REMOVAL OF PESTICIDES FROM WOOL WAX BY CONTINUOUS COUNTERCURRENT DUAL-SOLVENT EXTRACTION

摘要

Pesticide residues in raw wool raw were removed to below detectable levels by continuous countercurrent extraction with hexane and N,N-dimethylformamide (DMF) in a pilot-scale mixer-settler contactor. The disengagement of the phases in the settling compartments was promoted by the addition of a small amount of formic acid (3% vol/vol) to the DMF-rich feed. Empirical equations were developed to predict the effect on the pesticide partition coefficients of the wool wax concentration, the presence of small amounts of water, ethanol, and/or isopropanol in the solvents, and the temperature used in the contactor. These empirical equations were included in equations that describe the concentration of the pesticides in the different stages of the contactor and were used to develop a spreadsheet model that accurately predicted the mixer-settler's performance. The raffinate wool wax produced by this process after conventional neutralization met all BP and USP specifications for pharmaceutical lanolin. [References: 6]