A novel approach of accurately rationing adsorbent for capturing pollutants via chemistry calculation: Rationing the mass of CaCO3 to capture Br-containing substances in the pyrolysis of nonmetallic particles of waste printed circuit boards

Qin, Baojia; Lin, Mi; Yao, Zichun; Ruan, Jujun; Tang, Yetao; Qiu, Rongliang

doi:10.1016/j.jhazmat.2020.122410

Cited by 34 publications

(11 citation statements)

References 28 publications

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“…However, when the mass fraction of NaOH–KOH was greater than 0.15, the debromination efficiency remained almost unchanged due to the presence of sufficient active sites. Compared to calcium-based catalysts, the dosage of NaOH–KOH was significantly reduced. , However, the yields of pyrolysis oil and gas were decreased with the mass fraction of NaOH–KOH. This result could be explained as follows: (1) Some components in pyrolysis oil and gas such as HBr, Br 2 , and bromophenol can react with KOH or NaOH, resulting in the decrease of pyrolysis oil and gas.…”

Section: Resultsmentioning

confidence: 99%

NaOH–KOH Capillary Action Enhances the Pyrolysis and Debromination of Waste Printed Circuit Boards

Wang

Chen

et al. 2021

ACS Sustainable Chem. Eng.

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Catalytic pyrolysis was one of the most promising technologies for energy recovery and bromide removal from nonmetals of waste printed circuit boards (NM-WPCBs). However, the low efficiency of debromination, large dosage of catalysts, and high consumption of energy were the main reasons for limiting the application and popularity of catalytic pyrolysis. To solve these problems, the capillary action of molten NaOH–KOH was used to enhance the pyrolysis and debromination of NM-WPCBs. In this paper, the molten state of NaOH–KOH was achieved at an NaOH/(NaOH–KOH) mole ratio of 0.5 and a temperature of 182 °C. The maximum debromination efficiency reached 95.0%, while the average activation energy decreased from 201.4 to 112.6 KJ/mol. Kinetic results suggested that nucleation and diffusion action played key roles when α was below 0.6. Herein, the enhancing mechanism for the capillary action of catalysts was analyzed. First, molten NaOH–KOH spontaneously spread out on the surface of NM-WPCBs with the capillary force. Then, the Br atoms coordinated with Na/K to form [NM-WPCBs-Br···NaOH/KOH], in which the electrons transfer from Br to Na/K, resulting in the cleavage of the C–Br bond. Afterwards, the bromine radical (Br*) bonded with the hydroxyl radical (H*) to form HBr, which was removed by NaOH–KOH. This work offers inspiration for recycling other plastics by removing contamination and improving the efficiency.

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Section: Resultsmentioning

confidence: 99%

NaOH–KOH Capillary Action Enhances the Pyrolysis and Debromination of Waste Printed Circuit Boards

Wang

Chen

et al. 2021

ACS Sustainable Chem. Eng.

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“…Scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy (EDS): The morphology of waste glass was observed by SEM (Sigma 500) at School of Environmental Science and Engineering in Sun Yat-Sen University . The waste glass needed to be sprayed with gold before observation.…”

Section: Methods Of Testing and Characterizationmentioning

confidence: 99%

Analysis of the Products and Decomposition Mechanisms of the Different Organic Impurities in Waste Glass during the Heat-Desiccation Dissociation Process

Qin

Huang

Ruan

et al. 2021

ACS Sustainable Chem. Eng.

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The heat-desiccation dissociation technology is recommended to remove the organic impurity during the recovery of waste glass. Some organic impurity attaches to waste glass and the other falls off during transportation and storage. However, their differences in pollutant release during heat-desiccation dissociation have not been reported. In this study, the products and decomposition mechanisms of different organic impurities during heat-desiccation dissociation were investigated. Organic impurity attached to waste glass produced fewer pollutants, and the components of gas and residue were simpler. The main component of gas was alanine (a nontoxic substance), accounting for 40.94%. However, the main component of gas of pure organic impurity was propene (a low-toxic substance), accounting for 28.94%. Molecular dynamics showed that the decomposition degree of organic impurity attached to waste glass was low, leading to the simpler product component. The formation of NH2 • was the main reason for the generation of alanine. Thus, the organic impurity that has fallen off should be removed before the heat-desiccation dissociation process. This study provides technological guidance for the heat-desiccation dissociation technology during waste glass recovery.

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“…In 2016, the global amount of electronic waste, so called e-waste, was approximately 44.7 million metric tons (Mt) and has reached 57 Mt in 2021 [ 3 , 4 ]. Printed circuit boards (PCBs) are a major and critical constituent of electrical and electronic equipment [ 5 ] and the resultant waste PCBs (WPCBs) account for approximately 3–6 wt.% of total e-waste [ 6 , 7 ]. These WPCBs contain various precious metals, such as gold (Au), silver (Ag) and palladium (Pd) with concentrations tens or hundreds of times larger than than the natural ores [ 8 , 9 ] and have been regarded as an “urban mine” ( Figure 1 ).…”

Section: Introductionmentioning

confidence: 99%

Bioleaching of Typical Electronic Waste—Printed Circuit Boards (WPCBs): A Short Review

Yang

Wan

et al. 2022

IJERPH

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The rapid pace of innovations and the frequency of replacement of electrical and electronic equipment has made waste printed circuit boards (WPCB) one of the fastest growing waste streams. The frequency of replacement of equipment can be caused by a limited time of proper functioning and increasing malfunctions. Resource utilization of WPCBs have become some of the most profitable companies in the recycling industry. To facilitate WPCB recycling, several advanced technologies such as pyrometallurgy, hydrometallurgy and biometallurgy have been developed. Bioleaching uses naturally occurring microorganisms and their metabolic products to recover valuable metals, which is a promising technology due to its cost-effectiveness, environmental friendliness, and sustainability. However, there is sparse comprehensive research on WPCB bioleaching. Therefore, in this work, a short review was conducted from the perspective of potential microorganisms, bioleaching mechanisms and parameter optimization. Perspectives on future research directions are also discussed.

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A novel approach of accurately rationing adsorbent for capturing pollutants via chemistry calculation: Rationing the mass of CaCO3 to capture Br-containing substances in the pyrolysis of nonmetallic particles of waste printed circuit boards

Cited by 34 publications

References 28 publications

NaOH–KOH Capillary Action Enhances the Pyrolysis and Debromination of Waste Printed Circuit Boards

NaOH–KOH Capillary Action Enhances the Pyrolysis and Debromination of Waste Printed Circuit Boards

Analysis of the Products and Decomposition Mechanisms of the Different Organic Impurities in Waste Glass during the Heat-Desiccation Dissociation Process

Bioleaching of Typical Electronic Waste—Printed Circuit Boards (WPCBs): A Short Review

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