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Diss Factsheets
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EC number: 939-559-9 | CAS number: -
- 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
Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Type of information:
- other: inorganic constituent
- Remarks:
- The substance is water-soluble, dissociating readily into ammonium ions (NH+), oxalate-niobate (V) and oxalate anions, respectively. The presented data refers to the inorganic component Nb (V) representing a dissociation product.
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Well-documented publication
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Solubilities of the crystalline B-Nb2O5 were determined in five NaClO4 solutions (0.1 ≤ Im/mol·kg−1 ≤ 1.0) over a pH range of 1 to 13 at 25.0±0.1 °C and at 0.1 MPa.
- GLP compliance:
- no
- Radiolabelling:
- no
- Analytical monitoring:
- yes
- Details on sampling:
- - Sampling intervals for the parent/transformation products:after 5, 10, 15 and 30 days
- Sampling intervals/times for pH measurements: every sampling - Duration:
- 30 d
- pH:
- 4
- Initial conc. measured:
- 20 g/L
- Duration:
- 30 d
- pH:
- 7
- Initial conc. measured:
- 20 g/L
- Duration:
- 30 d
- pH:
- 9
- Initial conc. measured:
- 20 g/L
- Positive controls:
- not specified
- Negative controls:
- not specified
- Transformation products:
- not measured
- Remarks on result:
- not measured/tested
- Remarks on result:
- not measured/tested
- Endpoint:
- hydrolysis
- Type of information:
- other: inorganic constituent
- Remarks:
- The substance is water-soluble, dissociating readily into ammonium ions (NH+) and oxalate-niobate (V) and oxalate anions respectively. The presented data refers to the inorganic component Nb (V).
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Well-documented publication
- Radiolabelling:
- no
- Analytical monitoring:
- yes
Referenceopen allclose all
The solubility study indicated the possibleexistence of five mononuclear Nb(V) species in solution,viz., Nb(OH)32+, Nb(OH)4+, Nb(OH)50, Nb(OH)6-, Nb(OH)72-in equilibrium with B-Nb2O5, according to the generalized reaction:
0.5Nb2O5(cr) + 0.5(2n-5) H2O(l) → Nb(OH)n5-n + (n-5) H+ (n = 4 – 7)
However, the trihydroxo species Nb(OH)32+could only be detected in the analysis conducted at 70 °C (Im= 1.0 mol·kg−1). The sudden appearance of this species at the highest temperature study is counterintuitive, because hydrolysis of metal ions is known to increase with increasing temperature such that Nb(OH)32+should be destabilized with respect to Nb(OH)4+and Nb(OH)50with increasing temperature.
All of the solubility data at pHm> 9 show a discontinuity, probably favoring the transformation of Nb2O5to a more insoluble solid phase, especially when one considers that the solution speciation must follow continuously from that at pH < 9 such that the Nb(OH)72-would immediately predominate.
XRD analyses of solids recovered after equilibration with acidic (10−2mol·kg−1, HNO3) and basic (10−2mol·kg−1, NaOH) solutions at room temperature showed sharp peaks which are consistent only with crystalline B-Nb2O5.The result indicated that any mixed oxide/hydroxide solid phase(s) which may be formed in the latter medium is/are either present as a thin crystalline film on the B-Nb2O5particles or as a thin amorphous layer.
Description of key information
Solubility study of crystalline Nb2O5 indicated the presence of four species, Nb(OH)5−n/n (where n = 4–7).
Key value for chemical safety assessment
Additional information
Solubility measurements of well-characterized B-Nb2O5 as a function of temperature (10 – 70 °C), ionic strength (0.1 – 0.6 mol kg−1), and pH (1 – 9) have provided a unique thermodynamic platform for determination of the speciation of Nb(OH)n5-n, where n = 4 - 7.
For acidic (pH ≤ 4) solutions, equilibrium (i.e., constant niobium concentration) was attained after 15 days. In the solutions with pH range of 4 to 9, a minimum of 30 days was necessary to reach equilibrium. The ionic strength, Im, in the range of 0.1 – 6.0 mol kg−1 seemed to have no effect on the kinetics of dissolution of niobium oxide.
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