Preparation And Characterization Of Activated Carbons From The Tung Nutshell Using ZnCl₂ Activation

In this study, an agriculture waste-tung nutshell was used as precursor for thepreparation of activated carbon by zinc chloride activation. The two pyrolysis approaches,the traditional heating method and the microwave radiation were employed and comparedin the process. The prepared activated carbons denoted as TH-CT(from the traditionalheating method) and MW-CT (from the microwave radiation method) were characterizedby specific surface area and pore size distribution analyzer, elemental analyses, SEM,XRD,FT-IR, and Boehm titration. The experiments of adsorption phenol, methylene blueand copper cation onto the selected resultant activated carbons were also performed toinvestigate the adsorption capacity for organic and heavy metallic contaminant.The results showed that, for the traditional heating method, the optimal conditionsfor preparing TH-CT are: the ZnCl₂/tung nutshell mass ratio of 1/1, the activationtemperature of 400℃, the retention time of 1 h. Under the experimental conditions, theTH-CT's could be obtained from the tung nutshell with a high yield of 45.21%, and thehighest BET surface area and total pore volume of TH-CT's were as high as 1 995 m²/gand 1.521 mL/g, respectively. For phenol the TH-CT's showed a rapid adsorptionperformance, the adsorption equilibrium was established about 30 minutes. The particlesize of TH-CT and the solution pH seems to have a slight effect on the adsorptioncapacity. The phenol adsorption isotherms illuminate to be the L-type and fit both theLangmuir and the Freundlich equations satisfactorily, revealing favorable for phenoladsorption.For the microwave radiation approach, the optimal conditions for MW-CTpreparation are: ZnCl₂/tung nutshell mass ratio of 2.5/1, the microwave power of 650 W,and the radiation time of 20 min. The resultant activated carbons could be obtained fromthe tung nutshell by microwave radiation method. The yield, the highest BET surface areaand total pore volume of the MW-CT's were 41.1%, 1 602 m²/g and 1.115 mL/g,respectively. The MW-CT also revealed a methylene blue adsorption value of 300 mg/g, anda removal ratio of 99 % for a copper solution with a Cu² concentration of 40 mg/L.</sup>