How to reuse silica gel desiccant?
Silica gel is one of the commonly used materials in desiccants. Let’s talk about how to reuse silica gel desiccants. There are three points to pay attention to:
1. Regeneration of silica gel after adsorbing water vapor. 2. After silica gel absorbs water, it can be removed by thermal desorption. There are many heating methods, such as electric furnace, flue waste heat heating and hot air drying. It is appropriate to control the temperature of desorption heat between 120 and 180 ℃. For blue gel indicator, color-changing silica gel and DL type blue silica gel, it is appropriate to control it between 100 and 120 ℃. The maximum temperature during regeneration of various industrial silica gels should not exceed the following limits: coarse-pore silica gel should not be higher than 60 ℃; fine-pore silica gel should not be higher than 200 ℃; blue gel indicator agent (or color-changing silica gel) should not be higher than 120 ℃; aluminum silica gel should not be higher than 350 ℃. The moisture content of regenerated silica gel is generally controlled below 2% before it can be put back into use.
2. Things you should pay attention to when using silicone again:
(1). When drying and regenerating, attention should be paid to gradually increasing the temperature to avoid violent drying causing the rubber particles to explode and reducing the recovery rate.
(2). When roasting and regenerating silica gel, excessive temperature will cause changes in the pore structure of the silica gel, significantly reducing its adsorption effect and affecting its use value. For blue gel indicators or color-changing silica gel, the desorption and regeneration temperature should not exceed 120°C, otherwise the color development effect will be lost due to the gradual oxidation of the color developer.
(3). Regenerated silica gel should generally be screened to remove fine particles to make the particles uniform.
3. Regeneration of silica gel after adsorbing organic impurities:
(1). For the roasting method, dry coarse-pore silica gel can be placed in a roasting furnace and gradually heated to 500 to 600 ℃, and it will take about 6 to 8 hours until the colloidal particles turn white or yellowish brown. For fine-pore silica gel, the baking temperature cannot exceed 200°C. In the rinsing method, the silica gel is adsorbed in saturated water vapor until it reaches saturation, then soaked and rinsed in hot water. Detergent can be used in combination to remove waste oil or other organic impurities, and then washed with clean water and then dried and dehydrated.
(2). Solvent flushing method: According to the type of organic matter adsorbed by the silica gel, an appropriate solvent is selected to dissolve the organic matter adsorbed in the silica gel, and then the silica gel is heated to remove the solvent.