Improvement On The Synthesis Process Of M-cresol From M-toluidine

M-cresol is an important chemical material.M-cresol was synthesized from m-toluidine via diazo-reaction and hydrolization reaction, and the disposal process of its production waste acid and waste water were investigated in this paper.The sodium nitrite solution was slowly added by drops after the separation of massive ammonium salt crystals in the diazonium reaction. M-cresol was separated by vapor distillation in the hydrolization reaction. The results of orthogonal experiment showed that the better process condition was that the mass of m-toluidine was 21.6g; the consumption of sulfuric acid used in diazo-reaction was 180mL 30% sulfuric acid solution; the consumption of sulfuric acid used in hydrolization reaction was 240mL 50% sulfuric acid solution; the consumption of sodium nitrite was 60mL 35% sodium nitrite solution; the feeding speed of diazonium salt was 12mL·min^-1;the the temperature of diazo-reaction was 0～5℃; the temperature of hydrolization reaction was 110℃.Under this condition the yield of m-cresol was 85.5%, its purity was 99.6%.And the batch feeding experiment of kilogram level was done successfully.The organic compounds in the waste acid were disposed by adsorption method.The effect of activated carbon was better, and the better condition of 200×20mm adsorption column which contained 200g activated carbon was that the temperature was 20～25℃;The pH value was not more than 6;The flow speed was 4mL·min^-1. Under this condition its max adsorptive capacity was 750mL, the elimination rate of m-cresol and COD value were respectively 86.0%, 88.0%.The wasted acid which had been disposed by activated carbon was disposed by electrodialysis method to remove the sodium salt. And the enlargement experiment of the whole disposal process was done successfully.The m-cresol in the waste water was disposed by adsorption of XDA-1 resin. The results showed that the better condition of 200×20mm adsorption column which contained XDA-1 was that the temperature was 20～25℃;The pH value was not more than 6;The flow speed was 6mL·min^-1. Under this condition its max adsorptive capacity was 1.5L, the elimination rate of m-cresol was 99.3%, the concentration of m-cresol was 0.35 mg·L^-1, COD value was 260 mg·L^-1.And the enlargement experiment of waste water disposal process was done successfully.Compared with the traditional process, the yield of m-cresol enhanced 10%, the reuse of waste was good, and the waste water achieved the third discharged standard of industrial waste water.