Recuperação de metais de resíduo de diodo emissor de luz (LED): conjugação de técnicas hidrometalúrgicas e processos de separação por membranas

Abstract

The uses and applications of light emitting diode (LED) have been growing all over the world and, as a consequence, in the next years the generation of this kind of waste is expected to grow substantially. Despite the advantage of having a high energetic efficiency, LED contains heavy metals and, if it doesnt receive the proper final destination or correct treatment, it may cause serious harm to human health and environment. Adding to this the yet insipient knowledge about LED waste, for it is an emerging one, the purpose of this work is to evaluate the recovery of heavy metals from LED, using a combination of hydrometalurgical technics and membranes separation processes. The present heavy metals, their concentrations and recovery efficiencies were investigated. Synthetical and real solutions were used for such evaluations. The heavy metals identified in the studied LED waste were gallium (1350 mg.kg1), arsenic (1350 mg.kg-1), gold (360 mg.kg-1) and copper (29%). The heavy metals recovery efficiencies reached high as 99,75% for gallium, 74,64% for arsenic, 15,74% for gold and 98,85% for copper. Investigative studies of synthetic effluents showed rejections of 93,45% (pH -0,18) and 98,71% (for pHs ranging from 2,0 to 4,0) for gallium. In the experiment with the real effluent, the found rejection values were 85% for gallium, 52,67% for arsenic and 74,14% for copper. The high concentration of metals found in LED waste, the need to treat this waste and the urgent claim for lowering the environmental impacts caused by traditional mining are propelling factors to the continuity of studies on this topic