Abstract
Improper disposal of electronic waste in the environment facilitates migration of heavy metals, especially lead, into the soil and can contribute to the bioavailability of this species. Based on a simplex-centroid mixture experimental design, small-scale tests were performed for incubation of printed circuit boards (PCBs) in mixtures containing organic matter (OM), kaolinite (KA) and iron oxides (IO) to verify lead migration. Regression equations were acquired and were adjusted to the obtained responses. Results showed high total content of Pb, ranging from 400 to 4000 mg kg-1, depending on the mixture and incubation time. Mobility and/or bioavailability of lead in the mixtures were evaluated by a three-step sequential extraction. The bioavailability factor (BF) was obtained from the ratio of the sum of exchangeable fraction (F1) and the organically bound fraction (F2) by F1, F2 and the residual fraction (F3) and the values of bioavailability factor for Pb, the heavy metal considered of greatest environmental concern in this study, ranged between 0.16 and 0.52.
Highlights
Electronic waste (e-waste) is the term used to describe residues of obsolete electronic equipment such as televisions, cell phones, computers and other devices
Among the metals analyzed in the electronic waste, Pb is the heavy metal of greatest environmental concern, even though it is not found in greatest proportion, due to its greater toxicity and because it is exposed on the printed circuit boards (PCBs).[22]
The migration of Pb from the PCBs to the mixture of kaolinite, iron oxides and organic matter was investigated, in order to verify the influence of these mixtures on the release of Pb, demonstrating a great concern regarding its potential to negatively impact the environment
Summary
Electronic waste (e-waste) is the term used to describe residues of obsolete electronic equipment such as televisions, cell phones, computers and other devices. The increasing generation of electronic waste occurs mainly as a result of technological development that makes the time of use of electronic equipment become shorter. Cell phones are used for only 18 months on average before being replaced, even if they can be operated longer.[2] Waste from electrical and electronic equipment already constitutes 8% of municipal waste and is one of the fastest growing waste fractions.[3]. Brazil is considered one of the largest producers of electronic waste among emerging countries. It is estimated that currently about 679,000 t year-1 of e-waste is generated.[4] Regarding cell phones, about 10 to 20% of phones produced in Brazil are discarded each year.[5]
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