Hydrogen-enriched Compression Ignition Performance of RSM-optimized Neem–Karanja Hybrid Biodiesel Using Eggshell-derived Nano-catalyst
J. Environ. Nanotechnol., Volume 15, No 2 (June 2026) pp. 135-150
Abstract
Increasing demand of fossil is a big issue due to their finite abundance in nature. The present investigation explores the development of a hybrid biodiesel which refers to a fuel produced by blending Neem and Karanja non-edible oils and converting them into biodiesel via transesterification i.e., derived from vegetable feedstock (i.e.) neem and karanja seeds using Eggshell / CuO-NaOH nano catalyst through transesterification process thereby combining the complementary physicochemical properties of both feedstock into a single optimized fuel. The effects of this fuel on a 6.2 kW compression ignition engine were evaluated under hydrogen enrichment at flow rates of 2, 4, and 6 LPM (liters per minute). The main focus is on performance, combustion, and emission characteristics. The production process was optimized using a central composite rotatable design within a Response Surface Methodology (RSM) framework, considering molar ratio, catalyst concentration, agitation speed, and reaction temperature as input variables. The developed regression model was validated using analysis of variance (ANOVA) and showed statistical significance. An approximately 97% Bio-diesel yield can be achieved by optimizing the processes. The physicochemical properties, including calorific value, kinematic viscosity, and flash/fire point, showed improved performance compared to individual neem and karanja biodiesel. The engine study showed an BTE (Brake Thermal Efficiency) increase upto 38.27% when D80HyBD20 was fueled along with 6 LPM of hydrogen with relatively lower BSFC (Brake-specific fuel consumption) at part and full load operation. CO (Carbon monoxide) and UBHC (Unburned Hydrocarbon) emissions increased at partial and full load conditions; however, hydrogen injection significantly reduced CO emissions compared to baseline fuel operation. Nitrogen oxides (NOx) emissions were increase at all loads but significantly under full load. Enhanced in-cylinder pressure and heat release rate were observed at 4 LPM hydrogen supplementation for the D80HyBD20 (Diesel 80% and Hybrid biodiesel 20%) blend. Thus, the study presents a novel integration of hybrid neem–karanja biodiesel with hydrogen enrichment in order to achieve a significant BTE improvement so that it portrays the potential as a high-efficiency alternative fuel.
Full Text
Reference
Anwar, F., Tariq, M., Jan, N., Ali, G. and Kanwal, H., Optimization of biodiesel yield from non-food Karanja seed oil: Characterization and assessment of fuel properties, Sustain. Chem. Environ., 3, 100035 (2023).
https://doi.org/10.1016/j.scenv.2023.100035
Asaad, S. M., Inayat, A., Ghenai, C. and Shanableh, A., Response surface methodology in biodiesel production and engine performance assessment, Int. J. Thermoflu., 21, 100551(2023).
https://doi.org/10.1016/j.ijft.2023.100551
Aytav, E., Utilization of RSM to optimize the performance and emission of a single cylinder diesel engine using waste hazelnut biodiesel, Case Stud. Thermal. Eng., 58, 104385(2024).
https://doi.org/10.1016/j.csite.2024.104385
Bajwa, W., Adeel, I., Malik, M. A. I., Luqman, R., Khan, A. R., Latif, A., Fayaz, H. and Atika, Q., Optimization of biodiesel yield from waste cooking oil and sesame oil using RSM and ANN techniques, Heliyon, 10(15), e34804(2024).
https://doi.org/10.1016/j.heliyon.2024.e34804
Dubey, A., Ravi, P. S., Singh, J. K. and Nayyar, A., Combined effects of biodiesel-ULSD blends and EGR on performance and emissions of diesel engine using response surface methodology (RSM), Energy Nexus, 7, 100136(2022).
https://doi.org/10.1016/j.nexus.2022.100136
Folayan, A. J. and Anawe, P. A. L., Synthesis and characterization of Argania spinosa (Argan oil) biodiesel by sodium hydroxide catalyzed transesterification reaction as alternative for petro-diesel in direct injection compression ignition engines, Heliyon, 5(9), e02427(2019).
https://doi.org/10.1016/j.heliyon.2019.e02427
Garugubilli, R., Prasad, V. V. S. and Sagari, J., Experimental investigation of copper oxide nanoparticles dispersed in an Azadirachta indica oil-biodiesel blend: Stability and physicochemical properties approach, Nanosci. Technol. Int. J., 15(2), 39–50(2024).
https://doi.org/10.1615/NanoSciTechnolIntJ.2023048817
Gugulothu, S. K., Barmavatu, P. and Surya, M. S., Sustainable evaluation of 2-ethylhexyl nitrate in mahua biodiesel blends: Performance, emissions, thermal stability via RSM and ML, Case Stud. Therm. Eng., 72, 106381(2025).
https://doi.org/10.1016/j.csite.2025.106381
Hariram, V. and Bharathwaaj, R., Extraction and optimization of biodiesel yield from wax esters of Apis melifera (honey bee), Int. J. ChemTech Res., 8(9), 433-437 (2015).
Hariram, V., Dhanush, C., Ezhil, K. M., Akilandabharathu, K., Faizaan, A. M., Sivamani, S., Vasudev, K. L. and Micha, P. T., Performance assessment of artificial neural network on the prediction of Calophyllum inophyllum biodiesel through two-stage transesterification, Energy Sources, Part A: Recov. Utiliz. Environ. Eff., 43(9), 1060-1072 (2021).
https://doi.org/10.1080/15567036.2019.1634164
Hariram, V., Sathishbabu, R., Godwin, J. J., Vijayakumar, K., Sangeeth, K. E. and Kamakshi, P. K., Enhanced combustion and emission characteristics of diesel-algae biodiesel-hydrogen blends in a single-cylinder diesel engine, Res. Eng., 26, 104676 (2025).
https://doi.org/10.1016/j.rineng.2025.104676
Jamil, M. K., Usman, M., Ahsan, H., Haider, N., Yasser, F., Saleem, M. W., Abbas, N., Uzair, S. and Khalid, H., Multi-objective RSM-based optimization of diesel-diethyl ether blends in diesel engine to achieve sustainable development goals, Case Stud. Therm. Eng., 59, 104542(2024).
https://doi.org/10.1016/j.csite.2024.104542
John, G., Hariram, V., Seralathan, S. and Jaganathan, R., Effect of oxygenate on emission and performance parameters of a CI engine fuelled with blends of diesel-algal biodiesel, Int. J. Renewable Energy Res., 7(4), 2041-2047 (2017).
https://doi.org/10.20508/IJRER.V7I4.6401.G7251
Kumar, C. N., Krishnamurthy, K. N., Jayanna, V. B., Pate, M. G. C., Samuel, O. D. and Linul, E., Mesoporous CaO-ZnO-Fe3O4 catalyzed biodiesel production from Papaver somniferum: RSM + lyrebird optimization and life-cycle cost analysis, Renewable Energy, 262, 125428(2026).
https://doi.org/10.1016/j.renene.2026.125428
Naik, M., Meher, L. C., Naik, S. N. and Das, L. M., Production of biodiesel from high free fatty acid Karanja (Pongamia pinnata) oil, Biomass and Bioenergy, 32(4), 354–357(2008).
https://doi.org/10.1016/j.biombioe.2007.10.006
Rashid, U., Anwar, F., Ashraf, M., Saleem, M. and Yusup, S., Application of response surface methodology for optimizing transesterification of Moringa oleifera oil: Biodiesel production, Energy Convers. Manage., 52(8–9), 3034–3042(2011).
https://doi.org/10.1016/j.enconman.2011.04.018
Sahoo, P. K. and Das, L. M., Process optimization for biodiesel production from Jatropha, Karanja and Polanga oils, Fuel, 88(9), 1588–1594(2009).
https://doi.org/10.1016/j.fuel.2009.02.016
Sanatha, K., Bhatti, S. K. and Jaikumar, S., Influence of ZnO nanoparticles and dispersant in Baheda oil biodiesel blend on the assessment of performance, combustion, and emissions of VCR diesel engine, Appl. Nanosci., 11(11), 2689–2702(2021).
https://doi.org/10.1007/s13204-021-02233-4
Saravanan, S., Nagarajan, G., Rao, G. L. N. and Sampath, S., Feasibility study of crude rice bran oil as a diesel substitute in a DI-CI engine without modifications, Energy Sustain. Develop., 11(3), 83–92 (2007).
https://doi.org/10.1016/S0973-0826(08)60580-3
Sen, M., Optimization of performance and emission of a diesel engine fueled with isopropyl alcohol blends: A comparative ANN-GA and RSM-HCO application, Eng. Sci. Technol. Int. J., 55, 101733 (2024).
https://doi.org/10.1016/j.jestch.2024.101733
Shankar, A. A., Raj, P. P. and Prasad, R. K., Biodiesel synthesis from cottonseed oil using homogenous alkali catalyst and using heterogenous multi walled carbon nanotubes: Characterization and blending studies, Egypt. J. Petrol., 26(1), 125–133 (2017).
https://doi.org/10.1016/j.ejpe.2016.04.001
Sharma, Y., Singh, B. and Korstad, J., Application of an efficient nonconventional heterogeneous catalyst for biodiesel synthesis from Pongamia pinnata oil, Energy Fuels, 24(5), 3223–3231(2010).
https://doi.org/10.1021/ef901514a
Sruthi, K. S., Prasad, S. V. L. and Sagari, J., The investigation on stability and physicochemical properties of multi ferrites nanoparticle dispersed Tamarindus indica biodiesel, Int. J. Thermoflu., 26, 101147 (2025).
https://doi.org/10.1016/j.ijft.2025.101147
Thorve, U. U., Quazi, M. A., Bari, A. H. and Kunndu, D., Evaluation of Moringa oleifera biodiesel and ethanol blends: Impact on fuel properties and mathematical modelling, Next Energy, 7, 100231 (2025).
https://doi.org/10.1016/j.nxener.2024.100231
Venkatesan, H., Godwin, J. J. and Sivamani, S., Data set for extraction and transesterification of bio-oil from Stoechospermum marginatum, a brown marine alga, Data Brief, 14, 623-628 (2017).
