Indium (In) in Water Treatment

Quick Answer

Indium (In) is a post-transition metal with atomic number 49. PubChem lists its standard state as solid and its relative atomic mass as 114.818.

Indium is not a common target in ordinary water treatment but may occur in mining or specialized industrial wastewater. Total versus dissolved concentration, oxidation state, pH and complexing agents should be measured before evaluating precipitation, adsorption, ion exchange or membranes.

Interesting Facts

• Indium was identified by the indigo-blue line in its emission spectrum—the colour also inspired its name.
• Indium tin oxide combines electrical conductivity with optical transparency, which is why indium is important in touchscreens and flat-panel displays.
• In water, indium is more likely to signal electronics manufacturing, recycling or mining activity than a natural drinking-water problem.

Water-treatment Design Implications

An element name alone is not enough to select treatment equipment. Confirm chemical form or speciation, total and dissolved concentration, pH, alkalinity, competing ions and the product-water target. Send the water-analysis results to Watermart to identify additional testing and shortlist processes before equipment is specified.

Summary Data Sources

• PubChem — Indium
• IUPAC Periodic Table of Elements
• WHO chemical hazards in drinking-water

Indium (In)

1. Basic Information

Atomic Number	49
Symbol	In
Atomic Weight	114.82 g/mol
Category	Post-transition metal
Electron Configuration	[Kr] 4d10 5s2 5p1

2. Physical and Chemical Properties

Indium is a soft, ductile and lustrous metal with a silvery white color. It has a low melting point (156°C) and a high boiling point (2000°C). It is stable in air and water at room temperature, but soluble in acids. It can form various ionic and covalent compounds. Indium has the unique ability to wet glass.

3. Presence in Water and Health Effects

Indium is rarely found in natural water in significant concentrations. However, it can be present in wastewater from the electronics and mining industries. Chronic exposure to indium can cause lung, liver, and kidney problems. Indium compounds are considered toxic and should be handled with care.

4. Water Treatment Applications and Removal Methods

Although rarely a primary target in water treatment, indium can be removed by several methods:

• Ion exchange: Using specialized cation or anion exchange resins, depending on the chemical form of indium.
• Chemical precipitation: Precipitates indium as hydroxide at high pH.
• Adsorption: Using activated carbon or special adsorbents.
• Membrane filtration: Reverse osmosis or nanofiltration can be effective for removing indium ions.

5. Industrial Use in Water Treatment

Indium itself is rarely used in water treatment. However, some indium compounds have been investigated for specialized applications such as photocatalysis for degradation of organic pollutants in water.

8. Environmental Impacts and Sustainability Considerations

Releases of indium to the environment mainly come from the mining and electronics industries. Although its effects on ecosystems have not been extensively studied, there are concerns about potential bioaccumulation in the food chain. Recycling indium from used electronic equipment is becoming increasingly important for resource sustainability.