Study On Preparation Of Magnetic Trap And Removal Of Algae And Chromium In Water

Microcystis aeruginosa blooms may cause great harm to human living environment.In addition,sewage often contains Cr6+ ions,if not effectively treated will cause serious harm to the environment.Is it possible to prepare the material that can simultaneously remove these two harmful substances?To address this problem,we therefore initiated this research project.Firstly,we explore the optimal conditions to prepare the magnetic composite material which has a strong adsorption and coagulation ability to catch Microcystis aeruginosa in water.Secondly,it has the characteristics of simultaneously adsorbing part of Cr6+in water.Therefore,the magnetic field can be used to effectively remove the magnetic composite material from the water,removing both Microcystis aeruginosa and Cr6+ ions in the water.In addition,in order to obtain better performance,the optimized conditions for the preparation of materials were discussed,and the adsorption properties of the prepared magnetic trapping materials to Microcystis aeruginosa,Cr6+ and their coexistence in aqueous solution were studied.Isothermal adsorption and thermodynamic analysis as well as the mechanism of adsorption of Microcystis aeruginosa and Cr6+ were discussed.The main research contents are as follows:(1)Optimized screening conditions for the preparation of magnetic composite material.Find the best method for preparing magnetic composite materials and optimize the ratio of materials in the preparation process.The structure and properties of the magnetic composite material were characterized by Fourier transform infrared spectroscopy(FT-IR)and scanning electron microscope(SEM).(2)Cultivate Microcystis aeruginosa(No.FACHB-905)using BG-11 medium,and study the effectiveness of magnetic composite material to remove Microcystis aeruginosa.The effects of the amount of magnetic composite material,the concentration of algal cells,the time of action,pH value and temperature on the algae removal effect were studied experimentally,and the optimal algae removal conditions were determined;two kinetics of pseudo-first and pseudo-second The model explored the dynamic behavior of its adsorption and flocculation of Microcystis aeruginosa.(3)Experimental study on removal of Cr6+ in water by magnetic composite material.The effects of the addition amount,action time,pH value and temperature of the magnetic composite material on the Cr6+ removal effect were experimentally determined,and the optimal Cr6+ removal conditions were determined;the pseudo-first-order,pseudo-second-order,Elovich equations were used,Webber-Morris intraparticle diffusion and Boyd model five kinetic models to explore the kinetic behavior of Cr6+ adsorption by magnetic composite materials;Langmuir,Freundlich Temkin and Dubinin-Radushkevich(D-R)isotherms were used to evaluate the magnetic composite materials.Adsorption capacity,the adsorption isotherm model was determined,and thermodynamic analysis was performed to determine the type of reaction.(4)Experimental study on the simultaneous removal of algae and Cr6+ in water by magnetic composite material.Experiments were conducted to study the removal of Microcystis aeruginosa in the presence of Cr6+,the removal of Cr6+ in the presence of Microcystis aeruginosa,and the removal of Cr6+ under different pH conditions and when the algae feeding sequence is different.The experiments of removing Microcystis aeruginosa and Cr6+ alone were compared.Studies have shown that the chemical structure of the attapulgite has not changed during the synthesis of the prepared magnetic composite material.Fe3O4 only adhered to the surface of attapulgite with a simple physical action.The amount of magnetic flocculant adsorbed and flocculated Microcystis aeruginosa was 5.12×109 cells/g.Through the exploration of its algae removal mechanism,it is known that the magnetic composite material adsorbs the flocculated algal cells through charge neutralization and adsorption bridging;the data fitting shows that its adsorption flocculation behavior conforms to the secondary adsorption flocculation kinetic model.At room temperature,the amount of Cr6+ adsorbed by the magnetic composite material is 17.69 mg/g.The adsorption of Cr6+by magnetic composite materials conforms to the pseudo-second-order kinetics and Freundlich isotherm adsorption model.The adsorption process is a spontaneous and exothermic process.Magnetic composite material can remove algae and Cr6+in water at the same time,but the two will compete.