an official journal of: published by:
an official journal of: published by:
Editor in Chief: RAFFAELLO COSSU


  • Ateeq Rahman - Faculty of Agriculture Engineering and Natural Resources, University of Namibia, Namibia
  • Hilaria Hakwenye - Faculty of Agriculture Engineering and Natural Resources, University of Namibia, Namibia
  • Veikko Uahengo - Faculty of Agriculture Engineering and Natural Resources, University of Namibia, Namibia

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Copyright: © 2023 CISA Publisher


Sustainability is crucial for the survival of mankind, ecosystem for the development of society. There have been huge amount of waste have been dumped which creates pollutions. Hence, from Green chemistry perspective it is a protocol to design heterogeneous catalysts which can yield products from waste products with minimization of wastes pollution with environmentally friendly heterogeneous catalytic process for the developed environmentally friendly products with longevity. Such green synthesized heterogeneous catalysts will replace the existing homogeneous process to heterogeneous catalysts being developed from waste materials. This abstract highlight key aspects on the preparation of heterogeneous catalysts derived from waste materials such as egg shell, rice husk for synthesis of Ag Nanoparticles developed, which can applied for biomass conversions, to environmental remediation, heterogeneous catalysts for organic transformations. These egg shell CaO catalysts are characterized using analytical techniques, such as: X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), Thermogravimetric-Differential Thermal Analyzer (TG-DTA), Scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) surface area, which gives its complete picture of its structure, porosity, morphology, thermal stability, reusability, and activity of catalysts. Hence heterogeneous catalysts developed from egg shell wastes and medical plants will become increasingly popular since two decades. Since, the egg shell waste is developed into egg shell CaO catalysts for cleaner, reusable, eco-friendly catalysts for economic growth for Namibia and other developing and underdeveloped countries.


Editorial History

  • Received: 13 Jul 2023
  • Revised: 31 Aug 2023
  • Accepted: 14 Sep 2023
  • Available online: 31 Dec 2023


Abboud, Y., Saffaj, T., Chagraoui, A., Ei-Bouari, A., Brouzi, K., Tanane, O., & Ihssane, B. (2014). Biosynthesis, Characterization and antimicrobial activity of copper oxide nanoparticles (CONPs) produced using brown alga extract (Bifurcaria bifurcata). Applied Nanoscience (4,) 571–576.
DOI 10.1007/s13204-013-0233-x

Akhtar, M.S., Panwar, J., Yun, Y.S. (2013). Biogenic Synthesis of Metallic Nanoparticles by Plant Extracts. ACS Sustain. Chem. Eng. 1, 591–602.
DOI 10.1021/sc300118u

Alavi, M. M, & Morsali A (2010). Ultrasonic-assisted synthesis of Ca (OH)2 and CaO nanostructures. J Exp Nanosci., (5), 93–105.
DOI 10.1080/17458080903305616

Al-Ghouti, M. A., & Salih, N. R. (2018). Application of eggshell wastes for boron remediation from water. Journal of Molecular Liquids, 256, 599–610.
DOI 10.1016/j.molliq.2018.02.074

Ali, S., Butt, A. R., Ejaz, S., Baron, J. C., & Ikram, M. (2015). CaO Nanoparticles as a Potential Drug Delivery Agent for Biomedical Applications. Digest Journal of Nanomaterials and Biostructures, 10(3), 799 – 809

Aljabali A.A. A, Akkam Y, Zoubi MS Al, Al-Batayneh KM, AlTrad B, Abo Alrob O, Alkilany AM, Benamara M., & Evans D.J (2018). Synthesis of gold nanoparticles using leaf extract of Ziziphus zizyphus and their antimicrobial activity. Nanomaterials. (8), 174.
DOI 10.3390/nano8030174

Alobaidi, Y. M., Ali, M. M., & Mohammed, A. M. (2022). Synthesis of Calcium Oxide Nanoparticles from Waste Eggshell by Thermal Decomposition and their Applications. Jordan Journal of Biological Sciences, 15(2), 269–274. 73.
DOI 10.54319/jjbs/150215

Anantharaman A, Ramalakshmi S., & George M. (2016). Green synthesis of calcium oxide nanoparticles and its applications. International Journal of Engineering Research and Application 6(10): 27–31

Anastas P T. & Warner J.C. (1998). Green Chemistry: Theory and Practice. Oxford, England: Oxford University Press

Anastas, P .T. Warner, J.C. (2000). Green Chemistry: Theory and Practice. Oxford, UK: Oxford University Press:

Anjana P. A., Niju S.P., Begum, M, K., Narayanan, A. (2016). Studies on biodiesel production from Pongamia oil using heterogeneous catalyst and its effect on diesel engine performance and emission characteristics. Biofuels 7 (4), 377-387.
DOI 10.1080/17597269.2015.1138039

Arizzi, A., Gomez-Villalba, L.S., Lopez-Arce, P., Cultrone, G., & Fort, R. (2015). Lime mortar consolidation with nanostructured calcium hydroxide dispersions: the efficacy of different consolidating products for heritage conservation. Eur. J. Mineral. 27, 311–323

AshaRani, P.V., Mun, G.L.K., Hande, M.P., & Valiyaveettil, S. (2009). Cytotoxicity and genotoxicity of silver nanoparticles in human cells. ACS Nano 3(2), 279–290.
DOI 10.1021/nn800596w

Asri N.P, Podjojono B, Fujiani R & Nuraini (2017). IOP Conference Series: Earth and Environmental Science 67.
DOI 10.1088/1755-1315/67/1/012021

Ateeq R, Musere P, Uahengo V, Daniel L. S., John. N, Bhaskurani S V H, & Jonnalagadda S. B (2021). Biosynthesis of silver nanoparticles using pearl millet (Pennisetum glaucum) husk to remove algae in the water and catalytic oxidation of benzyl alcohol. Journal of Cleaner Production, 312, 127581

Awogbemi, O., Inambao, F., & Onuh, E. I. (2020). Modification and characterization of chicken eggshell for possible catalytic applications. Heliyon, (6).
DOI 10.1016/j.heliyon.2020.e05283

Badnore, A.U, Jadhav, N.L, Pinjari, D.V, Pandit, A.B, (2018). Efficacy of newly developed nano-crystalline calcium oxide catalyst for biodiesel production. Chemical Engineering and Processing Process Intensification, 133, 312-319.
DOI 10.1016/j.cep.2018.09.007

Balaz, M., Boldyreva, E. V., Rybin, D., Pavlovic, S., Rodríguez-Padrón, D., Mudrinic, T., & Luque, R. (2021). State-of-the-Art of Eggshell Waste in Materials Science : Recent Advances in Catalysis, Pharmaceutical Applications, and Mechanochemistry. Frontiers in Bioengineering and Biotechonolgy, 8, 1–28.
DOI 10.3389/fbioe.2020.612567

Bennet J. A., Wilson, K, & Lee, A. F. (2016). Catalytic applications of waste derived materials. Journal of Materials Chemistry A, 4, 3617-3637

Bhumkar, D.R., Joshi, H.M., Sastry, M., & Pokharkar, V.B. (2007). Chitosan reduced gold nanoparticles as novel carriers for transmucosal delivery of insulin. Pharm. Res. 24(8), 1415–1426.
DOI 10.1007/s11095-007-9257-9

Birla A., Singh B., Upadhyay S. N., & Sharma Y. C. (2012). Kinetics studies of synthesis of biodiesel from waste frying oil using a heterogeneous catalyst derived from snail shell. Bioresource Technology, 106, 95–100.
DOI 10.1016/j.biortech.2011.11.065

Boey, P. L., Maniam, G. P., & Hamid, S. A. (2009). Biodiesel production via transesterification of palm olein using waste mud crab (Scylla serrata) shell as a heterogeneous catalyst. Bioresource Technology, 100(24), 6362–6368.
DOI 10.1016/j.biortech.2009.07.036

Borhade, A.V., Uphade, B.K., & Gadhave, A.G. (2016). Calcined eggshell: an environmentally benign green catalyst for synthesis of 2-arylbenzothiazole derivatives. Research on Chemical Intermediate 42(7), 6301-6311.

Boro, J., Thakur, A. J., & Deka, D. (2011). Solid oxide derived from waste shells of Turbonilla striatula as a renewable catalyst for biodiesel production. Fuel Processing Technology, 92(10), 2061–2067.
DOI 10.1016/j.fuproc.2011.06.008

Chakraborty R., Bepari S. & Banerjee A (2010). Transesterification of soybean oil catalyzed by fly ash and egg shell derived solid catalysts. Chemical Engineering Journal (165), 798–805.
DOI 10.1016/j.cej.2010.10.019

Cheng, H., Wei, J., Liang, M., Dai, S., Liu, M., Wang, H., & Lai, F. (2021). Calcium Glycerolate Catalyst Derived from Eggshell Waste for Cyclopentadecanolide Synthesis. Frontiers in chemistry. (9), 770247.
DOI 10.3389/fchem.2021.770247

Cheong, S. Watt, J.D. & Tilley, R.D. (2010). Shape control of platinum and palladium nanoparticles for catalysis. Nanoscale, 10, 2045–2053

Chiu, C.Y., Ruan, L., & Huang, Y., (2013). Biomolecular specificity-controlled nanomaterial synthesis. Chemical Society Reviews, 7, 2512–2527

Choi H.J., Lee S. M. (2015). Heavy metal removal from acid mine drainage by calcined eggshell and microalgae hybrid system. Environmental Science and Pollution Research International, 22 (17), 13404–13411.
DOI 10.1007/s11356-015-4623-3

Chraibi, S., Moussout, H., Boukhlifi, F., Ahlafi, H., & Alami, M. (2016). Utilization of Calcined Eggshell Waste as an Adsorbent for the Removal of Phenol from Aqueous Solution. Journal of Encapsulation and Adsorption Sciences, 6(4), 132-146.
DOI 10.4236/jeas.2016.64010

Correia L. M., Saboya R. M. A., Campelo Nd. S., Cecilia J. A., Rodriguez-Castellon E. Cavalcante, C. L., & Vieira R. S. (2014). Characterization of calcium oxide catalysts from natural sources and their application in the transesterification of sunflower oil. Bioresource Technology, 51, 207–213

Darcanova, O., Beganskiene, A., & Kareiva, A. (2015). Sol-gel synthesis of calcium nanomaterial for paper conservation. Chemija. 26(1), 25–31

Dubey, S.P., Lahtinen, M., & Sillanpaa, M. (2010). Tansy fruit mediated greener synthesis of silver and gold nanoparticles. Process Biochemistry, 45(7), 1065–1071.
DOI 10.1016/j.procbio.2010.03.024

Dwivedi, A.D., Gopal, K. (2011). Plant-mediated biosynthesis of silver and gold nanoparticles. Journal of Biomedical Nanotechnology, 7(1), 163–164.
DOI 10.1166/jbn.2011.1250

Edison, T.J.I., & Sethuraman, M. (2012). Instant green synthesis of silver nanoparticles using Terminalia chebula fruit extract and evaluation of their catalytic activity on reduction of methylene blue. Process Biochemistry, 47, 1351–1357.
DOI 10.1016/j.procbio.2012.04.025

Eletta, O. A. A., Ajayi, O. A., Ogunleye, O. O., & Akpan, I. C. (2016). Adsorption of cyanide from aqueous solution using calcinated eggshells: Equilibrium and optimization studies. Journal of Environmental Chemical Engineering, 4(1), 1367–1375.
DOI 10.1016/j.jece.2016.01.020

Espitia, P.J.P., Soares, N.F.F., dos Reis Coimbra, J.S., de Andrade, N.J., Cruz, R.S., & Medeiros, E.A.A. (2012). Zinc oxide nanoparticles: Synthesis, antimicrobial activity and food packaging applications. Food Bioprocess Technology, 5, 1447–1464.
DOI 10.1007/s11947-012-0797-6

Farooq M., Ramli A., Naeem A., Mahmood T., Ahmad S., Humayun M., & Ul Islam M. G. (2018). Biodiesel production from date seed oil (Phoenix dactylifera L.) Via egg shell derived heterogeneous catalyst. Chemical Engineering Research Design, 132, 644-651

Fava, F.; Totaro, G.; Diels, L.; Reis, M.; Duarte, J.; Carioca, O.B.; Poggi-Varaldo, H.M.; & Ferreira, B.S. (2015). Biowaste biorefinery in Europe: Opportunities and research & development needs. New Biotechnology, 32(1), 100–108.
DOI 10.1016/j.nbt.2013.11.003

Freedman, B., Butterfield, R. O, & Pryde, E. H. (1986). Transesterification kinetics of soybean oil. Journal of the American Oil Chemists Society, 63, 1375-80.
DOI 10.1007/BF02679606

Furuta, S., Matsuhashi, H., & Arata, K. (2006). Green diesel fuel production with solid amorphouszirconia catalyst in fixed bed reactor. Biomass and Bioenergy, 30(10), 870-87

Gao, Y. J., Zhao, Q., Li, Y. H., Li, Y. Q., Gou, J. F., & Cheng, X. W. (2020). Degradation of sulfamethoxazole by peroxymonosulfate activated by waste eggshell supported Ag2O-Ag nano–particles. Chemical Engineering Journal, 405.
DOI 10.1016/j.cej.2020.126719

Gao, Y., & Xu, C., (2012). Synthesis of dimethyl carbonate over waste eggshell catalyst. Catalysis Today, 190(1), 107-111.
DOI 10.1016/j.cattod.2011.12.004

Ghiasi, M., & Malekzadeh, A., (2012). Synthesis of CaCO3 nanoparticles via citrate method and sequential preparation of CaO and Ca(OH)2 nanoparticles. Crystal Research Technology, 47(4), 471– 478.
DOI 10.1002/crat.201100240

Ghosh, P.R., Fawcett, D., Sharma, S.B., Pierera, D., & Poinern, G.E.J. (2016). Survey of food waste generated by Western Australian fruit and vegetable producers: Options for minimization and utilization. Food Public Health, 6(5), 115–122.
DOI 10.5923/j.fph.20160605.02

Goli, J., & Sahu, O. (2018). Development of heterogeneous alkali catalyst from waste chicken eggshell for biodiesel production. Renewable Energy, 128, 142-154.
DOI 10.1016/j.renene.2018.05.048

Granados M L, Poves M D Z, Alonso D M , Mariscal R, Galisteo F C, Moreno-Tost R, Santamaría J, & Fierro J L G (2007). Biodiesel from sunflower oil by using activated calcium oxide. Applied Catalysis B: Environmental, 73(3-4), 317–26.
DOI 10.1016/j.apcatb.2006.12.017

Guo, Y. L., Yang, D. P., Liu, M. H., Zhang, X. Y., Chen, Y. S., Huang, J. L., Li, Q., & Luque, R. (2019). Enhanced catalytic benzene oxidation over a novel waste-derived Ag/eggshell catalyst. Journal of Materials Chemistry A 7 (15), 8832–8844.
DOI 10.1039/C8TA10822F

Gupta A.R., Rathod V.K (2018). Waste cooking oil and waste chicken eggshells derived solid base catalyst for the biodiesel production: optimization and kinetics. Waste Management, 79, 169–178.
DOI 10.1016/j.wasman.2018.07.022

Habte, L., Shiferaw, N., Mulatu. D., Thenepalli, T., Chilakala. R., & Ahn J. W. (2019). Synthesis of nano-calcium oxide from waste eggshell by sol-gel method. Sustainability, 11, 3196.
DOI 10.3390/su11113196

Huang, X.; Jian, P. K.; El-Sayed, I. H.; & El-Sayed, M.A. (2006). Determination of the minimum temperature required for selective photothermal destruction of cancer cells with the use of immunotargeted gold nanoparticles. Photochemistry Photobiology, 82(2), 412–417.
DOI 10.1562/2005-12-14-ra-754

Huang, Y., Ji, Y., Kang, Z., Li, F., Ge, S., Ruan, Y., & Fan, X. (2020). Integrating eggshell derived CaCO3/MgO nanocomposites and chitosan into a biomimetic scaffold for bone regeneration, Chemical Engineering Journal, 395.
DOI 10.1016/j.cej.2020.125098

Ijaz, U, Bhatti, I. A., Mirza, S., & Ashar, A. (2017). Characterization and evaluation of antibacterial activity of plant mediated calcium oxide (CaO) nanoparticles by employing Mentha pipertia extract. Materials Research Express, 4(10).
DOI 10.1088/2053-1591/aa8603

Ilgen, O., & Akin, A. N. (2009). Development of alumina supported alkaline catalyst used for biodiesel production. Turkish Journal of Chemistry, 33(2), 281–287.
DOI 10.3906/kim-0809-29

Jha, A. K., Prasad, K., & Kulkarni, A. R. (2009). Plant system: Nature’s nanofactory. Colloids Surface B, Biointerfaces, 73(2), 219–223.
DOI 10.1016/j.colsurfb.2009.05.018

Jayathilakan, K., Sultana, K., Radhakrishna, K., & Bawa, A. S., (2012). Utilization of byproducts and waste materials from meat, poultry and fish processing industries: a review. Journal of Food Science and Technology, 49(3), 278–293.
DOI 10.1007/s13197-011-0290-7

Karoshi, G., Kolar, P., Shah, S. B., Gilleskie, G., & Das, L. (2015). Calcined eggshell as an inexpensive catalyst for partial oxidation of methane. Journal of the Taiwan Institute of Chemical Engineers. 57, 123-128.
DOI 10.1016/j.jtice.2015.05.025

Kaviya, S., Santhanalakshmi, J., Viswanathan, B., Multhumary, J., & Srinivvasan, K. (2011). Biosynthesis of silver nanoparticles using Citrus sinensis peel extract and its antibacterial activity. Spectrochimca Acta Part A Molecular Biomolecular Spectroscopy, (79), 594–598.
DOI 10.1016/j.saa.2011.03.040

Khan, S. G., Hassan, M., Anwar, M., Zeshan, Khan, U. M., & Zhao, C. (2022). Mussel shell based CaO nano-catalyst doped with praseodymium to enhance biodiesel production from castor oil Fuel, 330(15).
DOI 10.1016/j.fuel.2022.125480

Khan, S., Ali, S., Zahra, G., Jamil, S., & Janjua, M. R. S. A. (2020). Synthesis of monetite micro particles from eggshell waste and study of its environmental applications: Fuel additive and catalyst. Chemical Physics Letters, 755, 137804.
DOI 10.1016/j.cplett.2020.137804

Kim M J, Park S M, Chang D R & Seo G (2010). Transesterification of triacetin, tributryin, and soy bean oil with methanol over hydrotalcites with different water content. Fuel Processing Technology, 91(6), 618-624.
DOI 10.1016/j.fuproc.2010.01.008

Laca, A., Laca, A., & Diaz, M. (2017). Eggshell waste as catalyst: A review. Journal of Environmental Management, 15; 197, 351-359.
DOI 10.1016/j.jenvman.2017.03.088

Lanzon, M., Madrid-Mendoza, J. A., Navarro-Moreno, D., & García-Vera, V. E. (2023). Use of eggshell waste: A green and effective method for the synthesis of pure calcium hydroxide suspensions. Construction and Building Materials, 377(9).
DOI 10.1016/j.conbuildmat.2023.131106

Lee, H.J.; Lee, G.; Jang, N.R.; Yun, J.H.; Song, J.Y.; & Kim, B.S. (2011). Biological synthesis of copper nanoparticles using plant extract. Nanotechnology. (1), 371–374

Lin, X., Wu, M., Wu, B., Kuga, S., Endo, T., & Huang, Y. (2011). Platinum nanoparticles using wood nanomaterials: Eco-friendly synthesis, shape control and catalytic activity for p-nitrophenol reduction. Green Chemistry, 13(2), 283–287.
DOI 10.1039/C0GC00513D

Liu, X., He, H., Wang, Y., & Zhu, S, (2007). Transesterification of soybean oil to biodiesel using SrO as a solid base catalyst. Catalysis Communications, 8(7), 1107-11.
DOI 10.1016/j.catcom.2006.10.026

Loehr, R. (2012). Agricultural Waste Management: Problems, Processes, and Approaches: Amsterdam, Netherlands: Elsevier

Malins, C., Searle, S., Malins, C., Baral, A., Turley, D., & Hopwood, L. (2014) Wasted: Europe’s Untrapped Resource: An Assessment of Advanced Biofuels from Wastes. & Residues. International Council on Clean Transportation

Mignardi, S., Archilletti, L., Medeghini, L., & De Vito, C. (2020). Valorization of Eggshell Biowaste for Sustainable Environmental Remediation. Scientific Reports, 10(2436).
DOI 10.1038/s41598-020-59324-5

Mosaddegh, E. (2013). Ultrasonic-assisted preparation of nano eggshell powder: a novel catalyst in green and high efficient synthesis of 2-aminochromenes. Ultrasonics Sonochemistry, 20(6), 1436-1441.
DOI 10.1016/j.ultsonch.2013.04.008

Mosaddegh, E., & Hassankhani, A. (2014). Preparation and Characterization of nano CaO based on eggshell waste: novel and green catalytic approach to highly efficient synthesis of pyrano [4,3-b] pyrans. Chinese Journal Catalysis, 35(3), 351-356.
DOI 10.1016/S1872-2067(12)60755-4

Nadagouda, M. N., & Varma, R. S. (2008). Green synthesis of silver and palladium nanoparticles at room temperature using coffee and tea extract. Green Chemistry, 10(8), 859–862.
DOI 10.1039/B804703K

Nagarajan, S., & Kuppusamy, K. A. (2013). Extracellular synthesis of zinc oxide nanoparticle using seaweeds of Gulf of Mannar, India. Journal of Nanobiotechnology, 11(39), 1–11.
DOI 10.1186/1477-3155-11-39

Namvar, F., Rahman, H. S., Mohamad, R., Azizi, S., Tahir, P. M., Chartrand, M. S., & Yeap, S. K. (2015). Cytotoxic Effects of Biosynthesized Zinc Oxide Nanoparticles on Murine Cell Lines. Evidence-Based Complementary and Alternative Medicine.
DOI 10.1155/2015/593014

Nasrollahzadeh, M., Sajadi, S. M, & Hatamifard A. (2016). Waste chicken eggshell as a natural valuable resource and environmentally benign support for biosynthesis of catalytically active Cu/eggshell, Fe3O4/eggshell and Cu/Fe3O4/eggshell nanocomposites. Applied Catalysis: B Environmental, 191, 209-227.
DOI 10.1016/j.apcatb.2016.02.042

Ngayakamo, B., & Onwualu, A. Z, (2022). Recent advances in green processing technologies for valorization of eggshell waste for sustainable construction materials. Heliyon, 8(6).
DOI 10.1016/j.heliyon.2022.e09649

Noiroj, K., Intarapong, P., Luengnaruemitchai, A., & Jai-In, S. (2009). A comparative study of KOH/Al2O3 and KOH/NaY catalyst for biodiesel production via transesterification from palm oil. Renewable Energy, 34(4), 1145–50.
DOI 10.1016/j.renene.2008.06.015

Nooshkam, M., & Madadlou, A. (2016). Maillard conjugation of lactulose with potentially bioactive peptides. Food Chemistry, 1(192), 831-836.
DOI 10.1016/j.foodchem.2015.07.094

Nurfitri. I., Maniam G. P., Hindryawati N., Yusoff M. M., & Ganesan, S. (2013). Potential of feedstock and catalysts from waste in biodiesel preparation: A review. Energy Conversion Management, 74, 395–402.
DOI 10.1016/j.enconman.2013.04.042

Obadiah A., Swaroopa, S., Kumar, S. V., Jeganathan, K. R, & Ramasubbu, A. (2012). Biodiesel production from Palm oil using calcined waste animal bone as catalyst. Bioresource Technology, 116, 512–516.
DOI 10.1016/j.biortech.2012.03.112

Ok, Y. S., Lee, S. S., Jeon, W. T., Oh, S. E., Usman, A. R. A., & Moon, D. H. (2011). Application of eggshell waste for the immobilization of cadmium and lead in a contaminated soil. Environmental Geochemistry and Health, (33), 31–39.
DOI 10.1007/s10653-010-9362-2

Osman, A.I, Abu-Dahrieh, J.K, Laffir, F, C, Thompson, J.M., & Rooney, D.W. (2016). A bimetallic catalyst on a dual component support for low temperature total methane oxidation. Applied Catalysis B: Environmental (187), 408-418.
DOI 10.1016/j.apcatb.2016.01.017

Oulego,P, Laca, A, Calvo, S, & Díaz, M. Díaz (2020). Eggshell-supported Catalysts for the Advanced Oxidation Treatment of Humic Acid Polluted Wastewaters. Water, 12(1), 100.
DOI 10.3390/w12010100

Paciotti, G.F., Myer, L., Weinreich, D., Gola, D., Pavel, N., McLaughlin, R. E., & Tamakin, L. (2004). Colloidal gold: A novel nanoparticle vector for tumour directed drug delivery. Drug Delivery, 11(3), 169–183.
DOI 10.1080/10717540490433895

Parfitt, J., Barthel, M., & Macnaughton, S. (2010). Food waste within food supply chains: Quantification and potential for change to 2050. Biological Science, (365), 3065–3081.
DOI 10.1098/rstb.2010.0126

Patil, S., Jadhav, S. D., & Deshmukh, M. B. (2013). Calcined eggshell (CES): An efficient natural catalyst for Knoevenagel condensation under aqueous condition. Journal of Chemical Sciences, 125(4), 851–857

Rahman, W. U., Khan, A. M., Anwer, A. H., Hasan, U., Karmakar, B., & Halder, G. (2022). Parametric optimization of calcined and Zn-doped waste eggshell catalyzed biodiesel synthesis from Hevea brasiliensis oil. Energy Nexus, 6.
DOI 10.1016/

Rahman, W. U., Yahya, S. M, Khan, Z. A., Khan, N. A., Halder, G. N., & Dhawane, S. (2021). Valorization of waste chicken egg shells towards synthesis of heterogeneous catalyst for biodiesel production: Optimization and statistical analysis. Environmental Technology & Innovation, 22(4).
DOI 10.1016/j.eti.2021.101460

Ramola, B., Joshi, N. C., Ramola, M., Chhabra, J., & Singh, A. (2019). Green synthesis, characterizations and antimicrobial activities of CaO nanoparticles. Oriental Journal of Chemistry, 35(3).
DOI 10.13005/ojc/350333

Ravindran, R., & Jaiswal, A. K. (2016). Exploitation of food industry waste for high value products. Trends in Biotechnology, 34(1), 58–69.
DOI 10.1016/j.tibtech.2015.10.008

Roschat, W., Siritanon, T., Yoosuk, Y., Sudyoadsuk, T., & Promarak, V. (2017). Rubber seed oil as potential non-edible feedstock for biodiesel production using heterogeneous catalyst in Thailand. Renewable Energy, 101, 937-944.
DOI 10.1016/j.renene.2016.09.057

Roy, A., Gauri, S. S., Bhattacharya, M., & Bhattacharya, J. (2013). Antimicrobial activity of CaO nanoparticles. Journal of Biomedical Nanotechnology, 9(9), 1570–1578.
DOI 10.1166/jbn.2013.1681

Sadeghi, M., & Husseini, M. H. (2013). A novel method for the synthesis of CaO nanoparticle for the decomposition of sulfurous pollutant. Journal of Applied Chemical Research, 7(4), 39-49

Sakai, S., Hien, V. T. T., Tuyen, L. D., Duc, H. A., Masuda, Y., & Yamamoto, S. (2017). Effects of eggshell calcium supplementation on bone mass in postmenopausal Vietnamese women. Journal of Nutritional Science and Vitaminology, 63 (2), 120–124.
DOI 10.3177/jnsv.63.120

Salama, R., Khashaba, M., & El Rouby, D. (2019). Histomorphometric evaluation of a nanosized eggshell-containing supplement as a natural alloplast: an animal study. Saudi Dent. J. 31 (3), 375–381.
DOI 10.1016/j.sdentj.2019.03.011

Shah, M., Fawcett, D., Sharma, S., Tripathy, S., & Poinern, G. E. J. (2015). Green synthesis of metallic nanoparticles via biological entities. Materials, 8(11), 7278–7308.
DOI 10.3390/ma8115377

Shan, R., Zhao, C., Lv, P., Yuan H., Yao, J. (2016). Catalytic applications of calcium rich waste materials for biodiesel: current state and perspectives. Energy Conversion Management, 127(1), 273-283.
DOI 10.1016/j.enconman.2016.09.018

Siemiradzka, W., Dolinska, B., & Ryszka, F. (2018). New sources of calcium (chicken eggshells, chelates) - preparation of raw material and tablets. Current Pharmaceutical Biotechnology, 19 7(19), 566–572.
DOI 10.2174/1389201019666180723103853

Sinha, D., & Murugavelh, S. (2016). Comparative studies on biodiesel production from Waste Cotton Cooking Oil using alkaline, calcined eggshell and pistachio shell catalyst. International Conference on Energy Efficient Technologies for Sustainability (ICEETS), 130-133.
DOI 10.1109/ICEETS.2016.7582912

Tabatabaei M., Karimi, K., Horv’ath, I. S., & Kumar R., (2015). Recent trends in biodiesel production. Biofuel Research Journal, 2(3), 258–267.
DOI 10.18331/BRJ2015.2.3.4

Tan, Y. H., Abdullah, M. O. & Nolasco-Hipolito, C. (2015). The potential of waste cooking oil-based biodiesel using heterogeneous catalyst derived from various calcined eggshells coupled with an emulsification technique: a review on the emission reduction and engine performance. Renewable and Sustainable Energy Reviews, 47, 589–603.
DOI 10.1016/j.rser.2015.03.048

Tan, Y. H., Abdullah, M. O., Nolasco-Hipolito, C., & Taufiq-Yap, Y. H. (2015).Waste ostrich- and chicken-eggshells as heterogeneous base catalyst for biodiesel production from used cooking oil: Catalyst characterization and biodiesel yield performance. Applied Energy, (160), 58-70.
DOI 10.1016/j.apenergy.2015.09.023

Tangboriboon. N., Kunanuruksapong. R., & Sirivat. A. (2012). Preparation and properties of calcium oxide from eggshells via calcination. Materials Science-Poland, 30(4), 313-322.
DOI 10.2478/s13536-012-0055-7

Taufiq-Yap Y. H., Wong P., Marliza T. S., Nurul Suziana, N. M.Tang L. H., Sivasangar S. (2013). Hydrogen production from wood gasification promoted by waste eggshell catalyst. International journal of energy research 37(14), 1866-1871.
DOI 10.1002/er.3003

Torres-Chavolla, E., Ranasinghe, & R. J., Alocilja, E. C. (2010). Characterization and functionalization of biogenic gold nanoparticles for biosensing enhancement. IEEE Transactions on Nanobiotechnology 9(5) 533–538.
DOI 10.1109/TNANO.2010.2052926

Tran, Q. H., Nguyen, V. Q., & Le, A. T. (2013). Silver nanoparticles: Synthesis, properties, toxicology, applications and perspectives. Advances in Natural Sciences Nanoscience Nanotechnology 4(3).
DOI 10.1088/2043-6262/4/3/033001

Uslu, A., Pedersen, J., Resch, G., & Fritsche, U. (2008). Maximizing the Environmental Benefits of Europe’s Bioenergy Potential; European Environment Agency (EEA): Copenhagen, Denmark, ISSN 1725-2237

Vandeginste, V. (2021). Food waste eggshell valorization through development of new composites: A review. Sustainable Materials and Technologies, 29.
DOI 10.1016/j.susmat.2021.e00317

Viriya-empikul, N., Krasae, P., Nualpaeng, W., Yoosuk, B., & Faungnawakij, K. (2012). Biodiesel production over Ca-based solid catalysts derived from industrial wastes. Fuel, 92(1), 239–244.
DOI 10.1016/j.fuel.2011.07.013

Willems, & van den Wildenberg. (2005). Roadmap Report on Nanoparticles. Spain: Centro Italiano per le Nanotecnologie

Witoon, T. (2011). Characterization of calcium oxide derived from waste eggshell and its application as CO2 sorbent, Ceramics International, 37 (8), 3291–3298.
DOI 10.1016/j.ceramint.2011.05.125

Wong, Y. C., & Ang, R. X. (2018). Study of calcined eggshell as potential catalyst for biodiesel formation using used cooking oil. Open Chemistry, (16), 1166–1175.
DOI 10.1515/chem-2018-0127

Xie, W., & Li, H. (2006). Alumina supported potassium iodide as a heterogeneous catalyst for biodiesel production from soybean oil. Journal Molecular Catalysis A: Chemical, 255(1-2), 1-9.
DOI 10.1016/j.molcata.2006.03.061

Xu, J., Hu, S., Min, L., & Wang, S. (2022). Waste eggshell-supported CuO used as heterogeneous catalyst for reactive blue 19 degradation through peroxymonosulfate activation (CuO/eggshell catalysts activate PMS to degrade reactive blue 19. Water Science & Technology, 85(11).
DOI 10.2166/wst.2022.165

Yang, N., WeiHong, L., & Hao, L. (2014). Biosynthesis of Au nanoparticles using agricultural waste mango peel extract and its in vitro cytotoxic effect on two normal cells. 134(1), 67–70.
DOI 10.1016/j.matlet.2014.07.025

Zabeti, M., Daud, W. H. A. M., & Aroua, M. K. (2009). Activity of solid catalysts for biodiesel production: A review. Fuel Processing Technology, (90), 770-777.
DOI 10.1016/j.fuproc.009.03.010