Preparation And Application Of Biomass Based Activated Carbon And Its Composite Materials

Hydrothermal carbonization(HTC)is a thermo-chemical conversion technique which uses subcritical water for the conversion of biomass to carbonaceous products in relatively mild reaction conditions(180-350 ?,4-12 MPa).HTC results in efficient hydrolysis and dehydration of biomass,which can generate functional biomass carbon materials with good morphology and high OFG(oxygenated functional group)content.The products are widely used in adsorption,energy storage and other areas.In this thesis,corncob was used as raw material to prepare hydrothermal biochar by HTC,and the effects of carbonization temperature,substrate concentration and residence time on the physicochemical properties of hydrothermal biochar were studied.Hydrothermal biochar was characterized by x-ray diffraction analysis(XRD),infrared spectroscopy analysis(FT-IR),scanning electron microscopy(SEM)and other technical means.The experimental results showed that dehydration reactions took place in the process of hydrothermal carbonization,which generated amorphous carbon with high OFG content.The optimal conditions of HTC explored by the adsorption capacity for methylene blue were the temperature of 225 ?,substrate concentration of 5:100(g/g),reaction residence time of 5 h.Biomass activated carbon was prepared by microwave-assisted heating with hydrothermal biochar obtained in optimal HTC conditions and KOH as activator.The effects of impregnation ratio and activation time on the properties of biomass activated carbon were studied.The results of N2 adsorption-desorption and SEM showed that the surface morphology of activated carbon changed and the specific surface area increased dramatically.The optimal activation conditions explored by the adsorption capacity for methylene blue were the impregnation ratio of 2:1(g/g),activation time of 15 min.Polyaniline-activated carbon composite(PANI@AC)was prepared by in-situ polymerization and the PANI@AC with a PANI loading of 10,20,40 wt%.The composites were characterized by FT-IR,SEM,electrochemical cyclic voltammetry and AC impedance spectroscopy.The results show that the PANI@AC composite has a relatively smooth surface and greatly improved electrical conductivity.When the loading of polyaniline is 60 wt%and scanning rate is O.01V/s,the maximum specific capacitance can reach 118.2 F/g.