Preparation And Properties Of Ethyl Ester Biodiesel From Cottonseed Oil By Transesterification Process

Biodiesel is produced by transesterification with lipid feedstock and alcohol. The biodiesel derived from cotton seed oil and ethanol is really renewable, because the raw material to prepare biodiesel can not depend on petrochemical resources. Cottonseed oil ethyl ester contributes to renewble, non-toxic, biodegradable, higher flash piont and a reduction in most exhaust emissions. Cottonseed oil ethyl ester or blends mixing it with diesel fuel in any proportions can be used as diesel engines fuel directly. The reseach of cottonseed oil ethyl ester has nearly not been reported, and its preparation and performances has not furtherly disussed. Cottonseed oil ethyl ester produced from cottonseed oil and ethanol was investigated in the present dissertation, an eco-friendly process was developed by the optimziton of transesterification parameters. The biodegradability, lubricity, corrosion performance and volatilization behaviors of cottonseed oil ethyl ester were also thoroughly studied. All the results will be beneficial to preparation, transportation storage, usage of the cottonseed and ethanol-derived biodiesel.The kinetics of transesterification for biodiesel produced by cottonseed oil and ethanol in potassium hydroxide was studied well. The transesterification reaction between cottonseed oil and ethanol was carried out with excessful ethanol, the amount of KOH catalyst1.25wt%and reaction temperature at40-78℃. The reaction equilibrium took place after30minutes. The transesterification reaction between cottonseed oil and ethanol was a pseudo second order reaction during the first30minutes and a zero order reaction after30minutes. Reaction rate constants for the transestentcation of cottonseed oil with ethanol at40,60and78℃were0.0996,0.1126and0.1286L/(mol min) respectively, and the activation energy was21.6075kJ/mol. The rate constants of the transesterification reaction is slow, and the reactions demand more activation energy.In order to increase rate constants, biodiesel production by transesterification cottonseed oil with ethanol used tetrahydrofuran (THF) as cosolvent, KOH as catalyst. The main parameters for transesterification were also investigated. The maximal fatty acid conversion of97.90%was observed after1.5h with ethanol/oil of14:1, reaction temperature of78℃, the amount of KOH of1.25wt%and the ratio of THF/oil of1:1. The result showed that triglyceides and ethanol could easily dissolve each other with THF in the reaction mixture. THF has helpful effect on increasing conversion of triglyceides and lessening the time to reaction balance. THF could be used repeatedly by separating from mixture. All fuel properties of cottonseed oil ethyl or methyl ester were compared well with GB/T20828-2007. The biodegradabilities of biodiesels and its mixtures with diesel prepared from cotton seed oil via methyl, ethyl or diesel were investigated by the modified Sturm method. In aquatic aeration cultures, pure cotton seed oil methyl and ethyl esters biodegradability rates were99.7%and99.1%respectively after28days. Biodegradability rates of cotton seed oil ethyl esters in samples of100%,50%,20%,5%,2%were99.7%,95.7%,81.9%,65.4%,61.5%after28days. The more was cotton seed oil methyl and ethyl esters in mixtures, the easier was the biodegradability. The biodegradability of the fuel mixture was enhanced by adding biodiesel.Based on national standard method of petroleum products copper corrosion test (GBAT5096-1990), the corrosion character on copper in cottonseed oil methyl ester and cottonseed oil ethyl ester were detected at25"C and50"C. At the same time, the physical-chemical performances of the two samples were investigated and compared to diesel before and after corrosion. The results showed that variations of the corrosion phenomenon on copper which immersed in the two samples for two months at the25℃and50℃. The corrosion property of cottonseed oil methyl ester was changed seriously. Under the condition of25℃, the acid value of B100(CSOME) andB100(CSOEE) increased by13.92%and20.30%. Under the condition of50℃, the acid value of CSOME and CSOEE increased by35%and36%after60d. Temperature has obvious effect on the kinetic viscosity of biodiesel and its blends. The kinetic viscosity of B50(CSOME) and B50(CSOEE) increased by14.06%and15.75%at25℃, but the kinetic viscosity of B50(CSOME) and B50(CSOEE) increased by18.7%and19.7%at50℃with60d copper corrosion test.Biodiesels were synthesized by the transesterification reaction of cottonseed oil and methyl and ethyl, respectively. The biodiesel/diesel blends were then obtained by mixing the prepared biodiesels and commercial diesel. The lubrication properties of the obtained mixtures were studied on a four-ball tribometer. The results showed that the synthesized biodiesels could improve the lubrication properties of diesel obviously. The increase of the biodiesel had a positive effect on the lubrication properties of the mixtures. Moreover, the lubrication properties could be affected remarkably by the different alcohols. The extreme pressure (PB value) of the mixture was increased by94.1%and29.4%by adding20vol%methyl ester biodiesel and ethyl ester biodiesel, respectively. The biodiesel from ethyl alcohol could improve the lubrication properties more than that from methyl alcohol. Free fatty acids can also affect the lubricity of biodiesel. Finally, the volatilization behaviors of cottonseed oil methyl or ethyl ester and mixtures with diesel were investigated by glass surface dish volatile. The test was conducted in calm and humidity air at20℃,30℃and40℃, respectively. Volatilization loss order of cottonseed oil ethyl ester and it’s blends is D>B5>B10>B20>B50>B100. Volatilization loss will be decreased by diesel blends with cottonseed oil ethyl ester. Volatilization loss of biodiesel and it’s blends increase with temperature imcreasing.