Currently, VOCs emissions in my country involve a wide range of industries, and the types and components of VOCs emitted by each industry are numerous and complex, including hydrocarbons, alcohols, ethers, and esters. Industries that produce or use organic solvents, such as gas stations, decoration, catering, dry cleaning, spraying, and chemical manufacturing, all generate VOCs emissions. Furthermore, the VOCs treatment technology system is complex, involving more than a dozen technologies and combinations of technologies, and generally, an environmental treatment company can only master one or a few technologies.
One of the mainstream technologies for industrial VOCs treatment is activated carbon adsorption technology!
Activated carbon is the most widely used adsorbent, and its production and use can be traced back to the 19th century. Activated carbon is widely used mainly because of its large number of micropores and mesopores, and its huge surface area. The pore size distribution of typical activated carbon and its comparison with other adsorbents are shown in the figure below.
Image source: "Adsorption Principles and Applications," by Ralph T. Yang
It is understood that activated carbon adsorption technology is one of the mainstream technologies for VOCs treatment. It is mature, simple and easy to implement, has low treatment costs, and a wide range of applications. It occupies a very large market share among all treatment technologies and has been widely used in coating, packaging and printing, petrochemicals, chemical manufacturing, pharmaceutical chemicals, and odor control.
However, due to the lack of systematic understanding of the basic properties of activated carbon, the applicable scope and conditions of activated carbon adsorption technology among industry personnel, there is considerable arbitrariness in activated carbon selection, process design, and purification equipment design, resulting in low efficiency of purification equipment, safety hazards, and difficulties in activated carbon regeneration and replacement. Many environmental protection companies in the market underestimate activated carbon adsorption technology (simply mistakenly believing that activated carbon adsorption technology is nothing more than simple adsorption-desorption).
The various irregularities and process chaos in the industry have led many local environmental protection departments to fall into the misconception of being overly cautious about activated carbon. Meeting the actual needs of current domestic VOCs pollution control projects and correctly guiding the industry to standardize the application of activated carbon in the purification of volatile organic compounds (VOCs) is crucial.
Adsorption methods are mainly suitable for the adsorption, separation, and purification of low-concentration gaseous pollutants. For high-concentration organic gases, it is generally necessary to first undergo "concentration reduction" treatment through processes such as condensation before adsorption and purification. For the purification of high-concentration VOCs gases such as "oil and gas," adsorption methods (with pressure swing adsorption regeneration) can also be used, but this requires some special requirements for the activated carbon.