ALTERNATIVE HYDROCARBON SOLVENTS FOR COTTONSEED EXTRACTION

Hexane has been used for decades to extract edible oil from cottonseed . However, due to increased regulations affecting hexane because of th e 1990 Clean Air Act and potential health risks, the oil-extraction in dustry urgently needs alternative hydrocarbon solvents to replace hexa ne. Five solvents, n-heptane, isohexane, neohexane, cyclohexane, and c ylopentane, were compared with commercial hexane using a bench-scale e xtractor. The extractions were done with a solvent to cottonseed flake ratio of 5.5 to 1 (w/w) and a miscella recycle flow rate of 36 mL/min /sq cm (9 gal/min/sq ft) at a temperature of 10 to 45 degrees C below the boiling point of the solvent. After a 10-min single-stage extracti on, commercial hexane removed 100% of the oil from the flakes at 55 de grees C; heptane extracted 100% at 75 degrees C and 95.9% at 55 degree s C; isohexane extracted 93.1% at 45 degrees C; while cyclopentane, cy clohexane, and neohexane removed 93.3, 89.4, and 89.6% at 35, 55, and 35 degrees C, respectively. Each solvent removed gossypol from cottons eed flakes at a different rate, with cyclopentane being most and neohe xane least effective. Based on the bench-scale extraction results and the availability of these candidate solvents, heptane and isohexane ar e the alternative hydrocarbon solvents most likely to replace hexane.