Preparation Of Magnetic Sludge-based Adsorbent And Its Application For Tetracycline Remocal From Water

Sewage sludge is the remaining product in the water treatment process,which is very complex,contains a lot of heavy metals,organic pollutants and pathogenic microorganisms,and sewage sludge production is huge,provided that the treatment is unreasonable may cause severe environmental Destruction,therefore,sewage sludge treatment has been more and more attention.In this paper,the sludge-based adsorbent prepared by pyrolysis was used as the raw material from the perspective of sludge resource and the recovery of adsorbent.However,the sludge-based adsorbent prepared with the excess sludge as the raw material will encounter many problems when the adsorption test is carried out.The most serious problem is that the separation is difficult and difficult to recycle.Therefore,it is of great significance to solve the difficulty of separation and recovery of sludge-based adsorbents.In this paper,the method of coprecipitation on the sludge-based adsorbent was carried out on a sludgebased adsorbent to prepare a magnetic sludge-based adsorbent.The adsorbent was then used to remove contaminants such as tetracycline.Compared with the previously prepared sludge-based adsorbents,the most prominent advantage is that the magnetic sludge-based adsorbent exhibits the advantage that,on the one hand,its porous structure can better remove the target contaminants;on the other hand,as the surface of the sludge-based adsorbent loaded with nano-iron oxide,so the adsorbent with magnetic,to the magnetic field,is conducive to the separation of powder materials,both to solve the material for the treatment of water pollution problems,but also conducive to the recycling of materials.The mass ratio of the sludge-based adsorbent to the iron salt was optimized by measuring the iodine value and the methylene blue value of the magnetic sludge-based adsorbent.The magnetic sludge-based adsorbents were characterized by infrared spectroscopy,X-ray diffraction spectroscopy,BET specific surface area and hysteresis loop.The magnetic sludge-based adsorbents were used to remove tetracycline from water.Agent adsorption isotherm,adsorption kinetic model,explore its adsorption mechanism.The magnetic Fe3O4 was supported on the surface of the sludge-based adsorbent by coprecipitation method.The analysis of the iodine value and the methylene blue value showed that the surface supported magnetic iron oxide could not block the sludge-Of the pore structure.The magnetic sludge-based adsorbents are mesoporous materials.The specific surface area and pore volume of the magnetic sludge-based adsorbents are obviously higher than those of the sludge-based adsorbents by analyzing the pore structure of the adsorbents.Iron oxide is beneficial to increase the specific surface area and pore volume of the sludge-based adsorbent,mainly because the magnetic iron trioxide nanoparticles have a large specific surface area due to the size in the nanometer range,and when the load is in the sludge-The surface area of the adsorbent itself is increased,and its structure is relatively soft due to its agglomeration on the surface of the sludge-based adsorbent,so it contains a large amount of pore structure,thus increasing the pore volume of the sludge-based adsorbent.The adsorption capacity of the magnetic sludge-based adsorbent for tetracycline is best when the dosage of the magnetic sludge-based adsorbent is 2.5 g / l at p H 4.It can be seen in the experiment that with the increase of the dosage of the adsorbent,the effect of tetracycline removal is getting better and better,mainly because the adsorbent is increasing and the adsorption site will increase.Large tetracycline and magnetic sludge-based adsorbent probability of collision,so the removal of tetracycline is getting better and better.However,with the increase of the amount of adsorbent,the adsorption capacity will gradually decrease,mainly because the dosage of adsorbent increases,its specific surface area and adsorption site will increase,while the concentration of tetracycline unchanged,it will reduce the adsorption capacity of the adsorption site is reduced.The removal of tetracycline by magnetic sludge-based adsorbents is more consistent with the quasi-second order kinetic model,so the adsorption process is more prone to chemical adsorption.The adsorption isotherm model of tetracycline was established by the establishment of magnetic sludge adsorbent,and then the isotherm model was fitted.It was found that the Freundlich adsorption isotherm model was more suitable for the removal of tetracycline by magnetic sludge adsorbent.Externally pressurized gas bearing has been widely used in the field of aviation,semiconductor,weave,and measurement apparatus because of its advantage of high accuracy,little friction,low heat distortion,long life-span,and no pollution.In this thesis,based on the domestic and overseas researching……...