Conversion of waste cooking oil to biodiesel using ferric sulfate and supercritical methanol processes

Prafulla Patil, Shuguang Deng, J. Isaac Rhodes, Peter J. Lammers

Research output: Contribution to journalArticlepeer-review

148 Scopus citations


In this comparative study, conversion of waste cooking oil to methyl esters was carried out using the ferric sulfate and the supercritical methanol processes. A two-step transesterification process was used to remove the high free fatty acid contents in the waste cooking oil (WCO). This process resulted in a feedstock to biodiesel conversion yield of about 85-96% using a ferric sulfate catalyst. In the supercritical methanol transesterification method, the yield of biodiesel was about 50-65% in only 15 min of reaction time. The test results revealed that supercritical process method is probably a promising alternative method to the traditional two-step transesterification process using a ferric sulfate catalyst for waste cooking oil conversion. The important variables affecting the methyl ester yield during the transesterification reaction are the molar ratio of alcohol to oil, the catalyst amount and the reaction temperature. The analysis of oil properties, fuel properties and process parameter optimization for the waste cooking oil conversion are also presented.

Original languageEnglish (US)
Pages (from-to)360-364
Number of pages5
Issue number2
StatePublished - Feb 2010
Externally publishedYes


  • Biodiesel
  • Ferric sulfate
  • Supercritical methanol
  • Waste cooking oil

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry


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