2.2. Catalyst preparation
2.3. Catalyst characterization
2.4. Catalytic activity of the catalyst
The esterification reaction of PFAD was carried out by using the conventional reflux technique. A 150 mL two-necked round bottom flask was used and immerged in an oil bath. The condenser was coupled with the round bottom flask to recondense the evaporated methanol. In SYR-322 typical reaction, 5 g of PFAD was mixed with the calculated amount of methanol and catalyst. The suspension was then refluxed at the desired temperature with a stirring speed of 600 rpm. At the end of the reaction process, the catalyst was separated from the suspension by centrifugation at 4000 g within 15 min. The methanol was then separated and recovered from the product. The separated product (PFAD methyl ester) was collected for further analysis.
2.5. PFAD methyl ester analysis
The fatty acid conversion was calculated based on the difference of the acid value of the feedstock and acid value of the product according to the AOCS 5a-40 standard method . The FFA conversion was calculated according to Eq. (1), where, AVf and AVp stand for the acid value of the feedstock and the product, respectively.equation(1)FFAconversion,%=AVf−AVpAVf×100%