Study On Biodegradation Of Terephthalic Acid (TA) And Polyester (PET) Film

Terephthalic acid (TA) is one of the most important chemical materials. As it is produced in large quantities as one of monocases for synthesizing PET fiber and plastic all over the world, the wastes of Terephthalic acid have been steadily increasing and leading to a new type of environmental pollution. Considering the fact, biodegradation of Terephthalic acid is the one of best economical and usable technologies of purging waste of Terephthalic acid.In this experiment, ZY, Flower, H, F4 and p.ch were domesticated and cultivated with TA as only carbon sources. The optimum degraded conditions, included temperature 30℃, shaking frequency 140 r/min in HZQ-C air bath oscillator and the 1 mL of microorganism was transferred into culture medium, were defined through observing growth of strains with the 723-spectrophotometer at 420nm. The degradation kinetics of TA by F4 and p.ch were researched accords with Monod equation.The various concentrations of TA was degraded by crude enzymes extracted from interior or exterior of cells of five strains at temperature of 30℃, shaking frequency 140 r/min in HZQ-C air bath oscillator. The result indicated that TA could be degraded by all kinds of enzymes from different parts of cells, especially enzyme from of exterior of cells. By studying the kinetics of crude enzymes extracted from exterior of cells degradation of TA, the little Km of crude enzyme extracted from F4 and p.ch were showed by Michaelis-menton equation. The little Km and excellent effect of degradation reflected enzymes from F4 and p.ch have great ability of degrading TA.When TA or Diethylene glycol terephthalate (DTP) were applied to common metabolism, F4 and p.ch were used to degrade uncrystalline Polyethylene terephthalate (PET ) film, which was prepared by resolving PET fiber with organic solvent, at temperature of 30℃, shaking frequency 140 r/min in HZQ-C air bath oscillator from one month to three months, and then the scanning electron microscope (SEM) was applied to observe faces of PET film. As a result, there were many cicatrice sculptured in faces of PET film, which were degraded with TA as the common metabolism, after one month. These indicated the microorganisms that coulddegrade PET in shorter time have been found. Detail pathway of degradation of PET remains to be clarified but intact theory of degradation of PET still need to be explored.