| dc.description.abstract | With the continuous development of human industry, the burning of fossil fuels has become more frequent, resulting in increased emissions of greenhouse gases, which is the main cause of climate change. According to the third assessment report of the United Nations Intergovernmental Panel on Climate Change (IPCC), if no control measures are taken against greenhouse gas emissions, the global average surface temperature will increase by 1.4-5.8°C by 2100 compared to 1990. In order to slow down the greenhouse effect, it is necessary to develop new clean energy sources. The development potential of salinity gradient energy extracted from rivers and seawater by reverse electrodialysis (RED) system is huge. In theory, the difference between seawater and river water per cubic meter Generates 0.8 kWh of electrical energy. There are many factors that affect the power generation capacity of RED. The ion exchange membrane, the concentration and flow rate of sea water in the river, the concentration and type of electrolyte, etc. will all have an impact on the power generation capacity of RED.
This study aims to compare the power generation capacity of the RED system with three different electrolytes, ferric chloride-ferrous chloride, potassium ferricyanide-potassium ferrocyanide and sodium chloride, under different operating conditions. , and explore the ability to use the redox system to oxidize ammonia nitrogen in water when the power generation is maintained at a high level. For ferric chloride and potassium ferricyanide, the higher the electrolyte concentration, the higher the output current density, and the highest output current density of potassium ferricyanide is 0.17 W/m2. Sodium chloride is not suitable as an electrolyte because it is not a redox couple.
The way to remove ammonia nitrogen with sodium chloride in RED is to form active chlorine and indirectly oxidize ammonia nitrogen. The effect is affected by the concentration of chloride ions and ammonia nitrogen. The higher the concentration of chloride ions, the lower the concentration of ammonia nitrogen, the higher the removal rate. The removal rate reaches a maximum of 95% at 1 M sodium chloride and 50 ppm ammonia nitrogen. Potassium ferricyanide is not effective in treating ammonia nitrogen, which may be because the oxidation mechanism is direct oxidation of ammonia nitrogen by the electrode, so the results in this study cannot draw a more convincing rule. The concentration of nitrate nitrogen detected after the oxidation of ammonia nitrogen was all lower than 1 ppm. It can be seen that most of the ammonia nitrogen in this study was oxidized to nitrogen gas, and there was no peroxidation to nitrate nitrogen.
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