Toward environmentally-benign utilization of nonmetallic fraction of waste printed circuit boards as modifier and precursor

Hadi, Pejman; Ning, Chao; Ouyang, Weiyi; Meng, Xu; Lin, Carol Sze Ki; McKay, Gordon

doi:10.1016/j.wasman.2014.09.020

Cited by 75 publications

(40 citation statements)

References 95 publications

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“…The development of various electronic and electrical equipment continuously generates a large amount of electronic and electrical equipment wastes [1][2][3][4][5][6]. Printed circuit boards (PCBs) constitute one of the essential components in electronic and electrical products.…”

Section: Introductionmentioning

confidence: 99%

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Chemical Recycling of Used Printed Circuit Board Scraps: Recovery and Utilization of Organic Products

2019

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The disposal of end-of-life printed circuit boards (PCBs) comprising cross-linked brominated epoxy resins, glass fiber, and metals has attracted considerable attention from the environmental aspect. In this study, valuable resources, especially organic material, were recovered by the effective chemical recycling of PCBs. Pulverized PCB was depolymerized by glycolysis using polyethylene glycol (PEG 200) with a molecular weight of 200 g/mol under basic conditions. The cross-linked epoxy resins were effectively decomposed into a low-molecular species by glycolysis with PEG 200, followed by the effective separation of the metals and glass fibers from organic materials. The organic material was modified into recycled polyol with an appropriate viscosity and a hydroxyl value for rigid polyurethane foams (RPUFs) by the Mannich reaction and the addition polymerization of propylene oxide. RPUFs prepared using the recycled polyol exhibited superior thermal and mechanical properties as well as thermal insulation properties compared to conventional RPUFs, indicating that the recycled polyol obtained from the used PCBs can be valuable as RPUF raw materials for heat insulation.

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Section: Introductionmentioning

confidence: 99%

“…UPCBs can be disposed by various methods, including landfills, incineration, pyrolysis, and chemical recycling [5]. Landfills and incineration can cause several environmental problems due to the presence of heavy metals and hazardous components in UPCBs [7].…”

Section: Introductionmentioning

confidence: 99%

Chemical Recycling of Used Printed Circuit Board Scraps: Recovery and Utilization of Organic Products

2019

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“…Waste printed circuit boards (PCBs), including organic polymers, glass fibers, and various metals, are difficult to dispose of due to its complicated composition (Fogarasi et al, 2015;Hadi et al, 2015;Zhang et al, 2012). Besides, there are large amounts of bromine flame retardants and heavy metals in waste PCBs.…”

Section: Introductionmentioning

confidence: 99%

Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes

Liu

Zhang

2016

Waste Management

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a b s t r a c tThis work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water + H 2 O 2 ) and SCWO3 (water + H 2 O 2 /NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21 g, the H 2 O 2 volume of 9.04 mL, the time of 39.7 min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH > H 2 O 2 > time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO 2 Å , produced by H 2 O 2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO 2 , H 2 O and NaBr. In addition, the alkali-silica reaction between OH À and SiO 2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H 2 O 2 /NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs.

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“…During the last few decades, due to the absence of proper economically and environmentally friendly recycling technologies, a major fraction of e-waste generated has been either destined to landfills or incinerated. Recently, with the increasing public awareness over their environment and health issues and with the establishment of stricter regulations, environmentally friendly recycling processes have been an option (Hadi et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Fast copper extraction from printed circuit boards using supercritical carbon dioxide

et al. 2015

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Toward environmentally-benign utilization of nonmetallic fraction of waste printed circuit boards as modifier and precursor

Cited by 75 publications

References 95 publications

Chemical Recycling of Used Printed Circuit Board Scraps: Recovery and Utilization of Organic Products

Chemical Recycling of Used Printed Circuit Board Scraps: Recovery and Utilization of Organic Products

Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes

Fast copper extraction from printed circuit boards using supercritical carbon dioxide

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