Pollutant emissions during pyrolysis and combustion of waste printed circuit boards, before and after metal removal

Abstract

The constant increase in the production of electronic devices implies the need for an appropriate management of a growing number of waste electrical and electronic equipment.Thermal treatments represent an interesting alternative to recycle this kind of waste, but particular attention has to be paid to the potential emissions of toxic by-products. In this study, the emissions from thermal degradation of printed circuit boards (with and without metals) have been studied using a laboratory scale reactor, under oxidizing and inert atmosphere at 600 and 850 ºC. Apart from carbon oxides, HBr was the main decomposition product, followed by high amounts of methane, ethylene, propylene, phenol and benzene. The maximum formation of PAHs was found in pyrolysis at 850 ºC, naphthalene being the most abundant. High levels of 2-, *Corresponding author. E-mail: ja.conesa@ua.es. Phone: +(34)965903400 Fax: +(34)965903826 2 4-, 2,4-, 2,6-and 2,4,6-bromophenols were found, especially at 600 ºC. Emissions of PCDD/Fs and dioxin-like PCBs were quite low and much lower than that of PBDD/Fs, due to the higher bromine content of the samples. Combustion at 600 ºC was the run with the highest PBDD/F formation: the total content of eleven 2,3,7,8-substituted congeners (tetra-through heptaBDD/Fs) was 7240 and 3250 ng WHO 2005 -TEQ/kg sample, corresponding to the sample with and without metals, respectively.

Emissions of brominated compounds and polycyclic aromatic hydrocarbons during pyrolysis of E-waste debrominated in subcritical water

“…In order of abundance, phenol, styrene and benzofuran were the most abundant products detected in all runs. This is in accordance with results obtained by Ortuño et al (2014a). In addition to these, some of the most important degradation products consisted in nonsubstituted polyaromatic compounds (i.e.…”

“…Altarawneh and Dlugogorski (2014a) also found that the major product generated in the thermal decomposition of TBBPA was HBr. The total yield of HBr+Br 2 with the original PCB is similar as it is, only slightly higher than that detected in previous studies (Ortuño et al, 2014a). (Table 2) Figure 4 shows the results of emissions of the 16 priority PAHs during pyrolysis at 850ºC in the horizontal reactor.…”

“…Emissions from the original PCB were similar, being only, slightly higher than those detected previously in the pyrolysis at 850 ºC of waste PCBs after removal of metal (Ortuño et al, 2014a) and electronic circuits from mobile phones (Moltó et al, 2011).…”

“…However, another previous study (Ortuño et al, 2014b) shows that the amount of bromobenzene during the pyrolysis for the metal-free PCBs was 10 times higher than that observed for all PCBs.…”

14th congress of combustion by-products and their health effects—origin, fate, and health effects of combustion-related air pollutants in the coming era of bio-based energy sources

“…(Conesa et al 2013). Similarly, the thermal processing of printed circuit boards, which represent around six percent of all e-waste by weight, is particularly problematic because of the heterogeneous combination of organic materials, metals and glass fiber (Ortuño et al 2014). Studies have demonstrated that emissions of PCDDs and PCDFs were lower than emissions of PBDDs and PBDFs, probably due to the higher bromine content of printed circuit boards.…”