Investigation of the Parameters Influencing Alkaline Hydrolysis of Poly (Ethylene Terephthalate) for the Recovery of Pure Terephthalic Acid

Alkaline hydrolysis, as a chemical recycling method, was applied to the poly(ethylene terephthalate)(PET) taken from domestic post consumer soft drink. The flakes were mechanicaily powdered toreach the particle size down to 0.1 mm. The disodium terephthalate salt, as the main hydrolysisproducts, was then acidified to get the corresponding dicarboxylic acid. The influence of differentparameters such as NaOH concentration, PET particle size, type of PET powder, reaction time,hydrolysis temperature and the consumed neutralizing acid were investigated. The react ionprogress under different conditions was followed considering both the weight of isolatedterephthalic acid produced upon acidification as well as the unreacted PET. Highly pureterephthalic acid with overall yield of above 85% was achieved under optimized conditionswithin 4 h. Characterization of products was carried out by FTIR, HNMR and^( I3)CNMR.