Preparation And Properties Of Biomass Activated Carbon

Biomass activated carbon based on agricultural by-products and other biomass is receiving more and more attention because of its low cost,easy availability,eco-friendliness,availability,and large adsorption capacity.Meanwhile,due to its structural stability,good electrical conductivity and high specific surface area,electrochemical performance tests show its good potential for electrode materials.In this research,the biomass activated carbon was prepared from moringa seed shell,almond shell and sesame seeds shell by pyrolysis at different activation temperatures?800,900,1000,1100 ??.At the same time,Modified biomass activated carbon was obtained from moringa seed shell,almond shell and sesame seeds shell by pyrolysis at the same activation temperature,using potassium hydroxide as activator.Nitrogen adsorption-desorption?BET?,X-ray diffraction?XRD?and fourier transform infrared spectroscopy?FTIR?were used to study surface area and pore structure of biomass activated carbon before and after modification prepared at different temperatures.Biomass activated carbon before and after modification were utilized for the removal of Cu?II?from aqueous solution in sorption experiences.The effects of activation temperature,contact time,p H value,concentration of adsorbates of Cu?II?were explored,the adsorption properties of activated carbon were investigated.Via the data of experience,adsorption kinetics and isotherm models were analyzed to speculate the adsorptive process.Meanwhile,the electrochemical performance of supercapacitor was investigated by constant current charge / discharge and cyclic voltammetry?CV?.The major research results are listed as following:The specific surface area of the three biochars by KOH activation is significantly higher than before,this is because the biochars by KOHactivation contribute to the formation of pore structure.The surface functional groups of the biomiss activated carbon were mainly hydrophilic groups,such as carboxyl,carbonyl,and hydroxyl.The XRD test results show that the biochars has an amorphous structure,with a typical graphite-like structure.For three kinds of unmodified biochars,the Langmuir isotherm model fits the experimental data of Cu²⁺ adsorption by moringa seed shell and sesame seeds shell biochars,the Freundich isotherm model fits the experimental data of Cu²⁺ adsorption by almond shell biochar.As for the modified biochar,the Langmuir isotherm model fits the experimental data of Cu²⁺ adsorption by three kinds of biochars.In addition,Cu²⁺adsorptions followed the second order kinetics model.Electrochemical test results show that three kinds of biochars exhibit good electrochemical properties as electrode materials in 6 mol/L of KOH solution.The maximum specific capacitance of 447.33?505.83?271.33 F/g is obtained respectively for moringa seed shell?almond shell?sesame seeds shell biochar before activeted at the current density of 0.15A/g.The modified carbons of moringa seed shell?almond shell?sesame seeds shell with potassium hydroxide shows enhanced electrochemical performance,the maximum specific capacitance of 571.09 ? 790.56 ?825.29 F/g is obtained respectively at the same current density of 0.15A/g.The cyclic voltammetry curve of biochars exhibit a good rectangular shape,indicating that it has good capacitive properties.