Preparation of Surface Chemically Modified Magnesium Hydroxide Nanoparticles by Azeotropic Distillation

Azeotropic distillation is an effective method for preparing nanoparticles, especially for applications that require precise control of particle size and morphology. Nanoparticles with high dispersibility and good surface properties can be prepared by azeotropic distillation. The following is a typical method and principle for preparing surface chemically modified magnesium hydroxide (Mg(OH)₂) nanoparticles by azeotropic distillation.

Principle

The basic principle of azeotropic distillation is to utilize the low azeotropic point of organic solvents and water to evaporate the organic solvents and water together by heating, thereby promoting uniform mixing and reaction of reactants in the liquid phase. In the process of preparing magnesium hydroxide nanoparticles, the particle size and surface properties can be effectively controlled by controlling the reaction conditions (such as temperature, pH value, reaction time, etc.) and selecting appropriate surfactants.

Experimental materials and equipment

Raw materials: magnesium salts (such as magnesium chloride, magnesium nitrate), alkaline substances (such as sodium hydroxide, ammonia water), surface modifiers (such as stearic acid, silane coupling agents, etc.).

Organic solvents: Commonly used organic solvents include ethanol, isopropanol, etc.

Experimental equipment: reactor, magnetic stirrer, condensation reflux device, centrifuge, drying oven, etc.

Preparation steps

Solution preparation: First, dissolve the magnesium salt in an organic solvent to form a transparent solution.

Alkaline solution addition: Under stirring conditions, slowly add an alkaline solution (such as ammonia water) until the reaction system reaches the required pH value to promote the precipitation of magnesium hydroxide.

Surface modifier addition: After the magnesium hydroxide precipitate is formed, a surface modifier is added to modify the surface of the magnesium hydroxide particles by chemical bonding or physical adsorption.

Azeotropic distillation: Heat the reaction system to evaporate the organic solvent and water to form an azeotrope, promote uniform mixing of the reactants, and help the growth and surface modification of the particles.

Product separation and cleaning: After the reaction is completed, the magnesium hydroxide nanoparticles are separated by centrifugation, and are washed multiple times with deionized water and organic solvents to remove residual surfactants and other impurities.

Drying: The washed magnesium hydroxide nanoparticles are placed in a drying oven and dried at a suitable temperature to obtain the final product.

Advantages

Size control: By precisely controlling the reaction conditions, the size and morphology of magnesium hydroxide nanoparticles can be effectively regulated.

Surface modification: By adding appropriate surface modifiers, the dispersibility and compatibility of magnesium hydroxide nanoparticles in different media can be improved.

High purity: Azeotropic distillation can effectively remove reaction by-products and unreacted raw materials to obtain high-purity magnesium hydroxide nanoparticles.

Application

Flame retardant: Modified magnesium hydroxide nanoparticles can be used as efficient halogen-free flame retardants and are widely used in plastics, rubber and other materials.

Catalyst: Due to its large specific surface area and good chemical stability, magnesium hydroxide nanoparticles can also be used as catalysts or catalyst carriers.

Environmental governance: Modified magnesium hydroxide nanoparticles can be used for wastewater treatment and adsorption of pollutants such as heavy metal ions.

Azeotropic distillation is an efficient and controllable method for preparing surface chemically modified magnesium hydroxide nanoparticles. By precisely controlling the reaction conditions and selecting appropriate surface modifiers, magnesium hydroxide nanoparticles with excellent performance can be obtained, and these particles have broad application prospects in many fields.