Study On Preparation Of Amino Modified Magnetic Graphene Oxide And Application Of Adsorption For Heavy Metal Ions

With the rapid development of urbanization and industry,a large amount of heavy metals enter the natural environment through industrial wastewater discharge or daily necessities.Due to improper handling,a series of water pollution problems caused by heavy metals.Among the various methods for treating heavy metal pollution in water,the adsorption method is currently the most commonly used method due to its simple operation,large adsorption capacity and reproducible adsorbent.Graphene oxide?GO?is a sheet-layer carbon material with a high specific surface area and a large number of oxygen-containing functional groups,which can be used as an adsorbent for heavy metal ions.However,graphene oxide has the disadvantages of difficult separation and poor regeneration after adsorbing heavy metal ions,so it needs to be further modified.The magnetization of graphene oxide can effectively solve this problem,but the adsorption capacity will be significantly reduced after magnetization,and further modification is required to improve the adsorption performance.Since functional groups with lone pairs of electrons have strong complexing ability for heavy metal ions,N,S,O and other elements can be introduced into graphene oxide materials by doping or covalent grafting to improve the adsorption performance.Although there have been many studies on modified graphene oxide composite adsorbents,there are still few studies on modification with strong selective adsorption of heavy metal ions.In this paper,graphene oxide was used as a raw material,and two modified magnetic adsorbents with selectivity of adsorption for some heavy metal ions were successfully prepared by compositing with ferroferric oxide magnetic nanoparticles and grafting with some amides.The structure and morphology of the adsorbent were characterized by FT-IR,SEM,XRD,TGA and BET.The adsorption selectivity,adsorption kinetics,isothermal adsorption and adsorption thermodynamics of the adsorbent were studied.The effects of solution p H,temperature and adsorbent dosage on the adsorption of heavy metal ions were also studied.The main results are given as follows:?1?Preparation of thiosemicarbazide grafted magnetic graphene oxide adsorbent forThiosemicarbazide modified magnetic graphene oxide?TSC/MGO?was successfully prepared by compositing between graphene oxide and magnetic Fe₃O₄ and then grafting with thiosemicarbazide.The synthesis of the target adsorbent was verified by infrared spectrum.SEM analysis showed that there were many particles on the surface of adsorbent,and the structure was irregular.The results of adsorption for different heavy metal ions indicated that and Zn²⁺was spontaneous.After five adsorption desorption cycles,the adsorption capacity could still reach more than 78%of the first adsorption capacity,indicating that the adsorbent had regeneration.?2?Preparation of tetraethylene pentamine grafted magnetic graphene oxide adsorbentTetraethylenepentamine modified magnetic graphene oxide TEPA/MGO was prepared by using graphene oxide as raw material,compounding with Fe₃O₄ and grafting with tetraethylenepentamine.FT-IR analysis showed that the target product was successfully prepared.Scanning electron microscope analysis?SEM?showed that the surface of the adsorbent presents a wrinkled,loose and porous structure,and there were many irregular particles distributed.The results of adsorption experiments showed that the adsorbent had adsorption selectivity for Pb²⁺adsorption,and the maximum adsorption capacity was 287.6mg g^-1.The best adsorption p H was 6,and adsorption was an endothermic spontaneous chemical process.After five adsorption-desorption cycles,the adsorption capacity of the adsorbent could still reach more than 80%of the first time,indicating that the adsorbent was regenerative.The above research results showed that the prepared two amino-modified magnetic graphene oxide adsorbents had selective selectivity to mercury ions,zinc ions,and lead ions in aqueous solutions.The adsorption capacity was higher than that of the unmodified magnetic graphene oxide adsorbent.At the same time,it could be magnetically separated and could be regenerated by EDTA solution.Therefore,the above-mentioned adsorbents had high adsorption capacity,strong adsorption selectivity,easy separation and good regeneration performance,and are expected to be used to treat wastewater containing Hg²⁺ or Zn²⁺,Pb²⁺.