Banca de DEFESA: LORENA DOS SANTOS LOBO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LORENA DOS SANTOS LOBO
DATE: 01/03/2024
TIME: 09:00
LOCAL: Remota
TITLE:

ANALYTICAL STRATEGIES FOR DETERMINATION OF Ag, Au, Pd and Pt IN GEOLOGICAL WASTE MATERIAL FROM A COPPER METALLURGY BY ICP-MS

KEY WORDS:

Geological material; Precious metals (Ag, Au, Pd and Pt); Sample preparation; ICP-MS

PAGES: 100
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Análise de Traços e Química Ambiental
SUMMARY:

Platinum, palladium, rhodium, ruthenium, iridium and osmium are called precious metals (or noble metals). The natural occurrence of these chemical elements is extremely rare, and the abundance in the Earth's crust compared to other metals is of low concentration. The chemical analysis of geological materials to determine these precious metals has become a fascinating and challenging field of the Analytical Chemistry, due to the particularities in sample preparation and instrumental determination. The challenge becomes even more intriguing due to the financial value added to these metals, which also moves the world market. In this work, an analytical strategy was carried out to determine precious metals (Ag, Au, Pd and Pt) in waste geological material by inductively coupled plasma-mass spectrometry (ICP-MS). Two types of sample preparation were carried out, wet and dry digestion, as a strategy for precise and accurate quantification of these metals. For chemical analysis by ICP-MS, the use of the standard mode (STD) and the mode with kinetic energy discrimination (KED) were tested, where the second mode was efficient for the determinations of Ag, Pd and Pt. To evaluate the accuracy and precision was analyzed concomitantly with the certified reference material (CRM) of concentrated copper ore. The limits of detection (LD) obtained for Ag, Au, Pd and Pt in KED mode were of 1.0; 0.2; 2.0; 11.0 µg kg^-1, respectively, and the limits of quantification (LQ) were of 3.0; 1.0; 10.0; 49.0 µg kg^-1. Spectral interferences were eliminated with an extraction technique (pre-treatment) by Fire Assay, which generated satisfactory results for determining trace levels of Pd and Pt, mainly. Despite investigation, Au determinations were not satisfactory for accuracy due to non-spectral interferences. The analytical method was applied to four samples of geological waste resulting from the metallurgical process, obtaining results between 8.0 and 156.0 mg kg^-1 of silver, 0.20 and 1.30 mg kg^-1 of palladium with acid digestion, and, between 0.10 and 0.20 mg kg^-1 of platinum with dry digestion. However, the optimized analytical method showed good precision, accuracy, selectivity, and specificity in determining Ag, Pd, and Pt in geological waste samples by ICP-MS, using the KED mode.

COMMITTEE MEMBERS:
Presidente - 1698441 - RENNAN GEOVANNY OLIVEIRA ARAUJO
Interna - 2721446 - DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
Interna - 282814 - MARIA DAS GRACAS ANDRADE KORN
Externa à Instituição - TATIANE DE ANDRADE MARANHÃO - UFSC