Determination of Ca, Mg, Na, and K in biodiesel of oilseed from northern Brazil

Abstract

In this study, flame atomic absorption spectrometry (FAAS) was used to determine calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) contents in biodiesel produced with different oilseeds (bacaba, bacuri, Brazil nut, and palm). The samples were digested with nitric acid, sulfuric acid, and hydrogen peroxide using an open system with conventional heating. The recoveries obtained by the addition and recovery method for Ca, Mg, Na, and K were 86-113%, 81-101%, 96-118%, and 89-119%, respectively. The results showed that levels of Ca and Na ranged from 58.56-126.6 mg kg-1 and 3.06-4.61 mg kg-1 in the samples. The Mg levels in samples were below the limit of detection. Contents of K were found only in samples B2 and B4. This study showed that both the oleaginous and the catalyst used in biodiesel production during the synthesis process can influence the final concentrations of the metals in the biodiesel samples.