Simultaneous Determination of REEs in Coal Samples Using the Combination of Microwave-Assisted Ashing and Ultrasound-Assisted Extraction Methods Followed by ICP-OES Analysis

Abstract

The world during the COVID-19 pandemic has led to extensive use of virtual activities by means of electronic devices, which are made up of rare earth elements (REEs). This means that quantitative knowledge of REEs in various resources is crucial for the development of effective recovery methods. Therefore, this report describes a simple microwave assisted ashing followed by ultrasound-assisted extraction (MAA-UAE) for quantitative determination of REEs in coal samples using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Firstly, coal samples were ashed at 55 °C for 4.5 h to form white ashes, which were then treated with dilute HNO3 acid under ultrasonication to enhance the extraction of REEs. The quantitative recoveries (86–120%) of REEs were obtained when 1 mol L−1, 0.1 g, 40 °C, 20 min, and high frequency were applied for [HNO3], sample mass, ultrasonic bath temperature, extraction time, and ultrasonic bath frequency, respectively. The method detection limits of the proposed MAA-UAE method were between 0.0075 and 0.59 µg g−1 with satisfactory precision (<5%). The concentration levels of REEs in South African coals ranged from 1.4 to 105 µg g−1, suggesting that this coal can be a resource for REEs.

Semi-quantitative analysis study of the impact of microwave treatment on fly ash

“…This method can effectively determine the content of amorphous phases and improve the accuracy of sample analysis. Origin2022 software was used for infrared spectroscopic analysis to compare the molecular vibration information of fly ash particles under different microwave conditions within the wavenumber range of 1300-400 cm -1 and performed peak fitting (Zuma et al, 2021). The flow chart of the experimental method is shown in Fig.…”

Sensitive and accurate determination of REEs using a high-efficiency miniaturized ultrasonic nebulization sampling system coupled with the inductively coupled plasma mass spectrometer

“…Various analytical techniques have been developed for the determination of REEs, including ultraviolet visible spectrophotometry (UV-vis), 11 X-ray fluorescence spectrometry (XRF), 12 neutron activation analysis (NAA), 13,14 inductively coupled plasma optical emission spectrometry (ICP-OES), 15 and inductively coupled plasma mass spectrometry (ICP-MS). 10 Among these, ICP-MS is commonly preferred due to its multielement-analysis ability with high sensitivity and satisfactory anti-interference capabilities.…”

Application of Rare Earth Marking on Anti-Counterfeiting Waterless/Less-Water Dyeing Technology

“…24 The method has high accuracy, wide linear range, less matrix interference, and extremely high sensitivity for the determination of low content of REEs, which can fully meet the needs of fabrics for simultaneous determination of multiple REEs. 25 REEs in coal samples were determined by ICP-OES 26 with low detection limits (1.4 to 105 mg/g) and good precision (\5%), which was useful for quantitatively understanding REEs in various resources for developing effective recovery methods. Therefore, ICP-OES can be employed to detect traceable REEs added to non-aqueous medium dyeing products.…”