Premium
Recovery of Terephthalic Acid from Alkali Reduction Wastewater by Cooling Crystallization
Author(s) -
Wu S.C.,
Cheng Z.M.,
Wang S.D.,
Shan X.L.
Publication year - 2011
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.201100096
Subject(s) - terephthalic acid , crystallization , sulfuric acid , wastewater , mother liquor , solubility , alkali metal , chemistry , raw material , chemical oxygen demand , particle size , materials science , chromatography , nuclear chemistry , waste management , organic chemistry , polyester , engineering
Abstract A process for the recovery and purification of terephthalic acid (TA) from alkali reduction wastewater is reported. TA was first precipitated from alkali reduction wastewater by acidification with sulfuric acid, and then the produced crude TA was dissolved in dimethylacetamide (DMA) so that crude TA could be purified from the solution by cooling crystallization. The results indicated that acidification could reduce the chemical oxygen demand of the wastewater by 83 %, and the purity of TA by crystallization could reach 99.91 %. A correlation was proposed in describing the solubility of crude TA in DMA from 303.4 to 358.65 K, which gives a mean relative discrepancy of less than 1.14 %. The cooling rate of the mother liquor had a large influence on the crystal size distribution. At an average cooling rate of 1.18 K min –1 , the particle size distribution of TA was narrow and the average size was about 100 μm. In a bench‐scale study, it was demonstrated that the crystallized product can be recycled as the raw material for polyethylene terephthalate production.