Preparation Of Amino-Supported Graphene Oxide Coating Materials And Removal Of Cr(?) From Wastewater

With the accelerating development of Chinese economy,a large amount of heavy metals is inevitably discharged into the water,rendering heavy metal pollution.It has attracted significant attention,especially for the pollution caused by Cr???.Adsorption method has been considered as a promising pathway for the Cr???removal due to its advantages including low cost,high efficiency,and simple operation.In current study,graphene oxide?GO?was successfully prepared by modified Hummers method.It was further characterized by X-ray diffraction?XRD?and Raman spectroscopy.Furthermore,amino-modified graphene oxide?AS@GO?was successfully developed using GO and 3-aminopropyltriethoxysilane?AS?as functional materials.AS@GO was characterized by scanning electron microscopy?SEM?and Fourier transform infrared spectroscopy?FTIR?.It was then used for Cr???removal from aqueous solution.The effects of pH,initial concentration of Cr???,contact time and temperature on the adsorption process was carefully evaluated.The experimental results showed that the maximum adsorption capacity was 289.47mg g^-1at pH=2.Compared with similar adsorbents,AS@GO had the advantages of large adsorption capacity and high removal efficiency.As AS@GO could hardly be effectively separated from waste liquid,the casting material?CTS/AS@GO?was prepared with chitosan as the framework material.CTS/AS@GO membrane was prepared from the casting material to solve the difficulty on solid-liquid separation.In addition,this study also tried to cover the casting material to the solid matrix of activated carbon to investigate the adsorption performance of Cr???in different application forms.The CTS/AS@GO membrane was characterized by SEM and atomic force microscopy?AFM?.The effect of pH value,initial concentration of Cr???,contact time,temperature,coexisting anions and regeneration for Cr???adsorption by CTS/AS@GO membrane were investigated.The results showed that the maximum adsorption capacity of CTS/AS@GO films reached 298.86 mg g^-11 at pH=3.The adsorption isotherms showed that the adsorption process conformed to the Langmuir model and Temkin model.Among the coexisting ions,the higher valence anions(such as SO₄^2-and PO₄^3-)exhibited negative influence on the adsorption capacity of Cr???.At room temperature,the adsorption process of Cr???on CTS/AS@GO membrane was an endothermic process,and the adsorption process conformed to pseudo-second-order kinetics model.CTS/AS@GO membrane had the advantages of high adsorption capacity and easy solid-liquid separation.CTS/AS@GO film could be eluted and regenerated under alkaline conditions.The adsorption capacity of the regenerated CTS/AS@GO film was higher than 100 mg g^-1.Activated carbon?AC?-based CTS/AS@GO particles were successfully prepared by coating CTS/AS@GO to the surface of activated carbon?the functional content was about1.85%w?.The Cr???adsorption capacity on AC-based CTS/AS@GO particles was evaluated by a fixed column.The experimental results showed that the removal rate of Cr???in wastewater by CTS/AS@GO particles could be maintained above 95%.The CTS/AS@GO membrane before and after Cr???removal were characterized by X-ray photoelectron spectroscopy?XPS?.The mechanism analysis showed that the most Cr???was reduced into Cr?III?during the adsorption process.CTS/AS@GO was a promising adsorption material for reductive adsorption of Cr???.Adsorbents with various shapes could be fabricated by CTS/AS@GO and applied to the removal of Cr???.This experiment provides a new pathway for the removal of Cr???,which has significant meaning.