oa South African Journal of Chemical Engineering - The effect of pH on liquid-liquid extraction efficiency of phytosterols from tall oil soap

Volume 16, Issue 1
  • ISSN : 1026-9185



Phytosterols are important chemicals due to their applications as health products and as nutritional supplements. An important source of phytosterols is the waste tall oil soap from the Kraft process in pulp and paper production. Extraction of phytosterols therefore has two objectives: recovery of a valuable chemical and waste beneficiation. The effect of pH of tall oil soap on the extraction of phytosterols was conducted in laboratory tests before application in a counter-current, Vibrating Plate Extractor (VPE). A decrease of pH from 12 to 7 of the tall oil soap solution increased the content of phytosterols in the extracted phase. The extraction efficiency increased by 17-39%. Permanent emulsions were formed at a pH of 8, which should thus be avoided as an operating condition. Lastly, operating below a pH of 6 is not recommended due to the liberation of fatty and resin acids that contaminate the phytosterols in the extract.

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