Value-added products from thermochemical treatments of contaminated e-waste plastics

Das, Pallab; Gabriel, Jean‐Christophe P.; Tay, Chor Yong; Lee, Jongmin

doi:10.1016/j.chemosphere.2020.129409

Cited by 61 publications

(18 citation statements)

References 177 publications

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“…The acid solutions deteriorate the WPCB surface, allowing the leaching of some hazardous pollutants such flame retardants (Br) or heavy metals (Pb), as ruled by the European Directive on waste electrical and electronic equipment [30]. Removing brominated flame retardants added to the plastics used in WEEE require strong thermochemical treatments [31,32], not comparable with that presented in this study. However, despite a mild and short treatment, a significant rising trend in Br concentrations was detected in both the CA 334 and CA Com solutions (0.62 and 0.65 mg/L, respectively, p < 0.001).…”

Section: Metal Leachingmentioning

confidence: 81%

Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

et al. 2021

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A low-energy paradigm was adopted for sustainable, affordable, and effective urban waste valorization. Here a new, eco-designed, solid-state fermentation process is presented to obtain some useful bio-products by recycling of different wastes. Urban food waste and scraps from trimmings were used as a substrate for the production of citric acid (CA) by solid state fermentation of Aspergillus niger NRRL 334, with a yield of 20.50 mg of CA per gram of substrate. The acid solution was used to extract metals from waste printed circuit boards (WPCBs), one of the most common electronic waste. The leaching activity of the biological solution is comparable to a commercial CA one. Sn and Fe were the most leached metals (404.09 and 67.99 mg/L, respectively), followed by Ni and Zn (4.55 and 1.92 mg/L) without any pre-treatments as usually performed. Commercial CA extracted Fe more efficiently than the organic one (123.46 vs. 67.99 mg/L); vice versa, biological organic CA recovered Ni better than commercial CA (4.55 vs. 1.54 mg/L). This is the first approach that allows the extraction of metals from WPCBs through CA produced by A. niger directly grown on waste material without any sugar supplement. This “green” process could be an alternative for the recovery of valuable metals such as Fe, Pb, and Ni from electronic waste.

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Section: Metal Leachingmentioning

confidence: 81%

Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

et al. 2021

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“…Das reviewed WEEE recycling using thermochemical processes, including high-temperature extraction, incineration, hydrolysis, as well as catalytic and non-catalytic pyrolysis. [502] Molecular recycling of thermosetting composites used in automotive, windmill, and aerospace applications combined with fiber recovery is an end-of-life option and a viable alternative to the current practice of landfill and incineration. [453,[503][504][505] In their review, Gopalraj and Karki addressed the recovery of high-quality glass and carbon fibers, research challenges, as well as the economic and environmental impacts of mechanical, thermal, and chemical composite recycling.…”

Section: Gasification Liquefaction and (Hydro)pyrolysismentioning

confidence: 99%

Closing the Carbon Loop in the Circular Plastics Economy

Schirmeister

Mülhaupt

2022

Macromol. Rapid Commun.

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Today, plastics are ubiquitous in everyday life, problem solvers of modern technologies, and crucial for sustainable development. Yet the surge in global demand for plastics of the growing world population has triggered a tidal wave of plastic debris in the environment. Moving from a linear to a zero‐waste and carbon‐neutral circular plastic economy is vital for the future of the planet. Taming the plastic waste flood requires closing the carbon loop through plastic reuse, mechanical and molecular recycling, carbon capture, and use of the greenhouse gas carbon dioxide. In the quest for eco‐friendly products, plastics do not need to be reinvented but tuned for reuse and recycling. Their full potential must be exploited regarding energy, resource, and eco‐efficiency, waste prevention, circular economy, climate change mitigation, and lowering environmental pollution. Biodegradation holds promise for composting and bio‐feedstock recovery, but it is neither the Holy Grail of circular plastics economy nor a panacea for plastic littering. As an alternative to mechanical downcycling, molecular recycling enables both closed‐loop recovery of virgin plastics and open‐loop valorization, producing hydrogen, fuels, refinery feeds, lubricants, chemicals, and carbonaceous materials. Closing the carbon loop does not create a Perpetuum Mobile and requires renewable energy to achieve sustainability.

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“…Ashing was done at a lower temperature, 500 • C, without the addition of borax to combust any organics in the sample. The most common plastics in PCBs are acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) [66]. These plastics have boiling points of 145.2 • C and 430 • C, respectively [67].…”

Section: Ashingmentioning

confidence: 99%

A Comparison of Methods for the Characterisation of Waste-Printed Circuit Boards

Yken

Cheng

Boxall

et al. 2021

Metals

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Electronic waste is a growing waste stream globally. With 54.6 million tons generated in 2019 worldwide and with an estimated value of USD 57 billion, it is often referred to as an urban mine. Printed circuit boards (PCBs) are a major component of electronic waste and are increasingly considered as a secondary resource for value recovery due to their high precious and base metals content. PCBs are highly heterogeneous and can vary significantly in composition depending on the original function. Currently, there are no standard methods for the characterisation of PCBs that could provide information relevant to value recovery operations. In this study, two pre-treatments, smelting and ashing of PCB samples, were investigated to determine the effect on PCB characterisation. In addition, to determine the effect of particle size and element-specific effects on the characterisation of PCBs, samples were processed using four different analytical methods. These included multi-acid digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, nitric acid digestion followed by X-ray fluorescence (XRF) analysis, multi-acid digestion followed by fusion digestion and analysis using ICP-OES, and microwave-assisted multi-acid digestion followed by ICP-OES analysis. In addition, a mixed-metal standard was created to serve as a reference material to determine the accuracy of the various analytical methods. Smelting and ashing were examined as potential pre-treatments before analytical characterisation. Smelting was found to reduce the accuracy of further analysis due to the volatilisation of some metal species at high temperatures. Ashing was found to be a viable pre-treatment. Of the four analytical methods, microwave-assisted multi-acid digestion offered the most precision and accuracy. It was found that the selection of analytical methods can significantly affect the accuracy of the observed metal content of PCBs, highlighting the need for a standardised method and the use of certified reference material.

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Value-added products from thermochemical treatments of contaminated e-waste plastics

Cited by 61 publications

References 177 publications

Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

Closing the Carbon Loop in the Circular Plastics Economy

A Comparison of Methods for the Characterisation of Waste-Printed Circuit Boards

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