Response surface methodology guided adsorption and recovery of free fatty acids from oil using resin

Ramkrishna Singh, Bruce S. Dien, Vijay Singh

Research output: Contribution to journalArticlepeer-review


The presence of free fatty acids interferes with the conversion of plant oils to biodiesel. Four strong and weak base resins were evaluated for the removal of free fatty acids (FFA) from oil. Amberlite FPA 51 showed the highest adsorption capacity of FFA. A resin concentration above 3% could enable a higher percentage FFA adsorption. The adsorption process fitted a pseudo-first-order kinetic model and achieved equilibrium in approximately 8 h. A full factorial design was used to optimize the resin and FFA concentrations at a fixed temperature (40 °C). A ratio of resin to fatty acid concentrations above 1.875 was sufficient for 70% adsorption and the amount adsorbed continued to increase with further added resin. A two-step washing of resin using hexane and ethanol recovered approximately 67.55% ± 4.05% of the initially added fatty acid. The resin that was used was regenerated with 5% NaOH and re-used for a minimum of three consecutive cycles. However, the adsorption capacity diminished to 75% of the initial cycle in cycles 2 and 3. Thus, the work presents a resin-based process for deacidification of oil to reduce fatty acid content of oil for biodiesel production.

Original languageEnglish (US)
Pages (from-to)1485-1495
Number of pages11
JournalBiofuels, Bioproducts and Biorefining
Issue number5
StatePublished - Sep 1 2021


  • adsorption
  • free fatty acids
  • ion-exchange resin
  • resin regeneration
  • resin reusability

ASJC Scopus subject areas

  • Bioengineering
  • Renewable Energy, Sustainability and the Environment


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