Ytterbium

Typical wastewaters

• rare earth separation and processing (saponification wastewater) Yb³⁺ carried with the whole lanthanide row in ammonia rich separation plant wastewater (ammonia nitrogen 300 to 5,000 mg/L in Chinese saponification wastewater, 2005 estimate) no ytterbium specific concentration read
• coal mine drainage (acid) Yb³⁺ and the YbSO₄⁺ ion pair dissolved at low pH in sulfate rich drainage; total rare earths averaged 282 µg/L over 141 Appalachian sites, per-element values not read co-precipitates into the iron, aluminium and manganese hydroxide sludge when the drainage is neutralised

1 · Identity

Symbol, number

Yb, 70

Oxidation states in water

+3 only (Yb³⁺)

Note

The metal's reactions are in the book entry; in water ytterbium shares the trivalent carbonate and phosphate chemistry of the lanthanide row.

2 · Occurrence in water

Natural sources

Weathering of monazite and xenotime; heavy lanthanide, carbonate complexed and relatively mobile in alkaline water. Dutch acidic groundwater (pH below 6.2) ranged from 0.05 µg/L for Yb up to 105 µg/L for La.

Anthropogenic sources

None read as a point source; soft drink syrup enriched Yb, Lu and Ce in post-mix beverages relative to the tap water (Schmidt 2019). Rare earth separation wastewater carries the whole row.

3 · Speciation

Trivalent Yb³⁺ throughout the natural pH and Eh range. Below about pH 6, and in sulfate rich water such as mine drainage, the free ion and the YbSO₄⁺ ion pair dominate (sulfate complexes above 90 percent at pH 3.1 to 3.4 in the EPA groundwater study). From neutral to alkaline pH the carbonate complexes YbCO₃⁺ and Yb(CO₃)₂⁻ take over, and they bind the heavy lanthanides more strongly than the light ones (at pH 5.1 to 6.1 the carbonate share rose from 5.0 percent for La to 19.2 percent for Lu). Phosphate, carbonate and fluoride solids and sorption to iron and manganese oxides cap the dissolved concentration at ng/L in oxic neutral water, and the light lanthanides ride partly on colloids.

Solubility

Controlled by the phosphate, carbonate and fluoride solids and by sorption; the RIVM report puts total dissolved lanthanum and cerium in Dutch surface water at about 1 µg/L or less and the free ion fraction at 0.3 fM to 9 pM. No solubility product for a ytterbium solid was read this session.

Hydrolysis

Hydrolysis of Yb³⁺ is minor in natural water; the hydroxide Yb(OH)₃ forms only at high pH, so lime or caustic neutralisation of acid mine water strips the element with the iron and aluminium hydroxides rather than as its own hydroxide (no hydrolysis constant read this session).

Complexation

Sulfate at low pH, carbonate at neutral to alkaline pH (the sources read); humic substances compete for the element in organic rich water and are out-competed by carbonate in alkaline water. No stability constants were read this session.

Precipitates

YbPO₄ (hydrated phosphate), Yb₂(CO₃)₃, YbF₃ near fluoride rich discharges, Yb(OH)₃ at high pH; co-precipitated on iron, aluminium and manganese hydroxides.

4 · Role in treatment

Not relevant or not given for this element.

5 · Removal and control

6 · Analytics

Sampling pitfalls

Filtration defines the result: 0.2 or 0.45 µm filtrates still carry colloid bound lanthanides, and only ultrafiltration (10 kDa) separates the truly dissolved pool, which matters most for the light lanthanides. Acidify after filtration. Report the shale-normalised pattern so that anthropogenic anomalies (gadolinium, lanthanum, samarium) are visible.

7 · Regulatory limits

Limits change, and many are set locally. Treat these as the published values to start from, not as your compliance target: check the standard in force at your site and the numbers written into your own permit.

8 · Health and environmental effects

Toxicity

No human health guideline anywhere read; no acute or chronic human toxicity data for this element were read this session.

Bioaccumulation

Field bioconcentration factors in Rhine estuary amphipods fall from the light to the heavy lanthanides (La 28,840 to Lu 4,786; Yb 6,607); carp muscle takes up little (BCF 0.22 to 1.10 for Ce, La, Nd, Pr, Sm) while internal organs reach 634 to 978. Anthropogenic La and Sm in the Rhine are taken into mussel shells, anthropogenic Gd is not, so speciation decides bioavailability.

Ecotoxicity

No MPC was derived for ytterbium: the RIVM report set risk limits only for Y, La, Ce, Pr, Nd, Sm, Gd and Dy. The one ytterbium number it carries is a field bioconcentration factor in amphipods of 6,607 (porewater basis).

Flags

• The RIVM MPCs, where they exist, are environmental risk limits from a 2000 report (LC₅₀ divided by 1000, background at the detection limit), not permit limits.
• The seawater range is one western Pacific station.

Gaps

• WHO GDWQ and EU DWD 2020/2184 Annex I were not read this session (eur-lex returned the articles without the annexes), so their absence of a rare earth parameter is not asserted here; only the US EPA table was read.
• No GCC discharge standard was read; no GCC row is written.
• World average river water concentrations (Gaillardet et al. 2003) were not reachable; river figures come from the Rhine and Dutch waters only.
• No source read this session gives municipal wastewater concentrations for this element beyond the gadolinium literature.
• ICP-MS oxide interference corrections between lanthanides are standard practice but no method text describing them was read, so none is written.
• No stability constants or solubility products for this element's carbonate, phosphate or hydroxide were read; the speciation is qualitative, taken from the EPA groundwater study and the RIVM report.
• No ytterbium toxicity test was read.

Sources

Identity

Name and symbol

Ytterbium, Yb

Atomic number

70 protons

Position

no group (f-block) · period 6 · f-block · lanthanide

CAS number

7440-64-4

Atomic structure

Atomic mass

173.045 u

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴
[Xe] 6s²⁴f¹⁴

Electrons per shell

2, 8, 18, 32, 8, 2

Valence electrons

16 ns, (n-1)d and (n-2)f

Physical properties

State at room temperature

Solid

Melting point

1,092 K (818.85 °C)

Boiling point

1,469 K (1,195.85 °C)

Density

6.9 g/cm3

Appearance

silvery white; with a pale yellow tint

Thermal conductivity

38.5 W/(m·K)

Electrical resistivity

β, poly: 0.250 µΩ·m

Electrical conductivity

4 MS/m

Crystal structure

face-centered cubic

Molar heat capacity

26.74 J/(mol·K)

Chemical properties

Oxidation states

+3, +2

Electronegativity

not in sources

Ionisation energy

6.254 eV
1st 603.4, 2nd 1,174.8, 3rd 2,417 kJ/mol

Electron affinity

not in sources

Atomic radius

empirical 187, covalent 187, van der Waals 242 pm

Ionic radius

Yb²⁺ 102; Yb³⁺ 87 pm

Reactivity

The lanthanide with the fullest 4f shell (4f14 6s2), so its +2 state is relatively stable and its density and melting point are lower than its neighbours; still an electropositive metal that dissolves quickly in acids, slowly in water, and oxidises slowly in air.

with water

Dissolves slowly in cold water and quickly in hot water to the hydroxide and hydrogen: $\ce{2 Yb + 6 H2O -> 2 Yb(OH)3 + 3 H2}$, so it is stored in closed containers.

with oxygen, air

Tarnishes slowly in air, taking a golden or brown hue under a protective oxide layer; the finely divided metal oxidises readily and burns: $\ce{4 Yb + 3 O2 -> 2 Yb2O3}$, white ytterbia.

with acids

Readily attacked and dissolved by dilute and concentrated mineral acids, liberating hydrogen; in dilute sulfuric acid it gives colourless Yb3+ solutions: $\ce{2 Yb + 3 H2SO4 -> Yb2(SO4)3 + 3 H2}$, the sulfate.

with halogens

Reacts with all the halogens to the white trihalides: $\ce{2 Yb + 3 Cl2 -> 2 YbCl3}$, and the trihalides are reduced by hydrogen, zinc or the metal to the dihalides.

Typical compounds

• Yb₂O₃ ytterbium(III) oxide ytterbia, white oxide, dopant for fibre lasers
• YbCl₃ ytterbium(III) chloride white, soluble trihalide
• YbF₃ ytterbium(III) fluoride white trihalide used in dental composites
• YbCl₂ ytterbium(II) chloride divalent halide made by reducing YbCl3 with hydrogen
• Yb₂(SO₄)₃ ytterbium(III) sulfate colourless salt from sulfuric acid

Occurrence, production and use

Crustal abundance

3.2 milligrams per kilogram

Oceanic abundance

8.2×10-7 milligrams per liter

Occurrence and sources

Ytterbium occurs along with other rare earths in a number of rare minerals. It is commercially recovered principally from monazite sand, which contains about 0.03%. Ion-exchange and solvent extraction techniques developed in recent years have greatly simplified the separation of the rare earths from one another.

• monazite the principal source, with the other lanthanides

Extraction, production

not in sources

Uses

Ytterbium has few uses. It can be alloyed with stainless steel to improve some of its mechanical properties and used as a doping agent in fiber optic cable where it can be used as an amplifier. One of ytterbium's isotopes is being considered as a radiation source for portable X-ray machines.

Ytterbium metal has possible use in improving the grain refinement, strength, and other mechanical properties of stainless steel. One isotope is reported to have been used as a radiation source substitute for a portable X-ray machine where electricity is unavailable. Few other uses have been found.

Safety, toxicity

Ytterbium has a low acute toxic rating.

GHS classification, signal word Danger

• H228 Flammable solid Flammable solids
• H250 Catches fire spontaneously if exposed to air Pyrophoric liquids
• H252 Self-heating in large quantities; may catch fire Self-heating substances and mixtures
• H302 Harmful if swallowed Acute toxicity, oral
• H312 Harmful in contact with skin Acute toxicity, dermal
• H315 Causes skin irritation Skin corrosion/irritation
• H319 Causes serious eye irritation Serious eye damage/eye irritation
• H332 Harmful if inhaled Acute toxicity, inhalation
• H335 May cause respiratory irritation Specific target organ toxicity, single exposure; Respiratory tract irritation

Discovery and name

Discovered by

Jean Charles Galissard de Marignac

Discovered

1878

First isolated

Wilhelm Klemm and Heinrich Bommer

Named by

not in sources

Origin of the name

after Ytterby (Sweden), where it was mined

Ytterbium has a bright silvery luster, is soft, malleable, and quite ductile. Even though the element is fairly stable, it should be kept in closed containers to protect it from air and moisture. Ytterbium is readily attacked and dissolved by dilute and concentrated mineral acids and reacts slowly with water. Ytterbium has three allotropic forms with transformation points at -13°C and 795°C: The beta form is a room-temperature, face-centered, cubic modification, while the high-temperature gamma form is a body-centered cubic form. Another body-centered cubic phase has recently been found to be stable at high pressures at room temperatures. The beta form ordinarily has metallic-type conductivity, but becomes a semiconductor when the pressure is increased about 16,000 atm. The electrical resistance increases tenfold as the pressure is increased to 39,000 atm and drops to about 10% of its standard temperature-pressure resistivity at a pressure of 40,000 atm. Natural ytterbium is a mixture of seven stable isotopes. Seven other unstable isotopes are known.