Utilization of waste coral for biodiesel production via transesterification of soybean oil

Abstract

In the present study, the waste coral was utilized as a source of calcium oxide for transesterification of soybean oil into biodiesel (methyl esters). Characterization results revealed that the main component of the waste coral is calcium carbonate which transformed into calcium oxide when calcined above 700°C. The Box-Behnken design of experiment was carried out, and the results were analyzed using response surface methodology. Calcination temperature, methanol-soybean oil molar ratio and catalyst concentration were chosen as variables. The methyl ester content (wt%) was response which must be maximized. A second-order model was obtained to predict methyl ester content as a function of these variables. Each variable was placed in the three low, medium and high levels (calcination temperature of 700, 800 and 900°C; catalyst concentration of 3, 6 and 9 wt%; methanol-to-oil ratios of 12:1, 18:1 and 24:1). The optimum conditions from the experiment were found that the calcination temperature of 900°C, catalyst concentration of 6 wt% and methanol-tooil ratio of 12:1. Under these conditions, methyl ester content reached to 100 wt%. The waste catalyst was capable of being reused up to 4 times without much loss in the activity.

Application of K-Impregnated Staghorn Coral as Catalyst in the Transesterification of Waste Cooking Oil

“…However, when the ratio exceeded the optimum value, the reaction rate dropped significantly since too much methanol could result in the reduction of catalyst concentration and shifting the equilibrium to the reactant side (Sinha & Murugavelh 2016). In addition, the excessive amount of methanol caused the glycerol to dissolve and resulted in difficulty during the separation of biodiesel and glycerol (Moradi & Mohammadi 2014). The effect of reaction time on the percentage of biodiesel conversion using K-CaO catalyst is shown in Figure 6(b).…”

“…In the present work, the loading of the catalyst by more than 4 wt. % showed an adverse effect on the methyl esters conversion, which might be due to mass transfer problem and saponification process (Moradi & Mohammadi 2014). Meanwhile, the CaO catalyzed transesterification required higher catalyst loading (6 wt.…”

An experimental investigation of direct biodiesel production from castor seed using waste resource as economical catalyst

“…Finding alternative energy sources due to depletion in fossil fuel and increasing environmental issues has attracted many researchers' attentions to extend innovative research programs around the world . Biodiesel was found as the best substitution for petroleum‐based diesel fuel which it is similar in some properties such as cetane number, specific gravity, and boiling point with diesel fuel .…”