Disodium Octaborate Tetrahydrate (DOT): A High-Solubility Boron Source for Agriculture and Industry

Disodium Octaborate Tetrahydrate (DOT) is a highly water-soluble inorganic borate widely used in agriculture, wood preservation, pest-control formulations and a range of industrial applications.

Standard Chemical Formula: Na₂B₈O₁₃·4H₂O

CAS No.: 12280-03-4

Molecular Weight: 412.52 g/mol

Theoretical Boron Content: approximately 20.9% B

1. Chemical and Physical Properties

• Chemical Formula: Na₂B₈O₁₃·4H₂O

• CAS No.: 12280-03-4

• Molecular Weight: 412.52 g/mol

• Boron Content: approximately 20.9% by weight

• Appearance: White crystalline powder or granulated solid

• Water Solubility: Highly soluble in water, including relatively cool water, making it particularly suitable for aqueous formulations and agricultural applications

• pH: Aqueous solutions are mildly alkaline; a 1% solution typically has a pH of approximately 8–9

• Thermal Behavior: DOT does not exhibit a simple conventional melting point. Upon heating, it progressively loses crystalline water and eventually converts into other sodium borate phases.

• Stability: Stable under normal dry storage conditions. Prolonged exposure to humidity may result in moisture absorption and caking.

Its combination of high boron concentration and excellent water solubility distinguishes DOT from many conventional borate materials.

2. Chemical Characteristics

2.1 Acid-Base Behavior

When dissolved in water, DOT forms a borate-containing solution with mildly alkaline characteristics. Its borate chemistry allows it to participate in buffering and complex chemical equilibria depending on concentration and pH.

2.2 Thermal Behavior

Upon heating, DOT gradually loses its water of crystallization. At higher temperatures, dehydration and structural transformation produce anhydrous or partially dehydrated sodium borate phases.

This dehydration behavior also contributes to its functionality in certain fire-retardant and material-protection systems.

3. Production Methods

Several production routes can be used depending on raw-material availability, process economics and desired product specifications.

Method 1: Boric Acid–Sodium Hydroxide Route

A simplified theoretical reaction can be expressed as:

8H₃BO₃ + 2NaOH → Na₂B₈O₁₃·4H₂O + 9H₂O

Typical process:

1. Dissolve boric acid in water under controlled temperature conditions.

2. Slowly introduce sodium hydroxide solution while maintaining continuous agitation.

3. Adjust concentration, temperature and pH to obtain the desired sodium-to-boron ratio.

4. Concentrate and cool the solution to promote formation of the target borate phase.

5. Separate the product through crystallization or other controlled solid-forming processes.

6. Filter, dry and, where required, mill or granulate the finished material.

Method 2: Borax-Boric Acid Route

DOT can also be produced using sodium tetraborate, commonly known as borax, together with boric acid.

A simplified reaction using borax decahydrate can be represented as:

Na₂B₄O₇·10H₂O + 4H₃BO₃ → Na₂B₈O₁₃·4H₂O + 12H₂O

Typical process:

1. Dissolve borax and boric acid under controlled conditions.

2. Adjust temperature and concentration to obtain the appropriate borate composition.

3. Concentrate the reaction solution.

4. Control crystallization or drying conditions to obtain DOT.

5. Filter, dry, mill or granulate according to the required commercial specification.

In industrial production, boric acid and borax-based routes are commonly employed, while the precise process configuration depends on raw-material availability, energy consumption and targeted particle characteristics.

4. Major Applications

4.1 Pest-Control Formulations

Borates, including DOT, are used as active ingredients in certain professional and household pest-management systems, subject to local pesticide-registration requirements.

Termite Control

DOT-based formulations may be used for treating structural timber and other wood materials against termites and wood-destroying insects.

Application methods may include:

• Surface spraying

• Brushing

• Dipping

• Pressure or diffusion treatment

• Injection into susceptible timber structures

Borates interfere with biological and metabolic processes after ingestion by susceptible pests, helping protect treated materials.

Cockroach and Ant Control

Borate compounds may also be incorporated into:

• Dust formulations

• Liquid formulations

• Baits

• Professional pest-control products

Actual permitted uses and application rates depend on national and regional pesticide regulations.

4.2 Wood Preservation

Wood protection represents one of the most established non-agricultural applications of DOT.

DOT may help protect timber against:

• Wood-decaying fungi

• Mold

• Termites

• Certain wood-boring insects

Because of its high water solubility, DOT can penetrate wood through aqueous treatment systems.

Common treatment methods include:

• Dipping

• Spraying

• Brushing

• Diffusion treatment

• Pressure treatment

It is especially useful for interior or protected structural timber where prolonged leaching by rainwater is limited.

Properly treated wood can achieve improved biological durability and a longer service life.

4.3 Fire-Retardant Treatment

Borate compounds can contribute to the fire-retardant modification of wood, cellulose-based materials and selected construction materials.

When exposed to heat, borates can:

• Release chemically bound water

• Promote formation of protective inorganic layers

• Reduce the availability of combustible decomposition products

• Suppress flame propagation

• Reduce afterglow in certain materials

DOT is therefore used as one component in selected fire-retardant and wood-protection formulations, often in combination with other functional additives.

5. Industrial Applications

5.1 Glass Manufacturing

Borates are important components in many specialty glass formulations.

DOT can serve as a soluble source of boron and sodium in selected applications, although boric acid and borax remain more conventional raw materials in large-scale glass production.

Boron-containing glass formulations can provide:

• Improved thermal resistance

• Improved chemical durability

• Controlled thermal expansion

• Enhanced processing characteristics

Potential applications include specialty and borosilicate glass systems.

5.2 Ceramics and Glazes

Borates may be incorporated into ceramic bodies, frits and glaze systems to modify:

• Melting and vitrification behavior

• Surface characteristics

• Thermal properties

• Mechanical performance

• Glaze development

DOT may be selected where a highly soluble boron source is advantageous to the manufacturing process.

5.3 Coatings, Adhesives and Specialty Formulations

DOT and related borates may be used in selected formulations as:

• Boron sources

• Buffering components

• Crosslinking-supporting agents

• Formulation stabilizers

• Functional inorganic additives

Their exact function depends strongly on the chemistry of the final formulation.

6. Agricultural Applications

Agriculture is one of the most important commercial applications of high-solubility DOT.

High-Efficiency Boron Fertilizer

DOT contains approximately 20.9% elemental boron, normally commercialized around 20.5-21.0% B depending on product specification.

Boron is an essential plant micronutrient involved in:

• Cell-wall formation and structural stability

• Cell division and meristem development

• Pollen germination and pollen-tube growth

• Flowering and reproductive development

• Sugar and carbohydrate transport

• Root development

• Fruit and seed formation

Boron deficiency may result in:

• Poor flowering and fruit set

• Deformation of young leaves

• Death of growing points

• Hollow or cracked tissues in susceptible crops

• Reduced root development

• Lower crop quality and yield

Advantages of DOT as a Boron Source

Compared with less soluble conventional borate minerals, DOT offers:

• High water solubility

• High boron concentration

• Rapid preparation of fertilizer solutions

• Good suitability for foliar application

• Compatibility with many fertigation programs

• Convenient formulation into soluble micronutrient fertilizers

Typical application methods include:

• Foliar spraying

• Fertigation

• Soil application

• Incorporation into water-soluble fertilizer formulations

• Production of boron-containing compound fertilizers

Because the concentration range between boron deficiency and boron toxicity can be relatively narrow, application rates should always be determined according to crop type, growth stage, soil boron status and local agronomic recommendations.

7. Chemical and Formulation Applications

DOT can also serve as a soluble borate source in chemical manufacturing and specialty formulations.

Depending on the reaction system, borates may contribute to:

• pH buffering

• Boron introduction

• Complexation equilibria

• Formulation stabilization

• Reaction-condition control

In certain specialized chemical systems, borates may also function as reaction promoters or auxiliary components.

The specific role of DOT should therefore be evaluated according to the chemistry of the individual industrial process rather than regarded as a universal catalyst.

8. Storage and Handling

Store DOT in a cool, dry and well-ventilated warehouse.

Recommended storage practices include:

• Protect from excessive humidity and water exposure.

• Keep packaging tightly sealed.

• Avoid prolonged exposure to high temperatures.

• Prevent long-term direct sunlight where practical.

• Keep product labels complete and clearly identifiable.

• Store separately from food and drinking-water supplies where required by local regulations.

• Inspect packaging regularly for damage, moisture penetration or caking.

• Follow applicable local regulations regarding chemical storage, occupational safety and waste disposal.

DOT is generally stable under normal storage conditions but may absorb moisture and cake if exposed to humid environments for prolonged periods.

9. Product Summary

Disodium Octaborate Tetrahydrate (DOT) is a versatile, highly water-soluble inorganic borate distinguished by its approximately 20.9% boron content and broad range of applications.

Its major commercial uses include:

• Agricultural boron nutrition

• Wood preservation

• Termite and insect-control formulations

• Fire-retardant systems

• Specialty industrial formulations

• Glass and ceramic processing

• Chemical manufacturing

Among these applications, its excellent water solubility and high boron concentration make DOT particularly valuable as a high-efficiency boron source for modern agriculture.

Correct formulation, application rate, storage and regulatory compliance are essential for achieving optimum product performance and safe use.

Disodium Octaborate Tetrahydrate (DOT): A High-Solubility Boron Source for Agriculture and Industry