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Article

Size- and Surface-Dependent Solubility of Cadmium Telluride in Aqueous Solutions

1
Institute for Photovoltaics and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany
2
Institute for Sanitary Engineering, Water Quality, and Solid Waste Management, University of Stuttgart, 70569 Stuttgart, Germany
*
Author to whom correspondence should be addressed.
Energies 2021, 14(2), 398; https://doi.org/10.3390/en14020398
Received: 20 November 2020 / Revised: 18 December 2020 / Accepted: 23 December 2020 / Published: 12 January 2021
Due to the toxicity of cadmium (Cd) and the scarcity of telluride (Te), CdTe-based photovoltaic modules have been under discussion during the last few years. In particular, the stability of CdTe in aqueous solutions is under debate. Here we show that the stability of CdTe depends not only on the pH of water-based solutions but also on size and surface treatment of CdTe particles. We compare milled module pieces with CdTe powders of different particle size. The leaching of CdTe is conditioned by the outdiffusion of Cd and Te at the interface between CdTe particles and the aqueous solution. The smaller the particle size, the faster the leaching. Therefore, milled module pieces decompose faster than CdTe powders with relatively large grains. We observe a dependence on time t according to t0.43. The room temperature diffusion coefficients are calculated as DCd ≈ 3 × 10−17 cm2/s for Cd, and DTe ≈ 1.5 × 10−17 cm2/s for Te in pH4. The chemical instability in aqueous solutions follows thermodynamic considerations. The solution behavior of Cd and Te depends on the pH value and the redox potential of the aqueous solutions. Chemical treatments such as those used in solar cell production modify the surface of the CdTe particles and their leaching behavior. View Full-Text
Keywords: cadmium telluride; toxicity; solar cells; solubility elution; pH dependence cadmium telluride; toxicity; solar cells; solubility elution; pH dependence
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MDPI and ACS Style

Zapf-Gottwick, R.; Zorn, M.; Nover, J.; Koch, M.; Feifel, C.; Werner, J.H. Size- and Surface-Dependent Solubility of Cadmium Telluride in Aqueous Solutions. Energies 2021, 14, 398. https://doi.org/10.3390/en14020398

AMA Style

Zapf-Gottwick R, Zorn M, Nover J, Koch M, Feifel C, Werner JH. Size- and Surface-Dependent Solubility of Cadmium Telluride in Aqueous Solutions. Energies. 2021; 14(2):398. https://doi.org/10.3390/en14020398

Chicago/Turabian Style

Zapf-Gottwick, Renate, Matthias Zorn, Jessica Nover, Michael Koch, Carolin Feifel, and Jürgen H. Werner 2021. "Size- and Surface-Dependent Solubility of Cadmium Telluride in Aqueous Solutions" Energies 14, no. 2: 398. https://doi.org/10.3390/en14020398

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