What Is Terephthalic Acid?
Terephthalic acid (TPA), also known as p-phthalic acid or PTA, is an aromatic dicarboxylic acid with the molecular formula C8H6O4. It is predominantly produced by the catalytic oxidation of paraxylene with acetic acid, using catalysts such as cobalt and manganese.
Uses of Terephthalic Acid
TPA is primarily utilized as a precursor for making polyester fibers, PET resins for various industrial products, and PET bottles for beverages. Its application extends to chemical intermediates, synthetic fibers and resins, films, engineering plastics, medical devices, dyes, pigments, and agricultural chemicals, showcasing its versatility across industries.
Properties of Terephthalic Acid
With a molecular weight of 166.13 and CAS No. 100-21-0, terephthalic acid is a white, odorless, crystalline powder. It demonstrates remarkable stability and low flammability, making it suitable for fiber and resin production. Despite its insolubility in water and ethanol, it exhibits slight solubility in sodium hydroxide solution.
Physical Properties
It is characterized by its high melting point and resistance to thermal transformation, advantageous for manufacturing processes that require high-temperature conditions.
Chemical Properties
TPA’s reactivity with strong oxidizers demands careful handling, although it is generally safe under normal conditions. Its combustion can produce carbon monoxide and dioxide, necessitating precautions against high temperatures and oxidizing agents.
Other Information on Terephthalic Acid
Terephthalic Acid Safety
TPA may pose risks of eye and skin irritation, respiratory system irritation, and potential long-term organ damage. Immediate medical attention is recommended in case of exposure.
Handling of Terephthalic Acid
Appropriate personal protective equipment (PPE) and ventilation measures are crucial to minimize exposure risks. Facilities should be equipped with safety showers and eye wash stations to ensure workplace safety.
Production and Export Volume
The production of TPA has seen fluctuations, with a noted decline in domestic supply. Its significant use in the production of films, bottles, and fibers underlines its industrial importance.
Environmental Impact
Terephthalic acid is not hydrolyzed, as there are no chemical bonds that are susceptible to hydrolysis. In aerobic biodegradation tests, it’s benignly degradable, with 74.7% degradation in biochemical oxygen consumption (BOD) measurements and 100% degradation in high-performance liquid chromatography (HPLC).
In anaerobic biodegradability tests, it was reported to be 50% degraded after 55 days, suggesting that it is easily biodegraded and removed when discharged into the environment.