3.8 Characterization of crystal product
The shape and morphology images of the crystals in the slurry were
obtained by optical microscope (Motic (Xiamen) Electric Group Co., Ltd.,
Motic SMZ-168), and then the crystal size distribution (CSD) was
analyzed by Nano Measurer software. The results of each experiment were
repeated more than three times and the average value was reported.
Purity of the thiourea crystal is measured by the analytical laboratory
of the Shandong Jingbo Co., Ltd. In alkaline condition, thiourea and
iodine have quantitative reaction, while excess iodine solution was
titrated with standard sodium thiosulfate, to obtain the content of
thiourea.