Preparation,Characterization And Adsorption Properties For Cr(?) Of Activated Carbon From Typha Angustifolia L.

The adsorption performance and cost of adsorbents are the most important indexes to determine the process of adsorption.Thus,the appropriate materials,proper production processes,and readily regenerating technology determine the cost-effectiveness of activated carbon.In this work,we used Typha angustifolia L.as materials and H3PO4 as activation agents to prepare activated carbon,and applied response surface methodology design to optimize process parameters of T.angustifolia activated carbon(TAC)preparation,investigated the influence of difference factors on adsorption characteristics of Cr(?)on TAC,including the adsorption kinetics,isotherms,thermodynamics,and used RSM approach to determine the optimum adsorption conditions for Cr(?)adsorption on TAC.Finally,the regeneration properties of TAC were investigated to determine the reusability of adsorbent and evaluate the economic feasibility.The research of the optimal production condition of TAC.According to the principle of response surface methodology,experimental model was established to optimize the preparation process on the basis of the most significant factors(impregnation ratio?activation temperature,activation time)by the Box-behnken center combination method derived from Design-Expert statistical software.The regression equations of the Cr(?)removal efficiency and carbon yield of the as-prepared activated carbons was found basing on fitting experimental date by Design-Expert statistical software.The optimal process condition can be proposed according to the results of significant test and interaction analysis of the key single factors by response surface methodology.The results show that among three single factors,the effects of impregnation ratio was most significant on Cr(?)removal efficiency and carbon yield,the effects of activation temperature was minimum,and the optimum production conditions for TAC was 469.02 ? activation temperature,1.5 h activation time and impregnation ratio of 4:1.In this optimum production conditions Cr(?)removal efficiency was 90.01%and carbon yield was 38.23%.The research of the optimal adsorption condition of Cr(?)on TAC produced under the optimal process condition.According to the principle of response surface methodology,experimental model was established to optimize the adsorption condition on the basis of the most significant factors(initial pH,carbon dosage,initial concentration of Cr(?)solution)by the Box-behnken center combination method derived from Design-Expert statistical software.The regression equations of the Cr(VI)adsorption capacity of TAC was found basing on fitting experimental date by Design-Expert statistical software.The optimal adsorption condition can be proposed according to the results of significant test and interaction analysis of the key single factors by response surface methodology.The results show that among three single factors,the effects of carbon dosage was most significant on Cr(VI)adsorption capacity,the effects of initial pH was minimum,and the optimum adsorption conditions for TAC were pH of 2.21,initial Cr(?)concentration of 80 mg/L and 0.02 g carbon dosage which resulted in a 59.54 mg/g adsorption capacity of Cr(?).The research of the adsorption characterize of Gr(?)in aqueous solutions on TAG produced under the optimal process.The adsorption of TAC on Cr(?)was influenced by solution pH,reaction temperature,reaction time,dosage of TAC,and the initial concentration of Cr(?).The analysis of adsorption thermodynamics and kinetics showed that the adsorption process was spontaneous,endothermic,and depicted well by the pseudo-second-order,and the Langmuir isotherm fitted the equilibrium adsorption reasonably well.The maximum adsorption capacity of Cr(?)obtained from the Langmuir isotherm was 43.26 mg/g at the temperature of 25 ?.Physical adsorption apparatus are adopted to measure of TAC nitrogen isothermal adsorption-desorption at 77 K.We use BET equation to calculate specific surface area,total entrance,the average pore size and pore size.The scanning electron microscope(SEM),X-ray diffraction(XRD),fourier infrared spectrometer(FTIR),X-ray photoelectron spectroscopy(XPS)and Zeta potential were applied to analysis their microstructure,surface morphology,surface functional groups and elements,isoelectric point.The physicochemical properties analysis of TAC indicated that the surface of TAC was rough and porous,the specific surface area,total pore volume,and average pore diameter was 789.42 m2/g,0.81 cm3/g,and 4.09 nm,respectively.The TAC contained-OH,C=O,C-O,-COOH,P=O,the pHpzc was 2.8,and so on and XPS analysis results confirmed the strong oxidizing Cr(?)adsorbed on TAC surface was bound to C-O or C=O and reduced to Cr(?).