 2.5%CaO at 1:1 was recommended at rough conditions, by this way, gossypol could be decreased to 198mg/kg. Refined cottonseed oil reacted with methanol catalyzed by KOH. One factor and orthogonal design were carried out considering the percentage of biodiesel to material oil. It indicated that the four factors on the influence of the transesterification reaction in turn were reaction temperature, molar ratio of methanol to oil, usage amount of KOH catalyst and reaction period. The optimum conditions obtained were reaction temperature at 45℃, molar ratio of methanol to oil 7:1, amount of catalyst KOH 1.0 % and reaction period 60min. The oil obtained by centrifugal separation and the oil in the bottom deposition layer was tested. There was little different between the oil from the upper layer and the bottom except the residual solvents content. The residual solvents content of the bottom oil was about three times of the upper. In order to improve the economic profit of the bottom deposition layer oil, it could be used as material to prepare biodiesel. Biosiesel sample was tested. The qualities met the requirements of 0# diesel(GB252-2000). The qualities met the requirements of BD100(GB/T 20828-2007) except the 10% carbon residue and oxidation stability. |
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