Preparation Of New Doped Zn Metal-Organic Framework Material And Their Application For Antibiotic

Antibiotics,as a kind of drug that kills or inhibits the growth of bacteria,are widely used in all aspects of production and life.However,the discharge of antibiotic residues will cause a series of environmental problems.How to remove antibiotics efficiently from the environment has become a hot spot in current research.Adsorption disposal has become one of the most commonly methods to remove antibiotic residues from the environment.At present,they are several adsorbents which are commonly used,including:traditional carbon materials,resins,transition metal oxides,molecular sieves,clay adsorbents,etc.However,they also have certain disadvantages,such as insufficient adsorption effect,low repetition rate,inability to adsorb multiple types of antibiotics at the same time,complicated process,and high cost.Therefore,it is very important to find an adsorbent with high efficiency,wide application range,low cost and recyclable features.Metal organic framework materials（MOFs）have attracted much attention due to their advantages such as high specific surface area,adjustable pore size and porosity,and easy functionalization.They have great potential for application in adsorption-related fields.In this study,the basic material UiO-66-NH₂was used to modified by doping with Zn,and Zn-UiO-66-NH₂（Zn-containing materials）nanoparticles were synthesized by one-pot synthesis,When the molar rate of Zr⁴⁺:Zn²⁺was 1:1,we named 50Zn-UiO-66-NH₂.Through a series of characterization methods such as FT-IR,XRD,TG,SEM,BET,to verify the synthesis of materials and structural characteristics of the materials.It was found that 50Zn-UiO-66-NH₂nanoparticles have good thermal and chemical stability.Zn doping increased the pore volume and specific surface area of the nanoparticles,and the pore diameter remained basically unchanged.And 50Zn-UiO-66-NH₂nanoparticles were used as adsorbents to study the adsorption properties of three antibiotics,such as ceftriaxone sodium,tetracycline and oxytetracycline.The effects of p H,temperature,the content of Zn and initial concentration of antibiotics solution were explored,and the optimal p H for ceftriaxone sodium,tetracycline,oxytetracycline was 3,8,3 respectively;the optimal adsorption temperature of three antibiotic is 45°C;the initial concentration of antibiotic solution will affect the adsorption performance.At the optimal p H and the optimal adsorption temperature,the maximum adsorption capacity of50Zn-UiO-66-NH₂nanoparticles for each antibiotic was studied.The results showed that 50Zn-UiO-66-NH₂nanoparticles were effective for ceftriaxone sodium,tetracycline and oxytetracycline.The maximum adsorption capacity of three antibiotic was 484.38 mg/g,215.32 mg/g and 512.13 mg/g respectively.The kinetic model was used to study the mechanism of the adsorption process.The results showed that the adsorption process of 50Zn-UiO-66-NH₂nanoparticles for ceftriaxone sodium,tetracycline and oxytetracycline fitted the quasi-second-order kinetic model（R²>0.99）,indicating that the chemical role played a main role during the adsorption process.Furthermore,using the intra-particle diffusion model to analyze the diffusion information of each antibiotic molecule in 50Zn-UiO-66-NH₂.According to the data fitting analysis,the diffusion of each antibiotic molecule in50Zn-UiO-66-NH₂can be divided into the membrane diffusion stage,the channel diffusion stage,and the adsorption stage of the adsorption site,theX_i（particle diffusion constant）in the three stages of the diffusion process increased gradually,indicating the boundary layer diffusion had the greatest influence on the adsorption rate control step of the adsorbate at the adsorption site.Adsorption cycle regeneration experiments and actual sample studies showed that 50Zn-UiO-66-NH₂had good reusability,as we all know,Zn is an inexpensive and easily available transition metal element,so this material is expected to be widely used in antibiotic adsorption.