| At present, environmental pollution has become a very important issue affecting the livelihood. Nitrogen and phosphorus contained in industrial wastewater and domestic sewage, is the main cause of eutrophication in the water. Nitrogen, phosphorus and other pollutants exceeded will make water eutrophication. How to reduce emissions of nitrogen and phosphorus, has become an critical project to protect the water environment. In this research project, the phosphorus removal of simulated environmental water with phosphorus using LDH was mainly researched, the mechanism of action was preliminary analysised and the feasibility of its practical application was explored.Layered double hydroxides (Layer Double Hydroxide, referred to as LDH), also known as hydrotalcite, anionic clay. Especially in the field of water treatment, LDH has a unique pore structure and exchangeable anions, absorption catalysis, higher acid and alkali properties and thermal stability, so LDH show a very wide range of applications. In this study, liquid LDH were prepared by double titration method. Production processes were as follows, in accordance with the established ratio of mixed salt solutions, two-titration, training, washing, static settlement, constant volume. LDHs (Mn:Fe=3:1,Mg:Mn=3:1, Ca:Fe=3:1)were prepared in this experiment. Surface morphology and adsorption mechanism were studyed via environmental scanning electron microscopy, FT-IR analysis. Besides, the feasibility was also studyed, with changing the adsorption time, pH and concentration of phosphorus in water and mixed with coexistence of inorganic anions and other factors to research the removal of phosphorus.The following conclusions:(1)The material had connected porous, developed pore structure, good crystallinity, liminated structure of a layered double hydroxide.(2)Compare to LDH before adsorption,,after adsorption, Ca-Fe-LDH occurred the PO vibration absorption peak respectively IR 1132 cm-1,1068 cm-1 and 986 cm-1,Mg-Mn-LDH, occurred the PO vibration absorption peak respectively IR 1068 cm-1 and 1020 cm-1, Mn-Fe-LDH occurred the PO vibration absorption peak respectively IR 1068 cm-1 and 1014 cm-1,This indicated the absorption of PO433- HPO42- or H2PO4-, verified PO4or HPO4 or H2PO4 anion as an additional anion into the LDH interlayer, PO ions removed from the water in the form of LDH precipitation.(3)Mn-Fe-LDH, Mg-Mn-LDH, Ca-Fe-LDH on phosphorus removal rate can reached 97.41%, 82.41%and 97.00% on conditiongs of material amount 1 ml,40 mL phosphorus wastewater of 2 mg/L, processing time 1 h.(4)The pH of adsorption system, had little effect on the phosphorus removal.Langmuir model could well describe the material on the process of phosphorus adsorption, the maximum phosphorus adsorption capacity of three materials (Mn-Fe-LDH, Mg-Mn-LDH, Ca-Fe-LDH) were 6.18 mg/g, 35.29 mg/g,25.50 mg/g.(5)Coexisting ions effected on phosphorus removal.With the increasing concentration of chloride ions, Mg-Mn-LDH significantly reduced the removal rate of phosphorus, Ca-Fe-LDH and Mn-Fe-LDH removal rate of phosphorus was not changed much. With the increasing concentration of sulfate ions, Ca-Fe-LDH removal rate of phosphorus changed little, Mn-Fe-LDH has increased the removal rate of phosphorus, Mg-Mn-LDH to phosphorus removal rate increased first and then decreased. Humic acid can hinder the adsorption of phosphorus.Environmental water with phosphorus was treated by using LDH, simplicity in operation, better phosphorus removal.In recent years, it gradually becomed a hot research area in resolving the eutrophication. In this study, liquid unseparated LDH as adsorbents in wastewater phosphorus were synthesised. This method eliminated complex solid-liquid separation and drying operation in the prosess of LDH synthesis and low cost, which provided a new thinking.for the treatment of phosphorus in water. |
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