Boron (B) in Water Treatment

Quick Answer

Boron (B) is a metalloid with atomic number 5. PubChem lists its standard state as solid and its relative atomic mass as 10.81.

Boron is important in seawater desalination because boric acid is weakly rejected by reverse-osmosis membranes at neutral pH. High-pH second-pass RO, boron-selective resin or a combined process may be needed when the product-water target is strict.

Interesting Facts

• Boric acid is mostly uncharged at typical seawater pH, so it can pass through RO membranes more readily than many ions.
• Raising second-pass pH converts more boric acid to borate, which RO rejects more effectively.
• Boron is a plant micronutrient, but the useful-to-harmful concentration window can be narrow for sensitive crops.

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

Boron (B)

1. Basic Information

Atomic Number	5
Symbol	B
Atomic Mass	10.81 g/mol
Electron Configuration	1s22s22p1

2. Physical and Chemical Properties

• Boron is a metalloid element with three allotropic forms: amorphous, crystalline, and metallic.
• Has a melting point of 2076 ° C and a boiling point of 3927 ° C.
• Elemental boron is very hard, has good thermal conductivity, and is a semi-conductor
• Reacts with oxygen to form boron oxide (B2O3)
• Reacts with nitrogen to form boron nitride (BN)

3. Presence in Water and Health Effects

Boron occurs naturally in some groundwaters and geothermal waters and can also come from detergents or industrial streams. Concentrations are site-specific. Drinking-water and irrigation targets are not interchangeable: check the current requirement for the jurisdiction and intended crop or use.

4. Water Treatment Applications and Separation Methods

Boron is difficult to remove from water due to its properties similar to silica and its weak affinity for common ion exchange resins. The main methods of boron removal include:

• Reverse osmosis (RO): RO membranes can reject boron with high efficiency. Using a high pH (10-11) can enhance boron removal.
• Specialized ion exchange resins: Boron-selective anion exchange resins such as sorbitol-N-methylglucamine can be used effectively. Regenerate the resin using acidic and alkaline solutions.
• Adsorption: Oxide-based adsorbents such as activated alumina, zirconium oxide, and modified iron oxide are capable of adsorbing boron.
• Hybrid RO-IX: Combining RO and a specialized ion exchanger (usually in a lead-lag-polish scheme) provides maximum boron removal.

5. Industrial Uses in Water Treatment

FGD blowdown and mineral-processing brines can contain much more boron than ordinary source water. Boron-selective resins may be useful, but capacity, regeneration, background salinity, and the receiving-water discharge permit must be tested for the actual stream.

6. Practical Design Note

Two-pass RO with pH adjustment is a recognised boron-control configuration, but pH, membrane selection, recovery, scaling risk, and product-water stabilisation must be designed together.

8. Environmental Impact and Sustainability Considerations

Boron can damage sensitive crops at concentrations tolerated by less-sensitive species, so irrigation suitability depends on crop, soil, climate, and irrigation management. RO concentrate and resin-regeneration waste retain the removed boron and require an approved management route.