Recovery of valuable and toxic metals from crystalline-Si modules
Valuable and toxic metals including Ag, Pb, Sn and Cu can be recovered from end-of-life Si solar modules. This study presents the recovery of Ag, Pb, Sn and Cu from a simulated leach solution of crystalline-Si modules. 11.4% HNO3 is used as the leach solution. Ag, Pb, Sn and Cu pellets are dissolved in the solution to simulate the metals from front contacts and soldered wires in Si modules. Sn precipitates in the solution as SnO2, which can be separated by filtration or sedimentation. Voltammetry reveals the reduction potentials for Ag and Cu. It is demonstrated that 3-electrode sequential electrowinning can extract Ag and Cu one by one from the solution. The recovery rates of Ag and Cu are 74% and 83%, respectively. Toxic Pb is deposited on the anode as PbO2 during Cu recovery. The purity of the extracted metals is above 99%.
Research and development priorities for silicon photovoltaic module recycling to support a circular economy
Large-scale deployment of photovoltaic (PV) modules has considerably increased in recent decades. Given an estimated lifetime of 30 years, the challenge of how to handle large volumes of end-of-life PV modules is starting to emerge. In this Perspective, we assess the global status of practice and knowledge for end-of-life management for crystalline silicon PV modules. We focus in particular on module recycling, a key aspect in the circular economy of photovoltaic panels. We recommend research and development to reduce recycling costs and environmental impacts compared to disposal while maximizing material recovery. We suggest that the recovery of high-value silicon is more advantageous than the recovery of intact silicon wafers. This approach requires the identification of contaminants and the design of purification processes for recovered silicon. The environmental and economic impacts of recycling practices should be explored with techno–economic analyses and life-cycle assessments to optimize solutions and minimize trade-offs. As photovoltaic technology advances rapidly, it is important for the recycling industry to plan adaptable recycling infrastructure. The increasing deployment of photovoltaic modules poses the challenge of waste management. Heath et al. review the status of end-of of-life management of silicon solar modules and recommend research and development priorities to facilitate material recovery and recycling of solar modules.
History of Amateurism in Men's Intercollegiate Athletics: The Continuance of a 19th-Century Anachronism in America
Claiming that American intercollegiate athletics are amateur at the end of the 20th century is an anachronism, for colleges in the 19th century took on professional characteristics. The upper-class British concept of amateurism did not work effectively in a more egalitarian and achievement-oriented American society. Hypocrisy resulted when colleges claimed amateurism while accepting such professional practices as hiring professional coaches, allowing athletes to play summer baseball for money, and paying athletes through grants-in-aid. Attempts to preserve amateurism, such as the Graham Plan in the 1930s and the Sanity Code in the 1940s and 1950s, yielded to the professional spirit. Thus, while Americans had generally rejected the upper-class British social hierarchy that fostered amateurism, they retained the name amateur, continuing the hypocrisy that had begun in the previous century.