Lithium hexafluorophosphate(1-)

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption, other

Remarks:

adsorption/desorption

Type of information:

other: Due to its hydrolytic instability, the registered substance will not be present in surface waters. Evaluation of bioaccumulation potential must therefore be based on its hydrolysis products. This source gives information on fluoride

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well-described report of adsorption/leaching study in soils published in a peer-reviewed journal.

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex VIII 9.3.1 and Annex IX 9.3.3 under REACH in accordance with Annex XI Section 1.2. In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability: further, in accordance with REACH Annex XI section 1.2 testing is not scientifically necessary since it is the products of rapid LiPF6 hydrolysis which could enter the environment and existing information is available on the adsorptive properties of these.

Principles of method if other than guideline:

Adsorption: soil samples shaken with fluoride in water, fluoride removal determined by analysis.
Leaching: water leaching through packed soil columns analysed for fluoride content; this compared with total and water-soluble contents of the soil.
Six different soil types evaluated.

GLP compliance:

not specified

Type of method:

other: Adsorption: shake bottles. Leaching: soil column.

Media:

soil

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Fluoride (F-) is a hydrolysis product of the reaction of LiPF6 with water.

Test temperature:

25C

Analytical monitoring:

yes

Details on sampling:

Adsorption testing: solutions sampled after 4h shaking.
Leaching tests: column leachates, NaOH-digested soil samples (for total F-) and samples of soil washings (for water-soluble F-) analysed.

Details on matrix:

6 different Chinese soils, air-dried and sieved (100 mesh for adsorption testing, 20 mesh for leaching tests).
Total fluoride content determined by analysis of samples weighed then digested in NaOH.
Water-soluble fluoride determined by analysis of samples taken from 1:5 soil:deionised water mixes.

Details on test conditions:

Adsorption tests: sodium fluoride solutions at 0,5,10,15,20,25 and 30 mgF-/l added to 1g soil samples, made up to 20ml with deionised water and shaken for 4h. Tested in duplicate.
Leaching tests: 400-700g soil samples packed into columns giving 30cm depth. 2500 ml deionised water fed into columns, maintaining 4cm water above soil surface.

Remarks on result:

other: information on adsorption and leaching

Remarks:

See "any other information on results" section

Results of adsorption and leaching tests

Test soil	Total F- (µg/g)	Water-soluble F- (µg/mL)	WS (%)	SFC (µg/g)	% Total F- leached
Red earth	439	0.44	0.10	434	0.03
Purplish soil	230	0.62	0.27	476	0.04
Drab soil	374	1.40	0.38	370	0.19
Dark brown earth	225	0.41	0.18	400	0.02
Sierozen	412	2.87	0.70	167	0.16
Black soil	275	0.57	0.21	667	0.05

WS = water-soluble F expressed as % of total F

SFC = saturated F- adsorption capacity

Conclusions:

Alkaline soils adsorbed less, and leached more, fluoride than acid soil types. Increased contents of calcium and magnesium oxides correlated negatively with fluoride adsorbing capacity.

Reference 2

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

other: Due to its hydrolytic instability, the registered substance will not be present in surface waters. Evaluation of bioaccumulation potential must therefore be based on its hydrolysis products. This source gives information on fluoride

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Adequately described acount of adsorption testing published in the journal of a national Water Research Commission

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex VIII 9.3.1 and Annex IX 9.3.3 under REACH in accordance with Annex XI Section 1.2. In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability: further, in accordance with REACH Annex XI section 1.2 testing is not scientifically necessary since it is the products of rapid LiPF6 hydrolysis which could enter the environment and existing information is available on the adsorptive properties of these.

Principles of method if other than guideline:

Fluoridated water of known fluoride content was passed through test columns, each packed with one test substrate. Fluoride removal was monitored by ion electrode analysis.

GLP compliance:

not specified

Type of method:

other: Column adsorption

Media:

other: soil, charcoal, brick, fly-ash, serpentine

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Fluoride (F-) is a hydrolysis product of the reaction of LiPF6 with water.

Test temperature:

Ambient (not specified)

Analytical monitoring:

yes

Details on sampling:

Samples collected over intervals up to 120 minutes: 0-15, 15-30, 30-60, 60-90, 90-120

Details on matrix:

Red soil: ferruginous lateritic clay. Serpentine was considered similar or equivalent to Mg6Si4O10(OH)8. Untreated charcoal, fly-ash and brick were from local sources. In all cases, 25g of material was used in each column.


8.

Details on test conditions:

Water flow rate 1.5 ml/min

Remarks on result:

other: no quantified result

Remarks:

see "any other information on results" section

Concentration of test substance at end of adsorption equilibration period:

Initial 10 mg fluoride/l reduced to 0.029 mg/l by red soil column after 120 minutes (reduced to 0.64 mg/l after only 15 minutes).

Fluoride concentration at each sampling time

Time	Red soil	Charcoa	l Fly-ash	Brick	Serpentine
0	10	10	10	10	10
15	0.64	9.05	3.4	4.7	3.7
30	0.09	9.05	3.7	4	4.1
60	0.06	9.1	4.7	3.7	4.6
90	0.035	9.05	6	4	4.8
120	0.029	9	7.1	3.9	5.8

Conclusions:

Red soil proved to remove fluoride rapidly and effectively from aqueous solution. the authors attributed this to the presence of iron and aluminium oxides in the tested soil.

Reference 3

Endpoint:

adsorption / desorption, other

Remarks:

Phosphorus mobility

Type of information:

other: Due to its hydrolytic instability, the registered substance will not be present in surface waters. Evaluation of bioaccumulation potential must therefore be based on its hydrolysis products. This source gives information on lithium.

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well described report of soil column studies, reported in a peer -reviewed journal.

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex VIII 9.3.1 and Annex IX 9.3.3 under REACH in accordance with Annex XI Section 1.2. In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability: further, in accordance with REACH Annex XI section 1.2 testing is not scientifically necessary since it is the products of rapid LiPF6 hydrolysis which could enter the environment and existing information is available on the adsorptive properties of these.

Principles of method if other than guideline:

Soil column leaching study, with P supplied as inorganic phosphate or manures

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Phosphate, PO4(3-), is a hydrolysis product of the reaction of LiPF6 with water.

Test temperature:

12h dark/light cycle, with temperatures 30C/14C

Details on matrix:

Sandy loam collected from an agricultural field (0-20 cm depth), air-dried and filtered through a 5mm sieve (organic content 4.3 g/kg).

Details on test conditions:

24 soil columns: nylon mesh at base, with 2.5 cm acid-washed sand above. 3kg soil packed into each column.
P was applied to each column (except controls), either as inorganic phosphate or as manure (believed to be ca. 60-90% inorganic phosphate): in all cases, the application rate was equivalent to 167 kg/ha. Simulated irrigation water was dripped onto columns.
Column leachates were analysed for P content.

Remarks on result:

other: no quantified result

Remarks:

see "any other information on results" section for details

An overall average of 71.2% of the applied water volume was recovered as column eluate, with no significant difference between treatments.

Measurements of total P in the soil column at the end of the experimental period showed that P applied as inorganic phosphate moved to a greater depth than that applied in solid manures; passage of total P through the soil columns as leachate was markedly higher when applied in liquid manures than when applied either as inorganic phosphate or in solid manures. Approximately 2% of the total P applied as inorganic phosphate was leached from the soil column.

Reference 4

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

other: Due to its hydrolytic instability, the registered substance will not be present in surface waters. Evaluation of bioaccumulation potential must therefore be based on its hydrolysis products. This source gives information on lithium.

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Offical information database of the US National Institutes of Health

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex VIII 9.3.1 and Annex IX 9.3.3 under REACH in accordance with Annex XI Section 1.2. In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability: further, in accordance with REACH Annex XI section 1.2 testing is not scientifically necessary since it is the products of rapid LiPF6 hydrolysis which could enter the environment and existing information is available on the adsorptive properties of these.

Principles of method if other than guideline:

Expert summary of information on environmental occurrence and distribution of lithium.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
LiF and then ionic Li+ are hydrolysis products of the reaction of LiPF6 with water.

Details on matrix:

Aquifer material and humic soils.

Remarks on result:

other: no quantified result

Remarks:

see "any other information on results" section

Testing of lithium adsorption onto aquifer is cited: Freundlich coefficients of 4.5 -5 were reported.

Lithium is reported to adsorb slightly to humic soils (Kp 4.6 at pH 5).

Conclusions:

It is concluded that lithium compounds are not expected to show strong adsorption onto soils. In surface waters, adsorption onto suspended solids or sediments is not expected.

Reference 5

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

other: Due to its hydrolytic instability, the registered substance will not be present in surface waters. Evaluation of bioaccumulation potential must therefore be based on its hydrolysis products. This source gives information on lithium.

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Information cited in a lithium (toxicity to humans and the environment) literature review published in a peer-reviewed journal: includes summarised information on lithium adsorption by soils and sediments.

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex VIII 9.3.1 and Annex IX 9.3.3 under REACH in accordance with Annex XI Section 1.2. In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability: further, in accordance with REACH Annex XI section 1.2 testing is not scientifically necessary since it is the products of rapid LiPF6 hydrolysis which could enter the environment and existing information is available on the adsorptive properties of these.

Principles of method if other than guideline:

Expert review of information on lithium occurrence and distribution in the environment.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Lithium fluoride and then Li+ ions are hydrolysis products of the reaction of LiPF6 with water.

Details on matrix:

Transport/mobility in clays and river sediments is reviewed.

Remarks on result:

other: No quantified result

Remarks:

see "any other information on results" section

An affinity of lithium for secondary clays is considered to be a consequence of metal ion exchange (Mg2+ replacing Al3 +) which permits retention of Li+. In certain clay mineral and complex soil solutions, Li+ adsorption occurs preferentially over other cations.

Adsorption of lithium onto suspended material in rivers has been reported to be limited (e.g. 10% of available lithium adsorbing).

Conclusions:

The extent of lithium adsorption onto clays in related to content of metal ions, including those of magnesium and aluminium. Adsorption onto river sediments may be limited.

Reference 6

Endpoint:

adsorption / desorption, other

Remarks:

Fluoride mobility in soil

Type of information:

other: Due to its hydrolytic instability, the registered substance will not be present in surface waters. Evaluation of bioaccumulation potential must therefore be based on its hydrolysis products. This source gives information on fluoride

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Authoritative review produced by an expert group

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex VIII 9.3.1 and Annex IX 9.3.3 under REACH in accordance with Annex XI Section 1.2. In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability: further, in accordance with REACH Annex XI section 1.2 testing is not scientifically necessary since it is the products of rapid LiPF6 hydrolysis which could enter the environment and existing information is available on the adsorptive properties of these.

Principles of method if other than guideline:

Expert review of available information on fluoride mobility in soil

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Fluoride (F-) is a hydrolysis product of the reaction of LiPF6 with water.

Remarks on result:

other: no quantified result

Remarks:

see "Any other information on results" section

Soil pH and formation of aluminium and calcium complexes are cited as factors affecting inorganic fluoride mobility in the soil compartment. Complexation with metals (including aluminium and iron) are cited as major forms of bound fluoride in acidic soils. In alkaline soils, complexation with calcium can be important.

In lysimeter studies, 75% or more of added fluoride has been reported to be retained in loam soil over a period of 4 years (associated with aluminium content of the soil).

Conclusions:

The principal determinants of fluoride mobility in soil are reported to be pH and availability of aluminium and calcium for complex formation; lysimeter testing has shown extreme immobility of fluoride in loam soil.

Description of key information

In case of environmental release of LiPF6, the speed of its reaction with water and the subsequent dissociation of the soluble hydrolysis products will be such that only the adsorptive behaviour of the resultant ions has relevance for environmental mobility. 
Fluoride may be strongly adsorbed in acid soils and clays.  Lithium may be adsorbed onto certain clays, but is generally expected to show limited adsorption to most soils and to river sediments.
 Inorganic phosphate is expected to be fairly mobile in soils.

Additional information

HF

In the soil compartment, HF itself is not expected to be present: any fluoride introduced via unexpected release of LiPF6 will principally be present in the form of fluoride ion. For this reason, separate assessment of HF mobility is not meaningful or necessary.

 

Fluoride

A soil column of ferruginous lateritic clay was efficient at removing fluoride from aqueous solution: 10 mg F-/l reduced to 0.019 mg/l after 120 minutes: Chidambaram, Ramanathan and Vasudevan, 2003). Wang et al (2002) reported that clay and acid soils can strongly adsorb dissolved fluoride, leading to local accumulation of fluoride in soil; however in alkaline and quartz-sandy soils fluoride is not so well retained and leaches more into groundwater. A more extensive review of fluoride mobility in soil (WHO EHC 227, 2002) notes that the principal determinants of fluoride mobility in soil are pH and availability of aluminium and calcium for complex formation and cites extreme immobility of fluoride in loamy soil in lysimeter experiments. However the introduction of fluoride into the soil compartment through weathering of minerals means that fluoride is often found in groundwater: partitioning of fluoride entering the soil via pollution between soil solids and ground/pore water will depend on the local background concentration in groundwater as well as other soil characteristics.

 

Lithium

Lithium is selectively adsorbed in preference to other cations by certain clays, the extent of its retention in secondary clays is related to the local presence of magnesium (Li+ substituting for Mg2+); however it appears to be only poorly adsorbed onto river sediments (Aral and Vecchio-Sadus, 2008). Lithium also adsorbs slightly to humic soils, but in general lithium compounds are not expected to adsorb strongly to soils or sediments (Webwiser – US NLM, 2012).

 

Phosphate

Concerns arising from phosphate in runoff form agricultural lands indicate high soil mobility in some cases, and addition of inorganic phosphates have been shown to raise water-soluble phosphorus levels. Soil organic content affects phosphorus/phosphate mobility (Tarkalson and Leytem, 2009).