Preparation For Chitin-based Biomass Carbon Electrode Materials And Its Performance In Capacitve Deionization

As a clean desalination technology,capacitive deionization technology has received increasing attention.The electrode material is the core of the capacitive deionization module and plays a key role in the desalination process.In this study,chitin was used as carbon source,and chitin-based biomass charcoal was prepared by thermal decomposition and KOH activation,and the biomass carbon electrode was prepared to study the desalination performance.(1)The effect of pyrolysis temperature on the properties of chitin-based biochar was investigated,three kinds of biomass charcoal CS-600,CS-700 and CS-800 were prepared at different temperatures.The surface of CS-800 was fluffy and porous,its specific surface area was 126.43m~2/g,and the specific surface area of micropores is41.54m~2/g,thus 800°C is the suitable pyrolysis temperature.The specific surface area of HC-800 prepared after KOH activation was 833.76m~2/g,and the specific surface area of micropores was 498.55m~2/g.The specific surface area was obviously increased,and the number of micropores was also significantly increased.(2)CS-800 and HC-800 electrodes were prepared and their capacitive deionization characteristics were studied.When the mass ratio of biomass carbon:conductive carbon black:PVDF was 80:5:15,the desalination performance of the electrode was better.The capacitances of HC-800 and CS-800 bio-carbon electrodes were respectively 122.33F/g and 42.87F/g,and the charging resistance were respectively 4.16ohm and 18.75ohm.After activation,the electrochemical properties of HC-800 biomass carbon electrodet material was significantly improved,and the mass transfer resistance between ions and the channels was also reduced.The desalination process was in accordance with the quasi-secondary kinetic model and the Langmuir isotherm adsorption model.(3)The influencing factors of capacitive deionization process are systematically analyzed.The optimum operating parameters were:operating voltage of 2V,electrode spacing of 4mm,solution flow rate of 20L/min.Ion characteristics in electrolyte,such as hydration radius,mass and charge amount,had certain influence on the adsorption of ions by electrodes.HC-800 electrode had good reuse performance.When used repeatedly,the desalination efficiency reached 87.23%.