Study On Oxidation Modification Of Surface And Structure Of Wooden Activated Carbon Fiber

In order to understand the oxidation modification of surface and structural of wood active carbon fiber(WACF),WACF was prepared and modified with nitric acid and ammonium nitrate(CAN)to explore their synergistic modification regular pattern.The following conclusions were described as follows(1)The preparation process and basic properties of WACF were obtained Before modification,the concentration of oxygen atoms of WACF was 12.13%,the graphite was disordered carbon material and the vapor adsorption isotherm belonged to the V type.The pore volume was 50.16 nunoUg and the water adsorption specific surface area was 65.40 m2/g,thus the adsorption of HgC12 was in line with the Quasi-second-order kinetic equation.(2)The enhancement of nitric acid oxidation increased the proportion of oxygen atoms.The content of phenol and alcohol functional groups increased with the increment of nitric acid concentration,and decreased with time.The content of hydroxyl group increased signi ficantly with the increase of temperature,time and nitric acid concentration.The graphitization degree on the surface of WACF rose with the increase of nitric acid concentration,and the graphitization degree in the core increased as a whole,but it was not affected by the concentration gradient.The water adsorption pore volume of WACF decreased after nitric acid modification The specific surface area of water adsorption rose remarkably with an average increase of 164%and a maximum increase of 259%(3)The oxygen-containing functional groups increased after CAN modification,the oxygen atom concentration rose,and the hydroxyl functional groups changed to high valence state.Both the D peak and G peak appeared in the Raman spectra.CAN oxidation modification had no effect on the graphitization of WACF surface,however,it significantly increased the graphitization degree of WACF cross section.The pore volume reduced after WACF modification,but specific surface area of the water adsorption increased obviously.CAN modification improved the mercury adsorption capacity,but the mercury adsorption capacity was reduced when it was modified excessively.(4)The average value of oxygen/carbon ratio of synchronous modified WACF was 0.160.The content of phenolic groups and alcohol groups increase.It presented an inverse correlation between the content of carboxyeste and the intensity of oxidation.The content of carboxyl ester group was lower than that of umnodified sample.The degree of graphitization on the sample surface reduced slightly,and the degree of graphitization of the sample core increased subtly.After synergistic modification,the pore volume decreased.The specific surface area of water adsoiption increased significantly.The adsorption capacity of mercury and the specific surface area of water adsorption were linearly related to the concentration of oxygen atoms.Nitric acid can increase the content of functional groups,and has little effect on the structure.(5)Nitric acid oxidation modification focused on surface modification by increasing the functional groups of WACF surface,fine-tuning the pore structure and reducing pore volume.While the Oxidation modification of ceric ammonium nitrate focused on structural modification by improving the structure of graphitization,reducing the pore volume because of the corroded hole structure,adjusting the pore volume in both directions and fine-tuning the functional group content.The cooperation of the two can be used to fine-adjust the pore size and increase the oxygen-containing functional groups,which has guiding significance for targeted adsorption.