Study On The Preparation And Properties Of Carbon Matrix Composites With High Efficiency In Removing Antibiotics From Water

The abuse of antibiotics leads to increasingly serious water pollution,which in turn harms human health and ecological environment.The traditional sewage treatment process can not achieve satisfactory results,and how to effectively remove antibiotics from water is an urgent problem to be solved.Carbon-based materials are widely available and have excellent physical and chemical properties,which are often used in the restoration of water environment.Adsorption method based on modified biochar and photocatalytic method based on carbon nitride have great potential,and have the characteristics of easy preparation,high efficiency and low cost,which have obvious effects in water environmental treatment.In this paper,for two kinds of antibiotics（norfloxacin and tetracycline）,biochar-based adsorbents and graphite-phase nitridation-based photocatalysts were prepared.The morphology,structure and physical and chemical properties of the materials were characterized by adsorption and photocatalysis methods respectively.At the same time,the removal performance and influencing factors of antibiotics in water were deeply studied,and the structure-activity relationship between the structure and removal performance of the composite materials and the related adsorption and photocatalysis mechanisms were clarified.The key contents and conclusions are as follows:（1）Using sawdust as biomass raw material,magnetic biochar composites modified by Fe₂O₃ nanoparticles were synthesized by molten salt method.Magnetic biochar CPW-700 retains its porosity and rich surface functional groups,while introducing Fe-O groups,which can further improve its adsorption.Its adsorption capacity for norfloxacin is good,which can reach 38.77 mg/g when the dosage is 0.5g/L and the p H is 6.At the same time,the magnetic properties of the material enable it to be recycled,and the removal rate is 83.1%after four regenerative experiments.Adsorption is a monolayer adsorption,which is a spontaneous endothermic behavior.The adsorption mechanism is mainly hydrogen bonding,π-πelectron donor-acceptor interaction and the synergistic effect of pore filling,as well as other insignificant factors such as electrostatic repulsion.This work provides reference and ideas for the adsorption of norfloxacin in water by modified biochar.（2）The magnetic Ni Fe₂O₄ modified biochar composite（BCNF）was obtained by loading ferrite materials on biochar with carbon skeleton as matrix and integrating their respective advantages.BCNF material has more abundant oxygen-containing functional groups such as M-O,porous structure and large specific surface area,which makes its adsorption of tetracycline reach 92%when the dosage is 1 g/L.It is beneficial to the adsorption process in weak acidic water environment,and the concentration of Ca²⁺and Mg²⁺in water has a great negative impact on the adsorption capacity.The adsorption of tetracycline by BCNF reached an equilibrium state in about 2 hours,and the behavior conformed to the quasi-second-order kinetic model,which was mainly controlled by chemical adsorption.At the same time,adsorption belongs to the spontaneous endothermic reaction of monolayer,which is the result of the synergistic effect ofπ-πEDA（electron donor-acceptor）interaction,pore filling and hydrogen bonding.After four cycles of adsorption,the removal rate of TC is72.9%,and the recycling ability is good.This work provides ideas and reference for the adsorption of tetracycline in water by modified biochar.（3）The spinel-type metal oxide Ni Al₂O₄ was synthesized by sol-gel and calcination process,and it was compounded with graphite phase carbon nitride g-C₃N₄ to obtain NAO/CN series materials.NAO/CN-2 enhances the light absorption capacity and greatly reduces the recombination of photo-generated carriers through heterojunction,and the larger specific surface area also provides more active sites,which all enhance the photocatalytic activity of tetracycline.When NAO/CN-2 was irradiated by visible light for 120 min,the removal rate of tetracycline solution reached 80.3%,and the reaction rate constant was 6.7 times and 31.8 times that of Ni Al₂O₄ and g-C₃N₄,respectively.After five cycles of experiments,the composite photocatalyst NAO/CN-2 still has good magnetism and tetracycline removal ability,and OH and·O^2-are the main free radical species in the photocatalytic degradation process.This work provides reference for the degradation of tetracycline in water by nitridation carbon-based photocatalyst.