Fast Determination of Phosphorus Concentration in Phosphogypsum Waste Using Calibration-Free LIBS in Air and Helium

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 Ne and electron temperature Te 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 Te and Ne have significant changes linearly with P concentrations 4195, 5288, 6293, and 6905 ppm. The values of plasma Te and Ne increased from about 6900 to 10000 K and 1.1×1017 to 3.4×1017 cm− 3, respectively, for the non-purged PG. On the other hand, Te and Ne ranged from 8200 to 11000 K and 1.4×1017 to 3.5×1017 cm− 3, respectively, for the PG purged with helium. It is concluded that Te and Ne 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.

Simple defocus laser irradiation to suppress self-absorption in laser-induced breakdown spectroscopy (LIBS)

“…The first concerns the basic aspects of the LIBS plasma, such as plasma dynamics, electron number density, plasma temperature, line broadening and line shift, and plasma modeling [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. The second is primarily concerned with its numerous applications, which include qualitative and quantitative material analysis [ 11 , 12 , 13 , 14 , 15 , 16 ], biological applications such as clinical specimens and human blood [ 17 , 18 ], surface analysis including depth profile measurement [ 19 , 20 , 21 , 22 ], plant analysis [ 23 , 24 , 25 ], isotopic analysis [ 26 , 27 , 28 , 29 , 30 ], and many other interesting LIBS applications that are not discussed in detail in this paper.…”