Kinetics of epoxidation of jatropha oil with peroxyacetic and peroxyformic acid catalysed by acidic ion exchange resin

The kinetics of epoxidation of jatropha oil by peroxyacetic/peroxyformic acid, formed in situ by the reaction of aqueous hydrogen peroxide and acetic/formic acid, in the presence of an acidic ion exchange resin as catalyst in or without toluene, was studied. The presence of an inert solvent in the reaction mixture appeared to stabilise the epoxidation product and minimise the side reaction such as the opening of the oxirane ring. The effect of several reaction parameters such as stirring speed, hydrogen peroxide-to-ethylenic unsaturation molar ratio, acetic/formic acid-to-ethylenic unsaturation molar ratio, temperature, and catalyst loading on the epoxidation rate as well as on the oxirane ring stability and iodine value of the epoxidised jatropha oil were examined. The multiphase process consists of a consecutive reaction, acidic ion exchange resin catalysed peroxyacid formation followed by epoxidation. The catalytic reaction of peroxyacetic/peroxyformic acid formation was found to be characterised by adsorption of only acetic (or formic) acid and peroxyacetic/peroxyformic acid on the active catalyst sites, and the irreversible surface reaction was the overall rate determining step. The proposed kinetic model takes into consideration two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups and the reaction of the peroxyacid and epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using nonlinear regression method. Good agreement between experimental and predicted data validated the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for epoxidation reaction was found to be 53.6 kJ/mol. This value compares well with those reported by other investigators for the same reaction over similar catalysts.     

小桐子活性成分在农药方面的研究进展

综述了近年来小桐子在杀虫、抗菌以及杀软体动物等农药活性方面的研究进展。     

四种木本植物油制取生物柴油的研究

生物柴油原料成本是制约生物柴油商业化应用的主要障碍.麻疯树、光皮树、油茶、油桐主要分布于南亚热带和中亚热带,具有分布广、适应性强和经济产量高的特点,其果实或种子油均可作为生物柴油的原料油利用.为了筛选分布广、适应性强和经济产量高及价格低廉的原料,选择麻疯树油、光皮树油、茶油、桐油为原料油,以菜子油作对照通过正交试验筛选反应优化条件.结果表明,茶油、光皮树油及麻疯树油在以下条件:醇油比A((5～7):1),催化剂用量B(0.9～1.1),反应温度C(40～60 ℃),反应时间D(60～120 min)可以成功地制取生物柴油.最佳反应条件为:茶油A₂B₃C₂D₂;光皮树油A₁B₃C₂D₃;麻疯树油A₃B₂C₃D₃;桐油A₃B₁C₁D₁;对照菜油A₂B₁C₃D₂.     

固体酸催化麻疯树油酯交换制备生物柴油

采用固体酸催化酯交换方法,研究了由麻疯树油制备脂肪酸甲酯(生物柴油)过程中催化剂类型及工艺条件对生物柴油产率和产品组成的影响. 采用沉淀法制得两种固体酸催化剂ZrO2-SO42-和K4Zn4[Fe(CN)6]3,利用XRD, FT-IR, BET和元素分析仪表征了固体酸结构和性质. 以麻疯树油为原料油,分别比较了原料油的酸值及反应温度对2种催化剂的影响,利用气相色谱-质谱联用分析仪分析了产物的组成. 结果表明,ZrO2-SO42-和K4Zn4[Fe(CN)6]3催化高酸值麻疯树油时,ZrO2-SO42-容易失活,甲酯收率降为84%;以Fe-Zn为催化剂,甲酯收率达到93%,使用5次后甲酯收率仍达90%.     

Optimization of long-term storage stability of Jatropha curcas biodiesel using antioxidants by means of response surface methodology

The present paper reports the results of the study of the effect of metal contaminants on the storage stability of Jatropha curcas biodiesel (JCB) with and without antioxidants. Taking 1,2,3 -Trihydroxybenzene/Pyrogallol (PY) as the most effective antioxidant based on the earlier work of the authors, JCB was mixed with different transition metals – Fe, Ni, Mn, Co and Cu in different concentrations. Induction period (IP) was measured using Rancimat method (EN 14112) as the stability parameter. Based on results, several correlations were developed for assessing the storage stability in terms of IP as a function of antioxidant, metal concentration and storage time. For the purpose of design of experiment, response surface methodology (RSM) has been used. From the experiments it is found that if metal concentration is 0 then, 200 g m⁻³ of PY is sufficient to make biodiesel stable for 6 months. If metal (Fe) concentration is 2 g m⁻³ or more, then 800 g m⁻³ PY is sufficient to make biodiesel stable for 5.5 months. The value of storage time for Ni, Mn, Co and Cu contaminated JCB is found as 3.62, 3.24, 2.76 and 2.07 months respectively if metal and antioxidants concentration is same in all the cases.The models developed by RSM shall be highly useful for predicting the optimum antioxidant concentration to achieve maximum storage stability of JCB as well as biodiesel from other resources under the conditions set for 3 factors (antioxidant concentration, metal concentration and time).     

溶剂法从麻疯树饼粕中提取植物甾醇的研究

以麻疯树饼粕为实验材料,通过正交设计实验,探讨提取溶剂、提取时间、提取温度、转速对植物甾醇提取率的影响。研究表明,植物甾醇提取的最佳工艺条件:取25 g小油桐饼粕,乙酸乙酯100 mL,温度70℃。提取时间150 min,转速为900 r/min,优化工艺条件下植物甾醇的产率可达0.252%。     

Morphological,physico-chemical and micropropagation studies in Jatropha curcas L. and RAPD analysis of the regenerants

Four accessions of Jatropha curcas L. were characterized with respect to their yield and physico-chemical properties of seed-oil. Further, an efficient micropropagation protocol was developed followed by RAPD analysis of the regenerants. Although the highest 1000-seed-weight and seed-oil content were recorded in OJC1 and OJC5 accessions respectively, the seed-oil of OJC9 accession was more suited for biodiesel production due to the desirable characteristics like low values of free fatty acids, acid value, moisture content and total unsaturated fatty acids. An accession – independent micropropagation protocol of Jatropha was optimized by using axillary nodal explants with MS medium supplemented with a combination of growth regulators, glutamine and citric acid. All the accessions were amenable to in vitro culture, and the highest number of plantlets could be regenerated from the OJC5 accession. Although no somaclonal variation was recorded in the regenerants of all the accessions, RAPD analysis confirmed their genetic similarity and also the similarity of the clones with their respective mother plants.     

Biodiesel production from soybean and Jatropha oils using cesium impregnated sodium zirconate as a heterogeneous base catalyst

Cesium modified sodium zirconate (Cs-Na₂ZrO₃) was prepared by ionic exchange from sodium zirconate (Na₂ZrO₃), which was synthesized via a solid state reaction. Both ceramics, i.e., pristine Na₂ZrO₃ and the Cs-Na₂ZrO₃, were used as basic heterogeneous catalysts in biodiesel production. Soybean and Jatropha oils were used as triglyceride sources for transesterification reactions. Parameters, such as catalyst concentration (between 0.5 and 3 wt%), reaction time, different methanol/vegetable oil molar ratios, and temperature of the reaction, were evaluated. The cesium cation influence was evaluated from the basic transesterification reactivity. The results showed that the introduction of cesium significantly modified the catalytic activity in biodiesel production. Cs enhanced the reaction kinetics in obtaining biodiesel and reduced the reaction time in comparison with pristine Na₂ZrO₃. The results showed that Cs-Na₂ZrO₃ as a basic heterogeneous catalyst exhibited the best fatty acid methyl esters (FAME) conversion for soybean oil (98.8%) at 1 wt%, 30:1 methanol/oil ratio, 65 °C, and 15 min. The best conditions for Jatropha oil (90.8%) were 3 wt%, 15:1 methanol/oil ratio, 65 °C, and 1 h. The impregnation of Na₂ZrO₃ with cesium represents a very exciting alternative heterogeneous base catalyst for biodiesel production.     

Genetic variation and genotype by environment interaction in Jatropha curcas L. germplasm evaluated in different environments of Cameroon

Jatropha curcas L. (jatropha) is a perennial plant with a high untapped potential towards sustainable production of food and bioenergy. The transformation of jatropha into a competitive crop requires intensive breeding efforts. The objectives of our study were to (i) assess genetic variation of agronomic and quality traits in different environments, (ii) investigate genotype by environment interactions, and (iii) discuss potential selection strategies. Agronomic and quality traits were assessed on 277 jatropha genotypes that were evaluated over three environments in Cameroon. Genetic variation and heritability of agronomic and quality traits showed excellent prospects to select and breed improved cultivars rapidly. Selection for accumulated seed yield over years seems to be the best choice to increase annual seed and oil yield. Seed yield per month might be incorporated in selection indices to improve the efficiency of fruit harvesting. Selection based on a single testing environment was always inferior to the selection based on multiple environments. The magnitude of genotype by environment interaction (GxE) in jatropha is large. Therefore, testing in multiple environments is a requirement to select improved cultivars with local and broad adaptation.