Removal Of Pb(?) From Aqueous Solutions By Crayfish Shell Biochar

In this work,a novel approach was developed to prepare biochar treated crayfish shells through slow pyrolysis?300,450,600??.Studied on adsorption properties of heavy metal Pb???by biochar.A series of characterization tests?EA,XRF,FTIR,BET,SEM,XRD?were carried out to analyze the adsorption mechanism of the three kinds of biochar.Characterization experiments showed that three kinds of biochar surfaces contained a lot of O-H and C=O functional groups.Biochar treated crayfish shell through slow pyrolysis at 600? had large specific surface area.XRD showed that it didn't form new sediment after adsorption Pb???.When the pH value was 5,the adsorption had maximum capacity.Different concentration of nitric acid and coexistence of Na+ would have significant impact on adsorption capacity.Pseudo-first-order can better simulate the crayfish shell biochar adsorption process for Pb???.After 10h,the adsorption equilibrium can be reached.Langmuir isotherm equation can better fit crayfish shell biochar the adsorption isotherm process of Pb???solution.Biochar which treated with 600? had largest equilibrium adsorption capacity of Pb????190.70mg/g?.The biochar with the highest sorption of Pb???in the initial evaluation was selected to test the dynamic adsorption experiment and single factor experiment.The experiment showed that the three ions reached the saturation of adsorption at 1H,and the surface of the biochar continuously released ions with the increase of time.The adsorption order of three kinds of heavy metal ions by LS600 was Pb???>Cu???>As???,Thomas model can better fit the crayfish shell biochar dynamic adsorption of lead ions.The adsorption mechanism was the ion exchange between Ca???,Mg???and Pb???.First,Pb???was ion-exchanged with the Mg???,followed by the Ca???.Using MgCl₂ · 6H₂O?lmol/L?as modifier,the modified biochar was obtained by pyrolysis at 600?.A series of characterization,adsorption kinetics and adsorption isotherm experiments were carried out.Modified biochar has a larger specific surface area.MgO particles were loaded on the surface of biochar,MgO and Pb???ion exchange occurs,the Pb???removed from solution precipitation.Pseudo-two-order and Langmuir isotherm equation can better simulate the c modified biochar adsorption process for Pb???.The Langmuir maximum adsorption capacity can reach 1334.6mg/g.