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- All Subjects: Recycling
Description
In Professor Meng Tao and Wen-His Huang's paper's [1,2] the recycling process to create a sustainable Photovoltaic (PV) industry is laid out. The process utilized to recycle the materials requires the use of three semi-problematic chemicals including: Sodium Hydroxide (NaOH), Nitric Acid (HNO3), and Hydrofluoric Acid (HF). By utilizing a combination of reverse osmosis filtration, pre-lime treatment, neutralization by combination, and mineral specific filtering the chemicals can either by recycled as Environmental Protection Agency (EPA) standardized waste water or profitable byproducts such as Sodium Nitrate (NaNO3). For the recycling of hydrofluoric acid, a combination of pre-lime coagulation, microfiltration and a spiral wound reverse osmosis (RO) system, less than 1mg/L in line with national standards for human consumption. The sodium hydroxide and nitric acid recycling process handles more contaminants that just the byproduct of the chemicals and manages this through a combination of multi-stage flash/vapor distillation along with a reverse osmosis filtration system. By utilizing both systems of recycling, a completely closed loop system for recycling silicon solar cells is laid out and creates a new standard for clean energy management.
ContributorsHaft, Brock Todd (Author) / Tao, Meng (Thesis director) / Augusto, Andre (Committee member) / Barrett, The Honors College (Contributor)
Created2016-12
Description
As Energy needs grow and photovoltaics expand to meet humanity’s demand for electricity, waste modules will start building up. Tao et. al. propose a recycling process to recover all precious solar cell materials, a process estimated to generate a potential $15 billion in revenue by 2050. A key part of this process is metal recovery, and specifically, silver recovery. Silver recovery via electrowinning was studied using a hydrofluoric acid leachate/electrolyte. Bulk electrolysis trials were performed at varied voltages using a silver working electrode, silver pseudo-reference electrode and a graphite counter-electrode. The highest mass recovery achieved was 98.8% which occurred at 0.65 volts. Product purity was below 90% for all trials and coulombic efficiency never reached above 20%. The average energy consumption per gram of reduced silver was 2.16kWh/kg. Bulk electrolysis indicates that parasitic reactions are drawing power from the potentiostat and limiting the mass recovery of the system. In order to develop this process to the practical use stage, parasitic reactions must be eliminated, and product purity and power efficiency must improve. The system should be run in a vacuum environment and the reduction peaks in the cell should be characterized using cyclic voltammetry.
ContributorsTezak, Cooper R (Author) / Tao, Meng (Thesis director) / Phelan, Patrick (Committee member) / Chemical Engineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12