Co-treatment of waste printed circuit boards and polyvinyl chloride by subcritical water oxidation: Removal of brominated flame retardants and recovery of Cu and Pb

Abstract

h i g h l i g h t sWe report an effective process for co-treatment of waste PCBs and PVC. Brominated flame retardants can be decomposed efficiently in co-treatment. Dechlorination of PVC was complete and safe. Cu and Pb in waste printed circuit boards can be recovered efficiently. Sn and Cr can be immobilized efficiently in the residue after co-treatment. t r a c tIn this work, an effective process for removal of brominated flame retardants (BFRs) and recovery of Cu and Pb from waste printed circuit boards (PCBs) was developed. In the process, waste PCBs and polyvinyl chloride (PVC) were co-treated by subcritical water oxidation (SBWO). PVC was used as a hydrochloric acid source and waste PCBs was used as a neutralizing reagent for the produced HCl. The dechlorination of PVC, removal of BFRs, and recovery of Cu and Pb could be achieved simultaneously by the one-step SBWO reaction. Experimental results showed that the dechlorination of PVC was complete when SBWO temperature exceeded 250°C. SBWO co-treatment was high efficient for the leaching of Cu and Pb from waste PCBs, and XRD spectra indicated that Sn was immobilized as SnO 2 in the residue after co-treatment. The optimum SBWO co-treatment conditions were temperature of 350°C, time of 60 min, solidliquid ratio of 1:9 g/ml, and PVC-to-PCBs ratio of 1:1, respectively. In the optimized co-treatment, 98.9% of Cu and 80% of Pb were recovered, while the leaching efficiencies of Sn and Cr were 15.3% and 3.9%, respectively. Meanwhile, approximately 100% of the bromine was changed into HBr and enriched in water after co-treatment.

A novel reutilization method for waste printed circuit boards as flame retardant and smoke suppressant for poly (vinyl chloride)

“…Metal content in SCWO-treated PCBs was determined by ICP-OES (OPTIMA 2000, PerkinElmer) after digestion [30]. The bromine content in the FR1, FR2, and FR3 was measured by an oxygen combustion bomb-ion chromatography (IC, DionexICS2000, USA) according to a literature [31]. The structure of SCWO-treated PCBs were characterized by X-ray diffraction spectroscopy (XRD) at 50 kV and 100 mA using Cu K␣ radiation ( = 1.5418 Å).…”

Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

“…However, the toxic organic matters such as BFRs in waste PCBs cannot be removed efficiently during such processes above mentioned Vermaak, 2007, 2009). Chien et al (2000) firstly proposed the use of supercritical water oxidation (SCWO) as the pre-treatment technology for waste PCBs, and toxic organic matters such as BFRs in waste PCBs could be degraded efficiently in SCWO process (Xiu and Zhang, 2012;Xiu et al, 2013Xiu et al, , 2014. Hence, the decomposition of toxic organic matters and the enrichment of metals could be achieved at the same time by using SCWO as a pre-treatment technique for subsequent hydrometallurgical process.…”

Urban Mining and Electrochemistry: Cyclic Voltammetry Study of Acidic Solutions from Electronic Wastes (Printed Circuit Boards) for Recovery of Cu, Zn, and Ni

“…Gold, silver, copper, nickel and zinc are examples of elements in the "e-waste" [10]. These are basically present in computer components, printed circuits boards (PCBs), cell phones, etc.…”

“…Viewed from the different perspectives of the recycling of PCBs, scientists have developed many and varied methods involving physical and mechanical technology for separation, bio-technology, supercritical fluid technology, microwave treatment and processes of extractive metallurgy (hydro and pyrometallurgy). Despite the existence of these routes, the processing of "mechanical crushing + hydrometallurgy" is the more predominant technology and the most commonly used, because of the advantages reached in the recycling of PCBs [10,15,16].…”