Optimization of oil extraction from waste "Date pits" for biodiesel production

Highlights: • Oil extraction from "Date pits" has been optimized first time by using RSM. • Optimized conditions for oil extraction gave oil yield of 16.5%. • "Date pits" oil as non-edible feedstock was transformed to biodiesel. • Biodiesel from "Date pits" oil posses potential fuel properties. - Abstract: Biodiesel produced from non-edible feedstocks is increasingly attractive alternative to both fossil diesels and renewable fuels derived from food crops. Date pits are one such lipid containing feedstock, and are widely available in Oman as a waste stream. This study analyses the effects of soxhlet process parameters (temperature, solvent to seed ratio and time) on the extraction of oils from waste Date pits and the subsequent production of biodiesel from it. The highest yield of oil extracted from the Date pits was 16.5 wt% obtained at a temperature of 70 °C, solvent to seed ratio of 4:1 and extraction duration of 7 h. Gas Chromatography analysis showed that Date pits oil consisted of 54.85% unsaturated fatty acids (UFA). Transesterification of the oil extracted was undertaken at 65 °C, a methanol to oil ratio of 6:1 and a reaction time of 1 h for biodiesel production. Biodiesel produced from the Date pits oil was found to have a cetane number of 58.23, density 870 of kg m⁻³, cloud point of 4 °C, pour point of −1 °C, CFPP of −0.5 °C and kinematic viscosity of 3.97 mm² s⁻¹ (40 °C). In general, Date pit oil appears to be a potential alternative feedstock for biodiesel production.