Preparation And Adsorption Properties Of Beet Pulp-based Activated Carbon

In this paper，beet pulp was used as raw materials to produce activated carbon（GAC），which was prepared by steam activation process route.The activation process factors wereanalyzed and finally adopted L9（3） orthogonal experiment to determine optimum steam processconditions. the structure and property were investigated by means of FTIR，SEM，automatic poreanalyzer，Boehm functional group titration and so on.the performance of GAC adsorptionproperties is tested by the study of GAC adsorpting Cd²⁺and Cu²⁺，which mainly research theseheavy metal ions static and dynamic adsorption，specific conclusions are as follows：（1） The beet pulp was tested by industry analysis, chemical analysis and elemental analysis,The results indicated that the ash content of raw materials was2.76%;the palm fiber content was69.3%, which was suitable as a raw material to make activated carbon.（2） The effect of activation temperature, steam dosage and activation time on methyleneblue adsorption value, iodine adsorption value and yield were studied.Finally, the optimum steamprocess conditions is that the best activation temperature is850℃, steam dosageis1.5mL/g andactivation time is100min, under this condition, the beet pulp activated carbon have methyleneblue adsorption value of120mL/g, iodine adsorption value of937mg/g, the yield of25%; Rangeanalysis show the factor’s order of importance on methylene blue adsorption value and iodineadsorption value was steam dosage> activation temperature> activation time. the factor’s order ofimportance on the yield was activation time>steam dosage> activation temperature.（3） The study results showed that there were carbonyl group, anester group, ahydroxylgroup and aromatic ring structure, as well as the characteristic functional groups of the ligninlilac ring group in the GAC; By Boehm titration, the GAC total acidity was0.53.The N2adsorption-desorption isotherms of GAC are type II isotherm, GAC’s total surface area is1085m2/g and total pore volume is1.001cm3/g, which is mainly a microporous activated carbon,the1.4-2.3nm pore mainly contributed to the specific surface area and pore volume. The GACsurface was loose texture, many pores of different sizes, each level provides a wealth of GACpore structure.（4） pH, adsorption temperature, adsorption time and adsorbent dosage on the staticadsorption were studied; The results showed that GAC’s pH range was narrow in removalingCd²⁺and Cu²⁺, the best pH to removal Cu²⁺is about6and Cd²⁺is about8. Cd2+removal ratewith the increase of the temperature was drop and it was a exothermic reaction. the removal ofCu2+with the increase of the temperature was higher and it was a endothermic reaction.Cd²⁺andCu²⁺adsorption can be almost absorped balance in50min, when Cd²⁺and Cu²⁺solution initialconcentration is10mg/L, the removal rates can be up to93.7%and86%representively.theadsorption of Cd²⁺and Cu²⁺solution suit the Langmuir adsorption kinetics quasi-second-orderkinetic model; GAC adsorption of Cd²⁺and Cu²⁺were more suitable for the Langmuir adsorption isotherm model.（5） The flow rate, the adsorption column height and initial concentration on the dynamicadsorption were studied. The studies showed that the breakthrough time and exhaustion time ofCd²⁺and Cu²⁺were increasing with filler column higher and higer. the breakthrough time andexhaustion time of Cd²⁺and Cu²⁺were shortened as the flow rate and initial concentrationincreases.