Fate of bromine in pyrolysis of printed circuit board wastes

Chien, Yi-Chi; Wang, H Paul; Lin, Kuen‐Song; Huang, Yumeng; Yang, Yun

doi:10.1016/s0045-6535(99)00251-9

Cited by 120 publications

(66 citation statements)

References 8 publications

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“…PCBs contain between 5 to 15% of BFRs that are added in order to inhibit the combustion process in case of fire, limiting the amount of heat released (Chien et al, 2000). BFRs are the most used today because they have the best cost-benefit ratio.…”

Section: Introductionmentioning

confidence: 99%

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

2017

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Degradation of brominated flame retardants present in printed circuit boards (PCBs) was tested using subcritical water in a high pressure reactor. Debromination experiments were carried out in a batch stirred reactor at three different temperatures (225 ºC, 250 ºC and 275 ºC) keeping a solid to liquid (S/L) ratio of PCB:water=1:5 during 180 min. Results indicated that debromination efficiency was increased with temperature (18.5 to 63.6% of bromine present in the original PCB was removed).Thermal decomposition of the debrominated materials was studied and compared with that of the original PCB. Thermogravimetric analyses were performed at three different heating rates (5, 10 and 20 K min -1 ), studying both the pyrolysis (inert atmosphere) and combustion (in air). Pyrolysis runs of the debrominated materials were also performed in a quartz horizontal laboratory furnace at 850 ºC, in order to study the emission of pollutants. More than 99% of the bromine was emitted in the form of HBr and Br 2 . Emissions of polycyclic aromatic hydrocarbons (PAHs) and bromophenols (BrPhs) decreased with the increase in the treatment temperature; naphthalene (10800 -18300 mg kg -1 original sample) and monobrominated phenols (12.8 -16.9 mg kg -1 original sample) were the most abundant compounds.

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Section: Introductionmentioning

confidence: 99%

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

2017

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“…Chiang et al (Chiang and Lin, 2014;Chiang et al, 2010) carried out the pyrolysis of crushed WCB between 200 and 500 ºC and analyzed the composition of residue, liquid and gaseous fractions. Chien et al (Chien et al, 2000) studied the distribution of Br in pyrolysis products by using a fixed-bed reactor at 350 -800 ºC and thermogravimetry, and found that it mainly evolved as HBr and bromobenzene in the product gas. De Marco et al (de Marco et al, 2008) conducted pyrolysis experiments at 500 ºC on four different WEEE samples (polyethylene wires, table phones, mobile phones and printed circuit boards), with a focus on the solid and liquid fractions.…”

Section: Introductionmentioning

confidence: 99%

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

García

Conesa

Moltó

et al. 2014

Science of The Total Environment

100

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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.

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“…The most commonly WPCBs material is FR-4, which uses glass fibers as the reinforcing materials and brominated epoxy resins (BERs) as a binder [3]. BERs contain a large number of brominated flame retardants (5-15%, BFRs) for reducing the possibility of fire under the thermal stress [4]. Serious pollution can be generated if PCBs are not properly disposed of since the flame retardants therein may cause the formation of halogenated dioxin-like compounds, such as polybrominated dibenzo-p-dioxins (PBDDs) or polybrominated dibenzofurans (PBDFs) [5,6].…”

Section: Introductionmentioning

confidence: 99%

Degradation of brominated epoxy resin and metal recovery from waste printed circuit boards through batch sub/supercritical water treatments

Xing

Zhang

2013

Chemical Engineering Journal

130

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h i g h l i g h t s" This work provides an efficient and green approach for waste printed circuit boards recycling. " Debromination of brominated epoxy resins and recycling of metals was simultaneously achieved. " Brominated epoxy resins can be completely decomposed by sub/SCW treatments. " Glass fibers and copper foils in WPCBs were liberated and could be easily separated by crushing after sub/SCW treatment. a r t i c l e i n f o b s t r a c tWaste printed circuit boards (WPCBs) contain high amount of brominated flame retardants and heavy metals which may bring a series of environmental and health problems. In the present study, an effective and benign process using sub-and supercritical water (sub/SCW) to simultaneously degrade brominated epoxy resin and recover metals from WPCBs was developed. Experiments were performed in a batch-type reactor with temperatures ranging from 200 to 400°C, water adding amounts from 10 to 40 ml and holding times from 30 to 240 min. The results showed that brominated epoxy resins (BERs) could be quickly and efficiently decomposed under sub/SCW condition. The debromination rate was 97.8% by controlling the temperature, water adding amount and holding time at 400°C, 40 ml and 120 min, respectively. Most of the bromine was changed into HBr and around 97.7% was enriched in water. Meanwhile, bromine-free oil was obtained of which the main compositions were phenol (58.5%) and 4-(1-methylethyl)-phenol (21.7%). After the sub/SCW treatments, the glass fibers and copper foils in the residue can be easily liberated and recovered respectively. The copper recovery rate reached 98.11% in the purities of 96.74% (grain size >2.0 mm) and 92.74% (0.147-2.0 mm). This study provides an efficient and green approach for WPCBs recycling.

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Fate of bromine in pyrolysis of printed circuit board wastes

Cited by 120 publications

References 8 publications

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

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

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

Degradation of brominated epoxy resin and metal recovery from waste printed circuit boards through batch sub/supercritical water treatments

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