Preparation Of Magnetic Carbon Composites And Their Application In Dye Removal

In this thesis,the functionalised magnetic carbon composites with unique structures and surface properties were prepared and used to remove organic dyes,such as malachite green（MG）and methylene blue（MB）.In addition,the mechanism of removal and the influencing factors were investigated.The magnetic iron-incorporated carbon composite（FeO_x-MNAC）with highly enriched porous structure contains Fe₃O₄,Fe₂O₃ and Fe species.The maximum adsorption capacity of FeO_x-MNAC for MG was 2685.5 mg g^-1 and the dye removal efficiency reached 96.1%within 5 min.The adsorption capacity of FeO_x-MNAC for MG was 68.0%higher than that of NAC,indicating that iron species play an important role in the removal of MG.FeO_x-MNAC could be recovered after five recycles,maintaining 71.5%of FeO_x-MNAC in effective adsorption of MB,and demonstrating the excellent recyclable ability of FeO_x-MNAC in removing MG.The MG adsorption mechanisms of the FeO_x-MNAC included electrostatic interaction,hydrogen bond and mesoporous filling mechanism.A variety of magnetic iron carbon composites were prepared.Compared with other composites,Fe/C-800 showed the highest removal ability for MB(1015.3 mg g^-1).The adsorption efficiency for MB dye remained 80.3%after 5 cycles,demonstrating the excellent recyclable ability of Fe/C-800.The effect of solution temperature on the removal of MB dye was examinede from 5°C to 45°C,the removal efficiency of MB dyes by Fe/C-800 increased from 47.62%to 96.01%,indicateing the adsorption process is endothermic.When the solution p H increased from 3.28 to 10.95,the removal efficiency of Fe/C-800 increased from 26.6%to 97.8%for MB,demonstraing that the electrostatic interactions may play important role in dye removal.In addition,The results showed that small molecular dyes（MB and MG）were favored on Fe/C-800 due to the physiochemical nature of the material.It’s proposed that the Fe/C-800 could provide:i)efficient ion penetration pathway andfast ion diffusion channels;ii)strong chemical interactions.Three kinetic models were evaluated,the adsorption process of MG onto FeO_x-MNAC fitted the pseudo-second order kinetic model well.In addition,Langmuir isothermal model was found to be better model,indicating a monolayer adsorption process.