Carbon tetrachloride

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepable, well- documented publication/study report which meets basic scientific principles

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Batch and column tests were conducted to investigate the effect of reductant concentration, reductant contact time, and suspension pH on reductive dechlorination of CTC by soil manipulated with Fe(II) and HS(-). Kinetic rate constants were determined.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Carbon tetrachloride

EC Number:

200-262-8

EC Name:

Carbon tetrachloride

Cas Number:

56-23-5

Molecular formula:

CCl4

IUPAC Name:

tetrachloromethane

Constituent 2

Reference substance name:

abbrevation for carbon tetrachloride

IUPAC Name:

abbrevation for carbon tetrachloride

Results and discussion

Any other information on results incl. tables

Kinetic rate constants for the reductive dechlorination increased as the reductant concentrations increased. Fe(II) was more effective reductant than HS^-, resulting in higher rate constants. The contact time of 1 day for the soil with HS^-and that of 4h with Fe(II) showed the highest reaction rates, respectively. The kinetic rate constants increased as the pH of soil suspensions with Fe(II) (5.2-8.0) and HS^-(8.3-10.3) increased. Soil column with Fe(II) showed larger bed volumes (13.8) to reach a column breakthrough than that with HS^-(4.0). Fe(II) treatment showed better removal of CTC in the soil column with the addition of CaO than HS^-treatment did. In contrast, HS^-treatment was not producing toxic products.

Applicant's summary and conclusion

Executive summary:

Abiotic degradation of CTC under reductive conditions was simulated in soils where CTC and the iron(II) (Fe²⁺)and bisulfide ion (HS^-). Dechlorination of CTC in acidic soil has been observed and the related kinetic rate constants were measured. Iron(II) was more effective reductant than the bisulfide ion, resulting in higher rate constants. The kinetic rate constants were pH dependent and increased with more alkaline conditions. The purpose of the study was to give evidence on technical reduction of CTC contamination. The transferability to natural processes is limited and no valid quantification of the chemical reactions based on this study can be assessed. However it is evident that to some extend CTC will be abiotically transformed depending on the presence of HS^-and Fe²⁺ions.