Powdered activated carbon (PAC) modified bentonite, preparation method and application of PAC modified bentonite as well as green-liquor desilication method

Abstract

The invention belongs to the field of paper-making industry, and particularly relates to powdered activated carbon (PAC) modified bentonite, a preparation method and application of the PAC modified bentonite as well as a green-liquor desilication method. The preparation method comprises the following steps: preparing PAC modified bentonite, dissolving 5-20g of bentonite in 1-5L of water, stirring into suspension, adding 0.5-5g of PAC in the suspension, stirring for 1-5 hours, taking out, standing for 12-24 hours, pouring the supernatant, drying the lower turbid liquid in a drying oven for 12-24 hours, taking out, grinding and screening, namely obtaining the PAC modified bentonite, wherein the PAC modified bentonite prepared by the method is small in usage amount, large in interlayer spacing and large in specific surface area; pouring the clarified causticization section green liquor into a beaker, heating to the temperature to be 90-100 DEG C, weighing the PAC modified bentonite obtained in the step 1 according to the mass-volume concentration 0.5-5g/100mL of the PAC modified bentonite and green liquor, adding the bentonite into the green liquor, stirring and reacting for 5-30 minutes, and filtering. The desilication rate can reach 22-76%, the pH change is 0.08-1.1% of the original green liquor, and the method disclosed by the invention is simple in operation, small in usage amount of desilication agents, low in cost, high in desilication rate and slight in pH influence of the green liquor.

Description

[0001] 【Technical field】 [0002] The invention belongs to the field of papermaking industry, and in particular relates to a PAC modified bentonite, a preparation method, an application and a method for removing silicon from green liquor. [0003] 【Background technique】 [0004] Bentonite is a hydrous clay mineral mainly composed of montmorillonite. In the middle of montmorillonite is alumina octahedron, and the upper and lower sides are clay minerals with a three-layer sheet structure composed of silica tetrahedron. The main element of montmorillonite is Na , Al, O, Si, etc. There are also some cations in the unit cell, such as Mg, Na, K, Cu, etc., which are not firmly interacted with the unit cell and are easily exchanged by other cations. Therefore, bentonite has excellent physical properties, including water absorption, swelling, cohesiveness, adsorption, etc. Among them, swelling and adsorption have wide application value, and it is also an important indicator to measure t...

AI Technical Summary

Problems solved by technology

However, there is no research report on the adsorption of bentonite to silicon in papermaking waste liquid

Due to the lack of wood resources and the abundance of non-wood resources in China, the structure of papermaking raw materials in my country has quietly changed, and the input ratio of bamboo pulp and straw pulp has begun to increase, but the silicon content of straw pulp and bamboo pulp raw materials is higher than that of wood raw materials. These silicon elements are brought into the pulping black liquor after cooking. The presence of silicon dioxide makes the viscosity of the black liquor increase rapidly with the increase of the concentration during the evaporation process, thus affecting the evaporation of the black liquor and causing scaling of the evaporation equipment. After the liquid is burned, it is brought into the alkali recovery section along with the green liquid. The sodium silicate in the green liquid forms calcium silicate during the causticizing process. The particles are fine and difficult to precipitate and filter, which makes it difficult to wash the white mud and has a high amount of residual alkali in the white mud. , the large amount of alkali loss and the high consumption of lime mud calcined into lime will eventually cause a large loss of raw materials in the entire process section, which is called "silicon interference problem"

[0006] Ordinary bentonite works in strong alkaline or supersaturated solution, it must be swollen with water in advance, and the swollen bentonite is suspended in water to have swelling and adsorption properties, but this will reduce the pH and concentration of the green liquid