Chemical composition of e-waste and analysis of its potential use for urban mining of rare earth elements
Abstract
The research was focussed on the elemental composition of the luminophor imaging devices such as CRT (Cathode Ray Tube) and plasma TV. Luminophor samples (37), obtained from different luminophor imaging devices, and, according to the type of the device, were divided into four subgroups: black-and-white televisions, color televisions, color monitors and monochrome CRT monitors.
The research was done using multielemental analysis, including mass spectrometry with inductively coupled plasma (ICP MS), optical emission spectrometry with inductively coupled plasma (ICP OES), the combustion method with infrared spectroscopy (IR-RF) and atomic absorption spectrometry (AAS). Analysis results were used to define key elements (including REE) and potentially risky elements in each of the subgroups.
Concentrations of REE in luminophors within individual subgroups differed significantly. The highest average concentrations of Eu and Y were measured in color television subgroup (13 808 mg/kg of Eu; 217 000 mg/kg of Y).
The average concentrations of Dy and Tb were highest in black-and-white TV subgroup (3.33 mg/kg of Dy; 447 mg/kg of Tb). The highest concentration Ce (43.5 mg/kg) and La (21.3 mg/kg) were measured in samples from color monitors subgroup.
In the case of inappropriate handling of discarded imaging devices, they represent an environmental risk. Potentially hazardous elements in the luminophors were mainly Cd (in black-and-white TV phosphors 126 400 mg/kg) and also Zn (355 600 mg/kg).
Luminophors from color monitors subgroup showed highest concentrations of Pb (60100 mg/kg) and Sb (424 mg/kg). The average concentration of Co in the of luminophors in color TV subgroup was 850 mg/kg.
The highest concentration of Al (25100 mg/kg) and Ba (16200 mg/kg) were measured in the luminophors obtained from plasma TV. Mining (urban mining) of Y and Eu luminophors from color television sets hence could be economically significant.