Heavy Metals Detection in Zeolites Using the LIBS Method

Abstract

In this study, a possibility of laser-induced breakdown spectroscopy (LIBS) for the analysis of zeolites containing copper, chromium, cobalt, cadmium, and lead in the concentration range of 0.05–0.5 wt.% is discussed. For the LIBS analysis, microporous ammonium form of Y zeolite with the silicon to aluminum molar ratio of 2.49 was selected. Zeolites, in the form of pressed pellets, were prepared by volume impregnation from the water solution using Co(CH3COO)2.4H2O, CuSO4.5H20, K2Cr2O7, PbNO3, and CdCl2 to form a sample with different amounts of heavy metals—Co, Cu, Cr, Pb, and Cd. Several spectral lines of the mentioned elements were selected to be fitted to obtain integral line intensity. To prevent the influence of the self-absorption effect, non-resonant spectral lines were selected for the calibration curves construction in most cases. The calibration curves of all elements are observed to be linear with high regression coefficients. On the other hand, the limits of detection (LOD) were calculated according to the 3σ/S formula using the most intensive spectral lines of individual elements, which are 14.4 ppm for copper, 18.5 ppm for cobalt, 16.4 ppm for chromium, 190.7 ppm for cadmium, and 62.6 ppm for lead.

Filler-Modified Castor Oil-Based Polyurethane Foam for the Removal of Aqueous Heavy Metals Detected Using Laser-Induced Breakdown Spectroscopy (LIBS) Technique

“…In a LIBS spectrum, Cr presence was indicated by the three signal lines, respectively appearing at 425.4, 427.4, and 428.9 nm. As reported by other studies, the signal line at 425.4 nm appeared to be the highest [25,38]. Nevertheless, the trend exhibited by Cr I/ Ca I ratio at 425.4 nm was observably different from the other two.…”

“…In this research, however, we will employ PUF's applicability in heavy metal removal by incorporating activated carbon, bentonite, and zeolite as modifying fillers. These fillers are prominent heavy metal adsorbents that have been reported by many studies [3,[23][24][25][26].…”

“…Heavy metal precipitation is an adverse effect on adsorption. Note that, for Cr analysis, Ca I (422.6 nm) was selected as the standard line because Cr has similar ionization energy (Cr: 6.78 eV) [25]. Also, in this section of the analysis, each sample had the same proportion of Ca, since the same type and amount of filler (bentonite) was used.…”

“…Indeed, Rezk et al (2018) had deeply studied the adsorption of Cu (II) and Co(II) on the fishbone adsorbent, but they did not use polymeric material [8]. Horňáčková et al (2019) and Jiao et al (2015) only slightly discussed the heavy metal adsorption without touching the effect of contact time and pH [25,39]. It is also worth mentioning that LIBS analysis opens possibilities of investigating heavy metal adsorption in such high concentration, which can give a better insight into the future adsorption studies.…”

Development and Validation of a Spectrometric Method for Cd and Pb Determination in Zeolites and Safety Evaluation

“…In this case, the atoms can be obtained by electrothermal evaporation in a graphite furnace (GF-AAS) or in a flame (F-AAS) [25][26][27]. Beside these, other non-conventional techniques can also be used to determine metal analytes in different samples [28][29][30]. For specific elements (i.e., Hg) which have high volatility, the direct measurement in solid samples (including zeolites) by thermal desorption is possible [31].…”