VaPRRS -Technology for Effective Air Quality Control


The University's Vapor Phase Removal and Recovery System (VaPRRS) is a patented long-lasting filter that effectively removes dilute volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) from gas streams and recovers them as pure liquids. The technology can be integrated into a variety of manufacturing facilities and air pollution control (APC) systems to make them more effective. VaPRRS is a VOC/HAP recovery system that uses an activated carbon fiber cloth and electrothermal desorption (ED) to inexpensively and selectively remove vapors from gas streams. The system rapidly adsorbs and then efficiently regenerates the sorbent and allows for condensation of the sorbate gas all within one control volume. Experimental and numerical prototyping has successfully demonstrated the removal of 4-methyl-2-pentanone (MIBK), toluene, methyl propyl ketone (MPK), methyl ethyl ketone (MEK), and hexane from laboratory generated air steams.

This technology uses activated-carbon fiber cloth (ACFC) as an alternative adsorbent to traditional granular activated carbon (GAC) to remove and recover organic vapors from gas streams. The ACFC is microporous, has up to 250% of the adsorption capacity of GAC, has faster mass and heat transfer properties than GAC, and is ash free to inhibit chemical reactions between the ACFC and the adsorbed vapors. Electrothermal desorption can be used to rapidly regenerate the ACFC with lower energy requirements than steam- or heated nitrogen-based regeneration. ED also eliminates the need for an adsorbent drying step and the recovered solvent/water separation processes usually required with conventional steam regeneration technology.

As shown in Figure 1 attached, this technology consists of two adsorption/desorption units that enclose hollow elements containing ACFC and provide gas ports at either end. The compounds are adsorbed onto ACFC cartridges (Figure 2 attached) that are electrothermally regenerated at a very rapid rate, causing the adsorbate to condense within the adsorption vessel itself and produce two-phase flow of the effluent during regeneration. The ACFC elements provide controlled electrical resistance, allowing for direct electrothermal heating and rapid regeneration of the ACFC and recovery of the VOCs/HAPs. Rapid ED with in-vessel condensation results in significant reductions in system complexity, cycle times, and nitrogen consumption. This new system also operates without the use of steam, heated inert gas, vacuum, or a refrigeration system. The pilot-scale system regenerates the ACFC within 40 minutes.

Continuous VOC/HAP capture and recovery tests were performed with the bench-scale unit (125 mm diameter) while removing an array of solvents at a total gas flow rate ranging from 5-85 sLpm. The adsorption vessel contained 128 grams of ACFC. Single-component organic vapor tests were performed with MIBK; toluene; n-hexane, 2-pentanone (MPK); MEK; and n-hexane with controlled concentrations ranging from 100 to 10,000 ppmv in air. Overall removal efficiencies of greater than 99% were measured during the experiments.


Companies can license the VaPRRS technology for integration into existing manufacturing operations and APC systems for a wide variety of applications, including:

  • Painting and surface coating: This technology can capture and recover paint solvents such as toluene and 4-methyl-2-pentanone (MIBK) for reuse.
  • Printing: Printers who use this technology can reuse their printing solvents, including hexane, ethylbenzene, and MEK during production.
  • Dry cleaners: Dry cleaning solvents such as perchloroethylene can be recycled on location with this technology.
  • Chemical processing: The technology can be used to perform selective gas separation of organic vapors.
  • Indoor air quality control systems: This technology removes trace concentrations of vapors to improve indoor air quality.

Manufacturing: This technology can be used to recover VOCs/HAPs generated during the manufacturing of various products, including:

  • Aircraft
  • Pharmaceuticals
  • Semiconductors
  • Heavy equipment
  • Millwork, veneer, and plywood
  • Paint, ink, varnish, and lacquer


  • Lower maintenance costs: The adsorbent material offers an extended lifetime of operation with little to no degradation in performance. Consequently, this system substantially reduces the costs of maintaining the APC system.
  • Simpler and cheaper operation: This system has no moving parts except for the gas flow valves. VaPRRS also can provide a captured VOC as a liquid without the need for a steam generator, decanter, distillation tower, chiller, or other equipment.
  • Better filtration: This system removes a wide range of VOC/HAP concentrations, including very dilute concentrations (<1,000 ppmv) of contaminants, better than existing methods.
  • Improved VOC/HAP recovery: This system can easily recover valuable reagents that are lost or destroyed in other methods.
  • Scalability: This technology can be scaled to process any quantity of vapor exhaust (e.g., from dry cleaning operations to paint booths for aircraft).
  • Adaptable: The system can be customized to adsorb a wide variety of VOCs/HAPs, including ketones (e.g., MEK), aromatics (e.g., toluene), alkanes (e.g., hexane), halogens (e.g., methylene chloride), and many others.
  • Safer: This technology uses a microengineered sorbent that is ash free to minimize localized heating and chemical reactions with ash that are a concern with bed fires and granular activated carbon.


To license the entire Vapor Phase Removal and Recovery System portfolio, click here