Biosynthesis And Catalytic Application Of Iron Nanoparticles Using Tie Guanyin Tea Extract

Facile synthesis of zero-valent iron nanoparticles,CMC-Fe nanoparticles and Fe-chitosan composites has been developed using Tie Guanyin tea extract as reducing agent to reduce Fe3+,and the performances was evaluated towards the application of wastewater treatment.As follows:(1)Zero-valent iron nanoparticles were prepared by the reaction of Tie Guanyin tea extract and FeCl3 solution.The characterization was carried out by UV-Vis,SEM,TEM,XRD and FTIR techniques.The results showed that the nanoparticles exhibited spherical shape and the active ingredients of Tie Guanyin tea extract act as both reducing and capping agents.Catalytic degradation of bromothymol blue in the presence of H2O2 using the as-prepared iron nanoparticles catalysts were studied.The results indicated that the catalysts showed a high activity for bromothymol blue degradation when 0.05 M FeCl3 was added to 20 g/L Tie Guanyin tea extract in a 1:2volume ratio at 60 oC for 1h,and the highest reaction rate was achieved in the presence of 2% H2O2 and 0.33 mM iron nanoparticles when the bromothymol blue is150 mg/L.(2)CMC-Fe nanoparticles were synthesized by using the Carboxymethyl cellulose as dispersion agent.The characterization was carried out by TG,SEM,TEM,XRD and FTIR techniques.The results illustrated that the as-prepared nanoparticles were spherical in shape with better distribution and zero-valent iron nanoparticles are combined in the form of bidentate coordination.Catalytic degradation of bromothymol blue in the presence of H2O2 using the CMC-Fe as catalyst was studied.And the catalyst showed a high activity for bromothymol blue degradation when Carboxymethyl cellulose concentration was 3%,and the reaction rate has no significant change using different catalyst dosage,while the reaction rate decreased gradually with the increase of bromothymol concentration.(3)Fe-chitosan composites were prepared by using the chitosan as the support.The characterization was carried out by UV-Vis,SEM,TEM,XRD,XPS and FTIR techniques,and the results suggested that the nanocomposites were spherical in natureand chitosan molecules were combined on the surface of iron by N,O coordinate bonds and the nanocomposites reduced Cr(VI)into Cr(?).Removal of Cr(VI)using the Fe-chitosan composites were studied.The results proved that the nanocomposites showed a high reductive ability for Cr(VI)when it was synthesized with 0.1 mol/L FeCl3,1.5 mL chitosan,pH 6 at 60 oC for 1 h.The reduction rate increased gradually with increasing catalyst dosage,but decreased gradually with increasing Cr(VI)concentration.Moreover,it can be found that the Cr(VI)was adsorbed on the Fe-chitosan surface.Increasing the reaction temperature appropriately would improve the activity of Fe-chitosan,which exhibited a better reduction ability for the reduction of Cr(VI),the activation energy was 40.61 kJ/mol.