PTA (Purified Terephthalic Acid) is predominantly used as a raw material in manufacture of Polyester Staple Fibres, Polyester Filament Yarns and Polyethylene Terepthalate in conjunction with Mono Ethylene Glycol (MEG). PTA also finds use in small quantities in the manufacture of paints, etc. Modern technologies produce purified terephthalic acid by the catalytic liquid phase oxidation of paraxylene in acetic acid, in the presence of air. The process uses manganese or cobalt acetate as a catalyst. The resulting PTA is purified in a crystalliser where the unreacted xylene and water are flashed off.