Spent mushroom substrate of Ganoderma lucidum developed nanocatalyst (CSA/BaO@K2CO3) for efficient biodiesel synthesis from blended oil feedstock

Abstract

The dietary and biological advantages of mushrooms are driving a global boom in the mushroom industry. The widespread production of mushrooms corresponds to disposal challenge, generating a significant volume of biowaste known as spent mushroom substrate. Their use as a catalyst can assist in lowering the expense of producing catalyst and the issue related to their disposal. Hence, the current study focused on developing a nanocatalyst for biodiesel synthesis from a blend of eight different types of oil. The catalyst was synthesized by using spent mushroom substrate (sawdust) of Ganoderma lucidum as the foundation of the catalyst, which was impregnated by BaO and K₂CO₃ via the wet-impregnation method followed by calcination. The developed nanocatalyst CSA/BaO@K₂CO₃ (CSA, calcined spent substrate ash) was characterized via various sophisticated methods like XRD (X-ray Diffraction), BET (Brunauer-Emmett-Teller), FT-IR (Fourier Transform Infrared Spectroscopy), FESEM (Field Emission Scanning Electron Microscopy) - EDX (Energy Dispersive Spectroscopy), XPS (X-ray photoelectron spectroscopy), HRTEM (High Resolution Transmission Electron Microscopy), and SAED (Selected Area Electron Diffraction). The HRTEM data showed that the average particle size of CSA/BaO@K₂CO₃ was 14.368 ± 0.262 nm, which confirmed it as a nanocatalyst. The synthesized catalyst’s catalytic activity was investigated for the transesterification of the blended oil (BO), where the influence of different optimum parameters was investigated. The catalyst consisted of a BET surface area of 16.441 m² g⁻¹ and resulted in the highest biodiesel yield of 94.36 ± 0.29 % under the optimized reaction conditions of 10 wt% of catalyst load, 9:1 of methanol to oil molar ratio (MTOMR), 65 ℃ of reaction temperature, and 34.67 ± 0.58 min of reaction duration. The biodiesel conversion under the optimized condition was also determined and found to be 95.85 %. The conversion of biodiesel was confirmed using spectroscopic techniques. The reusability test was carried out and found that the catalyst was reusable for up to three cycles. The energy of activation for transesterification using the synthesized catalyst was evaluated to be 83.55 kJ/mol.