Chlorine dioxide

Phototransformation in water

Administrative data

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Incomplete evaluation of rate coefficients. Determination of the effects in natural sunlight were not assessed.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Photodecomposition of chlorine dioxide and chlorite by U.V.-irradiation – Part I. Photo-products

Author:

Karpel Vel Leitner N, De Laat J and Dore M

Year:

1992

Bibliographic source:

Wat. Res., 26 (12): 1655-1664

Reference 2

Reference Type:

publication

Title:

Photodecomposition of chlorine dioxide and chlorite by U.V.-irradiation – Part II. Kinetic study

Author:

Karpel Vel Leitner N, De Laat J and Dore M

Year:

1992

Bibliographic source:

Wat. Res., 26 (12): 1665-1672

Materials and methods

Study type:

direct photolysis

Principles of method if other than guideline:

The photolysis of chlorine dioxide and sodium chlorite was assessed using batch reactors equipped with a mercury vapour lamp. Photodegradation tests were performed at 20 °C and pH values ranging from 4 to 8.8 in buffered ultra-pure water. Degradation product concentrations were assessed by HPLC, colorimetric and potentiometric methods.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Chlorine dioxide

EC Number:

233-162-8

EC Name:

Chlorine dioxide

Cas Number:

10049-04-4

Molecular formula:

ClO2

IUPAC Name:

Chlorine Dioxide

Details on test material:

Purity: not stated (chlorine dioxide prepared from acidification of sodium chlorite solution).
Solutions of chlorine dioxide were prepared in ultra-pure buffered water (phosphate buffer: 4

Study design

Radiolabelling:

no

Analytical method:

other: acid chrome violet K colorimetric method

Details on sampling:

Not specified

Buffers:

Phosphate buffer: 4

Light source:

other: Low pressure mercury vapour lamp

Light spectrum: wavelength in nm:

253.7

Details on light source:

Incident photonic flux at 253.7 nm = 1.1 E+06 Einstein s-1 and 1.53 E+06 Einstein s-1

Details on test conditions:

Temperature: 20 °C
pH: initial ≈ 7, final ≈ 3 (when carried out in non-buffed ultra-pure water)
Duration of the test: 70 - 130 minutes

Reference substance:

no

Dark controls:

no

Results and discussion

Preliminary study:

Not applicable

Quantum yield (for direct photolysis):

0.27

Transformation products:

yes

Results with reference substance:

Not applicable

Any other information on results incl. tables

Table A7_1_1_1_2-5:       Specification and amount of transformation products from reaction of chlorine dioxide solution with uv light

CAS-Number	CAS and/or IUPAC Chemical Name(s)	Amount [%] of parent compound measured at
		pH 7	pH 4	pH 8
-	Chlorate	60 (final)	60 (final)	60 (final)
-	Chlorite (intermediate only – max % indicated)	5 (temporary)
-	Chloride	40 (final)	40 (final)	40 (final)
7782-50-5	Chlorine (intermediate only – max % indicated)	12 (temporary)

Table A7_1_1_1_2-6:       Specification and amount of transformation products from reaction of sodium chlorite solution with uv light

CAS-Number	CAS and/or IUPAC Chemical Name(s)	Amount [%] of parent compound measured at
		pH 7	pH 5	pH 8.8
-	Chlorate	40 (final)	40 (final)	40 (final)
10049-04-4	Chlorine dioxide (intermediate only – max % indicated)	12 (temporary)	12 (temporary)	12 (temporary)
-	Chloride	60 (final)	60 (final)	60 (final)
7782-50-5	Chlorine (intermediate only – max % indicated)	17 (temporary)	17 (temporary)	17 (temporary)

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable