The Preparation Of Layered Multiple Hydroxides And Modified Magnetic Composite Particles And Phosphorus Removal Performance Research

Phosphorus (as phosphate ions) is an important element that is widely used in agriculture and in industry. However, Phosphorus content of water effluent exceeding the public criteria is one of the important factors causing the natural water eutrophication, which results in a series of consequences, Such as the excessive growth of algae and other aquatic organisms, water dissolved oxygen reduction, transparency fall, water quality deterioration. Therefore, looking for a kind of high efficient phosphorus removal material used to remove phosphorus in water environment is an important research work. The research results in the dissertation have academic significance and promising application.ZnxCa(2-x)-Fe LDHs and ZnxCa(2-x)-Al LDHs adsorbent were synthesized by co-precipitation method at room temperature for mitigating water eutrophication efficiently, Both performed very well in phosphorus removal performance. Inspired by the basic and results of the two kinds of phosphorus removal adsorbent (ZnxCa(2-x)-Fe and ZnxCa(2-x)-Al), Another magnetic Fe3O4@SiO2@ZnAl microspheres with Fe3O4@SiO2core-ZnAl-LDHs shell structure were designed and prepared. The microstructure and surface charge of ZnxCa(2-x)-Fe and ZnxCa(2-x)-Al were characterized using XRD, SEM, FTIR and Zeta potential measurements and The composition, microstructure and magnetic properties of Fe3O4@SiO2@ZnAl were characterized using XRD, SEM, TEM, VSM and BET measurements. The phosphate removal performances of adsorbent were determined by the adsorption experiment. The amount of adsorbent, the contact time and the initial pH of the phosphate solution were varied to explore their effect.The adsorption was rapid in the first1hour and then gradually reached equilibration in4hours for most of ZnxCa(2-x)-Fe LDHs and the adsorption was rapid in the first2hour and then gradually reached equilibration in12hours for most of ZnxCa(2-x)-Al LDHs. This behave can be well modeled by pseudo second order kinetics. The phosphate adsorption isotherm using Ca2-Fe?Zn2-Fe?Ca2-Al and Zn2-Al as adsorbents were fitted with Langmuir model. The maximum adsorption amounts were calculated as228?95?323and93mg/g, respectively. The maximum adsorption amounts of ZnxCa(2-x)-Fe LDHs and ZnxCa(2-x)-Al LDHs were much higher than common MgAl-LDHs (31.3mg/g). The FTIR and Zeta potential measurements shed light on the mechanism that phosphate species were removed via electrostatic attraction, ion exchange, ligand exchange and chemical precipitation. The adsorption gradually reached equilibration in3hours for Fe3O4@SiO2@ZnAl. The phosphate adsorption isotherm using Fe3O4@SiO2@ZnAl as adsorbents were fitted with Langmuir model. The maximum adsorption amounts were calculated as19.25mg/g. Fe3O4@SiO2@ZnAl adsorbent can be isolated from liquid within30s under the action of an external magnetic field.To conclude, ZnxCa(2-x)-Fe LDHs, ZnxCa(2-x)-Al LDHs and Fe3O4@SiO2@ZnAl adsorbent with high adsorption capacities will be a promising material for phosphate removal from natural water and municipal wastewater.