A LASER-BASED TECHNIQUE TO CONTINUOUSLY MONITOR METAL AEROSOL EMISSIONS

We are developing an instrument to continuously monitor metal aerosol emissions in applications including industrial process vents (e.g., ex haust stacks from electroplating baths), waste treatment processes (in cinerators), and boilers and industrial furnaces (coal-fired power pla nts). The monitoring technique is based on laser spark spectroscopy (L ASS; also known as laser-induced breakdown spectroscopy - LIBS), in wh ich a pulsed laser is used to rapidly heat a particle and produce a pl asma (or laser 'spark'). The light emission from the spark is spectral ly resolved and analyzed to identify the elemental constituents of the particle and quantify the abundance of the measured species. One feat ure of LASS is that it can measure atomic species embedded in either s olid particles or fine liquid droplets, which account for a large perc entage of metal emissions from applications of interest. In the initia l work described here, we have focused on the application of the LASS technique for measuring chromium emissions from electroplating baths. This paper describes the approach used for measuring the total chromiu m concentration in laboratory simulations of electroplating aerosols. Chromium concentrations less than 1 mg/scm can be measured. This work forms the basis for future applications to incineration and fossil pow er plants.