Abstract
This work represents a novel method to determine phosphorus (P) concentration in phosphogypsum (PG) waste samples using calibration-free laser-induced breakdown spectroscopy (LIBS). A 50 mJ Q-switched Nd: YAG laser has generated the PG LIBS spectrum. Spectroscopic analysis of plasma evolution has been characterized by electron density N-e and electron temperature T-e using the emission intensity and stark broadening for P I characteristic lines 213.61, 214.91, and 215.40 nm under non-purged (air) and purged (helium) conditions. It was found that both T-e and N-e have significant changes linearly with P concentrations 4195, 5288, 6293, and 6905 ppm. The plasma Te and Ne values increased from about 6900 to 10,000 K and 1.1 x 10(17) to 3.4 x 10(17) cm(-3), respectively, for the non-purged PG. On the other hand, T-e and N-e ranged from 8200 to 11,000 K and 1.4 x 10(17) to 3.5 x 10(17) cm(-3), respectively, for the PG purged with helium. It is concluded that T-e and N-e values represent a fingerprint plasma characterization for a given P concentration in PG samples, which can be used to identify P concentration without a PG's complete analysis. These results demonstrate a new achievement in the field of spectrochemical analysis of environmental applications.