Wang Ruixue, Song Erxiao, Zhang Chenglong, Zhuang Xuning, Ma En, Bai Jianfeng, Yuan Wenyi, Wang Jingwei
Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University No. 2360 Jinhai Road Shanghai 201209 People's Republic of China
Shanghai Collaborative Innovation Centre for Waste Electrical and Electronic Equipment Recycling, Shanghai Polytechnic University No. 2360 Jinhai Road Shanghai 201209 People's Republic of China.
RSC Adv. 2019 Jun 10;9(32):18115-18123. doi: 10.1039/c9ra03582f.
Heating treatment is the mainstream method to separate the modules in the waste photovoltaic (PV) module recycling process, which has not been studied thoroughly. In the present study, a two-stage heating treatment was conducted to separate the waste crystalline silicon solar panels. The TPT backing material could be recovered integrally by heating at 150 °C for 5 min, which was conducive to further recycling and regeneration. The poly(ethylene--vinyl) acetate (EVA) binder was removed by the pyrolysis process at the temperature of 500 °C; acetic acid and several hydrocarbon compounds were the main products of the pyrolysis process. Analysis showed that the pyrolysis of the EVA binder could be divided into two stages: deacetylation process (acetic acid formation) and long chain scission with radical reactions (hydrocarbon formation). Furthermore, the pyrolysis kinetics and pyrolysis mechanisms were studied based on the experimental data and sufficient theoretical foundation. Acetic acid was generated by the deacetylation process through a six-member cyclic transition state, and several hydrocarbon compounds were generated through a series of long chain scissions, free radical migrations and Diels-Alder cycloadditions. In this study, undamaged TPT backing materials, glass and silicon wafers were obtained, which could be recycled by further treatment. This study could perfect the process of waste crystalline silicon solar panel recycling and provide a fundamental basis for recycling the waste crystalline silicon solar panels in an environmentally friendly and efficient manner.
热处理是废弃光伏组件回收过程中分离组件的主流方法，但尚未得到充分研究。在本研究中，对废弃晶体硅太阳能板进行了两阶段热处理。通过在150℃下加热5分钟可整体回收TPT背板材料，这有利于进一步的回收和再生。在500℃的温度下通过热解过程去除聚（乙烯-醋酸乙烯酯）（EVA）粘合剂；热解过程的主要产物是乙酸和几种碳氢化合物。分析表明，EVA粘合剂的热解可分为两个阶段：脱乙酰化过程（形成乙酸）和自由基反应的长链断裂（形成碳氢化合物）。此外，基于实验数据和充分的理论基础研究了热解动力学和热解机理。乙酸通过六元环状过渡态的脱乙酰化过程生成，几种碳氢化合物通过一系列长链断裂、自由基迁移和狄尔斯-阿尔德环加成反应生成。在本研究中，获得了未受损的TPT背板材料、玻璃和硅片，可通过进一步处理进行回收。本研究可以完善废弃晶体硅太阳能板的回收工艺，为以环保、高效的方式回收废弃晶体硅太阳能板提供基础依据。
