The invention discloses a preparation method of D-chiro-
inositol, and relates to the technical field of D-chiro-
inositol production, and the preparation method comprises the following steps: filtering a D-chiro-
inositol conversion liquid through diatomite and an
ultrafiltration membrane, carrying out cation exchange resin and anion exchange resin, then carrying out vacuum concentration on the
effluent through a
nanofiltration membrane until crystals are separated out, and then carrying out cooling
crystallization to obtain the D-chiro-inositol. Collecting a
filter cake I and a filtrate I, concentrating the filtrate I under vacuum until the
solid content is 50-60% w / w, then adding
ethanol, heating and filtering, collecting a
filter cake II and a filtrate II, cooling the filtrate II to 10-15 DEG C, filtering and collecting a
filter cake III and a filtrate III, adding pure water into the filter cake III for dissolving to obtain a dissolving solution, adding water which is 0.5-1 time of the weight of the filter cake and dissolving at 50-80 DEG C, cooling and crystallizing the dissolving solution, and filtering to obtain the product. Cooling to 10-15 DEG C, filtering and collecting a filter cake IV and a filtrate IV, and
drying the filter cake IV to obtain the D-chiro-inositol, the process is simple, the cost is low, and the yield is high.