Preparation, Surface Texture And Performance Of Activated Carbon From Kenaf

In this thesis, activated carbons were prepared from kenaf core for the first time,using potassium permanganate and potassium oxalate as chemical activators. Thepreparation of activated carbons from kenaf core was optimized through single factorexperiments (activation temperature, activation time, mass ratio, activatorconcentration, impregnation time). According to the principle of response surfacemethodology, experimental model was established to optimize the preparation processon the basis of the most three significant single factors by the Box-behnken centercombination method derived from Design-Expert statistical software. The resultsshow that activated carbons from kenaf core with excellent adsorption capacity can bereadily prepared, using potassium permanganate or potassium oxalate as a benignchemical activator, respectively. Regression equations of the iodine and methyleneblue adsorption value of the as-prepared activated carbons were deduced fromDesign-Expert statistical software. Results of validate experiment prove that there aregood fitness between the predicted and actual value. The optimal processing conditioncan be theoreticly proposed according to the results of significant test and interactionanalysis of the key single factors by response surface methodology.Textural characteristics of the activated carbons activated by potassiumpermanganate (PPAC) or potassium oxalate (POAC) were characterized by specificsurface area auto-analyzer, field emission scanning electron microscope (FE-SEM),fourier transform infrared spectroscopy (FT-IR), the point of zero charge (pH_pzc),energy dispersive X-ray spectrometer (EDX). The N2adsorption-desorption isothermsof PPAC show a typical type I adsorption isotherm, which is featured of microporositycharacter of its pore architecture. The morphology of the produced PPAC observed byFE-SEM indicates a relatively dense texture and a well-developed pore structure. Adominant micropores along with some mesopores can be seen in PPAC as well. Thepoint of zero charge (pH_pzc) of PPAC was determined as3.25, indicating an obviouslyacidic surface property. Meanwhile, a certain amount of MnO_x loaded onto theas-prepared PPAC was proved by EDX. Moreover, electrochemical performance of PPAC loading with MnO_x using as working electrode is improved in terms of cyclicvoltammetry and impedance characteristics by comparison with the neat PPAC.The N2adsorption-desorption isotherms of POAC are type I according to IUPACclassification. A majority of micropores in combination with significant mesopores inPOAC can be concluded according to the characteristics of the adsorption-desorptionisotherms. The surface mophorlogy of the selected POAC shows smooth texture witha well-developed homogeneous pore structure. The point of zero charge (pH_pzc) ofPOAC was2.94, implying strong acidity probably due to rich acidic functional groupsproduced on its surface when activated by potassium oxalate. Finally, the adsorptionbehavior of the optimal POAC was detected. The results show that the pH ofadsorbate solution, adsorption time, dosage of activated carbon and initialconcentration of Cr(VI) had a significant impact on the removal efficiency of Cr(VI)and adsorption capacity. The removal efficiency and adsorption capacity of Cr(VI)from aqueous solution were measured as94.13%and18.83mg/g, respectively, whenthe adsorption experiment was carried out at room temperature for1h with theadsorbate solution pH of3, the activated carbon dosage of0.1g and the initialconcentration of adsorbate solution of100mg/L.In summary, the preparation technology, surface texture and performance ofactivated carbon from kenaf core by potassium permanganate and potassium oxalatewere systemically studied in this work, which can provide a theoretical guide for thethe use of kenaf core resource with higher value as well as a favorable reference forsimply preparation of functional activated carbon using potassium permanganate andpotassium oxalate as potentially desirable activators.