A Real-Time, Sensitive and Affordable Fast-Response Elemental Carbon Monitor

"This SBIR Phase I project will develop an affordable, sensitive, fast-response solution to real-time monitoring of Elemental Carbon (EC). EcoChem will employ a proven sensor technology, the photoemission aerosol sensor (PAS) to detect EC. The PAS photoionizes carbonaceous aerosols with a unique excimer lamp [Burtscher, 1992] whose wavelength is chosen to selectively ionize EX and polycyclic aromatic hydrocarbons (PAH). The particles emit electrons and become positively-charged. The charged particles are collected by an electrometer filter where a current is measured. This signal is proportional to the concentration of EC and/or PAH. Previous studies have indicated the possibility that the PAS signal can be correlated to EC measurements [Prybilla et al, 202] [Tetra Tech, 2009]. The correlation is good when the aerosol is predominantly EC. However, there are systems where a coating of Organic Carbon (OC) can disturb the measurement. This challenge will be addressed by introducing a thermo-denuder and/or catalytic stripper. Elimination of the OC fraction will result in a solid carbonaceous core which can be detected by the PAS. Prototype pre-treatment devices will be designed and evaluated. Due to the unique needs of the EC application, this project will also improve the lamp lifetime, reduce the response time and increase the sensitivity of the existing instrument. The broader impact of the project will be to assess the health and environmental risks associated with carbonaceous aerosols. Air pollution is increasingly recognized as an important contributor to adverse health effects. Epidemiological studies have positively associated fine particle pollution with increased mortality from lung cancer and cardiovascular disease [Araujo 2009]. In addition, scientific interest in recent years has also focused towards the interaction of soot with inadvertent climate change and global warming [Penner 1998]. By providing high sensitivity real-time EC data at an affordable price, the EC monitor will contribute towards better understanding and quantifying the health and environmental risk posed by fine and ultrafine carbonaceous aerosols. Over the span of the last 18 years EcoChem has a track record of introducing breakthrough technology and creating commercially successful products. Using our previous experience and understanding of the current needs, we believe that a significant market exists for EC monitoring. The new analyzer will have faster response time, higher sensitivity and lower cost compared to all the existing EC instruments. Applications for this instrument include ambient air monitoring stations, traffic speed control systems, dynamometer testing and continuous emissions monitoring systems for industrial stacks. "