Phthalic acid

Phototransformation in water

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Study type:

direct photolysis

Principles of method if other than guideline:

A photochemical air-cooled reactor, using a medium-power mercury arc lamp for oxidation of organic matter in sea water

GLP compliance:

no

Radiolabelling:

no

Light source:

other: 380 W mercury lamp

% Degr.:

50

Sampling time:

0.93 h

Test condition:

sea water

Transformation products:

not measured

First order rate constant (hours E-1) for photooxidation in sea water
 was  0.75. That is equivalent with a half-life of  0.93 hours.

Executive summary:

In an irradiation experiment a first order rate constant (k/hour) for photooxidation in sea water was determined to be 0.75. That is equivalent with a half-life of 0.93 hours (Armstrong, 1968).

Description of key information

For phthalic acid in sea water a half-life of 0.93 hours was determined at 50°C (Armstrong 1968).

Key value for chemical safety assessment

Half-life in water:

0.93 h

Additional information

A photochemical reactor, using a medium power mercury arc lamp for oxidation of organic matter in sea water is used to measure the influence of light on degradation of phthalic acid. The decomposition of the substance in distilled water and in sea water at 50°C, using a 380 W lamp, was followed via titration. A first order rate constant for photooxidation of phthalic acid of about 0.75 h-1 that is equivalent to a half-life of 0.93 hours was obtained (Armstrong, 1968).