Preparation And Adsorption Of Lignin-Based Activated Carbon In Pyrolysis Processing

With the developing of global economics and society,it becomes increasing prominent of energy shortage caused by increasing demand of fossil energy.The efficient utilization of lignin biomass raises concern because of lignin biomass characteristic of widespread, renewable and abundant in nature.As an efficient adsorbing material with big specific surface area and flourishing hole structure,activated carbon widely used in many field like environment,chemical,medicine,catalyze.Thermo gravimetric technique used to investigate the pyrolysis process and mechanism of alkali lignin under different heating rate in this study.In the meantime,alkali lignin used as precursor to produce activated carbon through phosphoric acid activation under varying conditions to explore the optimal process parameters.And the adsorption of activated carbon prepared in optimal condition for dyestuff and heavy metal was also investigated.The main research contents and results as follows:?1?The research of lignin pyrolysis characteristic.TG technique was used to investigate the mechanism of lignin pyrolysis.The results showed that lignin pyrolysis include three stages.In first stage,mass loss mainly caused by evaporation of water.Second stage was main degradation stage which was fast pyrolysis phase.Integral method and differential method were used to deduce the parameter of thermal decomposition kinetics.?2?The process optimization of lignin-based activated carbon.Pyrolysis activation was used to produce lignin-based activated carbon.FT-IR,Specific Surface Area Analyzer were employed to evaluate the activated carbon prepared in vary condition.The results shows that the maximum BET of activated was 1215.82 cm²/g which prepared in activated temperature550?,soaking time 120 min,phosphoric acid concentration 50%,solid to liquid impregnation ratio 1:3.Its total pore volume was 0.754 cm³/g which show the lignin-based activated carbon have developed hole structure.?3?The research of adsorption of lignin-based activated carbon.The adsorption of activated carbon was explored through contact with different concentration of methylene blue and Cd²⁺in different contact time.It can be observed that with the increasing concentration of methylene blue,equilibrium time extension.The same tendency can be observed in Cd²⁺ solution.The results show that the removal rate of methylene blue and Cd²⁺could be 99%and 90%when adsorption equilibrium reached.Compared with current research,the activated carbon has the same adsorption capacity.It shows high capacity of adsorbing both organic pollutants and heavy metal cations in aqueous phase.In the meanwhile,adsorption kinetics were applied to described methylene blue and Cd²⁺adsorption.The results shows that sorption of methylene blue and Cd²⁺more accord with pseudo-second-order equation.