Conversion Of Waste Cooking Oil Research Articles

Efficient emulsifying properties of monoglycerides synthesized via simple and green route

Waste cooking oil is produced in enormous quantities every year, and may have negative effect on people’s health and environment in case of improper treatment. However, it is also a potential feedstock for production of bio-based materials. In this work, a low-temperature glycerolysis process had been established to convert waste cooking oil to monoglycerides which was found to be of excellent surface activity with surface tension of 29 mN/m at cmc of 3.5 10−4 mol/L. Meanwhile, monoglycerides could form stable O/W emulsion even under saturated brine conditions, implying its great potential in high salinity environment. Compared to the traditional method for monoglyceride production under high temperature and atmosphere of nitrogen, our method is easy-handling and low energy-consuming.

Directed evolution of a genetically encoded immobilized lipase for the efficient production of biodiesel from waste cooking oil

BackgroundWe have recently developed a one-step, genetically encoded immobilization approach based on fusion of a target enzyme to the self-crystallizing protein Cry3Aa, followed by direct production and isolation of the fusion crystals from Bacillus thuringiensis. Using this approach, Bacillus subtilis lipase A was genetically fused to Cry3Aa to produce a Cry3Aa–lipA catalyst capable of the facile conversion of coconut oil into biodiesel over 10 reaction cycles. Here, we investigate the fusion of another lipase to Cry3Aa with the goal of producing a catalyst suitable for the conversion of waste cooking oil into biodiesel.ResultsGenetic fusion of the Proteus mirabilis lipase (PML) to Cry3Aa allowed for the production of immobilized lipase crystals (Cry3Aa–PML) directly in bacterial cells. The fusion resulted in the loss of PML activity, however, and so taking advantage of its genetically encoded immobilization, directed evolution was performed on Cry3Aa–PML directly in its immobilized state in vivo. This novel strategy allowed for the selection of an immobilized PML mutant with 4.3-fold higher catalytic efficiency and improved stability. The resulting improved Cry3Aa–PML catalyst could be used to catalyze the conversion of waste cooking oil into biodiesel for at least 15 cycles with minimal loss in conversion efficiency.ConclusionsThe genetically encoded nature of our Cry3Aa-fusion immobilization platform makes it possible to perform both directed evolution and screening of immobilized enzymes directly in vivo. This work is the first example of the use of directed evolution to optimize an enzyme in its immobilized state allowing for identification of a mutant that would unlikely have been identified from screening of its soluble form. We demonstrate that the resulting Cry3Aa–PML catalyst is suitable for the recyclable conversion of waste cooking oil into biodiesel.

The Effect of H-USY Catalyst in Catalytic Cracking of Waste Cooking Oil to Produce Biofuel

The crisis in petroleum is caused by the diminishing supply of petroleum resources from nature. This phenomenon encourages researchers to continue to look for processes and methods to produce energy from other resources. One of these ways is to produce energy that can be utilized from waste, including converting waste cooking oil into biofuel. This method not only could provide a source of renewable energy, but also help resolve the issue of household waste. The process used to produce biofuel from waste cooking oil is by catalytic cracking, where waste cooking oil after pretreatment is converted into biofuel in the flow reactor with H-USY catalyst. In this research, the reaction temperatures used are 400 °C, 450 °C, 500 °C and 550 °C and reaction times are 30, 45 and 60 minutes with the mass ratio of the amount of waste cooking oil to the amount of catalyst used is 40:1 (w/w). The highest yield of liquid biofuel product was obtained at 60.98%. The use of H-USY catalyst shows that the distribution of components contained in biofuel are 28.02% of diesel products (C 17 -C 20 ), 23.96% of gasoline (C 6 –C 12 ) and 7.78% of Heavy oil (C 20 >) in catalytic cracking of waste cooking oil with a reaction time of 45 minutes at a temperature of 450 °C.

Optimization of process variables on two-step microwave-assisted transesterification of waste cooking oil

Scale-up and commercialization of biodiesel is often delimited by costly feedstock that adds up to the process costs. These underlying issues demand the exploration of unconventional cheap feed to improve the process economics. Conversion of waste cooking oil (WCO) into biodiesel could reduce the process costs by 60-70%. However, the continuous exposure to heat during frying leads to oxidation as well increase in the free fatty acid (FFA) content which intensifies the time and energy required for transesterification. The present study analyzes the effect of parameters over the conversion of WCO (with 8.17% FFA) into biodiesel via two-step acid-alkali-based microwave-assisted transesterification. Response surface methodology (RSM) was used to optimize the oil:methanol volume ratio, microwave power, and reaction time during the acid-catalyzed esterification to bring down the FFA below 1%. Microwave irradiation of 250W, with methanol:oil molar ratio of 19.57:1 [oil:methanol volume ratio of 1.31 (expressed as decimal)] and reaction time of 35s, resulted in 0.082% of FFA. Alkali-catalyzed transesterification with methanol:oil molar ratio of 5:1 with 2% sodium hydroxide at 65°C thereby produced fatty acid methyl esters (FAMEs) with the volumetric biodiesel yield of 94.6% in 30min. Physiochemical properties of the transesterified WCO were well comparable with the biodiesel standards. The study highlights the essentiality of multivariate optimization for the esterification process that could aid in understanding the interactive effects of variables over FFA content. Such studies would benefit in scaling up of the transesterification process at industrial level by improving the economics of the overall bioprocess.

Effect of Water Content in Waste Cooking Oil on Biodiesel Production via Ester-transesterification in a Single Reactive Distillation

A single-column reactive distillation is employed to convert waste cooking oil to biodiesel via simultaneous esterification and transesterification reactions. The waste cooking oil contained 10 wt% of free fatty acid (FFA) and the contaminated water (2-8 wt%) was used as feedstocks for biodiesel production. Esterification was occurred in the upper of column to reduce FFA content to less than 1 wt% and to prevent the simultaneous saponification by base catalyst. Moreover, the contaminated water and by-product water (from esterification) together was removed in-situ as the distillate product. The reactive distillation has been optimally designed to have 16 stages consisting of 5 esterification, 9 transesterification stages and each stage for reboiler and condenser. The feed locations of oil and methanol were at the top of the column and at stage 6, respectively. The optimum methanol to oil ratio was 6:1 with reflux ratio 0.1 while the reboiler duty was in the range of 100-150 kW depended on the water content. This condition successfully converts 97 wt% of waste cooking oil to biodiesel with 96.5% purity.

Metal hydrated-salts as efficient and reusable catalysts for pre-treating waste cooking oils and animal fats for an effective production of biodiesel

A very efficient chemical pre-treatment method that uses cheap and safe hydrated-salts as catalysts for the conversion of waste cooking oils and animal fats having a high Free Fatty Acids (FFAs) content into an oily feedstock convertible into biodiesel through a conventional route (basic catalysis) was investigated. These hydrated-salts allow FFAs to be efficiently (>99%) esterified with alcohols under very mild conditions (343 K, 2 h). At the end of this treatment, a very convenient separation of products was verified. Two different phases were eventually obtained: an upper alcoholic phase, which contains most of the unreacted alcohol, water obtained by direct-esterification (>95%), and the salt that was used as catalyst (recovery >99%); and a lower oily-phase mainly composed of glycerides, methyl-esters derived from direct-esterification of FFAs (residual acidity of about 0.8 mg KOH/g), and part of unreacted alcohol (7–10%wt). Such a separation was convenient because the oily-phase could be directly trans-esterified through conventional base-catalysis, without any further pre-treatments, thus avoiding production of salty-waste. Also, the alcoholic phase could be recovered and directly re-used for new pre-treatments cycles of fresh waste-oils. A final scheme of the proposed process was discussed and the relevant advantages with respect to conventional routes were highlighted.

High Cell Density Conversion of Hydrolysed Waste Cooking Oil Fatty Acids Into Medium Chain Length Polyhydroxyalkanoate Using Pseudomonas putida KT2440

Waste cooking oil (WCO) is a major pollutant, primarily managed through incineration. The high cell density bioprocess developed here allows for better use of this valuable resource since it allows the conversion of WCO into biodegradable polymer polyhydroxyalkanoate (PHA). WCO was chemically hydrolysed to give rise to a mixture of fatty acids identical to the fatty acid composition of waste cooking oil. A feed strategy was developed to delay the stationary phase, and therefore achieve higher final biomass and biopolymer (PHA) productivity. In fed batch (pulse feeding) experiments Pseudomonas putida KT2440 achieved a PHA titre of 58 g/l (36.4% of CDW as PHA), a PHA volumetric productivity of 1.93 g/l/h, a cell density of 159.4 g/l, and a biomass yield of 0.76 g/g with hydrolysed waste cooking oil fatty acids (HWCOFA) as the sole substrate. This is up to 33-fold higher PHA productivity compared to previous reports using saponified palm oil. The polymer (PHA) was sticky and amorphous, most likely due to the long chain monomers acting as internal plasticisers. High cell density cultivation is essential for the majority of industrial processes, and this bioprocess represents an excellent basis for the industrial conversion of WCO into PHA.

Pilot-scale production of biodiesel from waste cooking oil using kettle limescale as a heterogeneous catalyst

This study aimed to evaluate and optimize a pilot-scale microreactor to convert waste cooking oil (WCO) into biodiesel using kettle limescale. Box-Behnken design was used to determine the optimum conditions for producing biodiesel. Effects of main variables including reaction temperature, catalyst concentration, and alcohol/oil volume ratio were evaluated at a constant residence time of 10 min. Based on the results of analysis of variance, the quadratic regression model had the best coefficient of determination (R2=0.9930) and adjusted coefficient of determination (RAdj.2= 0.9804). After the optimization of temperature, catalyst concentration, and methanol/oil volume ratio, the residence time was optimized to achieve the maximum purity of the produced biodiesel. At a reaction temperature of 61.7 °C, catalysts concentration (oil based) of 8.87 wt %, methanol to oil volume ratio of 1.7:3, and a residence time of 15 min, we observed the optimal conditions for obtaining a maximum biodiesel purity of 93.41%.

Kinetics and Optimization of Catalytic Transfer Hydrogenation of WCO Using 2-Propanol as a Hydrogen Donor over NiOx–MoOx–CoOx/Zeolite

Process optimization and reaction kinetics of catalytic transfer hydrogenation (CTH) of waste cooking oil (WCO) into jet fuels using zeolite-supported Ni–Co–Mo oxides catalyst in a packed-bed reactor were studied. Experiments were conducted at three different temperatures (360, 390, and 420 °C) to determine the rate constants, the order of reaction, and the activation energy. The kinetics study showed a first-order reaction with the activation energy estimated to be 84 ± 18.7 kJ/mol WCO with 95% confidence. Design of experiment (DOE) was employed to estimate the optimum reaction parameters using the polynomial model (383.7 °C; 14.8 bar; WCO-to-2-propanol ratio = 1.57 mL/mL; weight hourly space velocity (WHSV) = 6.7 h–1). Validation of the model at the optimum operating conditions generated 80% yield of liquid products with 77% alkanes, 3.8% alkenes, and 12.3% aromatics composition, and 6.7% gases, and 100% conversion of WCO. The catalyst was prepared via the wet impregnation method and characterized by X-...

Synthesis and catalytic evaluation of hematite (α-Fe2O3) magnetic nanoparticles from iron sand for waste cooking oil conversion to produce biodiesel through esterification-transesterification method

Indonesia’s catalyst needs to reach 2000 tons/year with active period of 1 up to 2 years. The catalyst requirement is largely filled with import catalysts. Iron sand has a potential to be used as a catalyst mainly because of the hematite magnetic mineral content (α-Fe2O3). α-Fe2O3 can be synthesized from iron sand using coprecipitation and calcination method. Performance of these synthesized catalyst evaluated through the production of biodiesel from waste cooking oil by esterification-transesterification method. The catalyst preparation by chemical coprecipitation method followed with calcination. Catalyst was characterized by using XRD, SEM-EDX, BET, and PSA and tested for biodiesel production. α-Fe2O3 phase was obtained at calcination temperature 650°C, 700°C, 750°C and 800°C. The best character is given at temperature 700°C. Biodiesel obtained meets SNI (Standar Nasional Indonesia) based on density, viscosity, and acid number. Yield of biodiesel obtained by using α-Fe2O3 calcined at 700°C reaches 86.781% while Fatty Acid Methyl Ester (FAME) content obtained reaches 87.880%.

Study on effectiveness of activated calcium oxide in pilot plant biodiesel production

One of the main problems in large-scale biodiesel production is selection of suitable and economically viable heterogenous catalyst. This research work focuses on preparation of calcium oxide (CaO) as a catalyst for the effective conversion of waste cooking oil (WCO) to biodiesel in pilot plant. When the calcinated CaO was treated with methanol, the modified catalyst exhibits increased surface area, increased specific basicity and decreased crystalline size compared to unmodified catalyst, it was confirmed by Fourier Transform Inferred Spectrometry (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. High biodiesel yield of 92% with Calcinated CaO (C-CaO) and 96% with Activated CaO (A-CaO) was achieved under 80 °C with 3% catalyst (wt) and oil to methanol molar ratio of 1:06 at 400 rpm in 120 min. These optimized conditions were employed in 15 L pilot plant for biodiesel production. FTIR, Proton nuclear magnetic resonance (1H-NMR) and Thermogravimetry (TGA) studies were used to confirm the formation of Fatty Acid Methyl Esters (FAME) from WCO. Further, the physiochemical properties of produced biodiesel were analyzed and compared with (American Society for Testing and Materials) ASTM standards. Blending of biodiesel produced from waste material with petro-diesel considerably reduce the fuel cost, emissions also provide sustainable solution for management of fat-oil rich waste material.

Effect of transesterification on the result of waste cooking oil conversion to biodiesel

Biodiesel is one of the greenest alternative fuels and can be produced from vegetable, waste cooking, and animal oils. Waste cooking oil is one of the raw materials that have a high chance of making biodiesel because it contains a very abundant tryglicerides. It is reacted with alcohol and NaOH catalyst through a transesterification reaction. Transesterification takes place inside a three-neck flask that has been equipped with condenser reflux, magnetic stirrer, and a thermometer. To know the effect by using variations of 60 minutes, 90 minutes, 120 minutes, and 150 minutes In this study, the optimum biodiesel conversion of WCO catfish seller was 85.2% preselected at a 1: 6 molar ratio, with 1% NaOH catalyst in 60 minutes. Meanwhile, conversion biodiesel from WCO of household used and WCO of fried sellers were respectively 82.34% and 82.20%. Based on the test of biodiesel properties resulting from the density, viscosity, acid number, water content, flash point and PH that biodiesel have been compliant with SNI. Biodiesel density of 880 kg/m3, acid number 0.27 mg-KOH/g, and has a maximum water content of 0.05. This biodiesel has the main compound the name is palmitic acid which 45.73%.

Cost analysis of oil cake-to-biodiesel production in packed-bed micro-flow reactors with immobilized lipases

Biodiesel production depends to a great extent on the use of cheap raw materials, since biodiesel itself is a mass product, not a high-value product. New processing methods, such as micro-flow continuous processing combined with enzymatic catalysis, open doors to the latter. As reported here, the window of opportunity in enzyme-catalyzed biodiesel production is the conversion of waste cooking oil. The main technological challenge for this is to obtain efficient immobilization of the lipase catalyst on beads. The beads can be filled into tubular reactors where designed packed-bed provide porous channels, forming micro-flow. It turns out, that in this way, the immobilization costs become the decisive economic factor. This paper reports a solution to that issue. The use of oil cake enables economic viability, which is not given by any of the commercial polymeric substrates used so far for enzyme immobilization. The costs of immobilization are mirrored in the earnings and cash flow of the new biotechnological process.

Converting Waste Cooking Oil into Biodiesel using Microwaves and High Voltage Technology

Increasing fuel demand has an impact on decreasing fossil energy reserves. One of the solution to solve this problem is by increasing the production of biomass fuels, for example, biodiesel. Biodiesel can be produced from waste cooking oil through transesterification stage that reacts oil molecules with alcohol and catalyst to produce methyl esters. Heating method that can be used is combined of microwaves and high voltage technology. Microwaves technology utilizes wave emission which is absorbed and reflected by the sample to make sample’s temperature being higher than surface’s temperature of reactor’s wall. In the process of producing biodiesel, reaction temperature is one of the several factors that is affected for heating process. From this research, we had optimum reaction temperature to get good quality product is at 60°C with 88.88% yield, 0.88 gr/ml for density, 2.52 cSt for viscosity, 102.5°C for flash point, 0.27% for water content, and 0.33 mg-KOH/gr-sample.

Transesterification of waste cooking oil: Quality assessment via thermogravimetric analysis

Biodiesel is a good substitute for petrol-diesel at lower greenhouse emissions footprint. Biodiesel is commonly generated through transesterification of lipid, animal fat and waste cooking oil (WCO) with alcohol in the presence of catalyst. Assessment of the product quality of biodiesel and the byproduct for further utilization can be done using Thermogravimetric analysis (TGA) instead of more involved and specialized technique such as GC/MS and HLPC. TGA of biodiesel and the crude byproduct glycerol were investigated in this work following transesterification essay under different reactants ratio and catalysis concentrations. Biodiesel TA thermographs was characterized by four events and with two distinct peaks shown in the derivative of TGA curve. The crude glycerol showed three pronounced peaks. The best conversion of WCO to biodiesel was determined based on the fraction of biodiesel or the 2nd TGA event. Highest conversion was obtained at 12:1 Methanol:WCO molar ratio 93% compared to 65%, 77% and 89% at 3:1, 6:1, 9:1 ratio, respectively. The influence of the catalyst is observed at lower molar ratio by advancing the conversion from 65% to 77% and 79% to 93% at 3:1 and 6:1 Methanol:WCO ratio, respectively. Higher glycerol quality was obtained at lower catalyst concentration.

Synthesis of Pure and High Surface Area Sodalite Catalyst from Waste Industrial Brine and Coal Fly Ash for Conversion of Waste Cooking Oil (WCO) to Biodiesel

The ravaging environmental menace of coal utilization in power generation and high cost of biodiesel production had recently resulted to global energy discourse. Non-waste-derived heterogeneous catalysts prepared from waste materials could reduce production cost of biodiesel and thus make it economical and environmentally sustainable. In this preliminary study, coal fly ash and industrial waste brine of South African origin were beneficiated for synthesis of waste-derived solid Hydroxy Sodalite (HSOD) catalyst. Non-waste-derived catalysts are not economical and environmentally sustainable. However, hydrothermal synthesis technique was employed to synthesize the catalysts used to produce biodiesel in a batch reactor. The physicochemical properties of the catalysts were studied using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), Scanning electron microscopy equipped with Energy-dispersive X-ray spectroscopy (SEM-EDS). Textural property of the catalyst was obtained via nitrogen physisorption at 77 K. The catalyst was tested for producing biodiesel from waste cooking oil using these conditions: methanol-to-waste cooking oil ratio of 15:1, 3 wt % of catalysts, and agitation speed of 300-500 rpm, 8 h reaction time and temperature of 60 o C. The biodiesel yield for waste-derived catalyst and non-waste-derived catalyst were 89.4 and 85.0 % respectively, at a maximum waste cooking oil conversion of 97.0 %. Results of the BET analysis reveal that the surface areas of waste-derived and non-waste derived catalysts were 33.05 m 2 g -1 and 0.1645 m 2 g -1 , respectively.

Catalytic conversion of waste cooking oils for the production of liquid hydrocarbon biofuels using in-situ coating metal oxide on SBA-15 as heterogeneous catalyst

Liquid hydrocarbon biofuels obtained from the catalytic cracking of animal fats and plant oils have become attractive because of their possible environmental benefits, and the current concerns over the depletion of fossil-fuel sources. In this work, five different metal-oxide (ZnO, La2O3, CeO2, NiO and MgO) modified SBA-15 (MeO-SBA-15) samples were prepared by a simple one-pot synthesis method and were used in the catalytic cracking of waste cooking oils. The synthesized catalysts were characterized using X-ray diffraction, N2 physisorption, transmission electron microscopy and Fourier-transform infrared techniques, and their catalytic performances were investigated in detail in the cracking of waste cooking oils. To obtain high-quality biofuel, all the pyrolysis products were separated into two compounds by distillation: (a) liquid hydrocarbon biofuels including gasoline and diesel fractions (distillation temperature ≤ 350 °C); (b) heavy oils (distillation temperature >350 °C). The results indicated that the mesostructure of the SBA-15 was well preserved after metal oxide modification, and the MeO-SBA-15 catalysts improved the hydrocarbon biofuels yield and decreased the heavy oil yield. Among the catalysts, the ZnO-SBA-15 showed an excellent catalytic performance and produced the highest biofuel yield (37.3%) and the lowest yield of heavy oils (39.9%). The liquid hydrocarbon biofuels obtained using the ZnO-SBA-15 catalyst had a similar chemical composition to the diesel-based fuels and showed a lower density, lower viscosity and higher heating values than raw waste cooking oils. These results indicated that ZnO-SBA-15 can promote the chemical reactions, such as deoxygenation and decarbonylation.

Investigating the effect of n-hexane as solvent on waste cooking oil conversion to biodiesel using CaO on a new support as catalyst

In this study, CaO/scoria (a kind of ignition rock) was used as catalyst of transesterification reaction. We have tried to reduce production costs of biodiesel in different ways. n-hexane as solvent was used to enhance the solubility of methanol in oil. It improved mass transfer in catalysts surface and reduced reaction time. A Box-Behnken design was used to optimize four variables: Temperature, time, methanol to oil molar ratio and n-hexane to oil volume ratio. Response surface methodology was used to find the effect of n-hexane and find the optimum condition. The analysis of variance (ANOVA) indicated that n-hexane has a positive effect on conversion. The optimum reaction conditions were found to be temperature = 59.7 °C, time = 4 h and 22 min, methanol to oil molar ratio = 14.76:1 and n-hexane to oil volume ratio = 0.905:1, which in these conditions the predicted conversion was 99.6% and observed conversion was 97.7%.

Green Biofuel Production via Catalytic Pyrolysis of Waste Cooking Oil using Malaysian Dolomite Catalyst

Malaysian Dolomite has shown potential deoxygenation catalyst due to high capacity in removing oxygen compound and produce high quality of biofuel with desirable lighter hydrocarbon (C8-C24). The performance of this catalyst was compared with several commercial catalysts in catalytic pyrolysis of Waste Cooking Oil. Calcination at 900 °C in N2 produced catalyst with very high activity due to decomposition of CaMg(CO3)2 phase and formation of MgO-CaO phase. The liquid product showed similar chemical composition of biofuel in the range of gasoline, kerosene and diesel fuel. Furthermore, Malaysian Dolomite showed high reactivity with 76.51 % in total liquid hydrocarbon and the ability to convert the oxygenated compounds into CO2, CO, CH4, H2, hydrocarbon fuel gas, and H2O. Moreover, low acid value (33 mg KOH/g) and low aromatic hydrocarbon content were obtained in the biofuel. Thus, local calcined carbonated material has a potential to act as catalyst in converting waste cooking oil into biofuel.

Optimized Conversion of Waste Cooking Oil to Biodiesel Using Calcium Methoxide as Catalyst under Homogenizer System Conditions

Although many types of heterogeneous catalysts have been applied to the transesterification reaction, some of them are unsuitable for industrial applications due to their high price and the extra preparation required to synthesize them. Calcium methoxide is a low cost, strong base with high catalytic activity and is thus commonly used in the biofuels synthesis process during the transesterification reaction. The objective of this study was to determine the optimized conversion in the transesterification reaction of waste cooking oil (WCO) for biodiesel production by using a homogenizer with a calcium methoxide catalyst. It was shown that the optimal reaction conditions are a methanol-to-oil molar ratio of 6:1, 4 wt % Ca(OCH3)2, a reaction temperature of 65 °C, a rotation speed of 7000 rpm, and a reaction time of 90 min. The conversion rate under these conditions reached 90.2%. Ca(OCH3)2 thus has potential as a catalyst for industrial use. In addition, with a homogenizer system, the reaction time for synthesizing calcium methoxide catalyst can be reduced by half compared to that for conventional water-bath heating. In addition, the large amount of waste water required in the oil-water separation step can be reduced by using calcium methoxide instead of a homogeneous catalyst, significantly reducing manufacturing costs.