Smart Determination of Gold Content in PCBs of Waste Mobile Phones by Coupling of XRF and AAS Techniques

Nicolò Maria Ippolito,Luigi Piga,Valentina Innocenzi,Gianmaria Belardi,Loris Pietrelli,Franco Medici

doi:10.3390/pr9091618

Nicolò Maria Ippolito, Luigi Piga + Show 4 more

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https://doi.org/10.3390/pr9091618

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Journal: Processes	Publication Date: Sep 8, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: University of L'Aquila, Sapienza University of Rome

Abstract

Quantitative determination of most economic valuable metals in waste is the first fundamental operation of evaluating the feasibility of recycling processes. Field-portable X-ray fluorescence spectrometers (FPXRFs) represent a more practical, efficient, and economic tool in determining the elemental composition of samples with respect to conventional analytical techniques, such as atomic absorption spectrometry (AAS) and inductively coupled plasma emission spectrometry (ICP). In this paper, quick and smart determination of gold content in printed circuit boards (PCBs) of waste mobile phones was studied. The aim of the research was to combine the practicality of FPXRFs with the reliability of quantitative spectrometry analysis and evaluate the error between the two techniques. Several samples (33) of PCBs were ground to a size below 0.5 mm, and then, the powders were analyzed by FPXRFs at different acquisition times with five replications for each sample. The same analyzed samples then underwent chemical attack to determine the quantitative gold content by AAS. The obtained results were associated with FPXRFs response with the purpose of realizing a calibration curve (100–1000 mg/kg Au). The curve was validated for accuracy and precision by other PCBs waste samples; the control samples were added as standards to obtain a more reliable calibration curve. The curve was evaluated with RPD classification, regression linear, and Bolt–Altman analysis.

Highlights

In the current context of increasing pressure on resources and environment caused by production and consumption, the concept of circular economy responds to the desire for sustainable growth
The mean gold concentration measured by Field-portable X-ray fluorescence spectrometers (FPXRFs) is 54.81 mg/kg lower than those measured by atomic absorption spectrometry (AAS)
The main aim was to determine whether this technique can replace conventional analytical techniques, such as atomic absorption spectrometry (AAS), that are more expensive and require more time consumption

Summary

Introduction

In the current context of increasing pressure on resources and environment caused by production and consumption, the concept of circular economy responds to the desire for sustainable growth. The transition to a circular economy shifts the focus to reducing, reusing, and recycling existing materials and products, and what generally was considered as waste must necessarily be turned into a resource. Thanks to this approach, rather than waste being viewed as a problem, it is seen as a valuable resource that can be managed to produce sustainable benefits. The chemical characterization of waste is performed in laboratories using instrumental methods, and the most important are atomic absorption spectroscopy (AAS) Determination of chemical composition of waste is crucial to ensure it receives the most suitable management; information about elemental concentration, such as valuable or pollutant elements, allows for the identification of the best treatment to recover valuable elements and to remove pollutant ones.

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