Silica gel is one of the commonly used materials in the desiccant. Let’s talk about how to reuse the desiccant. There are three points to pay attention to:
1. Regeneration of silica gel after adsorbing water vapor. 2. Silica gel adsorbing water. After drying, the water can be removed by thermal desorption. There are many heating methods, such as electric furnace, flue waste heat heating and hot air drying. The temperature for removing the additional heat should be controlled at 120-180 ℃. For blue gel indicator, discoloration silica gel, and DL-type blue silica gel, the temperature should be controlled at 100-120 ℃. The maximum temperature during the regeneration of various industrial silica gels should not exceed the following limit: the coarse-pored silica gel should not be higher than 60°C. ℃; fine-pored silica gel should not be higher than 200 ℃; blue glue indicator (or discoloration silica gel) should not be higher than 120 ℃; silica-alumina glue should not be higher than 350 ℃. After the regenerated silica gel, its moisture content is generally controlled below 2% before it can be put into use again.
2. Matters needing attention when using silica gel again:
1. During drying and regeneration, attention should be paid to gradually increasing the temperature, so as to avoid violent drying causing the rubber particles to burst and reduce the recovery rate.
2. When calcining and regenerating silica gel, excessively high temperature will cause changes in the pore structure of silica gel, which will significantly reduce its adsorption effect and affect its use value. For blue gel indicator or color-changing silica gel, the temperature of desorption and regeneration should not exceed 120 ℃, otherwise the color development effect will be lost due to the gradual oxidation of the color developer.
3. The regenerated silica gel should generally be sieved to remove fine particles to make the particles uniform. Henan Zhengzhou Kaibiyuan silica gel absorbs water vapor or other organic substances in the medium during use, and its adsorption capacity decreases. It can be reused after regeneration.
3. Regeneration of silica gel after adsorbing organic impurities:
1. For dry coarse-pored silica gel, the roasting method can be placed in a roasting furnace to gradually increase the temperature to 500-600 ℃, and it will take about 6 to 8 hours until the rubber particles are white or yellow-brown. For fine-pored silica gel, the firing temperature should not exceed 200 ℃. In the rinsing method, silica gel is absorbed in saturated water vapor to reach saturation and then immersed in hot water for rinsing. It can be combined with detergent to remove waste oil or other organic impurities, and then washed with clean water and dried and dehydrated.
2. Solvent washing method According to the type of organic matter adsorbed by silica gel, select an appropriate solvent to dissolve the organic matter adsorbed in the silica gel, and then heat the silica gel to remove the solvent.