Sustainable microwave-supported biodiesel production using sandbox oil and its waste shell as a nanoparticle green alkali heterogeneous catalyst

Abstract

This present work explored the possible use of sandbox seed (Hura crepitans) shell (SSS) waste as a feedstock for synthesizing green solid alkali biocatalyst in the microwave-aided sandbox oil (SBO) transesterification to obtain SBO biodiesel (SBOB). The solid catalyst was produced using a calcination method by burning raw SSS in the open air to obtain ash heated for 3 h in a furnace at 500 oC. The calcined sandbox shell ash (CSSA) produced was characterized using standard techniques to establish its catalytic potency. Also, a model was developed to simulate the process and examine the interactive effect of process input variables on SBOB yield using the Taguchi approach. The CSSA characterization showed it composed of K (44.99%), Ca (1.54%), and Mg (1.87%) with crystalline compounds of K and Mg. The physisorption results gave a mean pore size of 18.142 nm and a surface area of 6.1125 m2/g. The best combination of the input variables determined for the process is a heating power of 450 W, methanol:SBO of 8:1, time of 1.5 min, and CSSA loading of 2 wt.% with an optimum SBOB yield of 98.27 wt.%. The SBOB produced met standard specifications for biodiesel. Microwave application to the SBO transesterification aided in rapidly completing the reaction. The study concluded that sandbox seeds and their shells are promising feedstock for cheap and sustainable biodiesel production.