What is the specific process of decolorization of activated carbon from oil?

Activated clay is the most important adsorbent for decoloration and purification of edible oil. There are two kinds of activated clay: natural activated clay and activated clay treated with inorganic acid. Generally, the adsorption capacity of the latter is stronger, because the surface area of activated clay is increased from 40 ~ 60m2/g to 250 ~ 350m2/g after proper acid treatment. Activated clay is also called acidic clay because it changes from neutral or weak acidity to high acidity after being treated with inorganic acid. It not only has strong adsorption activity, but also has the following obvious characteristics: solid acid properties; Performance of cation exchanger; Properties of acidic catalysts; Properties of filter aid. Therefore, the influence of acid clay on oil is various, and the appropriate dosage and use method of adsorbent should be selected according to different oils and different requirements.

● Activated carbon can be made from a variety of carbon-containing raw materials (coal, wood, fruit shells, etc.). ), and then activated by chemical activator (phosphoric acid, zinc oxide, etc.). ), air and steam to increase its surface area and improve its adsorption activity. This kind of activated carbon is often used in combination with activated clay to promote decoloration and oil purification. Activated carbon can effectively remove polycyclic aromatic hydrocarbons (PAHs) from polymers that clay can't adsorb (while deodorization process can only remove low molecular weight PAHs containing less than four). The adsorption of polycyclic aromatic hydrocarbons by activated carbon is particularly strong. Even if the activated carbon filter cake is pressed, the filtered oil does not contain polycyclic aromatic hydrocarbons.

A new type of decolorizing adsorbent is made of sodium silicate, which is treated with dilute sulfuric acid to prepare a special silica gel with a water content of 60% ~ 70% and a large specific surface area (about 800 m2/g). This silica gel has high activity and selective adsorption for trace metal soaps and phospholipids.