Preparation Of Magnetic Chitosan Modified Biochar And Removal Of Copper And Methylene Blue From Aqueous Solution

Water resources have always been in an indispensable position in human life and development.With the progress and development of my country’s modern industrialization,water pollution has continued to increase.Adsorption method has been widely used in water pollution treatment because of its simple operation and other advantages.However,traditional adsorption materials can no longer meet the requirements of water pollution treatment,so the development of new and efficient adsorbents has become a research hotspot.In this study,corn stalk-based biochar was used as a precursor to optimize and modify magnetic Fe₃O₄ and chitosan to prepare magnetic chitosan-modified biochar（M-BC-CS）and use it in aqueous solution for heavy metal copper and organic dyes.Removal of methylene blue.In this study,a magnetic chitosan modified biochar material was first prepared,by scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）to determine the M-BC-CS the physical and chemical properties of CS,and through the magnetic separation test to explore the separation of the modified materials recovery;Then in a single system（copper,methylene blue）by changing the p H of aqueous solution,initial concentration of solution,material dosage,adsorption reaction time to explore the effects of different conditions on M-BC-CS adsorption of copper and methylene blue in water,and were respectively carried out kinetic model,isotherm model fitting,and M-BC-CS reuse performance test.In order to further explore the synchronous removal law of modified materials,the simultaneous removal of copper and methylene blue in water by M-BC-CS was studied.By changing the adsorption reaction time,the initial concentration of copper and methylene blue and the kinetic model fitting,the competitive adsorption law was analyzed.Finally,through the FTIR analysis of the modified materials after adsorption of copper and methylene blue,the mechanism of adsorption of copper and methylene blue by M-BC-CS was explored.The main results are as follows:（1）M-BC-CS modified material was successfully prepared and characterized by SEM,XPS,XRD.The results showed that chitosan and Fe₃O₄ were successfully loaded into biochar.M-BC-CS have rich specific surface area and pore structure,good thermal stability and abundant surface functional groups.The modified material is magnetic,and the separation recovery is 90.18%,showing good magnetic separation ability.（2）M-BC-CS adsorbs Cu²⁺in water for 60 min.The adsorption equilibrium time is 60 minutes,and the equilibrium adsorption capacity is 54.42 mg/g.When the p H of the solution is greater than6,the solution produces a white precipitate,and the adsorption kinetics conforms to the quasi-secondary kinetic model fitting,so the adsorption process belongs to chemical adsorption.The isothermal adsorption data conforms to the Langmuir model and belongs to the monolayer adsorption.The removal rate of Cu²⁺in the adsorbed water is 65.21%after the modified material is recycled for four times.（3）The adsorption equilibrium time of M-BC-CS on methylene blue in water is 60 minutes,the equilibrium adsorption capacity is 67.23 mg/g,the optimum dosage of materials is 0.4 g/L,the optimal p H of the solution is 6,and the adsorption process is in line with quasi-secondary level The kinetic model is fitted with the Langmuir model,which belongs to monolayer chemical adsorption.M-BC-CS has better re-use performance of methylene blue in adsorbed water,and the removal rate of methylene blue in the adsorbed water for four times is 83.37%.（4）Binary synchronous removal system results show that the M-BC-CS of Cu²⁺and synchronization of methylene blue adsorption has certain competitive relationship,and under the condition of coexistence of Cu²⁺and methylene blue M-BC-CS adsorption conforms to level 2dynamic model fitting,through analyzing the FTIR characterization of adsorption after modified materials,M-BC-CS removal Cu²⁺mainly for ion exchange adsorption mechanism（C,N and-OH play a major role）,the removal of methylene blue adsorption mechanism mainly electrostatic interactions（C=O peak shift）.