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

Liu, Kang; Zhang, Zhiyuan; Zhang, Fu Shen

doi:10.1016/j.wasman.2016.05.022

Cited by 45 publications

(30 citation statements)

References 44 publications

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“…When using the pyrolysis method, fiber strength was reduced by 10%, compared to the combustion procedure, which resulted in a greater loss of strength at 50%. The electrical conductivity of pyrolyzed recycled fiber was identical to that of vCF [109][110][111]. Some oxygenated species could still be found on the surface after recovery by pyrolysis, and fibers have been shown to bind effectively to epoxy resin [89] in terms of structure-property connection.…”

Section: Pyrolysis Products and Their Reusementioning

confidence: 80%

RETRACTED: A Critical Review on Recycling Composite Waste Using Pyrolysis for Sustainable Development

Abdallah

Juaidi

Savas³

et al. 2021

Energies

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The rising usage of carbon and glass fibers has raised awareness of scrap management options. Every year, tons of composite scrap containing precious carbon and glass fibers accumulate from numerous sectors. It is necessary to recycle them efficiently, without harming the environment. Pyrolysis seems to be a realistic and promising approach, not only for efficient recovery, but also for high-quality fiber production. In this paper, the essential characteristics of the pyrolysis process, their influence on fiber characteristics, and the use of recovered fibers in the creation of a new composite are highlighted. Pyrolysis, like any other recycling process, has several drawbacks, the most problematic of which is the probability of char development on the resultant fiber surface. Due to the char, the mechanical characteristics of the recovered fibers may decrease substantially. Chemically treating and post-heating the fibers both help to reduce char formation, but only to a limited degree. Thus, it was important to identify the material cost reductions that may be achieved using recovered carbon fibers as structural reinforcement, as well as the manufacture of high-value products using recycled carbon fibers on a large scale. Recycled fibers are cheaper than virgin fibers, but they inherently vary from them as well. This has hampered the entry of recycled fiber into the virgin fiber industry. Based on cost and performance, the task of the current study was to modify the material in such a way that virgin fiber was replaced with recycled fiber. In order to successfully modify the recycling process, a regulated optimum temperature and residence duration in post-pyrolysis were advantageous.

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Section: Pyrolysis Products and Their Reusementioning

confidence: 80%

RETRACTED: A Critical Review on Recycling Composite Waste Using Pyrolysis for Sustainable Development

Abdallah

Juaidi

Savas³

et al. 2021

Energies

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show abstract

“…When GaAs oxidizes, arsenic oxides are easily lost in hydrothermal solution compared with gallium oxides. , On the other hand, packaging material degradation rate increased with increase in buffer pH and maximum degradation rate was observed at pH 8.2. This can be explained by the fact that with the increase of pH, weak alkaline environment promotes the degradation of organic components in packaging materials, and the degradation effect of weak alkaline environment on organic materials is stronger than that of hydrogen peroxide …”

Section: Resultsmentioning

confidence: 99%

“…It is mainly because of the relatively complex composition of packaging materials, including phenolic resin, epoxy resin, brominated flame retardant, accelerator, and other organic components . Generation of long-chain hydrocarbons is mainly attributed to the oxidation reaction of phenol ring and free radical reaction . Most of the major organic compounds were trapped in buffer solution, which is more environment-friendly.…”

Section: Resultsmentioning

confidence: 99%

“…Na + which dissociates from NaH 2 PO 4 or Na 2 HPO 4 in a phosphate buffer system is positive monovalently charged and can react with Br in bromophenols leading to the formation of NaBr . OH – which dissociates from phosphate buffer system (HPO 4 2– + H 2 O ↔ H 2 PO 4 – + OH – ) can undergo a nucleophilic substitution reaction with the Br-containing organic substances to convert the organic bromine to inorganic bromine. , It has been pointed out in the literature that the OH – also accelerates the ring opening of benzene rings. , More importantly, the OH – provided by the phosphate buffer can neutralize the acid generated during the hydrothermal degradation of the organic materials, so that the pH of the hydrothermal solution was stably maintained at about 6. Thus, the loss of arsenic and gallium caused by the GaAs being corroded by acidic hydrothermal solution was avoided .…”

Section: Resultsmentioning

confidence: 99%

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Novel Recycle Technology for Recovering Gallium Arsenide from Scraped Integrated Circuits

Zhan

Zhang

Ahmad

et al. 2020

ACS Sustainable Chem. Eng.

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From the environmental safety and resource recovery viewpoint, a novel method of recycling gallium arsenide (GaAs) from scrapped GaAs-based integrated circuits (ICs) was proposed in this study. A hydrothermal-buffering method (HBM) has been developed in which an oxidant (H2O2) in the presence of phosphate buffer solution reacted with ICs under hydrothermal conditions. The results have shown that the packaging material was effectively decomposed without any significant loss of GaAs under the HBM condition. Gallium and arsenic recovery rates were 99.9 and 95.5%, respectively. In addition, thermodynamically stable regions of Ga and As species in aqueous systems were identified by an Eh–pH diagram. The function of HBM has been studied and discussed in detail. Results have shown that Na+ and OH– ions provided by a buffer system accelerate the degradation of packaging materials. Meanwhile, the OH– plays an irreplaceable role in the recovery of GaAs. The states of As on the surface of the recovered GaAs were mainly positively trivalent and pentavalent, and the corresponding compounds were As2O3 and Na2HAsO4, respectively. Under optimum conditions, without releasing any toxic gases to the environment, 91.2% of the packaging materials were decomposed, probably the free radical reaction being the main mechanism; the probable decomposition pathways of packaging materials were investigated. The study provides an efficient and environmentally friendly process to treat the IC packaging material and recover maximum GaAs for further use.

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“…In addition, printed circuit boards and other electronic products fabricated viz. glass fibre-reinforced composites cumulatively end up generating 27.4-45.55 wt.% of glass fibres [32,35,36]. In the United Kingdom, generated waste glass fibres are recycled and reused up to 6% and the rest of the materials are treated waste, therefore ending up in landfill [37].…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behaviour of High-Strength Al 7005 Alloy and Its Composites Reinforced with Industrial Waste-Based Fly Ash and Glass Fibre: Comparison of Stir Cast and Extrusion Conditions

et al. 2021

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The stringent demand to develop lightweight materials with enhanced properties suitable for various engineering applications is the focus of this research work. Industrial wastes such as fly ash (FA) and S-glass-fibres (GF) were used as reinforcement materials for high-strength alloy, i.e., Al 7005. Stir casting routes were employed for fabricating the four samples, Al 7005, Al 7005 + 5% GF, Al 7005 + 6% FA and Al 7005 + 5% GF + 6% FA. The extrusion process with different extrusion ratios (ER: 5.32:1, and 2.66:1) was used to examine the properties of all four samples. Extruded samples with ER: 5.32: 1 resulted in equiaxed grains with refined structure compared to stir casting parts. The effect of the extrusion process and the addition of reinforcements (GF and FA) on the gravimetric, electrochemical, and electrochemical impedance corrosion behaviour of Al 7005 composites in 1M HCl (Hydrochloric acid) solution were investigated. The results of all three corrosion methods showed that Al 7005 + 6% FA exhibited higher corrosion resistance. Corrosion rate of Al 7005, Al 7005 + 5% GF, Al 7005 + 6% FA and Al 7005 + 5% GF + 6% FA is found equal to 3.25, 2.41, 0.34, and 0.76 mpy, respectively. The FA particles remain inert and act as a physical barrier with corrosive media during the corrosion test. GF undergoes fibre degradation or disrupts the continuity of the glass network as a result of fibre leaching, which increases the corrosion rate in the sample. The gravimetric study showed that the corrosion rates decreased with an increase in extrusion ratio, which might be due to corrosion passivation increases and improved properties. The scanning electron microscopy reveals that corrosion fits, flakes and micro-cracks were observed more in the as-cast composites than that of extrusion composites, promoting the corrosion rate.

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

Cited by 45 publications

References 44 publications

RETRACTED: A Critical Review on Recycling Composite Waste Using Pyrolysis for Sustainable Development

RETRACTED: A Critical Review on Recycling Composite Waste Using Pyrolysis for Sustainable Development

Novel Recycle Technology for Recovering Gallium Arsenide from Scraped Integrated Circuits

Corrosion Behaviour of High-Strength Al 7005 Alloy and Its Composites Reinforced with Industrial Waste-Based Fly Ash and Glass Fibre: Comparison of Stir Cast and Extrusion Conditions

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