Triglyceride Conversion of Waste Frying Oil up to 98.46% Using Low Concentration K⁺/CaO Catalysts Derived from Eggshells

Abstract

In this study, biodiesel, also known as fatty acid methyl ester (FAME), was synthesized from multi-stage frying waste soybean oil using chicken eggshell-derived CaO and potassium-impregnated K + -CaO heterogeneous catalysts. Potassium-impregnated catalysts (1.25% K + -CaO, 2.5% K + -CaO, and 5% K + -CaO) were developed by treating the calcined waste eggshell powder with KOH in different wt % ratios. The catalysts were characterized using FTIR, XRD, FESEM, EDS, BET, and particle size analysis techniques. Box–Behnken design-based optimization was exploited to optimize the reaction parameters. A maximum yield of 98.46%, calculated via 1 H NMR, was achieved following a 5% K + doping, 12:1 methanol to oil molar ratio, 3% catalyst amount, 180 min reaction time, and 65 °C reaction temperature. The catalyst (5% K + -CaO) responsible for maximum biodiesel production was found to be highly reusable, with a 30.42% conversion decrease in activity after eight cycles of reuse. Gas chromatography was used to determine the composition of FAME produced from different cycles of waste soybean oil. Physicochemical parameters of the synthesized biodiesel were found to be compatible with EN and ASTM standards. This study has shown that the waste eggshell-derived heterogeneous catalysts have significant catalytic activity at relatively low K + doping and catalyst loading leading to high biodiesel conversion.

Modification of Calcium Oxide from Green Mussel Shell with Iron Oxide as a Potential Adsorbent for the Removal of Iron and Manganese Ions from Acid Mine Drainage

“…The wavenumber at 416.6 cm -1 suggests the peak of the Ca-O bond. This result is similar to CaO synthesized from eggshell, appearing at a wavenumber of 412.0 cm -1[Hossain et al, 2021].…”

Effect of Reaction Parameters on CO2 Absorption from Biogas Using CaO Sorbent Prepared from Waste Chicken Eggshell

“…The eggshell was dried in an electric oven (Memmert, UN 55) at 105 °C for 8 h. Then, the eggshell was ground into a fine powder using a blender and passed through a sieve. The sieved powder was then placed in a muffle furnace (Carbolite Gero, 30−3000 °C) and heated to 900 °C at a rate of 20 °C min −1 before being calcined for 5 h. 32 2.2.2. Carbon Dioxide Absorption.…”

Biomass Waste-Derived Catalysts for Biodiesel Production: Recent Advances and Key Challenges

“…Hence, attempts have been made to increase the basicity, stability and activity of waste shellderived CaO by doping with active metals [37][38] [39], by catalyst support [40] (Fig. 3b), and by hydration-dehydration [41][42] [43][44] (Fig.…”

“…for M + upon calcination, leading to O − vacancies [56][57]. With the intention of preparing highly basic metal doped CaO, Hossain et al [37] treated eggshell-derived CaO with different concentrations of KOH to obtain K/CaO. Among several catalysts developed (1.25, 2.5, and 5…”

“…In other work, Etim et al [91] used AAS (Atomic Adsorption Spectroscopy) to investigate possible leaching, and observed that washed biodiesel product had Na + + K + and Ca 2+ + Mg 2+ concentrations of 1.8 and 0.42 ppm respectively, while unwashed biodiesel product had corresponding concentrations of 115.6 and 0.96 ppm, respectively, confirming leaching. In order to try and limit leaching of Ca 2+ , doping of CaO with metal ions such as Na + [38] and K + [37] has been attempted. For example, CaO has been impregnated with Na-ZSM-5.…”