Activated carbon filters play a vital role in laboratory air purification due to their excellent chemical gas adsorption capacity. They can effectively remove harmful gases, protect the health and safety of laboratory workers, and ensure the accuracy of experimental results. The manufacturing process of activated carbon filters directly affects their performance and reliability, and different manufacturing processes will produce different usage effects and maintenance requirements. This article will explore the manufacturing processes of activated carbon filters in depth, analyze how they affect the performance of the filters, and explore the application of these processes in laboratory air purification.    Two Manufacturing Processes of Activated Carbon Filters    In the manufacture of activated carbon filters, there are two main processes: granular activated carbon filters and bonded activated carbon filters. These two processes have significant differences in structure and performance, and their respective characteristics determine their applicability in specific application scenarios.   ▲ The pictures are from the Internet and are for reference only.    Granular activated carbon filter  Granular activated carbon filter is a common type in the market. This filter is manufactured by directly encapsulating carbon particles of a certain particle size in a box. Although its manufacturing process is relatively simple, this design brings some inevitable problems in practical applications.   A major problem with granular activated carbon filters is the penetration effect. Due to the uneven distribution of carbon particles in the filter, especially during transportation and handling, the carbon particles tend to gather at one end of the filter, causing the airflow to pass mainly through these loose areas, thereby reducing the overall adsorption efficiency of the filter.   Over time, these loose areas may form through-holes under the action of airflow, losing the efficiency of filtering chemical gases. To solve this problem, a grid-like or honeycomb partition structure is usually used to constrain the activated carbon particles, but this still cannot completely avoid the formation of local micro-perforations, and an overly dense partition structure will also destroy the uniformity and permeability of the ventilation surface.     Another problem with granular activated carbon filters is carbon leakage. During the movement and use of the filter, the friction and collision between the carbon particles will produce carbon chips with smaller particle sizes, which escape the filter with the airflow, forming a carbon leakage phenomenon.     Carbon leakage not only destroys the cleanliness of the laboratory, which is a fatal flaw especially for ultra-clean laboratories, but also the leaked carbon has absorbed a large amount of chemical pollutants, and the secondary pollution caused by this will have extremely serious consequences. In addition, carbon leakage also means a continuous reduction in the amount of carbon, affecting the adsorption efficiency of the activated carbon filter.   In order to avoid the consequences of carbon leakage, granular activated carbon filters usually need to be used in conjunction with an additional safety filter. The purpose of the safety filter is to absorb the leaked carbon and prevent secondary pollution. Despite this, this still cannot fundamentally solve the reduced adsorption efficiency caused by carbon leakage and the lack of safety performance caused by penetration.    Bonded activated carbon filter      The bonded activated carbon filter is a solution specially developed to address the defects of granular activated carbon filters. This filter uses a special chemical bonding process to firmly connect the carbon particles into a whole, thus avoiding the penetration effect and carbon leakage problems of granular activated carbon filters.   The main advantage of the bonded activated carbon filter is that its carbon particles maintain good uniformity on the entire ventilation surface, without any penetration effect or carbon leakage. This filter can be figuratively likened to sachima or rice candy. Although it is composed of small pieces of particles, these particles are connected to each other, will not fall off, and will not produce flying dust.     During the manufacturing process of the bonded activated carbon filter, it is necessary to ensure the bonding effect while ensuring that the ventilation and adsorption efficiency will not be significantly reduced. This makes the manufacturing process of the bonded filter relatively complicated.     When choosing an activated carbon filter, laboratory managers need to weigh the advantages and disadvantages of the two filters according to the specific application requirements and budget, and choose the product that best suits their laboratory environment. KLC believes that with the advancement of technology and the improvement of manufacturing processes, more efficient and safe activated carbon filters may be available in the future, providing more options for laboratory air purification.

  In the pharmaceutical and biotechnology industries, cleanrooms are key facilities to ensure product quality and safety. One of the core of aseptic technology is to control the laminar air flow speed in the cleanroom to maintain a sterile environment. This article will explore the scientific basis, regulatory requirements and how to combine Class A laminar air flow speed with cleanroom design.   Cleanrooms are designed to control particulate and microbial contamination to protect sensitive manufacturing processes and products. In these controlled environments, air flow is one of the key factors because it directly affects the particle distribution in the air and the removal efficiency of pollutants.     Both EU GMP Annex 1 and NMPA GMP mention that the unidirectional flow system should provide a wind speed of 0.36m/s to 0.54m/s in its working area, but this is only a guide value. This means that in actual operation, as long as it can be scientifically justified, the wind speed can be adjusted according to the specific situation.   EU GMP Annex1:4.30...Unidirectional airflow systems should provide a homogeneous air speed in a range of 0.36 – 0.54 m/s (guidance value) at the working position, unless otherwise scientifically justified in the CCS. Airflow visualization studies should correlate with the air speed measurement. NMPA GMP: Appendix Sterile Drugs Article 9: The unidirectional flow system must deliver air evenly in its working area, with a wind speed of 0.36-0.54m/s (guideline value). There should be data to prove the state of unidirectional flow and be verified.   The standard of 0.45m/s±20% actually comes from the US FS 209 standard, which is based on experience and does not consider energy consumption, but more on the noise of the fan. Studies have shown that higher cleanliness can be achieved at lower air speeds because lower wind speeds reduce turbulence around objects in the flow path.   When designing a clean room, it is necessary to consider the effect of wind speed on cleanliness. Wind speed not only affects the removal efficiency of particles, but also affects the comfort and energy consumption of operators. When designing, these factors need to be balanced to achieve the best sterile environment.     The regulatory standards for unidirectional airflow velocity in clean rooms vary in terms of measurement location and the weight of a specific velocity. According to the guidance of the US FDA, it is required to measure the airflow velocity at a distance of 6 inches below the filter surface. ISO 14644 requires that the airflow velocity be measured at approximately 150mm to 300mm from the filter surface. However, according to EU (and WHO) GMP, the airflow is measured at the working height, which is defined by the user.   Flow velocity and airflow are essentially for the purpose of removing contamination and preventing contamination. The optimal flow velocity can be determined through visualization studies as well as particle monitoring. The purpose of the visualization study is to confirm the smoothness, flow pattern and other spatial and temporal characteristics of the airflow in the device. To this end, the airflow is checked through airflow visualization mapping, by generating smoke and studying the behavior of the smoke, which is then captured with a camera.     Therefore, the Class A laminar air velocity of 0.36m/s to 0.54m/s is not a standard that must be strictly followed, but a guide value. In actual application, the wind speed can be adjusted according to the specific situation. The key is to be able to justify it through scientific methods.     When designing a clean room, it is necessary to comprehensively consider the impact of wind speed on particle control, operator comfort and energy consumption to achieve an optimal sterile environment. Through airflow visualization and particle monitoring, the optimal air speed can be determined to ensure the efficient operation of the clean room, thereby protecting the quality and safety of pharmaceutical products.

As environmental pollution becomes increasingly serious, people's demand for clean air and water becomes more urgent, which has promoted the rapid development of the filter material market. However, traditional petroleum-based filter materials are difficult to degrade after use and are prone to secondary pollution. It is urgent to find environmentally friendly alternatives. The silk nanofiber (SNF) aerogel developed by the Wuhan Textile University team has become a new focus in the field of materials science and environmental protection with its excellent air filtration performance and sustainable characteristics.    Unique structure lays the foundation for filtration performance  The preparation of SNF aerogel is based on solvent-mediated ice crystal growth technology, which can produce large aerogels with adjustable structures on a large scale. By adding a small amount of chitosan to SNF, the mechanical properties and water resistance of the aerogel are significantly improved, so that it can also play a stable role in complex and changeable actual environments. The three-dimensional porous network structure of the aerogel, which is interwoven by a large number of nanofibers, provides a physical basis for efficient air filtration. The tiny nanofibers can effectively intercept tiny particles in the air, while the porous network ensures the smooth flow of air, avoiding the influence of excessive resistance on the filtration effect, and achieving a good balance between filtration efficiency and air circulation.      Efficient filtration of air pollutants  In terms of air filtration, SNF aerogel has demonstrated extraordinary capabilities. It can efficiently filter air pollutants such as PM0.3 and smoke. PM0.3 is a fine particle that is extremely harmful to human health, and traditional filter materials have limited filtering effects on it. SNF aerogel, with its nano-scale fiber structure, can accurately capture these tiny particles, greatly reducing the concentration of particulate matter in the air and creating a healthier breathing environment for people. Whether it is a large amount of smog generated by industrial emissions and automobile exhaust in the city, or harmful gases and particles such as secondhand smoke indoors, SNF aerogel can effectively filter them. Its filtering effect has been fully verified in relevant experiments, providing strong support for improving air quality.      Sustainability advantages help environmental protection  Compared with traditional petroleum-based filter materials, the sustainability advantages of SNF aerogel are particularly prominent. In the natural environment, SNF aerogel is safely biodegradable. Commercial PP meltblown cloth basically does not degrade after one year of landfill, while the degradation rate of SNF aerogel waste after direct landfill is over 70%, greatly reducing the long-term pressure of waste on the environment. This feature not only fits the current environmental protection concept, but also conforms to the development trend of future filter materials, providing a new idea for solving the environmental problems of filter materials. In air filtration applications, the use of SNF aerogel can effectively reduce environmental pollution caused by the replacement and disposal of filter materials, and achieve the dual goals of air purification and environmental protection.     Silk nanofiber aerogel has shown great potential and value in the field of air filtration due to its unique structure, high-efficiency air filtration performance and excellent sustainability. In the future, KLC will continue to innovate, explore, upgrade production processes, and improve quality, and make positive contributions to the development of the global low-carbon economy and the construction of green ecological civilization.

Today we will further share the application of fiber materials, especially cellulose fibers, in air filters. These filters are not only vital in the aviation field, but also play a key role in the automotive industry. They are responsible for removing pollutants from the air, protecting passenger health and improving engine efficiency.   The selection and application of fiber materials directly affect the performance and environmental impact of the filter. Here is a detailed analysis of how these materials achieve a balance between environmental protection and durability in air filtration technology.    Cellulose fibers: ideal for air filters    Cellulose fibers are ideal for manufacturing air filters due to their excellent processing performance, ideal chemical and mechanical properties and low cost.     These fibers can be selected from a variety of materials, including cellulose, thermoplastics and glass fibers, which together form the basis of fuel filters, cabin air filters, engine oil filters and engine air filter paper in automobiles and aircraft.    Bio-based cellulose: an environmentally friendly solution for air filtration      As a bio-based material, cellulose fibers are derived from a natural polymer - cellulose, which is a structural component of plant cell walls.   The bio-based nature of this material means that if the production process is correct, their environmental impact may be less than that of petrochemical-based products such as polyethylene terephthalate (PET) and polypropylene (PP). In addition, cellulose fibers are biodegradable and can be broken down by microorganisms into water and carbon dioxide over a certain period of time, which is particularly important for reducing the environmental footprint of air filters.    Regenerated cellulose filter paper: a new choice for air filtration    Regenerated cellulose filter papers are slightly lower than new paper in burst resistance, stiffness and tensile index, but they are still suitable for some undemanding applications. In air filters, this material can reduce the demand for new resources while reducing waste generation.   Although it is not yet widely commercialized, the application potential of regenerated cellulose filter paper in the field of air filtration cannot be ignored.    Application of cellulose fibers in air filters    Although cellulose fibers have the advantages of being bio-based and biodegradable, they often need to be combined with other materials such as chemical fibers and glass fibers to improve durability and reliability in harsh environments. This is particularly important for air filters, as they need to maintain performance under a variety of temperature and humidity conditions.   Companies such as Ahlstrom have developed a series of patented technologies to produce self-sustaining pleated oil media with higher burst strength, which can also be applied to the manufacture of air filters.   After understanding the multifaceted applications and future development of cellulose fibers in air filtration technology, KLC will continue to deepen its air purification technology and continuously explore and develop more efficient and environmentally friendly air filtration solutions.   We are committed to applying the latest fiber technology to the innovation of air filters to meet the growing global demand for clean air and contribute to protecting our environment. With the continuous advancement of technology, we look forward to bringing more breakthrough results to the field of air purification in the future.