| Two kinds of novel magnetic nano Fe3O4 adsorbents with good adsorption performance and easy separation after adsorption were prepared based on the functionalization of superparamagnetic Fe3O4 nanoparticles in this paper.The adsorbents were used to remove acid black 10B dye and highly toxic heavy metal Cr(VI)in water,in order to achieve the efficient treatment of water pollutants.The detailed contents are as follows:The Fe3O4 nanoparticles were prepared by using the co-precipitation method,the effect of adding polyethylene glycol 2000(PEG2000)as dispersant on the dispersion of Fe3O4 was discussed.The products were characterizad by some instruments including XRD,TEM,FT-IR,TGA and VSM.The results showed that the addition of PEG2000 could effectively improve the dispersion of Fe3O4.The Fe3O4/PEG particle size was about 10nm,which could be as an ideal functionally modified magnetic core material.The magnetic Fe3O4@SiO2-APTES nanoparticles were prepared by using Fe3O4/PEG as the magnetic core,and the silica layer was successfully coated on the surface of Fe3O4 by sol-gel method,then ?-aminopropyltriethoxysilane(APTES)with amino functional group was grafted onto the surface of Fe3O4@SiO2.The specific surface area of Fe3O4@SiO2-APTES was 64.66m2/g and it had good dispersion and high magnetic response in solution.The gelatin base Fe3O4 magnetic nanocomposites were prepared by using gelatin as raw material,the gelatin molecules were bound to Fe3O4/PEG by electrostatic forces.And the result of XRD characterization showed that the addition of gelatin did not change the crystal structure of Fe3O4,while the particle size increased.Fe3O4 @SiO2-APTES and gelatin base Fe3O4 magnetic nanocomposites were separately used to remove acid black 10B dye and Cr(VI)in water.The effect of initial pH,adsorbent dosage,adsorption temperature and initial concentration of adsorbates on the adsorption effect were studied,and the adsorption kinetics and adsorption isotherm model were used to study the respective adsorption performance.The results are as follows:Using 0.05g Fe3O4@SiO2-APTES nanoparticles to treat 100mL acid black 10B dye solution with a mass concentration of 60mg/L,the removal rate of dye was above 95%when the pH was 3 and the temperature was 30?.The adsorption capacity of Fe3O4 @SiO2-APTES increased with the increase of the initial concentration of acid black 10B dye.And within a certain range of temperature,the increase of temperature could promote the adsorption.The adsorption process fitted well with the pseudo-second-order model and the Freundlich isothermal equation model.The adsorption mechanism was that the-NH2 groups on the surface of Fe3O4@SiO2-APTES were protonated to form a large amount of-NH3+ at low pH,while-NH3+ combined with-SO3-in acid black 10B molecule by significantly electrostatic attraction and hydrogen bonding.The gelatin base Fe3O4 magnetic nanoparticles showed excellent adsorption for the low concentration Cr(?)wastewater.When using 0.2g gelatin base Fe3O4 magnetic nanoparticles to treat 100mL Cr(?)solution with a mass concentration of 20mg/L at the pH was 2 and the temperature was 25 ?,the removal rate of dye was above 99.83%,as well as the mass concentration of the residual Cr(?)in the solution was only 0.033mg/L,which could achieve the Cr(?)discharge standards.Furthermore,the adsorption process was more consistent with the pseudo-second-order kinetics model.Both Langmuir and Freundlich isothermal adsorption model could depict the isothermal adsorption process of Cr(?)well.That is to say,the physical adsorption and chemical adsorption coexisted in the adsorption process.After the adsorption process finished,both of two-kind adsorbents could be moved fast and directionally in wastewater under the action of external permanent magnet,which could realize the rapid separation of the adsorbent and adsorbate. |
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