Publication Date:
2011-09-09
Description:
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. Terephthalic acid (TA) was successfully recovered and purified from alkali reduction wastewater, by acidification with sulfuric acid and by cooling crystallization with dimethylacetamide. The chemical oxygen demand of the wastewater was effectively reduced, and TA with a purity of 99.91 % was obtained.
Print ISSN:
0930-7516
Electronic ISSN:
1521-4125
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
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