The pH of the collected glycerol layer from the reaction was
reduced to 5–6 by the addition of phosphoric acid. After acidification,
the mixture was kept for settling for 12 h. After settling, two
layers appeared, a bottom layer of inorganic salts & glycerol and
a top layer of impurities. For the partial purification of glycerol,
the bottom layer was neutralized with 5 MNaOH and the inorganic
salt present in the layer was precipitated by the addition of methanol.
The precipitate was filtered out and the filtrate that contains
glycerol was distilled for the removal of solvent residues. The
amount of glycerol was determined by colorimetric method