Practical application of activated carbon in water treatment

What is activated carbon?

Activated carbon is a specially treated carbon with numerous tiny pores and a huge surface area, with a surface area of ​​500-1500 square meters per gram of activated carbon. Activated carbon has strong physical adsorption and chemical adsorption, and also has a detoxification effect. The detoxification effect is to use its huge area to adsorb the poison in the micropores of the activated carbon, thereby preventing the absorption of the poison. At the same time, activated carbon can bind to a variety of chemical substances, thereby preventing the absorption of these substances.

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Classification of activated carbon

There are many types of activated carbon used in production. Generally made into powder or granular.
Powdered activated carbon has strong adsorption capacity, easy preparation and low price, but it is difficult to regenerate and generally cannot be reused.
Granular activated carbon is more expensive, but it can be reused after regeneration, and the labor conditions when using are better, and the operation and management are convenient. Therefore, granular activated carbon is often used in water treatment.

Adsorption properties of activated carbon

Activated carbon adsorption refers to the use of the solid surface of activated carbon to adsorb one or more substances in water to achieve the purpose of purifying water.

Factors Affecting Activated Carbon Adsorption

  • The adsorption capacity and adsorption speed are the main indicators to measure the adsorption process. The size of the adsorption capacity is measured by the amount of adsorption. The adsorption rate refers to the amount of substances adsorbed by a unit weight of adsorbent in a unit time. In water treatment, the adsorption rate determines the time required for the contact between the wastewater and the adsorbent.
  • The adsorption capacity of activated carbon is related to the pore size and structure of activated carbon. In general, the smaller the particles, the faster the pore diffusion, and the stronger the adsorption capacity of activated carbon.
  • The pH value and temperature of sewage also affect the adsorption of activated carbon. Activated carbon generally has a higher adsorption capacity under acidic conditions than under alkaline conditions. The adsorption reaction is usually an exothermic reaction, so low temperature is favorable for the adsorption reaction.
  • Of course, the adsorption capacity of activated carbon is related to the concentration of sewage. At a certain temperature, the adsorption capacity of activated carbon increases with the increase of the equilibrium concentration of adsorbed substances.

Application of activated carbon in sewage treatment

Because activated carbon has high requirements for water pretreatment and the price of activated carbon is expensive, in wastewater treatment, activated carbon is mainly used to remove trace pollutants in wastewater to achieve the purpose of deep purification.

Activated carbon treatment of chromium-containing wastewater

Chromium is a metal raw material with a large amount in electroplating, and hexavalent chromium exists in different forms in wastewater with different pH values.
Activated carbon has a very developed microporous structure and high specific surface area, and has strong physical adsorption capacity, which can effectively adsorb Cr (VI) in wastewater. There are a large number of oxygen-containing groups on the surface of activated carbon such as hydroxyl (-OH) ), carboxyl group (-COOH), etc., all of which have electrostatic adsorption function and produce chemical adsorption to Cr(VI).
According to statistics, the discharged industrial wastewater not only contains highly toxic components such as cyanide, but also contains metal ions such as chromium, zinc and nickel. There are many treatment methods for wastewater, including chemical precipitation, electrolysis and membrane treatment.

Summarize

This article describes the activated carbon adsorption method. Activated carbon has a huge surface area and has high physical adsorption and chemical adsorption functions. Therefore, activated carbon adsorption is widely used in wastewater treatment. And it has the characteristics of high efficiency and good effect.

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