Preparation Of Metal-organic Framework Microspheres And Study On Their Adsorption And Antibacterial Properties In Aqueous Solution

With the development of society and the acceleration of industrialization,the development of Marine related industries is increasingly accelerated.A large number of waste water,waste oil and bacterial pollutants are inevitably discharged into the sea,exceeding its self-purification capacity,and the pollution problem is prominent.Heavy metal and bacterial contamination of water,in particular,is extremely serious and is increasing as a result of increased activity in the industrial and health sectors.These heavy metals are not biodegradable and therefore accumulate in the environment,ultimately affecting ecosystems.Microbial infections are also considered to be one of the greatest threats to human health and pose a challenge to global public health.Metal-organicframework（MOFs）is a kind of new coordination polymer.These compounds have attracted the attention of researchers due to their excellent properties such as adjustable structure,large specific surface area,regular pores,low density,high chemical and mechanical strength,strong adsorption and storage capacity,and modifiable after synthesis.MOFs have been widely used in adsorption and separation,drug storage and delivery,catalysis,sensing,and especially wastewater treatment.Metal-organic skeleton materials are not only good adsorbent materials,but also considered as the latest generation of antibacterial agents.Therefore,metal-organic framework antibacterial materials have good application prospects in antibacterial coating,medical diagnosis,food preservation,wastewater treatment and other fields.Metal-organic frame materials have become ideal adsorbents for wastewater treatment.However,because the adsorbent is powder,it has some shortcomings such as bad circulation and complicated operation process.In this paper,we use the in-situ synthesis method,Cu²⁺as the metal center ion,2-amino-terepthalic acid as the organic ligand,natural biopolymer as the matrix to synthesize antibacterial metal-organic framework microspheres,and study the adsorption properties and antibacterial properties of antibacterial metal-organic framework microspheres on Cr（Ⅵ）and organic dye malachite green.The research contents and conclusions of this paper are as follows:1.Chitosan modified Cu-metal-organic framework antibacterial microspheres（CS@Cu-MOF-M）were synthesized by in-situ synthesis method with Cu²⁺as the metal center ion,2-amino-terepthalic acid as the main organic ligand,and chitosan as the substrate for the adsorption of Cr（Ⅵ）in water environment.The effects of experimental parameters on the adsorption properties of chitosan modified Cu-metal-organic framework antibacterial microspheres（CS@Cu-MOF-M）were studied.The MOFs composite microspheres were systematically characterized by SEM,XRD,FTIR,BET,XPS,ZATE potential and TG analysis.The influence of adsorption conditions on the adsorption of Cr（VI）by CS@Cu-MOF-M was explored.The adsorption kinetics,isotherm and thermodynamic properties of adsorption materials were systematically evaluated.The kinetic study shows that the adsorption of Cr（VI）by CS@Cu-MOF-M conforms to the quasi-second-order kinetic model.Compared with the other two adsorption isotherms,the adsorption isotherm is more consistent with the Sips model.Under the best conditions,the maximum adsorption capacity of Cr（VI）by CS@Cu-MOF-M is 159.25 mg/g.Finally,the thermodynamic results show that the adsorption of Cr（VI）by CS@Cu-MOF-M is a spontaneous,endothermic and disordered process.After four recycling experiments,the adsorption rate of CS@Cu-MOF-M is still greater than80%of the former,showing excellent renewable adsorption performance.2.Sodium alginate modified Cu-metal-organic framework antibacterial microspheres（Cu-Alg-MOF-M）were prepared by in-situ synthesis using Cu²⁺as metal center ion,2-amino-terepthalic acid as main organic ligand and sodium alginate as matrix for the removal of malachite green（MG）from aqueous solution.A series of systematic characterization experiments of Cu-Alg-MOF-M were carried out.The adsorption mechanism of malachite green was explored by studying the optimal adsorption conditions for MG adsorption,fitting adsorption kinetics,isotherm curves and calculating thermodynamic experimental data.The results showed that Cu-Alg-MOF-M had good removal ability for MG in the range of study conditions.The pseudo second order kinetic model in the kinetic experiment illustrates the adsorption process of MG well.Langmuir model has the best simulation effect,and the maximum fitting adsorption capacity of Cu-Alg-MOF-M for MG is 222.92 mg/g.Thermodynamic analysis shows that the removal of MG is a spontaneous endothermic reaction.The adsorption rate of Cu-Alg-MOF-M is still more than 83.78%of the first time after four cycles of regeneration experiments,showing a good ability to remove MG.3.The antibacterial activities of the synthesized chitosan modified Cu-organometallic framework antibacterial microspheres（CS@Cu-MOF-M）and sodium alginate modified Cu-organometallic framework antibacterial microspheres（Cu-Alg-MOF-M）were studied.The antibacterial activities of two representative foodborne microorganisms（Escherichia coli and Staphylococcus aureus）were measured.The results showed that the antibacterial materials had strong bactericidal activities against the two pathogenic microorganisms.The antibacterial activity of CS@Cu-MOF-M was higher than that of Cu-Alg-MOF-M.In order to further explore the bactericidal mechanism of the antibacterial carrier,scanning electron microscopy was used to observe the morphology of the two bacteria after treatment with CS@Cu-MOF-M.The antibacterial activity results showed that it was the CS@Cu-MOF-M surface active groups and copper ions that acted on the bacterial cell membrane,resulting in the loss of bacterial activity.Therefore,MOFs composite microspheres have good antibacterial properties and have great potential in the treatment of wastewater containing bacterial pollution.This paper provides a new research idea for the design and development of novel broad-spectrum antibacterial adsorption materials with the advantages of easy synthesis,high efficiency and recycling,promotes the application of new metal-organic framework microspheres in the treatment of water pollution,antibacterial and other fields,and provides the corresponding experimental basis and theoretical basis.