Converting neem seed-derived oil into biodiesel using zeolite ZSM-5 as an efficient catalyst via electrosynthesis procedure: Optimization of operating variables using response surface methodology (RSM)

Abstract

Biodiesel has been contemplated as the best alternative to diesel fuel, owing to its distinctive qualities which cause environmental preservation. The purpose of this research is to convert Neem Seed-Derived Oil (NSDO) into biodiesel through zeolite ZSM-5 as a heterogeneous acid catalyst, by applying an electrosynthesis technique. The response surface methodology according to central composite design (RSM-CCD) was exerted to optimize the process conditions and obtain a reliable model. Based on the RSM-CCD technique, the parametric range for optimization study was as follows: voltage of 10–40 V, time of 0.5–1.5 h, Me/NSDO of 10–30 molar ratio, and catalyst amount of 2–6 wt%. The best yield of produced biodiesel, based on the design of the experiment's model predictions, was 85.96%, and based on the experimental observations, was obtained at 86.03%, which indicates a very high adaptation of experimental design with experimental data. The optimal operating conditions, to get the best process efficiency, were as follows: voltage of 25 V, time of 1 h, Me/NSDO (Methanol to Neem Seed Derived Oil) molar ratio of 20:1, and catalyst amount of 6 wt%. The reaction yielded satisfactory results due to the catalyst's exceptional efficiency, which also demonstrated impressive performance and reusability, exhibiting only a 14% reduction in yield after five successive cycles. The catalyst was characterized by analyses, and moreover the produced biodiesel was analyzed by qualitative and quantitative analyses of FT-IR (Fourier Transform Infrared Spectroscopy) and GC-FID (Gas Chromatography with Flame Ionization Detector). As well as, to investigate the produced biodiesel quality, physicochemical analyzes were used, according to ASTM (American Society for Testing and Materials) standards, and the measured results were completely consistent with the quality characteristics of diesel fuel.