Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar

Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar

Journal Pre-proofs Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar Shashi Kant Bhatia, Ranjit Gur...

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Journal Pre-proofs Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar Shashi Kant Bhatia, Ranjit Gurav, Tae-Rim Choi, Hyun Joong Kim, Soo-Yeon Yang, Hun-Suk Song, Jun Young Park, Ye-Lim Park, Yeong-Hoon Han, YongKeun Choi, Sang-Hyoun Kim, Jeong-Jun Yoon, Yung-Hun Yang PII: DOI: Reference:

S0960-8524(20)30141-3 https://doi.org/10.1016/j.biortech.2020.122872 BITE 122872

To appear in:

Bioresource Technology

Received Date: Revised Date: Accepted Date:

18 December 2019 17 January 2020 20 January 2020

Please cite this article as: Kant Bhatia, S., Gurav, R., Choi, T-R., Joong Kim, H., Yang, S-Y., Song, H-S., Young Park, J., Park, Y-L., Han, Y-H., Choi, Y-K., Kim, S-H., Yoon, J-J., Yang, Y-H., Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar, Bioresource Technology (2020), doi: https:// doi.org/10.1016/j.biortech.2020.122872

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Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar

Shashi Kant Bhatiaa,b, Ranjit Gurava, Tae-Rim Choia, Hyun Joong Kima, Soo-Yeon Yanga, Hun-Suk Songa, Jun Young Parka, Ye-Lim Parka, Yeong-Hoon Hana, Yong-Keun Choia, Sang-Hyoun Kimc, Jeong-JunYoond, Yung-Hun Yanga,b *

a) Department

of Biological Engineering, College of Engineering, Konkuk University, Seoul, South Korea b) Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, Seoul, South Korea c)School of Civil and Environmental Engineering, Yonsei University, Seoul, South Korea d)Intelligent Sustainable Materials R&D Group, Korea Institute of Industrial Technology (KITECH), Cheonan-si, Chungcheongnam-do 31056, South Korea *Author for correspondence (Fax: +82-2-3437-8360; E-mail: [email protected])

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Abstract In this study, a heterogeneous catalyst prepared by pyrolysis of waste cork (Quercus suber) was used for the transesterification of waste cooking oil (WCO). Physicochemical properties of the synthesized biochar catalyst were studied using BET, SEM, FTIR, and XRD. The experiment results demonstrate that heterogeneous catalyst synthesized at 600 °C showed maximum fatty acids methyl esters (FAMEs) conversion (98%) at alcohol: oil (25:1), catalyst loading (1.5% w/v) and temperature 65 °C. Biodiesel produced from WCO (Canola oil) mainly composed of FAMEs in following order C18:1>C18:2>C16:0>C18:0>C20:0. Properties of produced biodiesel were analysed as cetane number (CN) 50.56, higher heating value (HHV) 39.5, kinematic viscosity (ʋ) 3.9, and density (ρ) 0.87.

Keywords: Biodiesel, cork biochar, pyrolysis, transesterification, waste cooking oil

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1. Introduction In the present scenario, most of the energy demands are fulfilled by utilizing fossil based fuels. These energy resources are non-renewable, and overexploitation of these fuels will result in an energy crisis in few coming decades (Meena et al., 2019; Sindhu et al., 2016). There is a need to explore alternative sources of energy that are renewable to full fill the ever increasing energy demand (Parthiba Karthikeyan et al., 2018; Patel et al., 2019; Toor et al., 2020). Biodiesel is gaining worldwide attraction in the energy sector due to its production from renewable feedstocks (Anto et al., 2020; Bhatia et al., 2019b; Nguyen et al., 2020). It is biodegradable in nature, have minimum sulfur content and can be used in existing engines without any modification (Ma et al., 2018). Biodiesel is composed of fatty acid alkyl esters derived from transesterification of oils with alcohol (Bhatia et al., 2017a). Oil is present in the form of triacylglycerol in living organisms. Biodiesel production from various edible (castor oil, sunflower oil, mustard oil) and non-edible oils (jatropha oil, jojoba oil, pongamia oil) have been reported (Baskar et al., 2018; Bhatia et al., 2018; Thushari & Babel, 2018). Utilization of edibles oils has food security issue while non-edible oils crops require extra land for cultivation which restrict their use at a large scale. To make the biodiesel production process more economic there is a need to find alternative sources of raw material (Bhatia et al., 2020). Waste cooking oil (WCO) is the oil that left after the deep frying process can be a suitable option for biodiesel production. According to a published report, there is almost 16.5 million tons of WCO is produced every year (Loizides et al., 2019). Management of WCO is also an issue as its disposal in open space affects flora and fauna due to its lower solubility in water (Singh-Ackbarali et al., 2017). The collection of WCO and its conversion into biodiesel may help to solve its disposal problem and will contribute to the energy sector. Biodiesel is produced through transesterification reactions and requires alkaline, acidic or enzymatic

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catalysts. Alkali catalysts have a saponification problem and result in difficulty in product separation (Kolhe et al., 2017). Concentrated sulfuric acid is able to catalyze esterification and transesterification reactions simultaneously but cause corrosion of equipment and generate a lot of wastewater (Li et al., 2014). Theses waste requires extra treatment which add in cost and a matter of environmental concern. The use of enzymes is a costly process as their production is not economic and easily loose activity during the reaction (Badoei-dalfard et al., 2019). Recently there has been a renewed interest to use heterogeneous catalysts (biochar) for biodiesel production as these can be easily recovered after the reactions and reused several times (Jamil et al., 2018; Oliveira et al., 2017). Heterogeneous catalysts derived from different resources such as eggshell, mollusk shell, chicken manure, algal biomass and rice husk etc. have been reported for biodiesel production using different oils (Fu et al., 2013; Joshi et al., 2016; Jung et al., 2018). In this study cork produced from Quercus suber plant which is used as a stopper in wine bottles was used as raw material to prepare the catalyst. According to a survey around 282 million hectolitre wine is produced in 2018 and more than 50% of wine is produced in Italy, France and Spain. Cork is just as waste material that left over after wine consumption and be a cheap and easily available material for heterogenous catalyst preparation using pyrolysis process. In this study, cork waste was collected from local wine shops and transformed into biochar using the pyrolysis process. Biochar produced from cork has a porous structure and further treated with concentrated H2SO4 to prepare the heterogeneous active catalyst. The WCO was collected from the local restaurant and used as an oil source for biodiesel production. Heterogeneous active catalysts were characterized for their physicochemical properties and used to carry the transesterification reaction of WCO with methanol to produce biodiesel. Various reaction parameters such as alcohol: oil ratio, catalyst loading, reaction temperate and reusability of the catalyst were also studied to ensure the maximum

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conversion of WCO into biodiesel. Finally, biodiesel produced from the WCO was analyzed for its fatty acids alkyl esters composition and further subjected for properties analysis. 2. Materials and methods 2.1 Materials and chemical reagents Waste cooking oil (canola oil) and wine bottle cork were collected from the local restaurants. Concentrated H2SO4, chloroform, methanol, and FAME internal standard (heneicosanoate) were procured from Sigma Aldrich (St. Louis, USA). 2.2 Cork biochar preparation Wine bottle cork was chopped into small pieces, washed with distilled water and dried in an oven at 60 °C until a constant wait achieved. To prepare biochar, chopped cork was placed in a quartz tube furnace (1200x, MTI Corp. USA) and subjected to pyrolysis at 400 °C, 600 °C and 800 °C for 2 h at a heating rate of 10 °C min- under constant supply of N2 gas. Biochar produced at different temperature were named as CB400, CB600 and CB800. 2.3 Biochar screening and activation Biochar CB400, CB600, and CB800 were screened for their catalytic potential to carry transesterification reaction of WCO with methanol. Transesterification reactions were carried at 5 ml scale in a 10 ml capacity closed cape falcon tube using methanol and oil (10:1) and biochar as catalyst (0.5% w/v). Reactions were performed in a shaking incubator at 65 °C under continues shaking of 700 rpm min- for 10 h. Biochar was further reacted with concentrated H2SO4 to attach a strong acidic group on the carbon surface. For activation biochar was first grounded into fine particles using mortar and pestle and sieved through a 4-12 mesh screen sieves to obtain uniform sized biochar particles. Subsequently, 1 g of biochar was placed in a beaker and 10 ml of concentrated H2SO4 was added. The acid was mixed by incubating the mixture in a shaker at 300 rpm for 2 h and then excess acid was decanted. Solid residues were poured in a ceramic crucible and incubated at

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100 °C overnight. After treatment, the activated biochar was washed with distilled water until the pH of the rinsate becomes neutral. Biochar was recovered by vacuum filtration using a Whatman filter (20-25 µm), and solid biochar was dried in a hot air oven at 110 °C overnight. Activated biochar were named as ACB400, ACB600, and ACB800. All the biochar were further used as a catalyst to perform transesterification reactions as explained above. A reaction was also performed using concentrated H2SO4 as a catalyst to compare the FAME profile obtained with acid catalysts and activated biochar using the previously explained method (Bhatia et al., 2019a). 2.4 Biochar characterization Surface morphology of biochar (CB400, CB600 and CB800) was examined using a scanning electron microscope (SEM) at conductive mode with 5 kV voltage (HitachiTM4000Plus). Xray powder diffraction (XRD) of cork and biochar (CB600) was performed to find 2θ angle by scanning at 4 to 80° using X-ray diffractometer (Rigaku, SmartLab). Fourier transform infrared spectroscopy was performed (FTIR, JASCO-4100) to study functional groups present in biochar (CB600) and activated biochar (ACB600). X-ray photoelectron spectroscopy (XPS), a survey scan was performed to find basic elements present in biochar (CB600) and activated biochar (ACB600) (CasaXPS v 2.3.16 pr1.6). Brunauer-EmmettTeller (BET) analysis was performed to study the surface area, pore volume and pore size of biochar (CB600) and activated biochar (ACB600) using surface analyzer (Micromeritics TriStar II 3020). 2.5 Analytical methods Fatty acids methyl esters (FAMEs) analysis was performed using GC-MS under previously reported conditions (Bhatia et al., 2017b). After completion of the biochar catalyzed transesterification reaction of WCO with methanol, reaction mixture was centrifuged at 10000xg for 10 min to separate biochar and supernatant. The collected supernatant was added

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in a tube containing Na2SO4 to remove moisture. Samples were diluted with chloroform before applying for GC-MS analysis. FAME composition was analyzed by comparing with spectral data available in online libraries of NIST (http:// www.nist.gov). 2.6 Optimization of reaction parameters for biodiesel production The transesterification reaction of WCO with methanol was performed using activated biochar ACB600 as explained in section 2.3. Different reaction parameters such as methanol: oil ratio (5 to 30), catalyst loading (0.5% w/v to 2.5% w/v), reaction time (2 to 10 h) were optimized. The reusability of ACB600 was performed and studied up to five cycles. To perform reusability test activated biochar was recovered from the reaction mixture by centrifugation at 10000xg and washed with methanol to remove any fatty acids adsorbed in catalysts and then washed with water and dried in an oven at 110 °C and used to perform next reaction 2.7 Biodiesel properties analysis Biodiesel properties depend on the composition of biodiesel. After analyzing biodiesel compositions using GC-MS, data was further used to determine the properties of biodiesel. The cetane number (CN), higher heating value (HHV), density (ρ), kinematic viscosity (υ), cold filter plugging point (CFPP), oxidation stability (OS), and cloud point (CP) properties of the biodiesel were analyzed using online available software i.e. Biodiselanalyzer v1. 1 (http://www. brteam.ir/biodieselanalyzer) (Talebi et al., 2014). 3. Results and discussions 3.1 Biochar synthesis, screening, and characterization Cork biochar CB400, CB600, and CB800 were produced at different temperatures 400 °C, 600 °C and 800 °C, respectively. All the produced biochar were analyzed for surface morphology using SEM. At lower temperature (400 °C) biochar surface structure was more compact with very little pores, as the temperature increased further (600 °C) biochar surface

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become more porous. High temperature cause the evaporation of volatile compounds and gaseous components and results in the porous structure of biochar (Wijitkosum & Jiwnok, 2019). Further increase of pyrolysis temperature (800 °C) led to the decomposition of more components and results in the collapse of the porous structure. CB600 biochar showed uniform sized porous structured morphology and deemed to provide a higher catalytic area. Overall the SEM micrographs showed that 600 °C is the best pyrolysis temperature to obtain a porous catalyst of cork. All the biochar were screened for their transesterification activity under conditions mentioned in section 2.3 and maximum FAME conversion (4%) was recorded with CB600. Biochar CB800 showed only 2.1% FAME conversion, as at higher pyrolysis temperature biochar porous structure collapsed and have less active surface area. Similarly, biochar CB400 also showed reduced FAME conversion (1.5%), because at low pyrolysis temperature biochar has compact structure without any pores. Further XRD analysis of cork and biochar CB600 was performed to determine the crystallinity of biochar. The diffractogram displays peaks around 2θ = 21° which is associated with diffraction pattern of cellulose. A decrease in peak intensity in the case of biochar was observed, which is due to the loss in cellulose during pyrolysis and results in reduced crystallinity of biochar (Rafiq et al., 2016). Biochar CB600 was activated with concentrated H2SO4 and analyzed for any change in functional groups. FTIR spectra of CB600 and activated biochar ACB600 showed peaks at 3700 cm- corresponding to O-H stretching vibration of terminal carboxylic acids and phenols. The band located at 2920 cmshows C-H vibrations in methyl and methylene groups. The peaks at 1422 cm- were due to CH3 and -CH2, while peaks at 1237 cm- attributed to C-O stretching of phenolic and C-C-O stretching of esters. The intense peak at 1027 cm- were corresponding to alcohol groups (ROH). There was a slight decrease in intensities of various peaks that were observed in the case of activated biochar as compared to biochar, which might be due to the loss of some

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acid-soluble components present in biochar. A similar pattern of various functional groups have been shown for different biomass derived biochar by another research group (Choi et al., 2020; Gurav et al., 2019). Activated biochar ACB400, ACB600, and ACB800 were screened for their transesterification activity and maximum FAME conversion (43%) was observed with ACB600. With ACB400 and ACB800 only 15.7% and 35.5% FAME conversion was achieved, respectively, due to reduced porous structure and active surface area. Biodiesel produced using acid catalyst (conc. H2SO4) and different activated biochar was also analyzed and compared for its FAME composition. Same FAME profile (oleic acid (C18:1)> linoleic acid (C18:2)> palmitic acid (C16:0)> stearic acid (C18:0)> arachidic acid (C20:0)) and content of each fatty acids was observed with biochar and acid catalysts (Fig. 1). This result showed that activated biochar is able to transesterify all the fatty acids present in the WCO with the same potential as acid catalysts. For further study, only biochar produced at 600 °C was used. 3.2

Biochar XPS and BET analysis

Elemental analysis using XPS showed that CB600 and ACB600 were composed of 94% and 84.8% C, and 4.59% and 12.1% O, respectively followed by little content of other elements such as N and Si. Activated biochar ACB600 had a higher O/C ratio as compared to biochar CB600. A little content of S was also traced (1.05%) in the activated biochar ACB600, while there was no S detected in biochar CB600 (Table. 1). An increase in O/C ratio and presence of S element is due to H2SO4 which showed successful activation of biochar. BET analysis showed a decrease in surface area of biochar after activation from 447.86 to 179.66 m2/g (Table. 1). A decrease in pore size of activated biochar ACB600 was observed as compared to CB600 from 2.30 nm to 2.10 nm, while an increase in pore volume was observed. The

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decrease in surface area and pore size was due to the oxidation reaction between carbon and sulfonic molecule and pores were filled with -SO3H groups (Sandouqa et al., 2019). 3.3 Characterization of biochar for transesterification 3.3.1 Effect of alcohol: oil ratio on biodiesel production Alcohol and oil are the two main components required for the transesterification reaction and biodiesel production. The ratio of these components (alcohol: oil) was optimized by analyzing FAME conversion at different time intervals. Maximum FAME conversion (75.3%) was recorded at A:O of 25:1 (Fig. 2). There was a continues increase in FAME conversion was observed with the increase of A:O ratio (25:1) and the increase of time. At higher A:O (30:1) concentration there was a decrease in FAME conversion was observed with the increase of time beyond 6 h. The transesterification reaction is a reversible reaction and requires a higher concentration of alcohol to shift reaction equilibrium in the forward direction. Obadiah et al. reported that a higher concentration of methanol enhances methoxy species formation at the catalyst’s surface which led to an increase in biodiesel conversion (Obadiah et al., 2012). An increase in alcohol concentration above (25:1) results in a negative effect on biodiesel production. Glycerol which is the side product of transesterification reaction get dissolve in methanol and inhibit the reaction of methanol to fatty acids and catalyst (Tan et al., 2015). The FAME conversion rate was slow at 2 and 4 h due to the low mixing of alcohol and oil. It took 6 h to achieve maximum conversion, on further increase in reaction time a slight increase in conversion was observed. Stoichiometrically one mole of triacylglycerol requires three moles of alcohol for transesterification reaction. In our study maximum conversion was observed at 25:1. Alcohol: oil ratio also depends on the type of catalyst and quality of oils. Different metal catalysts studied to carry transesterification reaction of various oils reviewed by Mutreja et al. and reported different ratio of A:O for

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biodiesel production i.e. methanol: cotton seed oil (54:1), methanol: palm oil (45:1), methanol: sunflower oil (53:1) (Mutreja et al., 2014). 3.3.2 Effect of catalyst loading The effect of ACB600 catalyst concentration on the transesterification reaction of WCO with methanol (25:1) was investigated in the range of 0.5-2.5% w/v. With the increase of catalyst concentration, there was a continues increase in FAME conversion was observed up to 1.5% w/v catalyst concentration (Fig. 3). Maximum WCO to biodiesel conversion (98.58%) was recorded at 1.5% w/v catalyst concentration in 6 h, further increase in reaction time lead to a small change in FAME conversion. The increase in biodiesel conversion with increasing concentration of catalyst was due to the increase in catalytic sites involved in transesterification reactions of WCO (Farooq et al., 2015). Higher concentrations of catalyst beyond 1.5% w/v results in decrease in FAME conversion due to increase in viscosity of the reaction mixture. Hadiyanto et al. reported catalyst (Mollusk shell derived) loading of 6 % required for maximum biodiesel production from palm oil (Hadiyanto et al., 2016). Decrease in biodiesel production at higher loading of catalyst was also reported in previous studies due to mass transfer resistance and increased viscosity of the reaction mixture (Mutreja et al., 2014). 3.3.3 Effect of reaction temperature Transesterification reactions are affected by temperature and to optimize the optimum temperature for maximum FAME conversion, reactions were performed at different range of temperature (45-85 °C). With the increase of temperature an increase in reaction rate was observed and maximum FAME conversion was (98.6%) was recorded at 65 °C. Above this temperature a rapid decrease in FAME conversion was observed and only 37.4% FAME conversion was recorded at 85 °C. Transesterification reactions are endothermic in nature and requires high temperature to accomplish. Methanol: oil: heterogeneous catalyst exits in

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liquid: liquid: solid phase and shows diffusional resistance (Ho et al., 2014). Higher temperature increase collision between various reactants molecules and increase reaction rate (Thinnakorn & Tscheikuna, 2014). Increase in temperature above a limit (65 °C) led to a negative effect on FAME conversion because at higher temperature methanol starts to evaporate and its polarity get changed and lower the number of methoxide ions in the reaction (Lee & Saka, 2010). 3.3.4 Reusability of ACB600 catalyst The main advantage of heterogenous catalyst is its reusability as it can be easily separated from the reaction mixture. Reusability of ACB600 to catalyze transesterification reaction of WCO into biodiesel was studied up to 5 cycle by performing reaction at 65 °C for 6 h. A continues decrease in FAME conversion was observed with each cycle. After first cycle catalyst activity reduced and 86% FAME conversion was observed. Further recycle of catalyst results in rapid loss of catalyst activity and only 26.4% FAME conversion was recorded in 5th cycle. Other researchers also reported loss in catalyst activity with each cycle due to blockage of catalyst with deposition of glycerol, free fatty acids on active sites and leaching of -SO3H from biochar (Farooq et al., 2015; Sandouqa et al., 2019). After 5th cycle catalyst was not reused and reactivated again using the same activation process before using it again. Reactivated ACB600 catalyst results in 98% FAME conversion. 3.4 Properties analysis of biodiesel The properties of biodiesel directly depends on the composition of oil. Biodiesel produced from WCO (canola oil) mainly composed of FAMEs in following order C18:1>C18:2>C16:0>C18:0>C20:0. Various properties of biodiesel were analysed and compared with international biodiesel standard European (EN14214), American (ASTM) and Indian (IS 15607) (Table. 2). Cetane value (CN) for WCO oil derived biodiesel was 50.56 and satisfy the EN14214, ASTM (47) and IS 15607 (48) (Bhatia et al., 2019c). Cetane value

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of the biodiesel is related to the combustion behaviour of biodiesel and related to ignition delay time of a fuel in combustion engine. Oxidation stability of biodiesel was analysed as 7.7 h, while minimum value for biodiesel standard (ASTM and EN 14214) fixed in range of 3-8 h. Kinematic viscosity (υ) and density (ρ) of biodiesel were 3.8 and 0.87, respectively. Other properties of biodiesel HHV (39.55), CFPP (-8.7), CP (-1.79) were also analyzed to ensure the suitability of biodiesel as energy source. Poor cold flow properties (CFPP and CP) hampers engine starting as at lower temperature biodiesel starts to form crystal like structure and plug the engine filter. There is no fixed standard for these values as temperature varies region by region. 4. Conclusions Biodiesel is a renewable fuel, along with existing power sources it can ensure continues supply to meet the future energy demand. Heterogenous catalyst prepared by pyrolysis of cork at 600 °C and activated with conc. H2SO4 showed maximum FAME conversion in 6 h with alcohol: oil (25:1) ratio at catalyst loading of 1.5% w/v. Catalyst can be reused up to 5 cycles and require reactivation to reuse it further. These results showed that biodiesel production using WCO and heterogenous cork catalysts will not only contribute to proper disposal of waste but also provide a cheap raw material for biodiesel production. 5. Acknowledgements The authors would like to acknowledge the KU Research Professor Program of Konkuk University, Seoul, South Korea. This study was supported by Research Program to solve social issues of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017M3A9E4077234), National Research Foundation of Korea (NRF) (NRF-2015M1A5A1037196, NRF-2017R1E1A1A01073690, NRF-2019M3E6A1103979, 2017R1D1A1B03030766).

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Figure captions Figure. 1 Fatty acid methyl esters (FAMEs) composition profile of biodiesel produced using acid catalyst (conc. H2SO4) and H2SO4 activated biochar produced at different temperature. Figure. 2 Effect of alcohol: oil ratio on FAME conversion during different time course. Figure. 3 Effect of catalyst loading on waste cooking oil conversion into biodiesel.

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Table. 1 Surface area, porosity and elemental analysis of biochar and activated biochar.

Sample

BET surface area 2 (m /g) Biochar 447.86 Activated 179.66 biochar

Pore size (nm) 2.30 2.10

Total pore volume 2 (cm /g) 0.039 0.080

C

Elemental analysis (wt%) O N S

Si

94.0 84.8

4.59 12.15

0.85 0.73

0.73 1.26

1.05

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Table. 2 Properties analysis of WCO derived biodiesel and comparison with international standards

Properties Cetane number Higher heating value (MJ/kg) Oxidation stability (h) Kinematic viscosity (mm2/s) Density (kg/L) Cold filter plugging point (C°), Cloud point (°C)

WCO biodiesel 50.56

Petro diesel

IS 15607

ASTM

EN 14214

51

48

47

>51

39.55

45.9

-

-

-

7.7

-

-

-

-

3.9

1.2-3.5

2.5-6

1.9-6

3.5-5.2

0.87 -8.7

0.83-0.84 -

0.86-0.90 -

0.86-0.90 -

0.86-0.90 -

-1.7

-

-

-

-

20

Fig. 1

21

Fig. 2

22

Fig. 3

23

Credit author statement

Shashi Kant Bhatia: Conceptualization, Methodology, Writing - Original Draft. Ranjit Gurav: Formal analysis. Tae-Rim Choi: Investigation. Hyun Joong Kim: Validation, SooYeon Yang: Resources. Hun-Suk Song: Visualization. Jun Young Park:Validation. YeLim Park: Formal analysis. Yeong-Hoon Han: Resources. Yong-Keun Choi: Methodology. Sang-Hyoun Kim: Writing - Review & Editing. Jeong-Jun Yoon: Writing - Review & Editing, Yung-Hun Yang: Writing - Review & Editing, Supervision.

Graphical abstract

Highlights    

Cork biochar produced at temperature 600 °C has porous structure. Conc. H2SO4 activated biochar able to transesterify WCO into biodiesel. A:O ratio (25:1) at catalyst loading 1.5% w/v results in 98% FAME conversion. Produced biodiesel has CN (50.56), HHV (39.5), ʋ (3.9) and (ρ) 0.87.