Spongy Ni/Fe carbonate-fluorapatite catalyst for efficient conversion of cooking oil waste into biodiesel

Biodiesel produced from animal and plant fat oils is sustainable, but there is a need for efficient heterogeneous catalysts for transesterification of crude oils into biodiesel. Here, spongy carbonate-fluorapatite loaded with nickel and iron was synthesized and tested for conversion of waste cooking oil into biodiesel. The catalyst was synthesized by dissolution of phosphorite in nitric acid, and then nickel chloride was dissolved in the filtrate. The catalyst was then precipitated with ammonia and heated at 150 A degrees C for 12 h, thus yielding a spongy porous solid containing about 8% iron and 3% nickel. Results show a 97.5% biodiesel yield at 70 A degrees C in 2 h using 10 wt% catalyst dose and 8:1 methanol/oil ratio. The final biodiesel product matches the specification of ASTM D-6571 and most of EN 14214 biodiesel standards. This novel catalyst achieves better results than normally used hydroxyapatite and other calcium-based catalysts.