Preparation Of Magnetic Carbon-based Composites And Their Application For Adsorption Of Dyes And Pharmaceutical Contaminants

Traditional environmental pollutants such as dyes and heavy metals have been widely concerned because of their harmfulness for environment and human health.Due to the inadequate development of the traditional sewage treatment plants,various emerging pharmaceutical and personal care products(PPCPs)contaminants such as pharmaceuticals,sunscreen UV filters,disinfectants and endocrine disruptor compounds cannot be effectively removed and often detected in the environment.It was reported that these emerging contaminants have some potential toxicity for human.Compared with other environmental treatment techniques,adsorption method has some advantages including high performance,low cost and easy operation.In recent years,developing high-quality and biodegradable materials for environmental treatment is the development direction in order to avoid their secondary pollution for enviroment.Natural polymer,minerals and fibrous plant wastes can be used to prepare the eco-friendly adsorption materials.Compared with single component,the composting with different materials not only exhibits more efficient adsorption performance,but also obtains better mechanical strength and regenerability.Based on these ideas,three kinds of magnetic carbon material-based composites were designed and synthesized in this thesis.The main research contents and results are as following three parts:1.A new eco-friendly magnetic quaternized chitosan/graphene oxide self-assembled composite(Fe₃O₄@GO/HACC)was synthesized.The structure and morphology of the composite were characterized by Fourier transform infrared spectroscopy(FTIR),Zeta potentiometer,transmission electron microscope(TEM)and X-ray diffraction(XRD).The results showed that the Fe₃O₄@GO/HACC had good magnetism.X-3B and MB could be simultaneously adsorbed by the proposed composite at p H=5,respectively.The adsorption mechanism was mainly based on electrostatic and hydrophobic interactions.The adsorption equilibrium could be achieved quickly and followed pseudo second-order kinetic model.The maximum adsorption capacity for MB and X-3B were 2000.0 mg/g and 172.4 mg/g,respectively.The adsorption isotherms were simulated well by the Freundlich model and Langmuir model.After adsorption–desorpiton recyles for 6 times,the adsorption rates of the composite for X-3B and MB were 84%and 93%,respectively,indicating that the composite had good stability and repeatability.2.Magnetic crosslinked quaternized chitosan and graphene oxide composite(Fe₃O₄@crosslinked-GO/HACC)was synthesized by using epichlorohydrin as cross-linking agent.Compared with the self-assembled material,the adsorption rates of Fe₃O₄@crosslinked-GO/HACC for estriol,tetracycline and sulfonamide had significantly been improved.Adsorption mechanism of the material to estriol was dominated by hydrophobic and hydrogen bonding interaction,and tetracycline mainly based on hydrogen bonding and electrostatic interaction dominantly,and sulfonamide mainly depended on hydrophobic interaction.The adsorption equilibrium of estriol and tetracycline could be achieved quickly and followed pseudo second-order kinetic model.The adsorption isotherms were simulated well by the Freundlich model.After repeated 10 times,the adsorption rates of the composite for tetracycline and estriol ramined the same,indicating that the composite had good stability and repeatability.The elution rates of 2 m L of methanol for ethinylestradiol and estradiol were 101%and 90%,respectively,and the enrichment multiples were 5 and 4.5,respectively.It indicated that Fe₃O₄@crosslinked-GO/HACC could be used for the separation and enrichment of estradiol and ethinylestradiol.3.Cotton stalk biochar was prepared by calcining waste cotton stalks in inert gas,and magnetic cotton stalk biochar composite was synthesized by in-situ co-precipitation method.Fe₃O₄ nanoparticles were deposited on the cotton stalk biochar.The adsorption of propranolol on the magnetic biochar mainly depended on hydrophobic interaction,and the adsorption could be achieved quickly,and followed pseudo second-order kinetic model.The maximum adsorption capacity(q_m)for propranolol was 111.1 mg/g.The adsorption isotherm was simulated well by Langmuir model.After 6 times desorption and reusage,the adsorption rate of propranolol remained above 95%.The datas showed that the magnetic cotton stalk biochar composite had good prospect of practical application for the removal of propranolol in the environment.