Test Method for Water Capacity of Activated Carbon
Activated carbon is a specially treated porous carbon material. It is a black powdery, granular or porous adsorbent material produced from carbon-containing organic materials through high-temperature carbonization and activation. Its main component is carbon (accounting for more than 80%–90%), with small amounts of oxygen, hydrogen, sulfur and ash. Featuring a highly developed pore structure and large specific surface area, it can effectively remove harmful substances from gases or liquids via physical and chemical adsorption. It is widely used in air purification, water treatment, gas mask protection and other fields.
Experimental Purpose
The experiment for measuring the water capacity of activated carbon is mainly to evaluate its adsorption capacity for water molecules, so as to reflect the total pore volume and physical structure characteristics of activated carbon. Although this index does not directly represent the adsorption performance for specific pollutants, it can quickly judge the development degree of the pores of activated carbon, and is a common practical detection method in production and quality control.
1.Evaluate the pore structure of activated carbonWater capacity is closely related to the pore volume of activated carbon. Since water molecules can enter most micropores and mesopores, the measured water absorption can reflect the total volume of internal pores to a certain extent. The more developed the pores and the higher the water capacity, the stronger the potential adsorption capacity of the activated carbon.
2.Guide the production and quality control of activated carbonIn industrial production, water capacity can be used as a rapid detection index to monitor the activation degree and batch stability of activated carbon. Through standardized testing, enterprises can adjust process parameters in a timely manner to ensure consistent product quality.
3.Assist in model selection and application matchingAlthough water capacity cannot fully represent the adsorption capacity for organic substances or gases, in water treatment, air purification and other applications, a higher water capacity usually means better hydrophilicity and wettability, which helps to improve actual application performance. Therefore, this experiment can provide a reference for the selection of activated carbon for different purposes.
Experimental Apparatus
Sample:Activated carbon
Instrument: ST-62 Activated Carbon Water Capacity Tester, in compliance with GB/T 7702.5
Experimental Procedures
1.Sample weighingTake the treated sample from the desiccator, accurately weigh (25±1) mL of the sample (accurate to 0.001 g), and record the original mass as m0.
2.Soaking treatmentPut the weighed sample into a 250 mL beaker, add 100 mL of pure water to ensure the sample is completely immersed. Then place the beaker on a heating device, heat and boil for 15 minutes. Replenish pure water continuously during boiling to maintain the liquid level, so that the activated carbon is fully wetted and internal air is expelled.
3.Filtration saturation
Setup: Transfer the boiled sample together with the solution into a Buchner funnel with filter paper pre-installed. Connect the filtering flask and vacuum pump to complete the filtration setup.
Filtration operation: Turn on the vacuum pump, adjust the vacuum degree to (8.0±0.6) kPa, and maintain for 5 minutes to saturate the activated carbon with water under negative pressure. Observe the filtrate during filtration to ensure smooth flow; replace the filter paper promptly if clogging occurs.
4.Wet sample weighingWhile maintaining the vacuum, quickly move the funnel with the sample onto an electronic balance for weighing. Record the mass of the wet sample after filtration as m1 (accurate to 0.001 g). Perform the operation rapidly and accurately to avoid water evaporation caused by prolonged exposure to air, which may affect the weighing result.
Experimental Results and Analysis
This experiment was carried out in strict accordance with GB/T 7702.5, and the experimental data are accurate and reliable.The water capacity of a batch of coal-based granular activated carbon is 69.4%, indicating a well-developed pore structure and excellent water absorption performance. It is suitable for water treatment, moisture-proofing and other fields with high requirements for the water absorption capacity of activated carbon.