The Functional Materials Based On Populus Fibers

In this study,a natural sorbent based on natural populus fibers(PF)is prepared by transforming the cyano groups(AN)in polyacrylonitriles(PAN)grafted from PF into amidoxime groups(AO),which has strong ability to attract and chelate heavy metal ions.The prepared sorbent is characterized by Fourier Transform Infrared Spectra(FT-IR).thermogravimetric analysis(TGA),solid-state nuclear magnetic resonance(13C-NMR)and scanning electron microscope(SEM).First,as potassium dichromate solution(K2Cr2O7)is used as a target solution for detecting adsorption capacity of the sorbent,the adsorption of chromiun kinetics is consistent with the pseudo-second-order kinetic model by analyzing the adsorption amount as a function of the sorbent dispersed duration in solution at pH=2.0.Subsequently,the adsorption capability for the mixed ions solutions with the initial pH=2.0 to 6.0 under 25? is also studied.Then,a composite involving in in-situ chelating AgNPs on natural cellulose is prepared.Adsorption and in-situ reduction mechanism,and the catalytic activity in reducing 4-nitrophenol(4-NP)of the composite are also studied.The main research results are as follows:(1)The grafting ratio of acrylonitrile onto cellulose is 54%(125%)with the conditions that the concentrations of CAN,HNO3,and AN are 0.0730 mol/L(0.0146 mol/L),0.833 mmol/L(0.130 mmol/L).and 0.917 mmol/L(1.100 mmol/L).respectively.(2)The adsorption mechanism of chromium on the grafting rate of 54%PF-g-PAO is described as:the adsorption mechanism is that the Cr(?)in anionic ions Cr2O72-and HCrO4-is adsorbed through electrostatic attraction but when Cr(?)is reduced to Cr(?)by AO.the electronegative nitrogen and oxygen in AO chelate it through coordination bond.The maximum adsorption capacity(3.47 mmol/g)for chromium is found at pH=2.0 and 48.34%is the adsorption of Cr(?).(3)After desorption of PF-g-PAO-Cr in pH=9.5 sodium hydroxide solution,the adsorption capacity of that can not be completely restored.(4)The adsorption capacity of PF-g-PAO for the mixed ions in the solution with the initial pH=4.0 to 6.0.exhibits excellent adsorption behaviors especially in pH=5.0.Moreover,the order of adsorption amount is Cu(?)>Fe(?)>Cr(?)>Zn(?).The adsorption capacity for Zn(?)in the mixed solution with different pH is almost 0 attributing to the competition of adsorption in the mixed ion on PF-g-PAO.(5)One kind of composites involved in silver nanoparticles(AgNPs)loading in-situ on nature populus fiber(PF)matrix was prepared by polyamidoxime(PAO)functionalized the cellulose fiber.In which PAO worked as trapping and stabilizing agents chelating silver ions and made it reduced in-situ to obtain AgNPs by Sodium boronhydride(NaBH4)at room temperature.Moreover,the preparation of PF-g-PAO/AgNPs involved in adsorption and reduction of Ag(?)procedures have no obvious damage on the chemical structure of PF-g-PAO.(6)The composites showed significant catalytic activity 1.87 s-1·g-1 and repeated usability more than 7 cycles in reducing 4-nitrophenol(4-NP)into 4-aminophenol(4-AP)detected by UV-vis spectrophotometer in aqueous solution due to the surface-enhanced immobility and large amount of AgNPs.