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The Elements in the Second Rank

7 Lithium

7.1 Identity

Table 7.1
CAS No., EINECS No. and molecular weight for lithium

7.2 Physico-chemical properties

Lithium has the lowest density of all metals and is the lightest of those elements that are solid at room temperature. It is a group 1A element in the periodic table and has the valence +1 (Li(I)). Lithium is generally very reactive and reacts explosively with water. Li₂O is formed when lithium is burned. Lithium salts as e.g. Li₂CO₃, LiF and Li₂PO₄ are all only slightly soluble in water [1].

Table 7.2
Physico-chemical data for metallic lithium. Data from [1, 2]

7.3 Uses and consumption

7.3.1 Uses

An important use of lithium is as cathode (oxides of lithium) or anode material (metallic lithium) in batteries for electronic equipment. These batteries are especially used in equipment where low weight is required, e.g. cameras and portable video recorders, mobile phones and portable PC's [10. 11, 13].

Lithium is used in many lightweight metal alloys e.g. together with magnesium and aluminum in airplanes and cars [13, 20]. It is also used as additive in lead alloys [20].

The aluminum industry use significant amounts of lithium in the form of lithium carbonate for the production of aluminum and Al-Li-alloys [12].

In the production of glass and ceramics, lithium carbonate, lithium fluoride, lithium sulfate, lithium phosphate, and lithium orthophosphate are used as additives [13, 20].

Lithium compounds are added to some types of cement. For example, lithium sulfate is used as a general additive and lithium nitrate as inhibitor of the undesired alkali-silica-reactivity [13].

In the production of synthetic rubber, different lithium compounds are used [20]. In textiles, lithium chloride can be used as stabilizer [13]. Lubricants can contain lithium hydroxide [13].

Medicine for treatment of patients with mental disorders often contains lithium [14, 21], e.g. use of lithium carbonate in the treatment of manic-depression [15, 16, 18, 19, 21].

The compounds lithium aluminum hydride and lithium boron hydride are often used as reducing agents in chemical synthesis. Numerous lithium compounds find application in chemical synthesis [13].

7.3.2 Consumption

The global production was 11,000 tons in 1996-1997, and the consumption in USA was approximately 2,800 tons. From the per capita consumption in USA it is estimated that the Danish consumption of lithium is approximately 55-60 tons.

Table 7.3
The relative distribution of the global consumption and the Danish use of Lithium in 1996 based on [5]

7.4 Emissions to and occurrence in the environment

Generally, lithium is not regarded as having adverse effects on the environment, and it is found naturally in the aquatic and terrestrial environment. In fresh water and sea water lithium is found as Li⁺. Furthermore, it can be found as Li₂CO₃, LiCl or Li₂O in the terrestrial environment. Emission of lithium originates from e.g. combustion of fossil fuels or waste. In coal and oil the concentration of lithium is 10-50 mg/kg and approximately 0.002 mg/kg, respectively [5]. The concentration of lithium in waste from incinerators and in sewage sludge is low [5]. The concentration is high in leachate from landfills where MSW gas cleaning residuals have been disposed.

Table 7.4
Typical background concentration of lithium in the environment. Data from [4, 7]

A limited investigation of the levels of lithium (and the other elements covered by this study) in the major emissions and waste streams in society was conducted in the autumn of 2001, see Table 7.5.

Lithium was found in all environmental samples in relatively high concentrations. The concentration was high in especially compost, waste water, sewage sludge and sediment from road runoff retention basins, while the concentration in effluent from waste water treatment plants was low.

Table 7.5
Levels of lithium in selected emissions and waste products from measurements conducted as part of this study in the autumn of 2001.

7.5 Danger classification

Lithium, lithium aluminum hydride, and lithium methanolate are found on the Danish list of dangerous substances. The latter is along with metallic lithium classified as corrosive. No lithium compounds are classified for adverse environmental effects [6].

Table 7.6
Classification of and risk phrases for lithium and lithium compounds

7.6 Toxicology

The primary target organ for lithium toxicity is the central nervous system. Lithium is therefore used therapeutically on membrane transport proteins in the central nervous system when treating manic-depression. Lithium is moderately toxic with lethal dose of LiCl in rats of 526-840 mg/kg body weight [22]. After chronic exposure to 1 mEq/L decreased brain weight was observed in male offspring [22]. Chemically, lithium resembles sodium, but is more toxic: in humans 5 g LiCl can result in fatal poisoning [8]. In therapeutic doses, damages on the central nervous system and the kidneys have been reported [23].

7.7 Environmental properties

7.7.1 Environmental chemistry

Lithium is found primarily as Li+ in the aquatic environment. A release of lithium-containing waste can result in wide dispersal due to low biological uptake and sorption to particulate matter.

7.7.2 Environmental toxicology

The lithium concentration in fresh water and sea water is on the µg/L-level. The acute toxicity of lithium is low, and lithium is considered as not being acutely toxic to aquatic organisms at the concentrations found in treated municipal waste water. The acute environmental effect concentration measured as EC₅₀ on Daphnia magna was determined to be 33-197 mg/L, which is at least 1000 times higher than the level in fresh water. Both lithium chloride and lithium sulphate has high water solubility, and the compounds will dissociate in aqueous environment.

Table 7.7
Test results for environmental toxicity. Data from [3]

7.7.3 Bioaccumulation

No data regarding bioaccumulation of lithium was found, but based on its low affinity to particles it is not expected to bioaccumulate.

7.8 Conclusions

Lithium is used in e.g. batteries, lubricants, ceramics and chemicals. No point sources, which can give adverse effects in the environment, have been identified. Lithium is mainly found on ion form in the environment and is not expected to bioaccumulate. Toxicity and environmental toxicity are low.

7.9 References

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