Green Nano-Composite of CaO/K-Sulfated TiO2 and Its Potential as a Single-Step Reaction Solid Catalyst for Biofuel Production
In the esterification-transesterification method, a catalyst increases the reaction rate to produce biofuel (biodiesel). This study investigated the use of a solid catalyst consisting of green nano-CaO as a support modified by KOH solution and sulfated TiO2 for converting waste frying oil (WFO) into biodiesel in a single-step esterification-transesterification reaction. With nano-CaO prepared from eggshell, a green nanocomposite of CaO/K-sulfated TiO2 was synthesized by physical mixing and the hydrothermal method. Crystallite size, surface basicity-acidity, functional groups, and surface morphology were used to characterize the solid catalyst, which was then tested for its ability to convert WFO into biodiesel. The results showed that green-CaO had nanoparticles (93.13 nm) and that its size decreased after being modified with KOH (46.43 nm) and sulfated TiO2 (62.10 nm), with CaO/K-sulfated TiO2 being the optimum surface acidity-basicity. The optimum conditions for conversion were found to be 5% catalyst concentration to oil, a molar ratio of methanol/oil of 9:1, and a reaction time of 60 minutes, which resulted in a biodiesel mass yield of 94.17% higher than CaO/K (67.88%). WFO was successfully converted into fatty acid methyl esters, according to the GC-MS analysis of the biodiesel. The synthesized solid catalyst has the potential to be used in single-step esterification-transesterification reactions to produce biodiesel.
Keywords: Biofuel, CaO/K-sulfated TiO2Green Nano-composite, Eggshell, Single-step Reaction, Waste Frying Oil
 Sivasamy A, Cheah KY, Fornasiero P, Kemausuor F, Zinoviev S, Miertus S. Catalytic applications in the production of biodiesel from vegetable oils. ChemistrySustainability-Energy-Materials. 2009;2:278-300.
 Panudare DC, Rathod VK. Application of waste cooking oil other than biodiesel: Review. Iranian Journal of Chemical Engineering. 2015;12(3):55-76.
 Math MC, Kumar SP, Chetty SV. Technologies for biodiesel production from used cooking oil - A review. Energy for Sustainable Development. 2010;14:339-345.
 Zhang J, Chen S, Yang R, Yan Y. Biodiesel production from vegetable oil using heterogeneus acid and alkali catalyst. Fuel Processing Technology. 2010;89:2939- 2944.
 Enweremadu CC, Mbarawa MM. Technical aspects of production and analysis of biodiesel from used cooking oil-a review. Renewable and Sustainable Energy Reviews. 2009;13(9):2205-2224.
 Kulkarni MG, Dalai AK. Waste cooking oil-an economical source for biodiesel: A review. Industrial and Engineering Chemistry Research. 2006;45:2901-2913.
 Guo F, Fang Z. Biodiesel production with solid catalysts. Biodiesel Feedstocks and Processing Technologies. 2011;16(1):339-358.
 Atadashi IM, Aroua MK, Aziz AR, Sulaiman NMN. The effects of catalysts in biodiesel production: A review. Journal of Industrial and Engineering Chemistry. 2013;19(1):14– 26.
 Silva LCA, Silva EA, Monteiro MR, Silva C, Teleken JG, Alves HJ. Effect of the chemical composition of smectites used in KF/clay catalysts on soybean oil transesterification into methyl esters. Applied Clay Science. 2014;102:121–127.
 Simpen IN, Negara IMS, Puspawati NM. The characterization of heterogeneous nanocatalyst of biohydroxyapatite-lithium and its application for converting malapari seed oil (Milletia pinnata L.) to biodiesel. Oriental Journal of Chemistry. 2018;34(4):1817-1823
 Borges ME, Diaz L. Recent developments on heterogeneous catalysts for biodiesel production by oil esterification and transesterification reactions: A review. Renewable and Sustainable Energy Reviews. 2012;16:2839-2849.
 Salinas D, Guerrero S, Araya P. Transesterification of canola oil on potassiumsupported TiO2 catalysts. Catalysis Communications. 2010;11:773-777.
 Istadi I, Prasetyo SA, Nugroho TS. Characterization of K2O/CaO-ZnO catalyst for transesterification of soybean oil to biodiesel. Procedia Environmental Sciences. 2015;23:394-399.
 Carlucci C, Degennaro L, Luisi R. Titanium dioxide as a catalyst in biodiesel production. Catalysts. 2019;9(75):1-25.
 He J-Y, Wang H, Liao D-Z, Jin Y-K. Preparation, surface acidity and catalytic esterification activity of solid acid S2O82-/TiO2–La2O3. Paper presented at: 4th Annual International Conference on Material Science and Engineering (ICMSE); June 17-19, 2016. Guangzhou, Guangdong, China.
 Pratigto S, Istadi. Kinetika reaksi transesterifikasi minyak kedelai menjadi biodiesel dengan katalis CaO. Jurnal Kimia Sains dan Aplikasi. 2019;22(5):213-219.
 Colombo K, Ender L, Barros AAC. The study of biodiesel production using CaO as a heterogeneous catalytic reaction. Egyptian Journal of Petroleum. 2016;30:1-9.
 Marinković DM, Stanković MV, Veličković AV et al. Calcium oxide as a promising heterogeneous catalyst for biodiesel production: current state and perspectives. Renewable and Sustainable Energy Reviews. 2016;56:1387–1408.
 Mazaheri H, Ong HC, Amini Z et al. An overview of biodiesel production via calcium oxide based catalysts: Current state and perspective. Energies. 2021;14(3950):1-23.
 Degfie TA, Mamo TT, Mekonnen YS. Optimized biodiesel production from waste cooking oil (WCO) using calcium oxide (CaO) nanocatalyst. Scientific ReportsNatureresearch. 2019;9(18982):1-8.
 Sani YM, Daud WMAW, Aziz ARA. Activity of solid acid catalysts for biodiesel production: A critical review. Applied Catalysis A: General. 2014;470:140-160.
 Bobade SN, Khyade VB. Detail study on the properties of Pongamia pinnata (Karanja) for the production of biofuel. Research Journal of Chemical Sciences. 2012;12(7):16-20.
 Abbah EC, Nwandikom GI, Egwuonwu CC, Nwakuba NR. Effect of reaction temperature on the yield of biodiesel from neem seed oil. American Journal of Energy Science. 2016;3(3):16-20
 Peng Y-P, Amesho KTT, Chen C-E, Jhang S-R, Chou F-C, Lin Y-C. Optimization of biodiesel production from waste cooking oil using waste eggshell as a base catalyst under a microwave heating system. Catalysts 2018;8(81):1-16.
 Mirghiasi Z, Bakhtiari F, Darezereshki E, Esmaeilzadeh E. Preparation and characterization of CaO nanoparticles from Ca(OH)2 by direct thermal decomposition method. Journal of Industrial and Engineering Chemistry. 2014;20:113-117.
 Habte L, Shiferaw N, Mulatu D, Thenepalli T, Chilakala R, Ahn JW. Synthesis of nanocalcium oxide from waste eggshell by sol-gel method. Sustainability. 2019;11(3196):1- 10.
 Pandya S. Nanocomposites and its application - Review. Parul University. Gujarat, India; 2015.
 Benito HE, Sanchez TDA, Alamilla RG, Enriquez JMH, Robles GS, Delgalo FP. Synthesis and physicochemical characterization of titanium oxide and sulphated titanium oxide obtained by thermal hydrolysis of titanium tetrachloride. Brazilian Journal of Chemical Engineering. 2014;31(3):737-745.