| Domestic sewage and industrial wastewater contains high levels of phosphate and can reduce the water quality when being directly discharged into river or lake,bringing series of environmental issues,including eutrophication.Therefore,the treatment of phosphorus-containing wastewater is an urgent problem to be solved.At present,the treatment methods of phosphorus-containing wastewater both at home and abroad mainly include adsorption method,biological method and chemistry.Adsorption method is widely used because of its low cost,simple operation and relatively short processing cycle.However,the development of high efficiency and cheap adsorbent is the key to the adsorption and phosphorus removal.Due to its large adsorption capacity for phosphorus,zirconium oxide is used to remove phosphorus from wastewater but the disadvantage is that it is not easy to separate and recover.Magnetic iron oxides,such as Fe3O4 and Fe2O3,can be rapidly separated under external magnetic field conditions,but the disadvantage is their disappointed adsorption capacity for phosphate.Therefore,it is important to synthesize an adsorbent material which has both large phosphorus adsorption capacity and rapid separation under external magnetic field conditions.Based on the above reasons,this paper presents a magnetic nano-zirconium/iron oxide synthesis method,prepared four different zirconium molar ratio of magnetic zirconium-iron oxide nanoparticle,and used in wastewater removal of phosphorus,the main research results as follows:(1)Four different molar ratios of zirconium of magnetic zirconium-iron oxide nanoparticle(S1,S2,S3 and S4)were prepared.The magnetic zirconium-iron oxide nanoparticle were prepared by the method of chemical coprecipitation via controlling the molar ratios of the raw materials,which were ferric sulfate,ferrous sulfate,sodium hydroxide and zirconium oxychloride.The surface morphology of the magnetic adsorbent was characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FT-IR).The results show that the magnetic adsorbent particles are roughened with the increase of zirconium content.lt is found from the XRD diagram that the magnetic nano-zirconium/iron oxide is mainly composed of Fe3O4,?-Fe2O3 and ZrO2.S1,S2,S3 and S4 have a saturation magnetization of 52.2 emu/g,45.4 emu/g,44.8 emu/g and 21.3 emu/g,respectively.(2)The removal of phosphorus from the above four kinds of magnetic zirconium-iron oxide nanoparticle in artificial simulated wastewater was investigated.The effects of four kinds of magnetic zirconium-iron oxide nanoparticle on the isothermal adsorption,adsorption kinetics and thermodynamics of phosphorus were investigated.The effects of pH,ionic strength,and co-existing ions(including Cl-,SO42-,NO3-and HCO3-)were measured to evaluate the adsorption performance in batch experiments.Phosphate adsorptionon magnetic zirconium-iron oxide nanoparticle could be well described by the Freundlich equilibrium model and pseudo-second-order kinetics.The adsorption of phosphate was highly pH dependent and decreased with increasing pH from 1.5to 10.0.The adsorption was slightly affected by ionic strength.With the exception of HCO3-,co-existinganions showed minimum or no effect on their adsorption performance.After adsorption,phosphate on magnetic zirconium-iron oxide nanoparticle could be easily desorbed by 0.1 M NaOH solution.Additionally,the main advantages of MZION consisted in itsseparation convenience and highly adsorption capacity compared to other adsorbents.(3)adsorption-desorption and regeneration of materials was conducted by addition of 0.1 M NaOH solution to magnetic zirconium-iron oxide nanoparticle after adsorption equilibrium.Desorption time was 2 h,and adsorption temperature was 25 ± 26?.Results showed that after three cycles,removal efficiency ofphosphate by all as-obtained adsobents still remained above 70%. |
PDF Full Text Request