Optimization of oil and carotenes recoveries from palm oil mill effluent using response surface methodology

BACKGROUND: Palm oil mill effluent (POME) is a liquid waste that is highly polluting and has a significant impact on the environment if not dealt with properly. POME contains oil and carotenes that needs to be treated before discharge. In this work solvent extraction was used to recover oil‐containing carotenes from POME. Optimum conditions for the extraction of oil and carotenes from POME were determined using response surface methodology. RESULTS: A central composite design was used to investigate the effects of three independent factors, namely solvent:POME ratio, mixing rate (rpm) and mixing time (min) on the responses, extracted oil and carotenes recovery. The optimal conditions for extraction of oil and carotenes from POME were 8:10 solvent:POME ratio; 500 rpm mixing rate and 25 min mixing time. Under these conditions, the amount of oil extracted from POME was 7885 mg L^?1, and carotenes recovery was 87.1%. CONCLUSION: The experimental values agreed with those predicted, thus indicating the suitability of the model employed in optimizing the extraction parameters. A high yield of carotenes was obtained under the optimized conditions, with relatively low solvent levels. Copyright © 2009 Society of Chemical Industry     

响应面法优化酶催化酯交换反应研究

为了利用植物油生产可再生的绿色能源——生物柴油,文章利用Novo435固定化脂肪酶,在无有机溶剂存在下催化菜籽油与甲醇酯交换合成生物柴油。利用响应面实验设计和分析方法对菜籽油的酯交换反应条件进行优化,得到了最佳工艺条件:醇油摩尔比1.5∶1,反应温度52℃,搅拌转速200 r/min,脂肪酶与油脂的质量比为10%,反应时间10 h,在此工艺条件下油脂的酯交换率达到48%(理论为50%)。理论甲醇量分3批加入,反应36 h后菜籽油的总酯交换率达到95%(理论酯交换率为100%)。每批试验后利用有机溶剂对脂肪酶进行清洗,然后继续反应,连续使用10个批次,油脂的酯交换率基本未变。     

Lipase‐catalyzed production of medium‐chain triacylglycerols from palm kernel oil distillate: Optimization using response surface methodology

Optimization of lipase‐catalyzed esterification for the production of medium‐chain triacylglycerols (MCT) from palm kernel oil distillate and glycerol was carried out in order to determine the factors that have significant effects on the reaction system and MCT yield. Novozyme 435 from Candida antarctica lipase was found to have the highest activity at 52.87 ± 0.03 U/g. This lipase also produced the highest MCT yield, which is 56.67%. The effect of different variables on MCT synthesis was studied with a two‐level five‐factor fractional factorial design. The various variables include (1) reaction temperature, (2) enzyme load, (3) molecular sieves concentration, (4) reaction time and (5) molar substrate ratio. Reaction temperature, reaction time and molar substrate ratio strongly affect MCT synthesis (p <0.05). However, enzyme load and molecular sieve concentration did not have a significant (p >0.05) influence on MCT yield. Therefore, the significant variables such as reaction temperature, reaction time and molar substrate ratio were further optimized through central composite rotatable design (CCRD). Comparisons between predicted and experimental values from the CCRD optimization procedures revealed good correlation, implying that the quadric response model satisfactorily expressed the percentage yield of MCT in the lipase‐catalyzed esterification. The optimum MCT yield is 73.3% by using 2 wt‐% enzyme dosage, a molecular sieves concentration of 1 wt‐%, a reaction temperature of 90 °C, a reaction time of 10 h and a molar substrate ratio of 4 : 1 (medium‐chain fatty acid/glycerol). Experiments to confirm the predicted results using the optimal parameters were conducted and an MCT yield of 70.21 ± 0.18% (n = 3) was obtained.     

Optimization of biodiesel production from crude palm oil using ultrasonic irradiation assistance and response surface methodology

BACKGROUND: Production of biodiesel from crude palm oil (CPO) with 6 wt% of free fatty acid (FFA) using a low‐frequency ultrasonic irradiation (40 kHz) technique was investigated in the present work. The objective of this study was to determine the relationship between various important parameters of the alkaline catalyzed transesterification process to obtain a high conversion to biodiesel. Response surface methodology (RSM) was used to statistically analyze and optimize the operating parameters of the process. A central composite design (CCD) was adopted to study the effects of the methanol to oil molar ratio, the catalyst concentration, reaction temperature, and irradiation time on conversion to biodiesel. RESULTS: The result from the RSM analysis indicated that the methanol to oil molar ratio, catalyst concentration and irradiation time have the most significant effects on the conversion to biodiesel. Moreover, a coefficient of determination (R²) value of 0.93 shows the fitness of a second‐order model for the present study. Based on this second‐order model, the optimum conditions for alkaline catalyzed transesterification of CPO were found to be a methanol to oil molar ratio of 6.44:1, catalyst concentration 1.25 wt%, reaction temperature 38.44 °C and irradiation time 25.96 min. At the calculated optimum condition, the conversion to biodiesel reached 97.85%. Under these same conditions, the experimental value was 98.02 ± 0.6%. CONCLUSIONS: The mathematical model developed has been proven to adequately describe the range of the experimental parameters studied and provide a statistically accurate prediction of the optimum conversion to biodiesel. Copyright © 2011 Society of Chemical Industry     

介孔分子筛负载HPWA催化合成生物柴油

制备了介孔磷钨杂多酸催化剂HPWA/SBA-15,用XRD、FTIR和BET等方法进行表征,并用于催化大豆油酯交换反应制备生物柴油。结果表明,介孔磷钨杂多酸催化剂具有较好的催化性能,其催化性能与介孔杂多酸催化剂优良的扩散性能和均一的质子酸特性有关,在活性组分负载质量分数为35%、反应温度190℃、反应时间7 h、n(醇)∶n(油)为16∶1和催化剂用量为大豆油质量的5%条件下,生物柴油收率可达97%。     

Optimization of oil extraction from locust bean using response surface methodology

Optimization of oil extraction from locust beans (Parkia biglobosa) using central composite rotatable design of RSM was carried out. Independent variables were roasting temperature (90, 100, 110, 120, 130°C) and roasting duration (5, 10 15, 20, 25 min), while the responses were oil yield (OY), free fatty acid (FFA), color (CO), stability, anisidine value (AV), and specific gravity (SG). Data obtained from this study were analyzed using ANOVA and regression analysis. OY, FFA, CO, oil stability, AV, and SG of the oil ranged between (19.0–22.5%), (0.65–3.1%), (37.9–199.9 mg/L), (3.6–6.4%), (11.4–59.9 mg/L), (0.7–0.9), respectively. Roasting conditions significantly influenced all dependent variables at p<0.05. Coefficients of determination (R²) of the generated models ranged from 0.49 to 0.98. Optimum roasting condition was 108°C for 10 min. This gave 22.3% OY, 1.7% FFA, 54.9 mg/L CO, 4.1% stability, 16.5 mg/L AV, and 0.9 SG. Desirability of 0.8 was obtained for optimum conditions. Practical applications: Generally, African locust bean is fermented to give condiment. It has not been used for commercial oil production despite its richness in oil, but soybean with a similar oil content of about 18–20% has been used both for condiment and commercial oil production. Research into the potential of locust bean as a source of edible oil is desirable. Roasting is among pre‐treatment methods employed in vegetable oil industry. Information on degree of influence of these parameters on quantity and quality of oil recovered oil from African locust benefits both entrepreneur and researchers. Also, the developed mathematical expression for OY, FFA, CO, oil stability, AV, and SG, as influenced by roasting temperature and duration is an effective tool in predicting these parameters. The research output has both immediate and potential application.     

Optimization of ultrasonic-assisted heterogeneous biodiesel production from palm oil: A response surface methodology approach

The use of ultrasonic processor in the heterogeneous transesterification of palm oil for biodiesel production has been investigated. Response surface methodology was employed to statistically evaluate and optimize the biodiesel production process catalyzed by two alkaline earth metal oxide catalysts i.e. BaO and SrO. SEM, surface analysis, AAS analysis and the Hammett indicator methods were used for characterization of the catalysts. Four different variables including reaction time (10-60 min), alcohol to oil molar ratio (3:1-15:1), catalyst loading (0.5-3.0 wt.%) and ultrasonic amplitude (25-100%) were optimized. Mathematical models were developed and used to predict the behavior of the process. The models were able to accurately predict the biodiesel yield with less than 5% error for both catalysts. The basic strength of the catalysts was the main reason of their high activities. This study confirmed that the ultrasonic significantly improved the process by reducing the reaction time to less than 50 min and the catalyst loading to 2.8 wt.% to achieve biodiesel yields of above 95%. The optimum alcohol to oil ratio was found to be at 9:1 while the best amplitudes were ∼ 70 and ∼ 80% for the BaO and SrO catalysts, respectively.     

响应面法优化离子液体催化合成乳酸乙酯

以酸性咪唑离子液体为催化剂,乙酸乙酯为带水剂研究了乳酸乙酯的合成。应用响应面法预测醇酸摩尔比、离子液体（IL）酸摩尔比、全回流时间、带水剂用量、分水反应时间5个因素对产率的影响,并通过实验发现实际收率与预测值基本吻合。得到的最佳反应条件为：醇酸摩尔比4,IL酸摩尔比0.7,全回流1.2 h,加入带水剂用量为理论用量的74%,分水反应6.6 h,此时乳酸乙酯的收率可达80%。     

Catalytic activity of mesoporous V/SBA-15 in the transesterification and esterification of fatty acids

Mesoporous V/SBA-15 with different weight percentages (1, 2.5 and 5 wt%) of vanadia was prepared via the wet impregnation method. The mesoporous nature of the catalysts were investigated, using the X-ray diffraction analysis, N₂ adsorption–desorption isotherm and scanning electron microscope. All the catalysts showed the highly dispersed vanadia was confirmed by the result of the diffuse reflectance UV vis technique. From the NH₃-temperature programmed desorption, it is observed that, the acidity values of the prepared catalysts are in the range 72–102 µmol/g. 5 % V/SBA-15, possesses Bronsted and Lewis acid sites ensured by pyridine-adsorbed Fourier-transform infrared method. The acidity of the catalyst was experimented in the transesterification of sunflower oil. The reaction conditions were optimized with maximum conversion (100 %) of sunflower oil into biodiesel and the activity of the catalyst was found to be more in 5 wt% V/SBA-15 at 140 °C. Different fatty acids like butyric, valeric, caprylic and oleic acid were also studied under optimized conditions, and the isolated product was confirmed from the H¹ NMR spectroscopy.     

Optimization of process conditions using response surface methodology for the microwave-assisted transesterification of Jatropha oil with KOH impregnated CaO as catalyst

A transesterification reaction of Jatropha curcas oil with methanol in the presence of KOH impregnated CaO catalyst was performed in a simple continuous process. The process variables such as methanol/oil molar ratio (X₁), amount of catalyst (X₂) and total reaction time (X₃) were optimized through response surface methodology, using the Box–Behnken model. Within the range of the selected operating conditions, the optimal ratio of methanol to oil, amount of catalyst and total reaction time were found to be 8.42, 3.17% and 67.9 min, respectively. The results showed that the amount of catalyst and total reaction time have significant effects on the transesterification reaction. For the product to be accepted as a biodiesel fuel, its purity must be above 96.5% of alkyl esters. Based on the optimum condition, the predicted biodiesel conversion was 97.6% while the actual experimental value was 97.1%. The above mentioned results demonstrated that the response surface methodology (RSM) based on Box–Behnken model can well predict the optimum condition for the biodiesel production.     

Enzymatic incorporation of stearic acid into a blend of palm olein and palm kernel oil: Optimization by response surface methodology

Response surface methodology was used to model the incorporation of stearic acid into a blend of palm olein and palm kernel oil in hexane using the sn-1,3-regiospecific lipase Lipozyme RM IM. The factors investigated were incubation time, temperature, and substrate molar ratio. A second-order model with interaction was used to fit the experimental data. The coefficients of determination, R ² and Q ², were 0.96 and 0.90, respectively. The adjusted R ² was 0.95. The regression probability was less than 0.001, and the model showed no lack of fit. Also, a linear relationship was observed between the predicted and observed values. All parameters studied had positive effects on incorporation of stearic acid, with substrate molar ratio having the greatest effect. The interaction terms of substrate molar ratio with temperature and time also had positive effects on incorporation, whereas the effect of the squared term of substrate molar ratio was negative. The quadratic terms of temperature and time, as well as their interaction term, had no significant effect on incorporation at α_0.05. Model verification was done by performing a chi-square test, which showed that there was no significant difference between predicted values and a new set of observed responses.     

Heterogeneous catalysis of transesterification of soybean oil using KI/mesoporous silica

Heterogeneous catalysis of transesterification using KI/mesoporous silica catalyst was utilized to produce biodiesel from soybean oil and methanol. The effects of reaction temperature, percentage of KI loading, reaction time, and amount of catalyst on the conversion to methyl ester were studied. The results showed that increasing reaction temperature, KI loading and reaction time can enhance the conversion. The optimum condition was the reaction temperature at 70 °C, 15 wt.% of KI, a reaction time of 8 h., and a catalyst amount of 5.0% by weight of the oil which yielded 90.09% of the conversion. The fuel properties of biodiesel from the optimum condition were tested and found that only viscosity showed over standard. However, the high viscosity can be reduced by separation of non-reacting soybean oil.     

K_2O/SBA-15的制备及其催化性能研究

以介孔分子筛SBA-15为载体,负载KNO3后焙烧制得K2O/SBA-15固体碱催化剂,以合成丙烯酸正丁酯的酯交换反应为探针反应,在间歇式反应釜中对K2O/SBA-15催化剂进行催化活性评价。结果表明,当K2O负载量为2%,K2O/SBA-15催化剂对此酯交换反应的催化活性最高。     

Optimization of mesoporous alumina sol-gel synthesis by Taguchi and response surface methodology

Taguchi method (TM) and response surface methodology (RSM) have been employed to optimize three parameters, including the amounts of P123, the amounts of nitric acid and calcination temperature, in order to define an optimal setting for sol-gel synthesis of high surface area mesoporous alumina powder (MA). Herein, the comparison of the both statistical approaches has been examined and discussed considering the nitrogen adsorption as the response variable because this important character for mesoporous materials is exceedingly sensitive to the synthesis parameters. The BET surface area (S_BET) and pore volume of MA under Taguchi optimal condition were 323.5 m² g⁻¹ and 0.551 cm³ g⁻¹, respectively, by conducting confirmation test. Furthermore, the confirmation test showed high S_BET of MA (363.4 m² g⁻¹), which was in a good agreement with calculated S_BET result (431.25 m² g⁻¹) by a quadratic model under RSM optimal condition. Moreover, 3D response surface plots and 2D contour plots of desirability have been discussed to visualize the influence of input factors on response variable. It is also concluded that RSM shows more appropriate (12.33% higher S_BET than TM) and efficient optimal condition with determining a quadratic function as the relationship between S_BET and synthesis parameters.     

Analysis of parameters and interaction between parameters of the microwave-assisted continuous transesterification process of Jatropha oil using response surface methodology

A simple continuous process was designed for the transesterification of Jatropha curcas (J. curcas) oil to alkyl esters using microwave-assisted method. The product with purity above 96.5% of alkyl ester is called the biodiesel fuel. Using response surface methodology, a series of experiments with three reaction factors at three levels were carried out to investigate the transesterification reaction in a microwave and conversion of alkyl ester from J. curcas oil with NaOH as the catalyst. The results showed that the ratio of methanol to oil, amount of catalyst and flow rate have significant effects on the transesterification and conversion of alkyl ester. Based on the response surface methodology using the selected operating conditions, the optimal ratio of methanol to oil, amount of catalyst and flow rate of transesterification process were 10.74, 1.26 wt% and 1.62 mL/min, respectively. The largest predicted and experimental conversions of alkyl esters (biodiesel) under the optimal conditions are 99.63% and 99.36%, respectively. Our findings confirmed the successful development of a two-step process for the transesterification reaction of Jatropha oil by microwave-assisted heating, which is effective and time-saving for alkyl ester production.     

Characterization of mesoporous alumina prepared by surface alumination of SBA-15

Mesoporous aluminas of controlled pore sizes were synthesized by multiple grafting of Al isopropoxide in organic solvents on mesoporous silica SBA-15. These materials were characterized by N₂ physisorption, TEM, XRD, ²⁷Al NMR and their surface chemical properties were probed by DRIFT, cumene cracking and MoO₃ thermal spreading. The results show that the chemical nature of the Al-grafted materials varies continuously with the number of grafting from pure silica to pure alumina. Typically, after three graftings, this original method of synthesis allows one to prepare ordered mesoporous aluminas with specific surface areas above 300 m² g⁻¹ and a narrow pore size distribution centered on ca. 60 Å. In addition to the characterizations, different models were developed to understand the evolution of the specific surface area and to discard a possible pore blocking.     

SBA-15的改性及催化文冠果油制备生物柴油

以介孔分子筛SBA-15为载体,采用直接合成法和后合成法镀饰Al后再负载碱金属盐KNO₃,制得负载型固体碱催化剂KNO₃-AlSBA-15和KNO₃-Al-SBA-15。用XRD、BET、SEM以及CO₂-TPD对催化剂进行表征。结果表明：在SBA-15上镀饰Al可以保护分子筛的介孔结构;进一步负载KNO₃,能够增强催化剂的碱性。将其应用于催化文冠果油酯交换制备生物柴油,结果显示催化剂KNO₃-Al-SBA-15的催化活性最好,优于传统均相催化剂,所得生物柴油产率可达92%,重复使用多次仍具有较好的催化效果。     

Lipase catalyzed synthesis of oleyl oleate: Optimization by response surface methodology

Lipase catalyzed production of oleyl oleate, which is an analogue of jojoba oil, was carried out using oleic acid and oleyl alcohol in the solvent-free system. Novozym 435, immobilized Candida antarctica lipase, was used as a biocatalyst. Response surface methodology (RSM) based on five-level, four-variable central composite rotatable design was used to evaluate the effects of important parameters on the production of oleyl oleate. Acid/alcohol molar ratio (0.5-1.5), enzyme quantity (2-10% w/w of substrates), reaction temperature (40-60°C), and reaction time (30-90 min) were chosen as process variables for the optimization. Among these parameters, enzyme quantity and acid/alcohol molar ratio have significant effects compared with temperature and time on the production of oleyl oleate. Optimum conditions were found to be a acid/alcohol molar ratio of 1, enzyme quantity of 7% (w/w), reaction temperature of 51°C, and reaction time of 75 min. The coefficient of determination (R 2 ) for the model is 0.97. Probability value is 2.9 ‐ 10 m 9 (P-value<0.01). This P-value demonstrates a very high significance for the regression model. The maximum oleyl oleate concentration predicted by the equation (737 g/L) agrees well with the experimentalvalue (734 g/L) obtained from the experimental verification at the optimum values.