What is the Difference Between Colloidal Silica and Reactive Silica

In various industrial and scientific fields, the difference between colloidal silica and reactive silica poses a significant challenge. Understanding these two forms of silica is crucial for selecting the right material for specific applications. However, confusion often arises due to their distinct properties and functions.

What is the difference between colloidal silica and reactive silica? Colloidal silica generally displays low reactivity due to its stable and inert structure, while reactive silica displays high reactivity due to its porous structure and active surface sites.

Key Areas Covered

1. What is Colloidal Silica
      – Definition, Features, Applications
2. What is Reactive Silica
      – Definition, Features, Applications 
3. Similarities Between Colloidal Silica and Reactive Silica
      – Outline of Common Features
4. Difference Between Colloidal Silica and Reactive Silica
      – Comparison of Key Differences
5. FAQ: Colloidal Silica and Reactive Silica
      – Frequently Asked Questions

Key Terms

Colloidal Silica, Reactive Silica

Difference Between Colloidal Silica and Reactive Silica  - Comparison Summary

What is Colloidal Silica

Colloidal silica is a suspension of finely divided silicon dioxide particles in a liquid medium, typically water. These particles are extremely small, ranging from 1 to 100 nanometers in size, giving colloidal silica unique properties and applications. The term “colloidal” implies that these particles do not settle quickly due to Brownian motion, remaining dispersed in the liquid.

Differentiate Colloidal Silica and Reactive Silica

One of the key characteristics of colloidal silica is its high surface area, which results from the small particle size. This property makes colloidal silica an excellent material for various applications, particularly in coatings, electronics, and pharmaceutical industries.

In coatings and catalysts, colloidal silica serves as a crucial component. Its use in coatings enhances scratch resistance and durability and provides a smooth finish. Additionally, colloidal silica is employed as a catalyst support in chemical reactions due to its large surface area and unique surface chemistry.

In the electronics industry, colloidal silica finds application in the fabrication of integrated circuits. It is used in chemical mechanical planarization (CMP) processes to polish and flatten semiconductor surfaces, ensuring precise and uniform layers.

In the pharmaceutical field, colloidal silica acts as a pharmaceutical excipient, contributing to drug formulations. Its role includes enhancing the stability of suspensions, controlling rheological properties, and aiding in the controlled release of active pharmaceutical ingredients.

The versatility of colloidal silica extends to various other sectors, including ceramics, textiles, and wastewater treatment. Its ability to modify material properties at a nanoscale level makes it a valuable component in developing advanced materials.

What is Reactive Silica

Reactive silica is a form of silicon dioxide that exhibits an increased reactivity compared to regular silica. Silica is a common mineral found in various forms, such as quartz, and is a fundamental component of many minerals, rocks, and soils. Due to its unique properties, reactive silica gains significance in different industrial processes and environmental contexts.

In the realm of industrial applications, reactive silica plays a crucial role in various chemical and manufacturing processes. Its enhanced reactivity is often exploited in producing specialty glasses, ceramics, and catalysts. For instance, in the glass industry, reactive silica contributes to forming high-quality glass products with specific optical and mechanical properties. In catalyst production, its increased reactivity can catalyze certain chemical reactions more efficiently.

In environmental contexts, reactive silica is of interest in water treatment and agriculture. Moreover, in water treatment, the presence of reactive silica can impact the performance of filtration systems. The reactivity of silica with other substances in water can influence the removal of impurities, making it an important factor to consider in designing water treatment processes. In agriculture, reactive silica plays a role in soil fertility. Certain plants, like rice, benefit from the availability of reactive silica in the soil, contributing to enhanced growth and disease resistance.

Moreover, understanding and monitoring reactive silica levels are essential in various scientific fields, including geology and environmental science. Analyzing reactive silica content in rocks and sediments can provide insights into geological processes and the history of Earth’s crust.

Similarities Between Colloidal Silica and Reactive Silica

  • Both colloidal silica and reactive silica are composed of silicon dioxide molecules.
  • Depending on their formulation and application, they can exist in a liquid or solid state.

Difference Between Colloidal Silica and Reactive Silica


Colloidal silica are tiny particles of silica suspended in a liquid, whereas reactive silica is a form of silica that can undergo chemical reactions.


Colloidal silica particles are typically very small, in the nanometer range, contributing to their colloidal nature. Reactive silica may consist of larger particles or molecules that exhibit distinct chemical reactivity.


While colloidal silica tends to remain stable in solution due to its colloidal nature, exhibiting minimal settling, reactive silica may undergo transformations or reactions that can affect its stability under certain conditions.


While colloidal silica is generally non-reactive due to its stable structure, reactive silica shows high reactivity with other substances due to its porous nature and active sites.

FAQ: Colloidal Silica and Reactive Silica

What is colloidal silica used for?

Colloidal silica is used for densification of concrete and cement.

Is silica gel reactive?

Silica gel is non-reactive under normal usage.

What is another name for silica?

Another name for silica is silicon dioxide.


Colloidal silica is tiny particles of silica suspended in a liquid, whereas reactive silica is a form of silica that can undergo chemical reactions. The main difference between colloidal silica and reactive silica is that colloidal silica generally displays low reactivity, while reactive silica displays high reactivity.


1. “Colloidal Silica.” Wikipedia. Wikipedia Foundation.  
2. “Reactive silica: XVII. The nature of the reaction center.” Science Direct.

Image Courtesy:

1. “Schematic silica gel surface” By Stéphane Mons – Own work (CC BY 2.5) via Commons Wikimedia

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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