What is the replacement cycle standard for activated carbon? How long does it take to replace activated carbon?

In the field of environmental protection and water treatment, activated carbon plays an indispensable role. Whether it is air purification, waste gas treatment or water quality improvement, activated carbon is widely used.

 

What is the replacement cycle standard for activated carbon? How long does it take to replace activated carbon?

In the field of environmental protection and water treatment, activated carbon plays an indispensable role. Whether it is air purification, waste gas treatment or water quality improvement, activated carbon is widely used. However, many users often face some confusion when using activated carbon, such as "What is the replacement cycle of activated carbon? Is the higher the iodine value of activated carbon, the better?" etc. These problems have troubled many companies. Xingnuo Activated Carbon will discuss in detail the replacement cycle of activated carbon and whether its iodine value can be used as the only standard to measure its quality.

Standards for activated carbon replacement cycles  

The replacement cycle of activated carbon is one of the core issues that users are concerned about, especially in different application scenarios. The length of the replacement cycle not only affects the cost of use, but also directly affects the purification effect. Understanding the standards for the replacement cycle can help users replace activated carbon at the right time and ensure the efficient operation of the purification equipment.

1. The main factors affecting the replacement cycle of activated carbon

The service life of activated carbon is not fixed. It is affected by many factors, such as the use environment, the type and concentration of pollutants, temperature, humidity, etc. The differences in these conditions make it difficult to uniformly set the replacement cycle of activated carbon.

Use environment: An environment with high humidity will weaken the adsorption capacity of activated carbon, because water molecules will occupy the pores of activated carbon and reduce its efficiency in adsorbing harmful substances. In a relatively dry environment, the life of activated carbon will be extended.  

Temperature: In a high temperature environment, the desorption capacity of activated carbon is enhanced, which may cause the adsorbed pollutants to be released, reducing the purification effect. In this case, the service life of activated carbon will be shortened accordingly.  

Contaminant concentration: The higher the pollutant concentration, the faster the adsorption rate of activated carbon, and the faster the pores are blocked, which shortens the replacement cycle. Therefore, in a high-concentration pollution environment, activated carbon needs to be replaced more frequently.

2. Estimation method of activated carbon replacement cycle

Although there is no unified standard for the replacement cycle of activated carbon, it can be estimated through some calculation methods. For example, based on parameters such as the amount of activated carbon used, adsorption efficiency, and the concentration of pollutants treated, the replacement cycle of activated carbon can be roughly estimated. The following is a commonly used calculation formula:

Tips:

T—replacement cycle (days)

m—amount of activated carbon used (kg)

s—dynamic adsorption capacity (%), generally 10%

c—VOCs concentration reduced by activated carbon (mg/m³)

Q—air volume (m³/h)

t—operation time (hours/day)

For example, in an air purification project, if 1 ton of activated carbon is used, the VOCs concentration treated is 60mg/m³, the air volume is 5000m³/h, it runs for 8 hours a day, and the dynamic adsorption capacity is 10%, then the replacement cycle of activated carbon is 42 days. Through this calculation method, users can reasonably arrange the replacement time of activated carbon according to actual conditions.

3. How to judge whether activated carbon needs to be replaced  

In addition to estimating the replacement cycle through calculations, users can also use some intuitive methods to determine whether the activated carbon needs to be replaced. A common method is to observe the color change of activated carbon. Activated carbon is black at the beginning of use. As the adsorption capacity increases, its color will gradually turn to gray or brown. This often means that the adsorption capacity of activated carbon is close to saturation and should be replaced in time.

In addition, if the purification effect is found to be significantly reduced, the odor in the equipment is significantly increased, or the air quality is worsening, it may also be a signal that the activated carbon needs to be replaced. In this case, timely replacement of activated carbon can ensure the effectiveness of the purification system.

Is the higher the iodine value of activated carbon, the better?  

The iodine value of activated carbon is an important indicator to measure its adsorption capacity. Generally, the higher the iodine value, the stronger the adsorption capacity of activated carbon. However, iodine value is not the only factor that determines the quality of activated carbon. Whether a high iodine value of activated carbon means better depends on the scenario and purpose of use. Although iodine value is an important metric, it is only one aspect of the adsorption capacity of activated carbon. To evaluate the comprehensive performance of activated carbon, it is also necessary to consider the two key indicators of carbon tetrachloride adsorption value and methylene blue adsorption value.

1. Three main indicators of activated carbon:  

Iodine value: Definition: Iodine value is usually used to measure the adsorption capacity of activated carbon for small molecules, especially small molecules in liquids. The higher the iodine value, the more developed the microporous structure of the activated carbon and the stronger the adsorption capacity. Applicable scenarios: Mainly used for liquid adsorption, such as water treatment. Activated carbon with high iodine value performs well in removing organic pollutants from water, so it is more popular in the water purification industry.

Carbon tetrachloride adsorption value (CTC value): Definition: Carbon tetrachloride adsorption value is used to measure the adsorption capacity of activated carbon for gaseous substances (VOCs). The higher the CTC value, the stronger the adsorption capacity of activated carbon for gas.

Applicable scenarios: Mainly used for waste gas treatment and air purification. When dealing with volatile organic compounds, such as benzene and toluene, activated carbon with high CTC values performs better.

Methylene blue adsorption value: Definition: The methylene blue adsorption value measures the decolorization ability of activated carbon, indicating its adsorption effect on macromolecular substances. This indicator is usually used to judge the mesoporous adsorption capacity of activated carbon.

Applicable scenarios: Mostly used for dyes, decolorization and some industrial production processes. For example, in the food industry or pharmaceutical industry, activated carbon with high methylene blue adsorption value is used to remove color and macromolecular organic pollutants.

2.Applicability of different indicators:

From the above three indicators, it can be seen that different types of activated carbon need to be selected for different adsorption needs. Although the iodine value can reflect the adsorption capacity of activated carbon for small molecules, it does not mean that it has the best effect for all scenarios.

Water treatment: If the main purpose is to remove organic matter from water, activated carbon with a high iodine value will have a better effect, because its microporous structure is more suitable for adsorbing small molecular pollutants in water.

Waste gas treatment: For waste gas treatment, especially the adsorption of VOCs, the carbon tetrachloride adsorption value is a more important indicator. This type of waste gas treatment requires activated carbon to have more mesopores and macropores to adapt to the adsorption of gaseous molecules of different sizes.

Decolorization application: If the purpose is to remove color or larger molecular pollutants, the methylene blue adsorption value is the main reference indicator. Activated carbon with a high methylene blue value is suitable for industries that require strong decolorization ability.

Precautions for replacing activated carbon

Replacing activated carbon in time can not only ensure the purification effect, but also prevent secondary pollution caused by activated carbon saturation. The following are several key steps to pay attention to when replacing activated carbon:

Plan downtime in advance: According to the estimated replacement cycle, reserve enough downtime in advance to avoid affecting the normal operation of the equipment.

Properly handle waste activated carbon: Waste activated carbon often adsorbs a large amount of harmful substances and should be disposed of in accordance with the specifications for hazardous waste treatment to avoid secondary pollution to the environment.

Record the replacement process: Each time the activated carbon is replaced, the replacement date, usage and equipment operation status should be recorded for future tracking and management.

Honeycomb activated carbon with high iodine value is not always the best choice. Users should make reasonable judgments based on actual needs when choosing. Reasonable arrangement of replacement cycles to ensure the effective use of activated carbon can achieve its best purification effect.