New system captures and recycles air pollutants

The industrial system which is about the size of a large filing cabinet, according to the researchers, comprises activated-carbon-fibre cloth cartridges which, at low pollutant concentrations, have nearly twice the adsorption capacity of activated-carbon granules. An electric current, which passes through the fabric, allows for rapid heating and boiling the solvent off the fabric, termed electrothermal desorption. The solvent then condenses on the inside of the chamber and drains into a collection vessel for recovery and reuse.

“The new vapour-recovery system is fast, convenient, and can achieve new levels of air-quality control,” said Mark Rood, a University of Illinois professor of civil and environmental engineering. “The device uses activated-carbon-fibre cloth and electrical energy to collect and efficiently recover air pollutants that are emitted to the atmosphere from the use of materials such as paint solvents and cleaning solutions.”

Because the electrothermal desorption does not require an adsorbent drying step, the regeneration process can be faster and more energy efficient than conventional desorption techniques associated with activated-carbon granules, according to Rood. This means that a very dilute gas stream can now be treated, providing a pure liquid effluent.

“The vapour-recovery system could be used to control the emissions from large paint booths, for example, including the hangar-sized units used to paint entire aircraft,” said Patrick Sullivan, a US Air Force Research Laboratory worker, and University of Illinois post graduate student. “The exhaust from the booth would be blown through an adsorption bed containing a number of cylindrical cartridges of activated-carbon-fibre cloth, which would trap the solvent.”

The researchers have applied for a patent, and a pilot-scale programme for the device is being planned for later this autumn.