Study On The Adsorption Behavior Of Lanthanum Modified Magnetic Adsorbents On Pollutants In Water

Magnetic adsorbents have unique advantages in water treatment,in this study,coprecipitation was used to prepare lanthanum nitrate-modified Fe₃O₄ adsorbents.From analyzed of SEM,XRD,FTIR and Zeta potential,the Fe₃O₄ adsorbent modified by lanthanum nitrate is nanoscale,and the particle size is more uniform,the introduction of lanthanum in the rare earth element does not change the crystal structure of the magnetic substrate material;lanthanum is loaded on the surface of the Fe₃O₄ crystal in the form of La?OH?₃;compared with the unmodified Fe₃O₄,Fe₃O₄modified by lanthanum nitrate has weaker negative power and better dispersion in the solution,which is beneficial to the adsorption.When the temperature of the solution is70 degrees centigrade and the value of pH is about 11,the ideal modified adsorbents can be prepared.The use of a modified adsorbent with a La/Fe₃O₄ molar ratio of 1:50 is superior to other modified adsorbents in the adsorption of tetracycline.The neutral condition is favorable to the adsorption of tetracycline by La-modified Fe₃O₄,as the acidity and alkalinity of the solution increase,the adsorption effect gradually deteriorates.Kinetic tests show that the adsorption takes place mainly in the first 120 min,after which the adsorption gradually becomes more balanced.The linear pseudo-second-order kinetics and nonlinear Elovich model can better describe the adsorption process of tetracycline on La-modified Fe₃O₄,indicating that the adsorption may be chemisorbed and there is a significant diffusion control mechanism.According to the Freundlich isothermal adsorption model,the adsorption of tetracycline by La-modified Fe₃O₄ is dominated by monolayer adsorption,and the simultaneous adsorption and adsorption processes of physicochemical adsorption.According to the Langmuir equation fitting results,the maximum adsorption capacities at 15°C,25°C,and 35°C were 110.4 mg/g,145.9 mg/g,and 176.0 mg/g,it shows that the temperature increase is beneficial to the adsorption of tetracycline by lanthanum modified Fe₃O₄,and the adsorption process is an endothermic process.The La/Fe₃O₄ adsorbent with a molar ratio of 1:50 has better phosphorus adsorption capacity.Neutral conditions favor adsorption;the Elovich kinetics model is more in line with the adsorption kinetics of phosphorus on the La-modified Fe₃O₄process,suggesting that the adsorption may be based on chemical adsorption.From the results of Langmuir equation fitting,adsorption may be molecular layer adsorption,the maximum adsorption capacities at 15°C,25°C,and 35°C were 659.2 mg/g,791.5mg/g,and 800.6 mg/g,it shows that the increase of temperature is favorable to the adsorption of phosphorus by La-modified Fe₃O₄,so the adsorption process is an endothermic process.