The pH of the collected glycerol layer from the reaction was 151
reduced to 5–6 by the addition of phosphoric acid. After acidificat- ion, 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, 155
the bottomlayer was neutralized with 5 MNaOH and the inorganic salt present in the layer was precipitated by the addition of meth- anol. 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