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Environmental fate & pathways

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The substance is rapidly hydrolysed to terephthalic acid and HCl. HCl, an inorganic substance, is not biodegradable. HCl is readily solubilised in water and process water is neutralised before emission if significant release is expected. Therefore, the environmental fate and distribution for this substance will be based on the behaviour of the primary degradate, terephthalic acid.

Terephthalic acid will compartmentalise into water based on the predominance of the anionic species in the environment. An OECD 301B study showed that terephthalic acid was ready biodegradable with >80% CO2 evolution after 14 days. The biological oxygen demand was 74.7% after 28 days in an OECD 301C ready biodegradation test, also indicating that terephthalic acid is completely mineralised without any significant metabolites or degradation products. Direct UV analysis confirmed 99.3% loss of terephthalic acid. Therefore, persistence in the environment is not expected.

The pKa values of terephthalic acid (3.5 and 4.34; CSR section 1.3 Physico-Chemical Properties) indicate that terephthalic acid will exist as the anionic species in the environment. Terephthalic acid is not expected to adsorb to soil, suspended solids or sediment based upon the ACD labs ( log D value (-2.13) at pH 7. Terephthalic acid has the potential to move rapidly in soil; however, rapid biodegradation is expected to mitigate potential transport to groundwater. Volatilisation of terephthalic acid from water surfaces and soil is not expected to be an important fate process based upon this compound's low Henry's Law constant (1.33E-2 Pa*m3/mol) and the predominance of the anionic species in the environment.