Current scenario and potential of biodiesel production from waste cooking oil in Pakistan: An overview

Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion.Although,several debatable issues including feedstock availability and price,fuel and food competition,changes in land use and greenhouse gas emission have been raised by using edible as well as inedible feedstocks for the production of biodiesel.However,non-crop feedstocks could be a promising alternative.In this article,waste cooking oils have been recommended as a suitable option for biodiesel production bearing in mind the current national situation.The important factors such as the quantity of waste cooking oil produced,crude oil and vegetable oil import expenses,high-speed diesel imports,waste management issues and environmental hazards are considered.Moreover,process simulation and operating cost evaluation of an acid catalyzed biodiesel production unit are also conducted.The simulation results show that the production cost of waste cooking oil-based biodiesel is about 0.66 USD·L-1.We believe that the present overview would open new pathways and ideas for the development of biofuels from waste to energy approach in Pakistan.

Biodiesel Production from Waste Cooking Oil Using Sulfuric Acid and Microwave Irradiation Processes

A comparative study of biodiesel production from waste cooking oil using sulfuric acid (Two-step) and microwave-assisted transesterification (One-step) was carried out. A two-step transesterification process was used to produce biodiesel (alkyl ester) from high free fatty acid (FFA) waste cooking oil. Microwave-assisted catalytic transesterification using BaO and KOH was evaluated for the efficacy of microwave irradiation in biodiesel production from waste cooking oil. On the basis of energy consumptions for waste cooking oil (WCO) transesterification by both conventional heating and microwave-heating methods evaluated in this study, it was estimated that the microwave-heating method consumes less than 10% of the energy to achieve the same yield as the conventional heating method for given experimental conditions. The thermal stability of waste cooking oil and biodiesel was assessed by thermogravimetric analysis (TGA). The analysis of different oil properties, fuel properties and process parametric evaluative studies of waste cooking oil are presented in detail. The fuel properties of biodiesel produced were compared with American Society for Testing and Materials (ASTM) standards for biodiesel and regular diesel.

Investigation of performance and emission characteristics of waste cooking oil as biodiesel in a diesel engine

Biodiesel is one of the most popular prospective alternative fuels and can be obtained from a variety of sources. Waste frying oil is one such source along with the various raw vegetable oils. However, some specific technical treatments are required to improve certain fuel properties such as viscosity and calorific value of the biodiesel being obtained from waste cooking oil methyl ester （WCOME）. Various treatments are applied depending on the source and therefore the composition of the cooking oil. This research investigated the performance of WCOME as an alternative biofuel in a four-stroke direct injection diesel engine. An 8-mode test was undertaken with diesel fuel and five WCOME blends. The best compromise blend in terms of performance and emissions was identified. Results showed that energy utilization factors of the blends were similar within the range of the operational parameters （speed, load and WCOME content）. Increasing biodiesel content produced slightly more smoke and NOx for a great majority of test points, while the CO and THC emissions were lower.

Diester Derivatives from Chemically Modified Waste Cooking Oil as Substitute for Petroleum Based Lubricating Oils

In order to provide a new way for waste cooking oil(WCO) resource utilization, several diester derivatives were obtained from WCO through a three-step chemical modifications, viz.: transesterification, epoxidation and oxirane ring opening with carboxylic acids. The effects of the chain length of side chain groups on the viscosity, acid value, low temperature fluidity, thermo-oxidative stability, tribological properties and surface tension of diester derivatives were investigated. The results showed that increasing the chain length of side chain groups had a positive influence on the viscosity, viscosity index, acid value, pour point, friction coefficient and wear scar diameter along with a negative influence on the oxidation onset temperature, volatile loss, insoluble deposit, maximum non-seizure load and surface tension. These diester derivatives exhibited improved physicochemical and tribological properties that make themselves promising environmentally friendly biolubricant basestocks.

Supercritical Synthesis of Ethyl Esters via Transesterification from Waste Cooking Oil Using a Co-Solvent

Biofuels became more promising alternative to the fossil fuels because of the depletion of fossil resources, renewability, environmental benefits, and energy security. Ethanolysis of waste cooking oil with hexane as co-solvent was carried out for the production of fatty acid ethyl ester (FAEE). This process reduced the severity of process parameters with high purity biodiesel yield. Process variables such as co-solvent ratio, ethanol to oil molar ratio, reaction temperature and reaction time were optimized. The maximum biodiesel yield of 88% was obtained at ethanol/oil molar ratio of 40:1, co-solvent (hexane) to oil ratio of 0.2% (v/v), reaction temperature of 300°C in 20 min of reaction time. Fatty acid ethyl ester (biodiesel) samples produced from this process were measured and evaluated using GC-MS analytical instrument. Thermo gravimetric analysis (TGA) was also performed to examine the thermal stability of waste cooking oil, ethyl esters and fuel blends. Fuel properties of ethyl esters were determined and compared with the ASTM standards for biodiesel, regular diesel and ethyl esters from different feedstock.

Biodiesel Production from Waste Cooking Oil by Enzymatic Catalysis Process

Biodiesel is an excellent option for reducing dependence on fossil fuels with environmental advantages by reducing hazardous emissions. The enzymatic transesterification has attracted the attention of researchers in the last decade and the advantages of enzymatic catalysis show that the production of biodiesel by this route has good potential, mainly because it is friendly environment. For biodiesel, production process by enzyme catalysis is chosen the response surface methodology. It is an experimental strategy to find the best operating conditions oftransesterification reaction to improve the biodiesel quality. The Process has three variables： temperature, molar ratio oil-alcohol and catalyst quantity. The process was monitored by GC-FID （gas chromatography with flame ionization detector）. The yield of the transesterification reaction by enzymatic catalysis decreases with increasing temperature, and may be due to inactivation of the enzyme by denaturation at temperatures above 50 ℃. The second-order design used was the ＂CDC （central design composition）＂ which produced a maximum yield of 95.5% in the transesterification reaction by enzymatic catalysis obtained at a temperature of 45 ℃, molar ratio methanol：oil of 8：1 and a catalyst loading of 8% wt.

Ultrasound-assisted Biodiesel Production from Waste Cooking Oil at Room Temperature

Waste cooking oil(WCO) is considered to be a promising alternative for vegetable oils that have been traditionally used for biodiesel production. In this study, WCO with a fairly high free fatty acid content was transesterified into biodiesel in a one-step procedureat room temperature(25℃) under ultrasound irradiation and in the presence of potassium hydroxide(KOH) as catalysts. Response surface methodology(RSM) was used to investigate the effects of the methanol/oil molar ratio, reaction time,and catalyst loading on the fatty acid methyl ester(FAME) yield and the biodiesel yield. The optimal reaction conditions for the production of WCO biodiesel were found to be a methanol/oil molar ratio of 8.6:1, a reaction time of 25 min, and a catalyst loading of 2.43 wt%. Under these optimal settings,the FAME and biodiesel yields were 96.4% and 92.7%, respectively. The properties of the resultant WCO biodiesel, including kinetic viscosity, acid number, water content, and flash point, were measured according to ASTM D6751 standards. The obtained results provide useful information for the large-scale production of WCO biodiesel.

Rheological properties and microscopic mechanism of waste cooking oil activated waste crumb rubber modified asphalt

In this paper,the surface activated crumb rubber with waste cooking oil(WCO)was studied to improve the performance of crumb rubber modified asphalt.The activated waste crumb rubber modified asphalt(OCRMA)with different amount of crumb rubber was prepared to study the microscopic appearance of OCRMA by scanning electron microscope and fluorescence microscope and analyze the surface performance.The rheological properties and microscopic mechanism of OCRMA were characterized by dynamic shear rheological test,multiple stress creep recovery(MSCR)test,BBR test and infrared spectroscopy.The results show that the dissolution degree of waste crumb rubber is improved after WCO activation,and the compatibility with asphalt components is enhanced,and the stable cross-linking structure is formed,which improves the asphalt performance.The several new absorption peaks,which were obvious,were all caused by the composition of WCO,that is,there was no significant chemical change during the interaction between the activated crumb rubber and base asphalt.Compared with the common waste crumb rubber modified asphalt(CRMA),activation with WCO can significantly reduce the viscosity of CRMA,decrease the difference of segregation softening point by 27%,and enhance the low temperature performance by 30%.The aging degree is greatly reduced,and the anti-aging performance of OCRMA is increased by about 20%with the same dosage.The high temperature performance,though higher than that of base asphalt,decreases to some extent.After comprehensive analysis,the optimal dosage of crumb rubber for OCRMA is 30%.

Utilization of Waste Cooking Oil as Diesel Fuel and Improvement in Combustion and Emission

Due to high price of Straight Vegetable Oil （SVO） for bio-diesel production, the use of Waste Cooking Oil （WCO） will be cost effective. Furthermore, utilization of WCO will refrain waterways pollution and endanger ecosystem. In Malaysia, more than 50-tone of WCO from various sources was produced every day. This study evaluates combustion performance and exhaust emission characteristics of several WCOs with different sources. Modification on fuel properties has been done to improve the combustion and exhaust emission of using WCO as diesel fuel. Regular diesel fuel also has been used for comparison in the test. A 0.6 liter, single-cylinder, air-cooled direct injection diesel engine was used to perform this experiment. Experiment was done at variable engine loads at constant speed.

Biodiesel Production from Waste Cooking Oil over Mesoporous SO42-/Zr-SBA-15

Biodiesel production from waste cooking oils over SO42-/Zr-SBA-15 catalyst was successfully carried out and investigated. SO42-/Zr-SBA-15 catalyst was prepared by one-step process using anhydrous zirconium nitrate as zirconium resource, and endowed with the strong Lewis acid sites formed by supporting the zirconium species onto the SBA-15 surface. The asprepared SOt2-/Zr-SBA-15 showed excellent triglyceride conversion efficiency of 92.3% and fatty acid methyl esters （FAME） yield of 91.7% for the transesterification of waste cooking oil with methanol under the optimized reaction conditions： the methanol/oil molar ratio of 30, the reaction temperature of 160 ℃, the reaction time of 12 h and 10wt% of catalyst. It was noticed that the as-prepared SOa2-/Zr-SBA-15 materials with the higher area surface of mesoporous framework and the surface acidity displayed excellent stability and reusability, maintaining high FAME yield of （74±1）% after seven runs of reaction.

Esterification of Free Fatty Acids in Waste Cooking Oil by Heterogeneous Catalysts

Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%.

Engine performance and combustion characteristics of a direct injection compression ignition engine fueled waste cooking oil synthetic diesel

Biodiesels produced from various feedstocks have been considered as alternative fuels used in internal combustion engines without major modifications.This research focuses on producing biodiesel from waste cooking oil(WCOSD)by the catalytic cracking method using MgO as the catalyst and comparing the engine operating characteristics of the test engine when using WCOSD and traditional diesel(CD)as test fuels.As a result,the brake power of the test engine fueled WCOSD,and traditional diesel is similar.However,the engine fuel consumption in the case of using WCOSD is slight increases in some operating conditions.Also,the nitrogen oxides emissions of the test engine fueled WCOSD are higher than those of CD at all tested conditions.The trend is opposite for hydrocarbon emission as the HC emission of the engine fueled by WCOSD reduces 26.3%on average.The smoke emission of the test engine in case of using WCOSD is lower 17%on average than that of CD.However,the carbon monoxide emissions are lower at the low and medium loads and higher at the full loads.These results show that the new biodiesel has the same characteristics as those of commercial biodiesel and can be used as fuel for diesel engines.

The Kinetics of the Esterification of Free Fatty Acids in Waste Cook- ing Oil Using Fe2（SO4）3/C Catalyst

The esterification of free fatty acids(FFA) in waste cooking oil with methanol in the presence of Fe2(SO4)3/C(ferric sulfate/active carbon) catalyst was studied.The effects of different temperature,methanol/FFA mole ratio and amount of catalyst on the conversion of FFA were investigated.The results demonstrated that under optimal esterification conditions the final acid value of the resultant system can be reduced to ～1(mg KOH)·g-1,which met fully the requirements in post-treatment for efficient separation of glycerin and biodiesel.The kinetics of the esterification were also investigated under different temperatures.The results indicated that the rate-control step could be attributed to the surface reaction and the esterification processes can be well-depicted by the as-calculated kinetic formula in the range of the experimental conditions.

Diffusion and Regeneration Mechanism of Waste Composite Oils Rejuvenator in Aged Asphalt

The physical performance of recycled asphalt was used as the main evaluation index to study the optimal range of a self-made rejuvenator.Through the penetration,viscosity and gel permeation chromatography(GPC)tests,the diffusion degree of the rejuvenator under different temperatures and time process was analyzed,and the diffusion efficiency of the rejuvenator was evaluated from the macro and micro perspective.The regeneration mechanism of the rejuvenator in the aged asphalt was also analyzed using the Fourier transform infrared spectroscopy(FTIR),scanning electron microscope(SEM)and chemical composition tests.The research results showed that the optimum rejuvenator content was about 3%.Higher temperature and longer time were beneficial to improving the permeability and diffusion of the rejuvenator.During the aging process,the light components were reduced,and more macromolecular asphaltenes were generated as well as a large number of carbonyl and sulfoxide.After diffusion and regeneration,the light components in the asphalt were supplemented,the wrinkles and gullies of the aged asphalt were almost improved to the surface state of the matrix asphalt.

Demonstrative Study of Vehicles Using Waste Vegetable Oil as Fuel

SVO （straight vegetable oil） method means the direct use of vegetable oil as car fuel through installation of a heater unit in the car to decrease vegetable oil viscosity. In this study, the authors carried out performance tests on the direct use of waste cooking oil using a car with a heater unit, Moreover, the authors carried out long run driving on road tests in five years using a public car of Minami-Aizu Town in Fukushima Prefecture and analyzed the case of troubles and clarified the availability and problems of SVO vehicles. As a result, the car with a heater unit shows similar performance in both cases using vegetable oil or diesel fuel as fuel. The tested SVO vehicle of Minami-Aizu Town could be driven 38,127 km mainly by waste vegetable oil with a total driving distance of 52,293 km in long run driving tests in five years, and decreased about 3,813.5 liters of light oil which corresponds to 9.99 t of CO2.

Biodiesel production from waste cooking oil using calcium oxide derived from scallop shell waste

Biodiesel is one of the alternative forms of diesel fuel and can be obtained using the transesterification process of waste cooking oil with a catalyst to accelerate the reaction.The heterogeneous catalyst from waste scallop shells is used due to its potential for being reused in the subsequent transesterification reactions.Heterogeneous catalysts can also be recycled,contributing to their environmentally friendly nature.This study aims to identify the performance of recycling a calcium oxide(CaO)catalyst from scallop shell waste on synthesis biodiesel.The method used is the transesterification method with the basic ingredients of waste cooking oil using a CaO catalyst.Then,after the transesterification process is complete,the catalyst is separated from the biodiesel and recycled to be reused in the transesterification process up to five times.The biodiesel samples obtained are identified for yield value,physico-chemical properties,thermal properties and performance.X-ray diffraction characterization results for the CaO catalyst show that it has a crystal size of 67.83 nm.Scanning electron microscope characterization shows that it has spherical particle shapes.Fourier transform infrared characterization shows the presence of Ca-O bonds.The highest biodiesel yield value of 74.23%is obtained in biodiesel Cycle 1.The flash point value of biodiesel samples ranges from 141.2℃ to 149℃.Further,all of the biodiesel samples exhibit a cetane number of 75.The highest lower heating value of 38.22 MJ/kg is obtained in biodiesel Cycle 1 and the viscosity of the biodiesel samples ranges from 5.65 to 5.88 cSt.The density of the biodiesel samples ranges from 881.23 to 882.92 kg/m3.Besides,ester functional groups(C=O)and methyl functional groups have been successfully formed in all samples,with the methyl oleate compound observed as dominating the biodiesel samples.The cloud point value of the biodiesel samples ranges from 12℃ to 13℃,and their pour point value ranges from 10℃ to 12℃.The lead content in biodiesel is 0.8826 mg/kg.The lowest sulphur content is obtained from biodiesel Cycles 1 and 2 at 0.005%.Performance tests show that biodiesel has lower torque and brake power values than commercial diesel fuel and higher specific fuel consumption values than commercial diesel fuel.

Efficient catalytic conversion of jatropha oil to high grade biofuel on Ni-Mo_(2)C/MCM-41 catalysts with tuned surface properties

The activity of Mo_(2) C-based catalyst on vegetable oil conversion into biofuel could be greatedly promoted by tuning the carbon content,while its modification mechanism on the surface properties remained elusive.Herein,the exposed active sites,the particle size and Lewis acid amount of Ni-Mo_(2) C/MCM-41 catalysts were regulated by varying CH_(4) content in carbonization gas.The activity of Ni-Mo_(2) C/MCM-41 catalysts in jatropha oil(JO)conversion showed a volcano-like trend over the catalysts with increasing CH_(4) content from 15%to 50%in the preparation process.The one prepared by 25%CH_(4) content(NiMo_(2) C(25)/MCM-41)exhibited the outstanding catalytic performance with 83.9 wt%biofuel yield and95.2%C_(15)-C_(18) selectivity.Such a variation of activity was ascribed to the most exposed active sites,the smallest particle size,and the lowest Lewis acid amount from Ni^(0) on the Ni-Mo_(2) C(25)/MCM-41 catalyst surface.Moreover,the Ni-Mo_(2) C(25)/MCM-41 catalyst could also effectively catalyze the conversion of crude waste cooking oil(WCO)into green diesel.This study offers an effective strategy to improve catalytic performance of molybdenum carbide catalyst on vegetable oil conversion.

Research progress of vegetable oil and derivative in microbial fermentation for high-value-added metabolite production

Vegetable oil and derivative,as well as waste cooking oil,are important resources for microbial fermentation to produce high-value-added metabolites.Diversity of their compositions not only provides more choices for the fermentation by different microorganisms,but also is a challenge for their systematic utilization.According to the previous literature,4 main functions of vegetable oil and derivative can be summarized,such as carbon source,precursor,inducer and cell protectant during fermentation process.Currently,there is still insufficient knowledge about application of vegetable oil and derivative for high-value-added metabolite production.Therefore,this article firstly presented a comprehensive summary of compositions of vegetable oils and their derivatives,variety of corresponding microbial metabolites,limiting factors and optimization of fermentation process.

不同生物油再生沥青性能比选

为确定生物油对老化沥青性能的恢复能力,比选出再生能力较强的一种生物油并确定其最佳掺量,采用植物沥青、餐厨废弃油脂和工业用动物油3种生物油作为再生剂,分别对老化SBS改性沥青进行再生,通过测定生物油再生沥青的针入度、延度、软化点和布氏黏度并进行薄膜加热试验,研究生物油种类和掺量对老化沥青各项性能的影响规律。结果表明,3种生物油对老化SBS改性沥青的基础性能和耐老化性均有一定的恢复能力,其中餐厨废弃油脂对老化沥青再生能力较强,并且社会和经济效益较高,植物沥青和工业用动物油次之;餐厨废弃油脂被选为最佳再生生物油,掺量为4%时能够使老化SBS改性沥青的黏滞性和高温性能得到完全恢复,因此被确定为最佳掺量。

生物柴油原料中不皂化物和脂肪酸分析

旨在确定生物柴油原料的可利用性,以可作为生物柴油原料的木本植物油脂、餐饮废油和酸化油为研究对象,分析其不皂化物和脂肪酸组成及含量。结果表明:棕榈油等7种木本植物油脂不皂化物含量低于1.10%,脂肪酸含量均高于91.50%,脂肪酸组成以油酸、亚油酸和亚麻酸为主(除棕榈油外);餐饮废油的不皂化物含量变化较大,脂肪酸含量在83.99%~94.87%之间,大部分餐饮废油脂肪酸组成以亚油酸和亚麻酸为主;5种酸化油的脂肪酸含量在71.35%~92.05%之间,椰子酸化油饱和脂肪酸占比为80.06%,其他4种酸化油的脂肪酸组成以不饱和脂肪酸为主。综上,7种木本植物油脂是优良的生物柴油原料,餐饮废油和酸化油作为原料制备生物柴油时要严格控制其质量指标。