To remove gaseous contamination, molecular air filters require particular varieties of media. In this blog post Segment Leader for Molecular Contamination Control, Victor Rengel, describes gaseous contamination, outlines the different molecular media types, and highlights molecular filter media that is new to market.
Molecular media is the root of all successful molecular filtration solutions. Without it, gaseous contaminants can not be effectively removed as they must be “captured” differently than particles via the technique known as adsorption. This is the process where molecules are drawn into porous materials with extremely high surface areas. The reason for this is that particulate filters can’t effectively remove gases as molecules can be 1,000-10,000 times finer than PM1, which is already less than 1 micron in size. Unlike particulate filters, molecular media does not increase in pressure drop as it loads so initial pressure drop design is the only consideration for new applications.
It is important to understand exactly what is included in gaseous contamination, and possible consequences of contact or inhalation.
What is Gaseous Contamination? What Are the Consequences?
Airborne molecular contamination (AMC) can be categorized as either anthropogenic (man made) or natural. Examples of man made contaminants are vehicle exhaust, power generation, and industrial processes. Natural sources can be forest fires, hot springs, and volcanoes.
The risks of molecular contaminants can be divided into four principal areas:
- Odour issues.Odour issues can occur from sources such as food, traffic fumes, fragrances, domestic waste and industrial processes. Oftentimes, odour problems at an elevated level do not affect only those in the given space, they also impact residents living nearby.
- Irritants. Some molecular contaminants can be irritants and cause long term health effects, particularly on the respiratory system.
- Toxicity. Toxic gas contaminants can be hazardous at high concentration levels. Highly toxic gases commonly found in industrial areas are hydrogen sulfide, hydrogen fluoride, sulfur dioxide and chlorine. Some volatile organic compounds (VOCs) can be toxic as well.
- Corrosivity. Corrosive contaminants are moreso a threat to equipment rather than people. Control rooms in mining, oil and gas, pulp and paper, and wastewater treatment need protection against these contaminants. Museums, art galleries and other cultural heritage buildings are also known for using molecular filtration1.
For more on the processes and materials that are impacted by corrosion: What is Corrosion and How Does it Impact Processes in Canada?
What Are the Types of Molecular Filter Media?
Molecular adsorbents can be organized into four groups:
There are over one hundred and thirty million catalogued chemicals. Activated carbon is a powerful and versatile adsorbent that can be used to remove most molecules. This media is also important for controlling unknown or variable chemicals due to its “Broad Spectrum” adsorptive capacity.
Impregnated Activated Carbon
For the molecules that cannot be controlled using Broad Spectrum media, there are “impregnated” carbons that target individual molecules or a family of contaminants2. Carbon can be specifically impregnated for removal of ammonia, acid gases, aldehydes, or mercury vapours.
Impregnated Activated Alumina
Activated alumina has a different physical structure and chemical characteristics than activated carbon. Activated aluminas are surface modified and are typically impregnated with potassium permanganate. They are used for targeted adsorption3.
Blended media consists of a mix of activated carbon and impregnated activated alumina, typically 50% each by volume. This allows broad spectrum removal of contaminants in a filter which does not allow separate filling of successive media beds.
Hybrid media are another variation of this concept, with carbon and alumina powders being mixed and pre-formed into spheres. Hybrid media are UL certified and particularly efficient at controlling hydrogen sulfide and other acid gases in heavy duty industrial applications.
What Molecular Media Solutions Should Canadians Use?
Molecular media can be made from different raw materials, in different qualities and different shapes and sizes. Adjusting these factors allows us to optimize efficiency, lifetime and pressure loss for different customer applications. Depending on uses, molecular filtration media specifically can operate with a physical adsorption or chemical adsorption.
We offer loose adsorbents for control of molecular gaseous contamination. These include Activated Carbon, Impregnated Activated Carbon, Activated Alumina, Blended Media, and Hybrid Media. These adsorbents can be placed inside molecular air filtration vessels from the CamCarb family including cylinders, VG modules, and panels. For heavy duty applications, they can be placed in deep bed filtration systems like the ProCarb.
We also have a new, high-quality chemical adsorbent: CamPure 32. The media is particularly effective for the removal of hydrogen sulfide, sulfur dioxide, and nitrogen dioxide in biogas applications. It is also UL 900 rated for flammability, and is vacuum packed to ensure low dust content.
For more on biogas and how it can be converted to energy: Renewable Energy Creation in Canada with Biogas
There are a variety of factors that determine which clean air solutions work best for molecular filtration. Be sure to contact an experienced air filtration consultant to find choices right for your building.
About Camfil Canada Clean Air Solutions
For more than half a century, Camfil has been helping people breathe cleaner air. As a leading manufacturer of premium clean air solutions, we provide commercial and industrial systems for air filtration and air pollution control that improve worker and equipment productivity, minimize energy use, and benefit human health and the environment. We firmly believe that the best solutions for our customers are the best solutions for our planet, too. That’s why every step of the way – from design to delivery and across the product life cycle – we consider the impact of what we do on people and on the world around us. Through a fresh approach to problem-solving, innovative design, precise process control, and a strong customer focus we aim to conserve more, use less and find better ways – so we can all breathe easier.
The Camfil Group is headquartered in Stockholm, Sweden, and has 33 manufacturing sites, six R&D centers, local sales offices in 30 countries, and about 4,800 employees and growing. We proudly serve and support customers in a wide variety of industries and in communities across the world. To discover how Camfil Canada can help you to protect people, processes and the environment, visit us at www.camfil.com/en-ca/.
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