Photocatalysis and its applications for remediation: some problems before safe industrial use?

Photocatalysis and its applications for remediation: some problems before safe industrial use? For more than 20 years, scientists and companies have considered photocatalysis as a potentially inexpensive and effective process for removing organic pollutants from air and water, but commercial systems have reached the market only recently. Because the development of equipment for worker protection in the workplace is one of the missions of the INRS and photocatalysis appears to be a potentially attractive technology for that purpose, the authors, in cooperation with the CNRS, explored this process and its mechanisms to assess its potential use in improving ambient air quality. Our tests of the commercially available systems of photocatalytic purification revealed that they do not always provide the efficacy they claim. The aim of this paper is to demonstrate the limitations of this emerging technology, which is currently completely unregulated. The marketing of these ineffective, or even hazardous, devices may therefore lead to some abuses. In one case, the device was totally ineffective, producing no photodegradation at all (of ethanol). This example suggests that the potential for improvement of ambient air appears to range from questionable to nonexistent.