Pyrolysis-based separation mechanism for waste crystalline silicon photovoltaic modules by a two-stage heating treatment

Wang, Ruixue; Song, Erxiao; Zhang, Chenglong; Zhuang, Xuning; Ma, E.; Bai, Jianfeng; Yuan, Weijie; Wang, Jingwei

doi:10.1039/c9ra03582f

Cited by 55 publications

(22 citation statements)

References 29 publications

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“…The outcome of the respective processes shows a great variety including a simple procedure of crushing the panels 3–6 and reusing the impure remnants as a material feedstock for the industry. More advanced procedures utilize more careful techniques for the separation of the individual layers with organic solvents 7–9 or thermal methods 10–12. Moreover, copper and silver can be recovered by hydrometallurgic processes, mainly with nitric acid 10, 13, 14.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Recycling of Photovoltaic Modules to Recover Metals and Silicon Wafers

Modrzynski

Blaesing

Hippmann

et al. 2021

Chemie Ingenieur Technik

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An electrochemical‐assisted leaching process using boron‐doped diamond (BDD) electrodes was developed to recover valuable metals from photovoltaic modules. With BDD electrodes peroxydisulfate is generated from sulfuric acid to oxidatively dissolve copper, tin and silver from solar cell contacts. Since the oxidant is regenerated in the developed process, no additional hazardous and volatile chemicals are required, and the process can be operated solely by electricity. In addition, the dissolved metals can be electrochemically recovered at the cathode of the same cell.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Recycling of Photovoltaic Modules to Recover Metals and Silicon Wafers

Modrzynski

Blaesing

Hippmann

et al. 2021

Chemie Ingenieur Technik

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“…The use of a pyrolysis process for delamination (e.g. Dias et al, 2016;Wang et al, 2019) has been investigated as well. Finally, thermal processes have also been explored as an integrated step in PV recycling processes, not as a delamination step but rather after mechanical crushing (Ardente et al, 2019;Pagnanelli et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Thermal delamination of end-of-life crystalline silicon photovoltaic modules

2021

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Thermal delamination – meaning the removal of polymers from the module structure by a thermal process – as a first step in the recycling of crystalline silicon (c-Si) photovoltaic (PV) modules in order to enable the subsequent recovery of secondary raw materials was investigated. A correlation between treatment temperature and duration was established by an iterative process. Furthermore, chemical characterization of the resulting solid outputs (glass, cell, ribbons and residues) was performed in order to assess their further processing options. Additionally, the effect of removing the backsheet as a pre-treatment before the actual delamination process was investigated in relation to the aforementioned aspects of treatment duration and output quality. Results show that increased temperatures reduce the necessary treatment duration (65 minutes at 500°C, 33 minutes at 600°C) while generating the same output quality. The backsheet removal leads to an additional duration decrease of more than 45% at each considered temperature, while also having positive effects relating to fewer solid residues and easier flue gas handling. In regard to the main output specifications no significant influence of the pre-treatment is observed. Overall thermal delamination can be seen as a feasible method in order to obtain high value secondary raw materials from c-Si PV modules, while backsheet removal as pre-treatment should be considered as advantageous from multiple standpoints.

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“…The kinetic triplet can benefit reactor design, process modeling of the pyrolysis delamination of PV modules, and aid in the scaling up of the effective recycling processes. To the best of the authors’ knowledge, two existing kinetic studies on the EVA encapsulant were found in c-Si PV modules from De-wen et al and Wang et at. , These studies reported activation energies 15 years apart, but differ considerably from one another in terms of results, kinetic modeling methods used, and did not evaluate the kinetic triplet. This could be due to experimental error, a difference in the grade of EVA used in the study, or the kinetic modeling method employed in their study.…”

Section: Introductionmentioning

confidence: 99%

Pyrolysis Kinetic Modeling of a Poly(ethylene-co-vinyl acetate) Encapsulant Found in Waste Photovoltaic Modules

Farrell

Osman

Harrison

et al. 2021

Ind. Eng. Chem. Res.

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As the global cumulative installation of solar photovoltaic (PV) devices grows every year, a proportionate number of waste PV modules arises because of their limited lifespan. It is estimated that by 2050, there will be approximately 60−78 million tonnes of PV waste (Farrell, C.; Osman, A. I.; Zhang, X. et al. Sci Rep. 2019, 9, 5267). These modules are bound in a strong encapsulated laminate that is prone to imminent degradation. Subsequently, a form of treatment is required to remove a problematic polymeric material such as the encapsulant poly(ethylene-co-vinyl acetate) (EVA) in order to recycle. Pyrolysis is an ideal option that facilitates clean delamination by removing the polymer fraction, and it does not promote chemical oxidation to any of the constituents left behind after pyrolysis. To date, there are limited studies on the pyrolysis of EVA found in PV modules, resulting in significant gaps in the knowledge of pyrolysis kinetic parameters. This work aims to investigate the pyrolysis reaction kinetics concerning the EVA encapsulant found in end-of-life (EoL) crystalline silicon (c-Si) PV modules. The thermoanalytical technique employed was thermogravimetric analysis, which was carried out at 0.5, 1, 2, 4, and 5 °C min −1 to ensure accuracy and high resolution while analyzing the kinetics. The kinetic triplet was determined and reported for the first time using the Advanced Kinetics and Technology Solutions (AKTS) Thermokinetics software. The main kinetic modeling method employed was the Friedman differential isoconversional method. Other conventional kinetic modeling approaches were also used, such as the integral (Ozawa) and ASTM-E698 methods for comparison of apparent activation energy. It was observed that the activation energy values for each method were 167.66−260.00, 259.70, and 167.00−252.65 kJ mol −1 for EVA pyrolysis. Additionally, isothermal, nonisothermal, and step-based predictions were reported for the first time using the thermokinetics package. Furthermore, pyrolysis of EVA can have a triple role in the successful delamination of PV modules, recovery of additional constituents, and aiding of waste management of this problematic polymer.

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Pyrolysis-based separation mechanism for waste crystalline silicon photovoltaic modules by a two-stage heating treatment

Abstract: A two-stage heating treatment was conducted to separate the waste crystalline silicon solar panels. The TPT backing materials were recovered integrally by heating at 150 °C, and the EVA binder was removed at the temperature of 500 °C.

Cited by 55 publications

References 29 publications

Electrochemical Recycling of Photovoltaic Modules to Recover Metals and Silicon Wafers

Electrochemical Recycling of Photovoltaic Modules to Recover Metals and Silicon Wafers

Thermal delamination of end-of-life crystalline silicon photovoltaic modules

Pyrolysis Kinetic Modeling of a Poly(ethylene-co-vinyl acetate) Encapsulant Found in Waste Photovoltaic Modules

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