Overview
Colloidal Silicon Dioxide, commonly referred to as fumed silica, is a synthetic amorphous silicon dioxide with high purity and a large surface area. It is produced through the vapor-phase hydrolysis of silicon tetrachloride in a hydrogen-oxygen flame. This material is widely used as a flow aid, anti-caking agent, and viscosity modifier in various industries. Its unique properties, such as high surface area and thixotropic behavior, make it indispensable in pharmaceuticals, food processing, and industrial applications.
Physical and Chemical Properties
Colloidal Silicon Dioxide is characterized by its fine, white powder form with a high surface area ranging from 50 to 400 m²/g. It is chemically inert, thermally stable, and insoluble in water and most organic solvents. The material exhibits thixotropic behavior, meaning it forms a gel-like structure when undisturbed but flows under shear stress. This property is particularly valuable in coatings, adhesives, and sealants, where it prevents sagging and settling.
Main Applications
In the pharmaceutical industry, Colloidal Silicon Dioxide is used as an excipient to improve the flowability of powders and prevent caking in tablet formulations. It is also employed as a stabilizer in suspensions and ointments. In the food industry, it serves as an anti-caking agent in powdered products like spices, milk powder, and instant coffee. Industrial applications include its use in paints, coatings, and adhesives to enhance viscosity control and reinforcement.
Safety and Storage
While generally recognized as safe (GRAS) for food and pharmaceutical use, Colloidal Silicon Dioxide can pose respiratory hazards if inhaled in powder form. Proper personal protective equipment (PPE), such as masks and gloves, should be used during handling. Storage should be in a cool, dry environment, away from moisture and incompatible materials like strong acids and bases. Containers must be tightly sealed to prevent contamination and moisture absorption.
B2B Procurement Guide
When procuring Colloidal Silicon Dioxide, buyers should prioritize suppliers who provide certificates of analysis (COA) confirming compliance with relevant pharmacopeial standards (USP, EP, JP) for pharmaceutical-grade material. Key specifications to verify include particle size distribution, surface area, moisture content, and heavy metal limits. Bulk buyers should negotiate prices based on volume, with reference prices typically ranging from $5 to $20 per kg.