接洽中，请勿再来信，谢谢
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[必]截 稿 日： 2021 03 06 (4号才能给稿)
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a.
Glycerol with high purity has a wide application in various industry such as
pharmaceutical, cosmetic, and food products. However, the percentage of
purity of the glycerol from the biodiesel industry is limiting its conversion
to a high valued product. The crude glycerol contains a large number of
contaminants such as soap, salts, ethanol, methanol, water, fatty acid,
methyl esters, glycerides, and ash. Yang et al. (2012) stated that the
impurities in the crude glycerol could greatly influence its conversion into
other value-added products. Venkataramanan et al. (2012) also reported that
soaps in the crude glycerol have a strong inhibitory effect on the
utilization of the glycerol by bacteria, which affects the performance of
crude glycerol as the carbon source in the fermentation process.
b.
the most commonly used processes are distillation, ion exchange resin,
membrane separation technology, acidification, followed by neutralization and
solvent extraction. Acidification is a commonly used technique to neutralize
the impurities like catalyst into inorganic salt. Besides acidification, it
is also able to reduce the amount of soaps by converting them into insoluble
free fatty acid as they can adversely impact the separation and cause loss of
yield. Since acidification process does not remove all impurities, it needs a
further purification step to remove other impurities like methanol, oil,
water, and ester. However, the distillation process has some limitation over
others as it requires high energy input for vaporization and causes thermal
decompositions. Besides, high vacuum is also required in distillation to
prevent high-temperature denaturation of glycerol through acrolein formation.
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