Research of Purifying Terephthalic Acid and Recycling PET

Recovery of high pure Terephthalic Acid (TA) from Alkali weight-reduction wastewater by PET hydrolyzing has been researched by purified mother liquid with activated carbon adsorption. The characters of TA obtained were investigated by various indexes. The effects of activated carbon on crystaled TA were also been studied by scanning electronic microscopy (SEM) and particle size analysis. Results has shown that the characters of TA was great improved in view of high recovery rate by activated carbon adsorption on conditions of 4-5g/l quantity of activated carbon and 70 minutes of operating time. The crystal size of recovered TA is greater, it is in high purity, easily washed, and contains few impurities. The TA containing 30% of the covered TA when esterified and polycondensed with EG gave a pure white polymer that showed an intrinsic viscosity, [η]=0.61dl/g. So activated carbon adsorption by pretreatment is an effective method in recycling TA. The study is also very useful in recycling of PET and treating TA industrial wastewater.