Characterization of alkaline modified anthill and investigation of its catalytic behaviour in transesterification of Chrysophyllum albidium seed oil

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

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 ¹H 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.

Sonocogreen Decoration of Clinoptilolite by CaO Nanorods as Ecofriendly Catalysts in the Transesterification of Castor Oil into Biodiesel; Response Surface Studies

A CaO/clinoptilolite green nanocomposite (CaO/Clino) was synthesized by a green modification technique using calcium nitrate and green tea extract. The CaO/Clino nanocomposite promises a total basicity of 4.82 mmol OH/g, surface area of 252.4 m²/g, and ion exchange capacity of 134.3 mequiv/100 g, which qualifies the product as an effective catalyst in the transesterification of castor oil. The transesterification performance of the CaO/Clino catalyst was addressed statistically based on the response surface methodology and central composite rotatable design, considering the essential experimental parameters. Based on the interaction effect between the studied variables, the CaO/Clino catalyst can achieve an experimental biodiesel yield of 93.8% after 2.5 h at 120 °C with 3.5 wt % catalyst loading and 15:1 ethanol/castor oil molar ratio. The optimization function of the design suggested enhancement in the performance of the CaO/Clino catalyst to achieve a yield of 95.4% if the test time interval increased to 2.65 h and the ethanol content increased to 16:1 as a molar ratio to castor oil. The produced biodiesel over CaO/ClinO has acceptable technical qualifications according to the international requirements (EN 14214 and ASTM D-6751). The synthetic green CaO/Clino nanocomposite has better recyclability as a heterogeneous catalyst and higher activity than some investigated catalysts in literature.

Titania-termite hill composite as a heterogeneous catalyst: preparation, characterization, and performance in transesterification of waste frying oil

To reveal the catalytic potential of abandoned naturally occurring material, we synthesized titania-termite hill composite (Ti-THC) via an incipient wetness impregnation route, characterized by various techniques and tested as a catalyst for transesterification of waste frying oil (WFO). The reusability of the prepared catalyst was also studied to evaluate its stability. The effects of reaction process parameters, such as temperature, time, catalyst loading and methanol/WFO molar ratio on fatty acid methyl ester (FAME) yield, were investigated using a central composite design approach. SEM result revealed pores formation on the catalyst surface, while XRD and EDX analyses confirmed successful insertion of titania into the aluminosilicate layer of the termite hill. The maximum FAME yield of 90.78% was obtained at optimum experimental conditions of 71.16 °C reaction temperature, 2.12 h reaction time, 1.03 wt.% catalyst loading and 9.96:1 methanol/WFO molar ratio. The catalyst still maintained its better stability after being reused for three reaction cycles.