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EC number: 233-069-2 | CAS number: 10028-15-6
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
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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: Peer-reviewed well documented publication
Data source
Reference
- Reference Type:
- publication
- Title:
- Ozone Decomposition in Water: Kinetic Study
- Author:
- Sotelo JL, Beltran FJ, Benitez FJ, and Beltran-Heredia J
- Year:
- 1 987
- Bibliographic source:
- Ind. Eng. Chem. Res. 26,39-43
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Kinetic studies on ozone decomposition in water were performed over a range of temperatures from 10 to 40 °C and pH range from 2.5 to 9.The ozone decomposition chemical reaction was followed by determining the concentration of dissolved ozone by reaction with a buffered potassium iodide solution, measuring the triodide ions liberated spectrophotometrically at the wavelength of 352 nm.
- GLP compliance:
- no
Test material
- Reference substance name:
- Ozone
- EC Number:
- 233-069-2
- EC Name:
- Ozone
- Cas Number:
- 10028-15-6
- Molecular formula:
- O3
- IUPAC Name:
- trioxygen
- Test material form:
- gas
Constituent 1
- Specific details on test material used for the study:
- - Test material: ozone gas
- An ozone-oxygen mixture was produced in an ozonator (SLO Constrema) which is able to operate at a maximum rate of 6 g of 03/h.
- Oxygen was taken directly from a commercial cylinder and dried with silica gel traps before entering the ozonator.
- Water was ozonated with an 02-03 stream, containing about 4% (v/v) ozone, at a flow rate of 40 L/h for 30 min.
Results and discussion
Any other information on results incl. tables
Effects of Agitation Speed,
Temperature, and pH.
Though the process studied is only a homogeneous chemical reaction,
agitation was provided to keep the temperature of the water uniform
during the experiment. Agitation speed was varied between 100 and 700
rpm. At speeds below 300 rpm, the ozone conversion remained constant at
a given reaction time. However, the decomposition rate was found to be
higher when agitation speed was above 300 rpm, probably due to ozone
desorption (Figure 1). Hence, the rest of the experiments were performed
at 100 rpm.
Experiments were carried out
while varying the temperature from 10 to 40 °C and pH from 2.5 to 9.
When these variables were increased separately, a higher ozone
conversion at a given reaction time was observed (see Figures 2 and 3).
Decomposition was extremely fast in experiments performed at
temperatures and pHs higher than 30 °C and 8, respectively.
Figures 1, 2 an 3 can be found
under illustration.
Interpretation of Kinetic Data.
Experimental data and kinetic calculations based also on previous
work from various other authors lead to the conclusion that the ozone
decomposition in water involves two major contributions: direct ozone
decomposition, and the overall hydroxide ion attack.
The global ozone decomposition rate
was expressed as:
-rO3= 3.26 x 105(-4964/T)[O3] + 5.69 x 1018 x
exp(-10130/T)[OH-]1/2[O3]3/2(mol/(L.min))
It was found that experimental and
calculated values agreed ± 10% in 95% of cases. Figure 8 (see
illustration) shows the comparison among the ozone half-lives obtained
from this work and previous reports.
From figure 8 we can see that the calculated half-life in deionized and
distilled water, at 20°C and pH 7, was calculated to be circa 2000
seconds (ca. 32 min).
Applicant's summary and conclusion
- Conclusions:
- Ozone is unstable in water. The half-life in deionized and distilled water, at 20°C and pH 7, was calculated to be circa 2000 seconds (ca. 32 min). In any real water (containing ions and other subtsances) the half-life will be much shorter.
- Executive summary:
Kinetic studies on ozone decomposition in water were performed over a range of temperatures from 10 to 40 °C and pH range from 2.5 to 9. The ozone decomposition chemical reaction was followed by determining the concentration of dissolved ozone.
Ozone decomposition was observed to follow a two-term rate equation supported by a reaction mechanism. It was shown that at pHs lower than 7, whatever the temperature was, direct ozone decomposition and the initiation step involving the hydroxyl radicals are the main cause of ozone decomposition. At higher pHs, the importance of the peroxy radicals and of the hydroxide ion initiation step increases. Thus, at pHs around 9, the ozone decomposition rate depends on two major contributions: direct ozone decomposition, which leads to the formation of hydroxyl radicals, OH·, and hydroxide ion action, which produces not only peroxy radicals, HO2·, but also hydroxyl radicals.
Finally, the nature of the ionic species (carbonate, sulfate, phosphate, etc.) present in the water greatly influences ozone decomposition, inhibiting some of the reactions in the mechanism proposed.
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