Study On The Removal Performance And Mechanism Of Nano-Fe/Mn Bimetal For Tetracycline In Groundwater

In recent years,nano-zero-valent iron has been favored by researchers because of its advantages of environmental friendliness,low cost,easy preparation,and recyclability,and it has been applied to the in-situ remediation of groundwater at the site.However,due to the nano-effect of easy agglomeration,nano-zero-valent iron particles have hindered related applications.Manganese is a transition metal element with lively properties and high abundance of elements in the earth's crust.It can be fully utilized,environmentally friendly,and other characteristics.The nano-Fe/Mn bimetallic composite material was prepared by liquid phase reduction,with tetracycline?TC?as the target Pollutants.After adding manganese to zero-valent iron,it was found that it not only improved the agglomeration effect of nano-zero-valent iron,but also increased the catalytic degradation ability of tetracycline.In order to investigate the application potential of nano-Fe/Mn bimetal composites in simulating groundwater environment Studying the migration and distribution characteristics of bimetals in the media revealed that the composite material not only has no impact on the environment,but also can use the bimetallic materials trapped in the media to degrade the pollutants present.The main research results achieved are as follows:?1?The study on the preparation factors of nano-Fe/Mn bimetal found that the better preparation temperature is 25?,the solvent system is ethanol:water=5:5,and Fe:Mn=15:1.The nano-Fe/Mn bimetal composite material prepared was tested and analyzed for morphology,element content,element valence state,magnetic properties,etc.It was found that the composite material was successfully prepared,and the bimetallic particles were distributed evenly,The analysis found that there are both zero-valent state and partial oxides of Fe and Mn elements;it has good magnetic properties and is easy to be recycled after use.Studying its passivation performance,it was found that after 15 days of passivation time,the degradation efficiency of tetracycline can still reach 54.30%,indicating that the composite material has certain prospects for environmental adaptability and practical application.?2?The effects of nano-Fe/Mn bimetallic dosage,initial TC concentration,initial p H of the solution,reaction temperature,coexisting ions and other conditions on the degradation efficiency were studied.Comprehensive consideration,the reaction conditions are:nano Fe/Mn bimetallic dosage 0.3 g/L,reaction temperature 25?,initial p H=3,considering actual water conditions,the effect of coexisting anions and cations in the reaction system on the reaction was found In the system,the order of inhibition of degradation of TC by anions in the system is:Cl^->CO₃^2->SO₄^2->NO₃^->HPO₄^2-,the inhibition of cations on degradation ability is:Mg²⁺>K⁺>Na⁺>Ca²⁺.The concentration of tetracycline in the application process is based on the actual situation.In this study,it was found that high concentration?1.0 g/L?of tetracycline can also be completely degraded by nano-Fe/Mn bimetal.?3?The migration and distribution of nano-Fe/Mn bimetal in the medium is critical to its successful application.A one-dimensional plexiglass column was used to simulate the experiment to investigate the migration and distribution of nano-Fe/Mn bimetal in the simulated groundwater environment.Happening.Through the change of the injection conditions,it was found that during the entire migration process,the retention of fine sand,medium sand and coarse sand to nano-Fe/Mn bimetal was about 0.43,0.33 and 0.30 mg?iron?/g?sand?respectively.With the increase in the concentration of injected Fe/Mn bimetal,the retained bimetal content increased significantly,especially in the two high-concentration cases of 750 mg/L and 1000mg/L,the retention amounts were about 0.68 and 0.96 mg?iron?/g?sand?respectively.with the increase of injection speed,the interception amount at the maximum interception position at flow rates of 50,100,and 200 cm/d are:0.28,0.34,and 0.57mg?iron?/g?sand?respectively.The Box-Behnken Design model was used to design and evaluate the effects of three factors on the maximum migration distance and the deposition rate coefficient.Finally,the degradation of tetracycline by the trapped bimetallic material in the medium was studied.The results showed that the injection volume was 15 pv?pore Volume?,tetracycline has been detected successively,with a concentration of between 1%and 3%of the initial concentration,indicating that nano-Fe/Mn bimetal has a good degradation ability to tetracycline in the environment,but nano-Fe/Mn bimetal The application in the actual environment provides a certain basis.