A novel heterogeneous catalyst synthesis from agrowastes mixture and application in transesterification of yellow oleander-rubber oil: Optimization by Taguchi approach

This study focused on preparing a new green heterogeneous alkali catalyst from cocoa, kola nut, and fluted pumpkin wastes and its application to the transesterification of yellow oleander-rubber seed oil (YORSO) blend. The mixture of chars from cocoa, kola nut, and fluted pumpkin husks in ratio 1:1:1 by weight was heated in a muffle furnace from 300 to 1100 degrees C for 4 h at 300 degrees C intervals. Different blends of YORSO were evaluated to select the best ratio suited to produce quality biodiesel. The Taguchi design approach was used to model and optimize the esterification and transesterification processes by considering catalyst concentration, methanol: YORSO, time, and temperature. The oil blend of ratio 50:50 had the best properties for biodiesel production, but it required acid pretreatment due to its high acid value (31.64 mg KOH/ g). The agrowastes mixture calcined at 500 degrees C for 4 h (named CCKP) was selected due to its catalytic potentials (K (48.4%), Ca (5.1%), Fe (1.1%), a large surface area of 17.266 m2/g, and a pore diameter of 12.59 nm). The optimum values for the esterification of the YORSO were achieved with H2SO4 of 1 wt%, methanol:YORSO of 9:1, 55 degrees C, and 45 min with a resultant FFA of 0.52%. In contrast, the optimum values for the transesterification of the esterified YORSO were methanol: esterified YORSO of 9:1, CCKP of 1.5 wt%, 55 degrees C, and 40 min with a resultant biodiesel yield of 95.02 wt%. The biodiesel composition met standard specifications, making it a likely transportation fuel. The CCKP could be used for four reaction cycles with high yields. Thus, the feedstock used offers a promising prospect to the biodiesel sustainability and economy while serving as a value-addition for the agrowastes.

Automated summary

This study developed a new green heterogeneous alkali catalyst from cocoa, kola nut, and fluted pumpkin wastes for transesterification of yellow oleander-rubber seed oil blend. By optimizing catalyst concentration, temperature, and time, high yields of biodiesel were achieved, demonstrating the potential for sustainable and economic biodiesel production using agricultural waste materials.