To investigate the effect of water and other impurities in solvents on crystallization of carbazole from crude anthracene

the accumulation amount of impurities in xylene and water in ethanol in the solvent recycling were studied. Results showed that with the increase of xylene recycling

the main impurities in mother solution gradually accumulated in xylene

with the concentration of naphthalene up to 0.35 mg·ml-1 after recycling twice

and the carbazole content in the corresponding filter cake was reduced about 2.77% (mass) and the yield decreased 7.05% (mass). At the same time

the accumulation of impurities makes solvent recovery difficult

and the loss ratio of xylene increased from 44.75% (vol) to 79.17% (vol) after recycling three times. Water was gradually accumulated to 6.65% (vol) in ethanol. The purity of carbazole was higher than 98% (mass) when the water content added was between 0 to 12% (vol). The relative crystallinity of carbazole decreased from 45.67% to 40.79% when added water content is between 0 and 6% (vol) in ethanol; with the added water content of 9% (vol) and 12% (vol) in ethanol

it increased to 48.85% and 48.52%

respectively.