| Microbial fuel cell is a new type of wastewater treatment and production equipment,not only to achieve sewage treatment,but also can produce energy,will not cause harm to the environment,but the microbial fuel cell in the actual operation of the process will be subject to a variety of factors lead to microbial Fuel cell power generation is low.At present,scholars from the battery electrode material,battery substrate,battery temperature and start conditions and other aspects of research and found that microbial fuel cells will be affected by temperature,and the battery matrix in the copper ion concentration will also affect the power generation.How to measure the concentration of copper ions in the microbial fuel cell is of great significance to improve the electric power of the microorganism.As the conventional measurement method will destroy the microbial fuel cell operating environment,the microbial activity of a certain damage,this paper uses long-period fiber grating and Bragg fiber grating to achieve the microbial fuel cell temperature and copper ion concentration for effective measurement.This article from the following aspects of the study:(1)The sensing principle of the combined grating is analyzed,and the relationship between the center wavelength of the LPFG and the concentration of the copper ions is studied.A combole grating copper ion sensor in the form of FBG and LPFG is designed and analyzed.The relationship between the wavelength of LPFG and the concentration of copper ions was investigated.MFC was designed and started.The combined grating was installed in MFC,and the copper ion concentration in MFC cathode chamber was measured and the output voltage of MFC was monitor.(2)The covalent bond method was used to fix the copper ion sensitive film on the surface of the optical fiber.In this paper,the surface of the fiber surface hydroxylation,silanization and CMC fixation were compared experiments,the use of infrared spectroscopy analysis of the experimental results to verify the composition of fiber surface material,to prove that the fiber surface sensitive film immobilization effect;and also use the scan Electron microscopy and stereomicroscope were used to observe the morphology of the sensitive surface of the fiber.The method of fixing the copper ion sensitive film on the surface of the optical fiber was optimized.(3)The combined grating copper ion sensor is designed to cascade FBG and LPFG,and is designed in the form of two gratings in parallel so that the two gratings can measure the same area.The experimental results show that the combined wavelengths of FBG and LPFG are shifted in the long wavelength direction,and their central wavelengths are linearly related to the temperature.The sensitivity of the FBG is 0.0085 nm/?.The sensitivity of the LPFG is 0.0747 nm/?.When only the concentration changes,the center wavelength of the FBG is not shifted,and the center wavelength of the LPFG is shifted to the short wavelength direction,the sensitivity of the LPFG is-32 nm /RIU offset occurs.(4)The design of the combination of grating copper ion sensor placed in copper sulfate solution for measurement,to measurement the different concentrations of copper sulfate solution.The copper ion sensor based on LPFG can measure the concentration of copper ion by monitoring the center wavelength shift,and fit the fitting coefficient R~2 =0.94335.The combined grating is applied in MFC,and the copper in the cathode chamber ion concentration for effective measurement,to explore the relationship between copper ion concentration and MFC output voltage.(5)The measurement of copper ion concentration of plastic optical fiber was carried out.The measurement principle of plastic optical fiber sensor and the optical transmission in plastic optical fiber were studied.The optimum coating conditions and measurement methods were made to make the best of the copper ion sensor,by monitoring the output light intensity changes to measure the size of copper ion concentration.The experimental results show that the fitting correlation coefficient R~2 = 0.94939 of the measurement curve and the measurement result of the sensor have high accuracy,and the measurement of copper ion concentration is realized.In this paper,a copper ion sensor based on combined grating and a copper ion sensor based on plastic optical fiber are designed.The two schemes have achieved some experimental results.Based on the combination of grating sensors are conducive to the realization of miniaturization,the application in MFC is more easy to achieve;based on the plastic fiber copper ion sensor is more conducive to achieve low,in the application of MFC has some limitations,but compared to the combination of grating Copper ion sensor is more convenient and inexpensive.The experimental results of this paper have some guiding significance for the engineering design of copper ion fiber evanescent wave sensor. |
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