Optimization of biodiesel production from waste cooking oil using waste bone as a catalyst

This work determined the association between several parameters of biodiesel production from waste cooking oil (WCO) using waste bovine bone (WBB) as catalyst to achieve a high conversion to fatty acid methyl ester (%FAME). The effect of three independent variables was used as the optimum condition using response surface methodology (RSM) for maximizing the %FAME. The RSM analysis showed that the ratio of MeOH to oil (mol/mol), catalyst amount (%wt), and time of reaction have the maximum effects on the transform to FAME. Moreover, the coefficient of determination (R²) for regression equations was 99.19%. Probability value (P < 0.05) demonstrated a very good significance for the regression model. The optimal values of variables were MeOH/WCO ratio of 15.49:1 mol/mol, weight of catalyst as 6.42 wt%, and reaction time of 128.67 min. Under the optimum conditions, %FAME reached 97.59%. RSM was confirmed to sufficiently describe the range of the transesterification parameters studied and provide a statistically accurate estimate of the best transform to FAME using WBB as the catalyst.     

ESTIMATION OF BIOACCESSIBILITY OF HEAVY METALS IN OYSTERS USING THE PHYSIOLOGICALLY BASED EXTRACTION TEST

A physiologically based extraction test (PBET) was applied to estimate the oral bioaccessibility of cadmium, mercury, and lead from oyster tissues. The PBET measures the fraction of a metal that is solubilized from the sample under simulated gastric and intestinal conditions. Both gastric and intestinal extracted solutions as well as microwave digested residue were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The bio accessibilities (relative to the total metal concentrations) of cadmium and lead in the oyster samples were 33.8–59.2% and 28.3–51.4%, respectively. The bioaccessibility of mercury was non detectable (<0.019 mg/kg wet weight) due to the relatively low levels of mercury in the oyster samples (<0.110 mg/kg wet weight).