Dechlorination of polyvinyl chloride electric wires by hydrothermal treatment using K2CO3 in subcritical water

Gandon-Ros, Gerard; Soler, Aurora; Aracil, Ignacio; Gómez-Rico, María Francisca

doi:10.1016/j.wasman.2019.10.050

Cited by 41 publications

(17 citation statements)

References 34 publications

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“…On the other hand, Figure 1 shows the evolution of DE over time including all the debromination runs carried out at 225 °C and for the solid/liquid ratio of 1:2, taking the average value when duplicates were available. As can be observed, degradation of large pieces of WCBs occurred in two stages: First, DE increased over time following an elongated “S”-shaped curve as was already shown in previous studies using K 2 CO 3 , where small particles completely submerged in liquid during the whole hydrothermal treatment were dechlorinated 27 and debrominated. 19 This part of the process takes place once the minimum temperature for the thermal degradation of the material is reached around 250 °C for PVC 35 , 41 , 42 and for WCBs.…”

Section: Resultssupporting

confidence: 63%

“…Metal-free WCBs were used to ensure the absence of metallic catalysts, beneficial for dehalogenation purposes but whose presence is not environmentally friendly. 27 These were composed of high-quality standard FR-4 epoxy fiberglass substrates, were supplied by CISA (Circuitos Impresos S.A., Spain), and had a thickness of 1 mm in which five overlapping laminates of cross-linked glass fibers were bonded with the resin. Previous studies 14 already used this material and confirmed by Raman spectroscopy that these FR-4 WCBs contained TBBPA as BFR.…”

Section: Methodsmentioning

confidence: 99%

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Debromination and Reusable Glass Fiber Recovery from Large Waste Circuit Board Pieces in Subcritical Water Treatment

et al. 2022

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The great economic, social, and environmental interest that favors an effective management of the recycling of waste printed circuit boards (WCBs) encourages research on the improvement of processes capable of mitigating their harmful effects. In this work, the debromination of large WCBs was first performed through a hydrothermal process employing potassium carbonate as an additive. A total of 32 runs were carried out at 225 °C, various CO 3 2– /Br – anionic ratios of 1:1, 2:1, 4:1, and 6:1, treatment times from 30 to 360 min, proportion of submerged WCBs in the liquid of 100, 50, and 25% that corresponded with the use of three WCB sizes of 20 mm × 16.5 mm, 20 mm × 33 mm, and 80 mm × 33 mm, respectively, and solid/liquid ratios of 1:2 and 1:1 g/mL without other metallic catalysts. A debromination efficiency of 50 wt % was reached at only 225 °C (limited by mechanical reasons) and 360 min, using a CO 3 2– /Br – anionic ratio of 4:1 and a solid/liquid ratio of 1:2 for a large WCB with only 25% of its volume submerged in the liquid. This means conservation of water and energy compared to previous studies. A muffle furnace was used later to thermally treat a total of 101 debrominated samples, at constant temperature or following a temperature scaling program. An estimated decrease in resistance to rupture of glass fibers of only around 50% was accomplished by following a temperature scaling program up to 475 °C, obtaining clean glass fibers of large size. The simple techniques proposed to obtain reusable glass fibers from WCBs as large as the size of the reactor allows (as it might be in their original size) could significantly improve interest in the industry.

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Section: Resultssupporting

confidence: 63%

Section: Methodsmentioning

confidence: 99%

Debromination and Reusable Glass Fiber Recovery from Large Waste Circuit Board Pieces in Subcritical Water Treatment

et al. 2022

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“…It can be seen that the dechlorination efficiency of PVC increased from 61.02 to 96.08% when the reaction time increased from 30 min to 120 min. In a previous report, Gandon-Ros et al 40 investigated the dechlorination of PVC in subcritical water over K 2 CO 3 and observed that the dechlorination of PVC mainly occurred within a time of 1−3 h. In another study, Fonseca et al 41 reported that PVC dechlorination increases considerably after the first 60 min, yielding maximum after 180 min. However, in the present study, as time further increased to 150 min, the dechlorination of PVC showed a slight decrease.…”

Section: Effect Of Reaction Timementioning

confidence: 96%

Recovery of Valuable and Hazardous Metals (Ni, Co, and Cd) from Spent Ni–Cd Batteries Using Polyvinyl Chloride (PVC) in Subcritical Water

Khan

Rana

Nshizirungu

et al. 2022

ACS Sustainable Chem. Eng.

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In recent years, recycling of waste Ni−Cd batteries has drawn substantial attention due to the severe environmental pollution they cause and to avoid the dissipation of valuable metals. Although a considerable amount of research has been conducted, efficient recycling of valuable and hazardous metals from waste Ni−Cd batteries through an environment-friendly and economical process is still a challenge. The present study focuses on leaching of valuable and hazardous metals from waste Ni−Cd battery powder via a PVC-assisted subcritical water extraction method. The effects of various factors, such as time, temperature, liquid/solid ratio, and mass ratio (PVC:Ni−Cd battery powder), on the recovery efficiencies of Ni, Cd, and Co are also investigated. After metal extraction, the solid residues were analyzed by XRD, XPS, FT-IR, FE-SEM, and EDS element mapping to anticipate the chemical compounds before and after the recycling experiment. Meanwhile, ICP-OES analysis was used to determine the metal content in the leachate. The ICP-OES results showed that more than 96.38, 92.98, and 99.96% of Ni, Cd, and Co, respectively, were satisfactorily recovered from the waste Ni−Cd battery powder under the optimized conditions: 300 °C temperature, 120 min reaction time, 15 mL/g liquid/solid ratio, and 1:3 Ni−Cd battery powder:PVC mass ratio. The results obtained from this study suggest that the applied subcritical water extraction could be an efficient, environment-friendly, and sustainable technology for the recovery of valuable and hazardous metals from waste Ni−Cd batteries.

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“…The interest of these dechlorination and debromination processes is centered on either having a material that can be used again [ 22 ] or preparing it for destruction in thermal treatment furnaces profiting from its energetic value [ 23 ], in which the formation of dioxin-like compounds can be more effectively controlled [ 24 ]. In both cases, the strategy would mean net energy savings and a very positive environmental balance.…”

Section: Introductionmentioning

confidence: 99%

Debromination of Waste Circuit Boards by Reaction in Solid and Liquid Phases: Phenomenological Behavior and Kinetics

et al. 2023

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The debromination of waste circuit boards (WCBs) used in computer motherboards and components has been studied with two different pieces of equipment. Firstly, the reaction of small particles (around one millimeter in diameter) and larger pieces obtained from WCBs was carried out with several solutions of K2CO3 in small non-stirred batch reactors at 200–225 °C. The kinetics of this heterogeneous reaction has been studied considering both the mass transfer and chemical reaction steps, concluding that the chemical step is much slower than diffusion. Additionally, similar WCBs were debrominated using a planetary ball mill and solid reactants, namely calcined CaO, marble sludge, and calcined marble sludge. A kinetic model has been applied to this reaction, finding that an exponential model is able to explain the results quite satisfactorily. The activity of the marble sludge is about 13% of that of pure CaO and is increased to 29% when slightly calcinating its calcite at only 800 °C for 2 h.

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Dechlorination of polyvinyl chloride electric wires by hydrothermal treatment using K2CO3 in subcritical water

Cited by 41 publications

References 34 publications

Debromination and Reusable Glass Fiber Recovery from Large Waste Circuit Board Pieces in Subcritical Water Treatment

Debromination and Reusable Glass Fiber Recovery from Large Waste Circuit Board Pieces in Subcritical Water Treatment

Recovery of Valuable and Hazardous Metals (Ni, Co, and Cd) from Spent Ni–Cd Batteries Using Polyvinyl Chloride (PVC) in Subcritical Water

Debromination of Waste Circuit Boards by Reaction in Solid and Liquid Phases: Phenomenological Behavior and Kinetics

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