The comparatively greater cost of producing biodiesel in comparison to petroleum diesel is one of the key drawbacks. Eggshells and leftover chicken fat are examples of poultry wastes that can be used to produce biodiesel at a low cost as catalysts and oil, respectively. In this study, eggshell-derived CaO and its doping with sodium methoxide catalyst for enhancing catalytic activity was synthesized for the transesterification of waste chicken fat and characterized by FT-IR and XRD analyses. XRD studies confirmed the crystalline structure of the developed catalyst and doping of sodium with eggshell-derived CaO. The transesterification reaction was performed at different reaction parameters such as the catalyst loading, the methanol to oil ratio, the reaction temperature, and the reaction time. The biodiesel produced at the maximum yield was evaluated by gas chromatography mass spectrometry analysis. A maximum yield of 96% biodiesel was obtained with catalyst loading of 2 wt% of oil, as well as a methanol to oil ratio of 13:1 at 60 °C in 1 h. The output demonstrates that eggshell waste is a potentially accessible source of biomass-derived nano catalyst for the synthesis of biodiesel using chicken fat as a feedstock.

In the current study, magnetic oxide nanoparticle-impregnated tea waste (TW-Fe₃O₄) is employed as an adsorbent to remove phosphate ions (PO₄³⁻) from an aqueous solution. By utilizing a variety of analytical methods, the TW-Fe₃O₄ nano-adsorbent was characterized by FE-SEM, TEM, EDX, BET, FTIR and XRD. The FE-SEM of TW-Fe₃O₄ demonstrated the adsorbent’s granular morphology with a variety of magnetic nanoparticle sizes and shapes. The XRD of TW-Fe₃O₄ showed two diffraction peaks at 2θ values 30.9° and 35.4°, which are in correspondence with the diffraction pattern of magnetite. The synthesis of a TW-Fe₃O₄ adsorbent with a greater surface area and porosity was demonstrated by BET analysis. Numerous adsorption factors like initial concentration of PO₄³⁻ ion, pH of the medium, contact time, temperature and adsorbent dose were optimized for phosphate removal. The maximum removal of 92% was achieved by using the adsorbent dose of 1.2 g at 323 K (pH 5). Pseudo-second-order and intra-particle diffusion models were fitted to the sorption kinetic, whereas adsorption isotherm data were found well fitted to Freundlich and Dubinin–Radushkevich (D-R) models. The highest adsorption capacity of TW-Fe₃O₄ towards phosphate ions was 226.8 mg/g, which is significantly higher than other reported bio-adsorbents. According to thermodynamic data, phosphate adsorption at the solid–liquid interface was of an endothermic and spontaneous nature and characterized by enhanced inevitability.