Capacitive Deionization Performance Of Carbon Aerogels Loaded Manganese Dioxide Composites

Because of the increasing water pollution,the available freshwater resources aregradually reduced,so it is an important way to study the green and efficient desalting technology to solve the shortage of fresh water resources.The common desalting technologies,such as distillation,reverse osmosis and electrodialysis,have many problems,such as high cost,high energy consumption and secondary pollution,but capacitance deionization technology has the advantages of low energy consumption and small environmental pollution.The principle of capacitance deionization technology is based on the theory of electrochemistry double layer,so selecting high performance electrode material with high specific surface area,good conductivity,high specific capacitance and good electrochemical stability is the key to obtain better desalting effect.As the only conductive aerogel,carbon aerogels are an ideal electrode material which have the advantages of high specific surface area,good conductivity,wide range of porosity and so on.Manganese dioxide is an electrode material with high theoretical specific capacitance,wide range of distribution,environmental friendliness and so on.In this paper,carbon aerogel loaded Mn O2 composite materials were prepared,and their structure and capacitance deionization properties were studied.The main research contents and conclusions are as follows:(1)The carbon aerogels were prepared by the sol-gel method.The microstructure of the carbon aerogels was studied by Characterization methods such as electron microscope analysis,isothermal adsorption analysis of nitrogen and X ray diffraction analysis.The effects of catalyst concentration and electrode quality on the specific capacitance and electrochemical stability of carbon aerogels were studied by electrochemical performance testing.The influence of electrode preparation method on desalination effect of capacitance deionization technology was also studied.It is found that the carbon aerogel is a disordered three-dimensional pore structure with high specific surface area,high conductivity,small aperture and so on.When the ratio of catalyst R/C is 1000,the maximum specific capacitance is obtained.With the increase of the electrode mass,the specific capacitance decreases gradually.When the electrode is prepared by pressed mode,the effect of desalination is better.(2)The carbon aerogel loaded manganese dioxide composite was prepared by hydrothermal synthesis,and load situations of manganese dioxide on the carbon aerogel was studied by structural characterization.The effects of loading amount on the specificcapacitance and electrochemical stability of the composite were investigated by the electrochemical performance test,and the changes of desalting effect before and after the load were also studied.It is found that manganese dioxide is uniformly loaded on the carbon aerogel.With the increase of the load,the specific capacitance increases first and then decreases.When the KMn O4/CA is 2,the maximum specific capacitance is 164 F/g,and the composite has a good cyclic stability.After the carbon aerogels were loaded with Mn O2,the specific adsorption capacity increased from 18.71 mg/g to 23.84 mg/g,and increased by 27%.(3)The composite material was used in the capacitance deionization technology to study the influence of the operating conditions of the influent concentration,voltage and electrode distance on the desalting effect,and the desalting process was analyzed by adsorption kinetics.The results show that the desalination effect is best when the influent flow velocity is 10 m L/min,the voltage is 1.2 V and the influent way is upflow.The smaller the electrode distance,the better the desalination effect.With the increase of the influent concentration,specific adsorption capacity increases gradually.When the power supply is disconnected,the ions adsorbed on the electrode can be completely desorbed,indicating that the electrode has good reproducible performance.The adsorption of ions is basically consistent with the quasi two order dynamic fitting,and the adsorption rate is affected by liquid film diffusion,surface adsorption and internal diffusion.(4)The composite material is used to the simulated the brackish water,the simulated heavy metal wastewater and the actual seawater treatment.The results show that specific adsorption capacity of composite materials for simulated brackish water is lower than that of the neutral water,and treatment of simulated brackish water needs to consume more energy.The composite material has good desalination effect on the simulated heavy metal wastewater,and the desalination efficiency of Cu2+ is close to 100%.composite materials also have good desalination effect on seawater,and the specific adsorption capacity can reach 201.72 mg/g.