Document Type : Original Article
Authors
1 University of Benin
2 University of Benin, Nigeria
10.22044/rera.2026.17889.1553
Abstract
High production costs, environmental concerns, and optimization complexities limit conventional biodiesel viability. To address this, a novel bio-based heterogeneous catalyst was synthesized by impregnating Coconut Shell BioChar (CS-BC) with copper-doped Calcined Periwinkle Shell (CPS). The morphology and stability of the catalyst was assessed using SEM, EDX, FTIR, XRD, and BET. The catalyst was applied to transesterify an optimized blend of Waste Cooking Oil (WCO) and Animal Fat (AF). The process was modeled using Support Vector Regression (SVR), Artificial Neural Networks (ANN), Random Forest (RF), and Extreme Gradient Boosting (XGBoost), then globally optimized via the Manta Ray Foraging Optimization (MRFO) algorithm. XGBoost outperformed the other models, achieving a coefficient of determination (R2) of 0.899 with the lowest error metrics. SHAP analysis identified reaction temperature as the most influential feature. The MRFO-optimized conditions were a reaction temperature of 66.3°C, catalyst loading of 6.37 wt.%, reaction time of 104.6 minutes, and a methanol-to-oil ratio of 8.84:1. Under these optimized conditions, a maximum predicted biodiesel yield of 81.9% was achieved, which closely matched the experimentally validated yield of 82.3 ± 0.8%. The synthesized catalyst demonstrated excellent stability, maintaining a 97.1% biodiesel yield after five consecutive reaction cycles, highlighting its potential for sustainable, large-scale application. Physicochemical analysis confirmed that the produced biodiesel complies with ASTM D6751 and EN 14214 standards. This integrated framework of waste-derived feedstocks, green catalysis, and metaheuristic optimization provides a sustainable, data-driven approach to biofuel production.
Keywords
Main Subjects
[1] Foster V, Brophy AF, Fankhauser S, Jenkins S, McGivern A, Srivastav S. Development transitions for fossil fuel-producing low and lower–middle income countries in a carbon-constrained world. Nat Energy 2024;9:242–50. doi:10.1038/s41560-023-01440-3
[2] Shi W, Shao J, Han G, Deng N, Wan Y. Biodiesel production from waste chicken fat with low free fatty acids by an integrated catalytic process of composite membrane and sodium methoxide. Bioresour Technol 2013;139:316–22. doi:10.1016/j.biortech.2013.04.040.
[3] Singh SP, Singh D. Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: A review. Renewable Sustainable Energy Rev 2010;14:200–16. doi:10.1016/j.rser.2009.07.017.
[4] Suhara A, Karyadi, Herawan SG, Tirta A, Idris M, Roslan MF, Putra NR, Hananto AL, Veza I. Biodiesel sustainability: Review of progress and challenges of biodiesel as sustainable biofuel. Clean Technol 2024;6:886–906. doi:10.3390/cleantechnol6030045.
[5] Shahid EM, Jamal Y. Production of biodiesel: A technical review. Renewable Sustainable Energy Rev 2011;15:4732–45. doi:10.1016/j.rser.2011.07.079.
[6] Tang Y, Meng X, Li C, Zhang H, Zhang S, Han J. Biodiesel production from vegetable oil by using modified CaO as solid basic catalysts. J Cleaner Prod 2013;42:198–203. doi:10.1016/j.jclepro.2012.11.001.
[7] Emeji IC, Patel B. Box-Behnken assisted RSM and ANN modelling for biodiesel production over titanium supported zinc-oxide catalyst. Energy 2024;307:132765. doi:10.1016/j.energy.2024.132765.
[8] Balat M. Potential alternatives to edible oils for biodiesel production – a review of current work. Energy Convers Manage 2011;52:1479–92. doi:10.1016/j.enconman.2010.10.011.
[9] Balat M, Balat H. Progress in biodiesel processing. Appl Energy 2010;87:1815–35. doi:10.1016/j.apenergy.2010.01.012.
[10] Trisunaryanti W, Wijaya K, Triyono T, Adriani AR, Larasati S. Green synthesis of hierarchical porous carbon prepared from coconut lumber sawdust as Ni-based catalyst support for hydrotreating Callophyllum inophyllum oil. Results Eng 2021;11:100258. doi:10.1016/j.rineng.2021.100258.
[11] Brahma S, Nath B, Basumatary B, Das B, Saikia P, Patir K, Basumatary S. Biodiesel production from mixed oils: A sustainable approach towards industrial biofuel production. Chem Eng J Adv 2022;10:100284. doi:10.1016/j.ceja.2022.100284.
[12] Ali Ijaz Malik M, Zeeshan S, Jamil F, Al-Haj L, Myint MT, Al-Muhtaseb AH. A review of major trends, opportunities, and technical challenges in biodiesel production from waste sources. Energy Convers Manage X 2024;23:100675. doi:10.1016/j.ecmx.2024.100675.
[13] Amenaghawon AN, Omede MO, Ogbebor GO, Eshiemogie SA, Igemhokhai S, Evbarunegbe NI, Ayere JE, Osahon BE, Oyefolu PK, Eshiemogie SO, Anyalewechi CL, Okedi MO, Chinemerem BA, Kusuma HS, Darmokoesoemo K, Okoduwa IG. Optimized biodiesel synthesis from an optimally formulated ternary feedstock blend via machine learning-informed methanolysis using a composite biobased catalyst. Bioresour Technol Rep 2024;25:101805. doi:10.1016/j.biteb.2024.101805.
[14] Adepoju TF, Akens HA, Ekeinde EB. Synthesis of biodiesel from blend of seeds oil-animal fat employing agricultural wastes as base catalyst. Case Stud Chem Environ Eng 2022;5:100202. doi:10.1016/j.cscee.2022.100202.
[15] Oiwoh O, Amenaghawon AN, Eshiemogie SA, Muonanu OC, Eliake ME, Ndukwe CG, Oghenehwosa OJ, Okoduwa IG, Osazuwa O, Mulopo J, Kusuma HS. Explainable tree-based machine learning modeling and optimization for intelligent oil feedstock formulation towards enhanced biodiesel production. Biomass Bioenergy 2026;205:108491. doi:10.1016/j.biombioe.2026.108491.
[16] Osagiede CA, Ugbodu FU, Oniovosa RO, Adetunji IA, Avanrenren GO. Physicochemical properties of optimized hybrid feedstock blend from waste cooking oil and animal fat for biodiesel production. J Appl Sci Environ Manage 2025;29:3312–9. doi:10.4314/jasem.v29i1.12.
[17] Mahmood Khan H, Iqbal T, Ali CH, Garcia RA, El-Din MM, El-Kady MA. Sustainable biodiesel production from waste cooking oil utilizing waste ostrich (Struthio camelus) bones derived heterogeneous catalyst. Fuel 2020;277:118091. doi:10.1016/j.fuel.2020.118091.
[18] Singh D, Sharma D, Soni SL, Inda S, Sharma S, Sharma PK, Jhalani A. A review on feedstocks, production processes, and yield for different generations of biodiesel. Fuel 2020;262:116553. doi:10.1016/j.fuel.2019.116553.
[19] Amenaghawon AN, Evbarunegbe NI, Obahiagbon K. Optimum biodiesel production from waste vegetable oil using functionalized cow horn catalyst: A comparative evaluation of some expert systems. Cleaner Eng Technol 2021;4:100184. doi:10.1016/j.clet.2021.100184.
[20] Osagiede CA, Aisien FA. Biochar-based bi-functional catalyst derived from rubber seed shell and eggshell for biodiesel production from waste cooking oil. Fuel 2024;358:130076. doi:10.1016/j.fuel.2023.130076.
[21] Osagiede CA, Akhabue CE. Kinetics and thermodynamics studies of the transesterification of waste cooking oil using biochar-based catalyst derived from rubber seed shells. J Sci Technol Res 2024;6:319–30. doi:10.4314/jstr.v6i2.25.
[22] Aderibigbe FA, Ikhazuagbe HO, Ogbeide SE, Betty O. Development of bi-functional heterogeneous catalyst for transesterification of waste cooking oil to biodiesel: Optimization studies. Adv Mater Res 2021;1163:128–47.
doi:10.4028/www.scientific.net/AMR.1163.128.
[23] Akhabue CE, Osa-Benedict EO, Oyedoh EA, Otoikhian SK. Development of a bio-based bifunctional catalyst for simultaneous esterification and transesterification of neem seed oil: Modeling and optimization studies. Renewable Energy 2020;152:724–35. doi:10.1016/j.renene.2020.01.095.
[24] Osagiede CA, Aisien FA. Calcined eggshell–doped biochar as catalyst for biodiesel production from waste cooking oil: a process optimization study. Trans Niger Assoc Math Phys 2024;20:93–102.
[25] Amenaghawon AN, Osarollor T, Eshiemogie SO, Anyalewechi CL. Optimized biodiesel production from waste cooking oil using a functionalized bio-based heterogeneous catalyst. Cleaner Eng Technol 2022;8:100501. doi:10.1016/j.clet.2022.100501.
[26] Bedir Ö, Dogan TH. Use of sugar industry waste catalyst for biodiesel production. Fuel 2021;286:119476. doi:10.1016/j.fuel.2020.119476.
[27] Betiku E, Etim AO, Pereao O, Ojumu TV. Two-step conversion of neem (Azadirachta indica) seed oil into fatty methyl esters using a heterogeneous biomass-based catalyst: an example of cocoa pod husk. Energy Fuels 2017;31:7134–40. doi:10.1021/acs.energyfuels.7b00801.
[28] Falowo OA, Oloko-Oba MI, Betiku E. Biodiesel production intensification via microwave irradiation-assisted transesterification of oil blend using nanoparticles from elephant-ear tree pod husk as a base heterogeneous catalyst. Chem Eng Process - Process Intensif 2019;140:157–70. doi:10.1016/j.cep.2019.05.008.
[29] Basumatary B, Basumatary S, Das B, Nath B, Kalita P. Waste Musa paradisiaca plant: an efficient heterogeneous base catalyst for fast production of biodiesel. J Cleaner Prod 2021;305:127089. doi:10.1016/j.jclepro.2021.127089.
[30] Goh CMH, Tan YH, Mubarak NM, Kansedo J, Rashid U, Khalid M, Walvekar R. Synthesis of magnetic basic palm kernel shell catalyst for biodiesel production and characterisation and optimisation by Taguchi method. Appl Nanosci 2021;11:2243–54. doi:10.1007/s13204-021-01931-1.
[31] Okoduwa IG, Oiwoh O, Amenaghawon AN, Okieimen CO. A biobased mixed metal oxide catalyst for biodiesel production from waste cooking oil: reaction conditions modeling, optimization and sensitivity analysis study. J Eng Res 2025;13:1344–57. doi:10.1016/j.jer.2024.08.012.
[32] Oloyede CT, Jekayinfa SO, Alade AO, Ogunkunle O, Laseinde OT, Adebayo AO, Veza I, Fattah IMR. Potential heterogeneous catalysts from three biogenic residues toward sustainable biodiesel production: Synthesis and characterization. ChemistrySelect 2022;7:e202203816. doi:10.1002/slct.202203816.
[33] Nwachukwu IM, Ulakpa WC, Eyide O, Ekpenkhio JE, Akhabue CE. Synthesis and characterization of novel bi-functional catalyst from mixture of agro-wastes using hydrothermal-sulphonation method. Equilibrium J Chem Eng 2025;9:1–10. doi:10.20961/equi.v9i1.88123.
[34] Shafagh S, Siamak Talesh S, Maleki B. A novel peanut shell-derived biochar/KOH heterogeneous catalyst for biodiesel production from waste cooking oil: RSM optimization and diesel engine performance assessment. Energy Convers Manage 2026;358:121344. doi:10.1016/j.enconman.2026.121344.
[35] Ishola NB, Epelle EI, Betiku E. Machine learning approaches to modeling and optimization of biodiesel production systems: State of art and future outlook. Energy Convers Manage X 2024;23:100669. doi:10.1016/j.ecmx.2024.100669.
[36] Mwenge P, Rutto H, Seodigeng T. Application of machine learning for methanolysis of waste cooking oil using kaolinite geopolymer heterogeneous catalyst. Eng Proc 2024;67:23. doi:10.3390/ENGPROC2024067023.
[37] Ishola NB, Bankole AO, Betiku E. Adaptive neuro-fuzzy inference system-genetic algorithm vs. response surface methodology: A case of optimization of ferric sulfate-catalyzed esterification of palm kernel oil. Process Saf Environ Prot 2017;111:211–22. doi:10.1016/j.psep.2017.07.006.
[38] Silitonga AS, Hidayat R, Ong HC, Kusumo F, Mahlia TMI, Sulaeman A, Ibrahim H. Optimization of Cerbera manghas biodiesel production using artificial neural networks integrated with ant colony optimization. Energies 2019;12:3811. doi:10.3390/en12203811.
[39] Zhao W, Zhang Z, Wang L. Manta ray foraging optimization: An effective bio-inspired optimizer for engineering applications. Eng Appl Artif Intell 2020;87:103300. doi:10.1016/j.engappai.2019.103300.
[40] Gharehchopogh FS, Shahi H, Maleki I, Khodadadi N, Pop CD, Chifu VR. Advances in Manta Ray Foraging Optimization: A Comprehensive Survey. J Bionic Eng 2024;21:953–90. doi:10.1007/s42235-024-00488-8.
[41] Oyedoh EA, Okoduwa GU, Madojemu GO, Akhabue CE. Production of biodiesel from the transesterification of waste cooking oil using biobased sulphonated catalyst prepared from coconut shells. J Appl Sci Environ Manage 2022;26:1977–87. doi:10.4314/jasem.v26i12.13.
[42] Shakir M, Ahmad M, Mansur FZ, Abdul Khalil HA. Biomass to biofuel: Palm kernel shells as catalyst supports for enhanced biodiesel production. Biofuels 2024;15:109–18. doi:10.1080/17597269.2023.2215682.
[43] Uzuegbu JN, Babayemi A, Ezeugo J, Umeuzuegbu JC. Biodiesel production from Jatropha seeds using a waste-derived periwinkle shell heterogeneous catalyst. Chem Sci Int J 2026;35:19–34. doi:10.9734/csij/2026/v35i2911.
[44] Aisien F, Uwadiae KO, Aisien ET. Process optimization for blended waste frying oil in biodiesel production using CaO derived from African periwinkle shell catalyst through response surface methodology. Sustain Chem Environ 2023;2:100018. doi:10.1016/j.scenv.2023.100018.
[45] Oshim FO, Uzomah V, Akujiokwu A, Ebenyi MO, Osman YZ. Environmental and public health implications of waste management practices in Ebonyi State, Nigeria: Evidence from a cross-sectional survey of residents. J Geogr Environ Earth Sci Int 2026;30:127–45. doi:10.9734/jgeesi/2026/v30i3815.
[46] Osagiede CA, Aisien FA. Carbonization of rubber seed shells: effect of process variables and optimization study. J Niger Inst Prod Eng 2022;26:88–100.
[47] Abdullah RF, Rashid U, Hazmi B, Hanif MA, Alharthi FA, Al-Zahrani AA. Synthesis of bifunctional nanocatalyst from waste palm kernel shell and its application for biodiesel production. RSC Adv 2020;10:27183–93. doi:10.1039/D0RA04859C.
[48] Vinoth Arul Raj J, Samuel T, Vinoba M, Alqahtani MS, Al-Zaqri N, Al-Mubaddel FS, Govarthanan M. Modelling and process optimization for biodiesel production from Nannochloropsis salina using artificial neural network. Bioresour Technol 2021;329:124872. doi:10.1016/j.biortech.2021.124872.
[49] Abdolrasol MGM, Hussain SMS, Ustun TS, Sarker MR, Al-Olaiti S, Mohamed R, Wahab MA. Artificial neural networks based optimization techniques: A review. Electronics 2021;10:2689. doi:10.3390/electronics10212689.
[50] Bobadilla MC, Bobadilla FMC, Castillo JMC, Martinez-Gomez EG. Optimizing biodiesel production from waste cooking oil using genetic algorithm-based support vector machines. Energies 2018;11:2995. doi:10.3390/en11112995.
[51] Lundberg SM, Allen PG, Lee SI. A unified approach to interpreting model predictions. Adv Neural Inf Process Syst 2017;30:4765–74.
[52] Lundberg SM, Erion G, Chen H, DeGrave A, Prutkin JM, Nair B, Katz R, Himmelfarb J, Bansal N, Lee SI. From local explanations to global understanding with explainable AI for trees. Nat Mach Intell 2020;2:56–67. doi:10.1038/s42256-019-0138-9.
[53] Ponce-Bobadilla AV, Kim S, Chanu P, Samineni R, Chien J. Practical guide to SHAP analysis: Explaining supervised machine learning model predictions in drug development. Clin Transl Sci 2024;17:e13712. doi:10.1111/cts.13712.
[54] Paputungan M, Suleman N, Yunus YR. Adsorption power of activated charcoal from coconut shells on lead metal (Pb) in well water. J Penelitian Pendidikan IPA 2023;9:9270–7. doi:10.29303/jppipa.v9i11.5123.
[55] Aimikhe VJ, Lekia GB. An overview of the applications of periwinkle (Tympanotonus fuscatus) shells. Curr J Appl Sci Technol 2021;40:31–58. doi:10.9734/cjast/2021/v40i2131454.
[56] Priscilla Okonkwo C, Azubike C, Ifeanyi O, Chukwudi O. Modelling and optimization of biodiesel production process parameters from Jansa seed oil (Cussonia bateri) using artificial neural network. Am J Appl Chem 2022;10:7–15. doi:10.11648/j.ajac.20221001.12.
[57] Oke JA, Obaji NO, Ikoya AA. Strength characteristics of oyster shell ash and periwinkle shell ash stabilized lateritic soil for pavement construction. NIPES J Sci Technol Res 2022;4:112–21. doi:10.37933/nipes/4.2.2022.12.
[58] Olofinnade OM, Ndambuki JM, Ede AN, Booth C. Recycling of periwinkle shell waste as partial substitute for sand and stone dust in lightweight hollow sandcrete blocks towards environmental sustainability. Materials 2023;16:1853. doi:10.3390/ma16051853.
[59] Sarkar JK, Wang Q. Different pyrolysis process conditions of South Asian waste coconut shell and characterization of gas, bio-char, and bio-oil. Energies 2020;13:2134. doi:10.3390/en13092134.
[60] Fahruddin F, Samawi S, Haeruddin H, Nursalim N. Biochar from coconut shell biomass for the removal of sulfate and cadmium reduction in acid mine drainage treatment. Pol J Environ Stud 2024;33:5627–34. doi:10.15244/pjoes/182315.
[61] Okechi Ifeanyi-Nze F, Benjamin O, Chukwuemeka S, Oluchi A. Optimization of biodiesel production from coconut oil using a bifunctional catalyst derived from crab shell and coconut shell. Eur J Sustainable Dev Res 2024;8:em0246. doi:10.29333/ejosdr/14102.
[62] Keiluweit M, Nico PS, Johnson MG, Kleber M. Dynamic molecular structure of plant biomass-derived black carbon (biochar). Environ Sci Technol 2010;44:1247–53. doi:10.1021/es9031419.
[63] Karunadasa KSP, Manoratne CH, Pitawala AMT, Rajapakse RMG. Thermal decomposition of calcium carbonate (calcite polymorph) as examined by in-situ high-temperature X-ray powder diffraction. J Phys Chem Solids 2019;134:21–8. doi:10.1016/j.jpcs.2019.05.023.
[64] Ramón-De los Santos C, Mtz-Enriquez AI, Ramos-Hernandez JG, Garcia-Gomez NA. Effect of the thermal annealing on the phase transitions of biogenic CaCO3 nanostructures. J Mex Chem Soc 2019;63:1–12. doi:10.29356/jmcs.v63i4.938.
[65] Gurunathan B, Ravi A. Biodiesel production from waste cooking oil using copper doped zinc oxide nanocomposite as heterogeneous catalyst. Bioresour Technol 2015;188:124–7. doi:10.1016/j.biortech.2015.01.071.
[66] Kumar S, Gautam RE, Kumar S, Upadhyay R. Advancements of biochar-based catalyst for improved production of biodiesel: A comprehensive review. Energies 2023;16:644. doi:10.3390/en16020644.
[67] Ioannidou O, Zabaniotou A. Agricultural residues as precursors for activated carbon production—A review. Renewable Sustainable Energy Rev 2007;11:1966–2005. doi:10.1016/j.rser.2006.03.013.
[68] Radha AV, Forbes TZ, Navrotsky A. Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate. Proc Natl Acad Sci USA 2010;107:16438–43. doi:10.1073/pnas.1009959107.
[69] Chen X, Wang Y, Luan C, Zhao C. Preparation and thermal decomposition mechanism of copper nitrate/carbon composite. J Therm Anal Calorim 2021;146:1625–34. doi:10.1007/s10973-020-10141-9.
[70] Comber A, Brunsdon C, Charlton M, Harris P. A route map for successful applications of geographically weighted regression. Geogr Anal 2023;55:155–78. doi:10.1111/gean.12316.
[71] Suvarna M, Ng YT, Perez-Ramirez J, Ok YS, Wang CH. Predicting biodiesel properties and its optimal fatty acid profile via explainable machine learning. Renewable Energy 2022;189:245–58. doi:10.1016/j.renene.2022.02.118.
[72] Şahin S, Torun A. Comparison of engine performance and emission values of biodiesel obtained from waste pumpkin seeds with machine learning. Agriculture 2024;14:227. doi:10.3390/agriculture14020227.
[73] Laskar IB, Rajkumari K, Gupta R, Chatterjee S, Paul B, Rokhum L. Waste snail shell derived heterogeneous catalyst for biodiesel production by the transesterification of soybean oil. RSC Adv 2018;8:20131–42. doi:10.1039/C8RA02397B.
[74] Mekonnen KD, Sendekie ZB. NaOH-catalyzed methanolysis optimization of biodiesel synthesis from desert date seed kernel oil. ACS Omega 2021;6:24082–91. doi:10.1021/acsomega.1c03383.
[75] Aleman-Ramirez JL, Torres-Rodriguez M, Morelos-Gomez A, Okoye PU, Sebastian PJ. Crystal phase evolution of high temperature annealed Fe3O4-CaO catalysts for biodiesel production. Biofuels Bioprod Biorefin 2023;17:843–58. doi:10.1002/bbb.2483.
[76] Kedir WM, Wondimu KT, Weldegrum GS. Optimization and characterization of biodiesel from waste cooking oil using modified CaO catalyst derived from snail shell. Heliyon 2023;9:e16475. doi:10.1016/j.heliyon.2023.e16475.
[77] Yusuf BO, Oladepo SA, Ganiyu SA. Efficient and Sustainable Biodiesel Production via Transesterification: Catalysts and Operating Conditions. Catalysts 2024;14:581. doi:10.3390/catal14090581.
[78] Gadore V, Sharma S, Ahmaruzzaman M. Metal oxide-based heterogeneous catalysts for biodiesel production. Next Sustainability 2023;2:100012. doi:10.1016/j.nexsus.2023.100012.
[79] Enguilo Gonzaga V, Romero R, Natividad R, Martinez-Vargas S. Biodiesel production from waste cooking oil catalyzed by a bifunctional catalyst. ACS Omega 2021;6:24092–105. doi:10.1021/acsomega.1c03525.
[80] Abdulla Yusuf H, Olutoye MA, Ramasamy SM. Optimization of biodiesel production in a high throughput branched microreactor. Energy Nexus 2024;13:100276. doi:10.1016/j.nexus.2024.100276.
[81] Pranita ZA, Budiman A, Waluyo J. Optimization of oil and methanol ratio, time, and reaction temperature of biodiesel making from Kemiri Sunan oil (Trisperma Oil Reuteals) with two stage transesterification. J Vocational Stud Appl Res 2020;2:25–30. doi:10.14710/jvsar.v2i2.9348.
[82] Mahmood SS, Al-Yaqoobi AM. Production of biodiesel by using CaO nano-catalyst synthesis from mango leaves extraction. Int J Renewable Energy Dev 2024;13:1025–34. doi:10.61435/ijred.2024.60334.
[83] Ogunsola AD, Durowoju MO, Ogunkunle O, Laseinde OT, Rahman SMA, Fattah IMR. Shea butter oil biodiesel synthesized using snail shell heterogeneous catalyst: Performance and environmental impact analysis in diesel engine applications. Sustainability 2023;15:8913. doi:10.3390/su15118913.
[84] Hanifi S, Cammarono A, Zare-Behtash H. Advanced hyperparameter optimization of deep learning models for wind power prediction. Renewable Energy 2024;221:119700. doi:10.1016/j.renene.2023.119700.
[85] Bejani MM, Ghatee MA. A systematic review on overfitting control in shallow and deep neural networks. Artif Intell Rev 2021;54:6391–438. doi:10.1007/s10462-021-09975-1.
[86] Zhang T, Wu S, Shen W, Fang Y. On the alkalinity of solid catalysts for transesterification of dimethyl carbonate and ethanol. Appl Sci 2025;15:7225. doi:10.3390/app15137225.
[87] Erwanto E, Warsito W, Sabarudin A, Mardiana D, Iftitah ED. Immobilized L-arginine on methacrylate polymer as reusable heterogeneous catalyst for crude palm oil transesterification. Int J Renewable Energy Dev 2026;15:522–31. doi:10.61435/ijred.2026.61761.
[88] Basumatary S, Nath B, Das B, Kalita P, Basumatary B. Utilization of renewable and sustainable basic heterogeneous catalyst from Heteropanax fragrans (Kesseru) for effective synthesis of biodiesel from Jatropha curcas oil. Fuel 2021;286:119357. doi:10.1016/j.fuel.2020.119357.
[89] Saetiao P, Kongrit N, Jitjamnong J. Waste-derived mesoporous biochar for glycerol to glycerol carbonate upgrading: intensified process design and techno-economic analysis. RSC Adv 2026;16:10984–1004. doi:10.1039/D5RA09460G.
[90] Aleman-Ramirez L, Moreira J, Torres-Arellano S, Longoria A, Okoye PU, Sebastian JP. Preparation of a heterogeneous catalyst from moringa leaves as a sustainable precursor for biodiesel production. Fuel 2021;284:118983. doi:10.1016/j.fuel.2020.118983.
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