Optical sensor development for toxic elements detection in liquids

Laser induced breakdown spectroscopy (LIBS) based sensor methodology was developed for the detection of three toxic elements; As, S, and Se in liquid. This concept will be used to develop a sensor for the in-situ analysis of coal power plant wastewater. Real time probe for the monitoring of the EPA regulated species is needed to control effluent streams in the power plants. Single and double pulse LIBS systems with 1064 nm Nd:YAG lasers were utilized to generate micro plasma from the surface of liquid jet containing these elements in ppm levels. Plasma emission was collected at 45 degree with the laser beam for As and Se emission lines detection in UV range while that was collected in collinear mode with laser beam for S line detection in near IR. Atomic emission lines at wavelengths 274.4 nm, 278.0 nm for As, 921 nm for S, and 196.09 nm, 203.9 nm, and 206.32 nm for Se were detected in LIBS spectra.