Simultaneous recycling of waste solar panels and treatment of persistent organic compounds via supercritical water technology

• Published in: Environmental pollution (1987) 2023-10, Vol.335, p.122331, Article 122331
• Main Authors: Pereira, Mariana Bisinotto, Botelho Meireles de Souza, Guilherme, Romano Espinosa, Denise Crocce, Pavão, Leandro Vitor, Alonso, Christian Gonçalves, Cabral, Vladimir Ferreira, Cardozo-Filho, Lucio
• Format: Article
• Language: English
• Subjects: Depolymerization; Organic degradation; Silicon solar panel; Supercritical treatment; Urban mining
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2023.122331

The study addresses the application of the supercritical water technology in the simultaneous recycling of obsolete solar panels and treatment of persistent organic compounds. The obsolete solar panels samples were characterized by TEM-EDS, SEM, TG-DTA, XRD, WDXRF, MP-AES and elemental analysis. Initially, the optimized parameters for the degradation of solid organic polymers present in residual solar panels via oxidation in supercritical water were defined by an experimental design. Under optimized conditions, 550 °C, reaction time of 60 min, volumetric flow rate of 10 mL min−1 and hydrogen peroxide as oxidant agent, real laboratory liquid wastewater was used as feed solution to achieve 99.6% of polymers degradation. After the reaction, the solid product free of organic matter was recovered and characterized. On average, a metal recovery efficiency of 76% was observed. Metals such as aluminum, magnesium, copper, and silver, that make up most of the metallic fraction, were identified. Only H2, N2 and CO2 were observed in the gaseous fraction. Then, initial data on the treatment of the liquid decomposition by-products, generated during ScW processing, were reported. A total organic carbon reduction of 99.9% was achieved after the subsequential treatment via supercritical water oxidation using the same experimental apparatus. Finally, insights on the scale-up, energy integration and implementation costs of a ScW solid processing industrial unit were presented using the Aspen Plus V9 software. [Display omitted] •ScW technology was efficiently used in the recycling of the waste PV cells.•Clean water is not mandatory for the treatment of PV cells via ScW technology.•High polymer degradation was achieved via supercritical water technology (>99%).•The inorganic fraction of the waste PV cells is mainly composed of silicon dioxide.•Only non-harmful compounds (H2, N2 and CO2) were observed in the gaseous fraction.