| In recent years,with the improvement of living standard and strengthening of environmental protection consciousness,the treatment of heavy metal ions in industrial wastewater becomes a hot topic.Hydroxyapatite(HA)has a unique crystal structure,which leads HA having a widely compatibility and stationarity adsorption,and the exchange capacity of HA is relatively strong.In addition,HA also has the advantages of simple preparation process,low cost and so on.Therefore,HA becomes a new kind of environment function material,and is used to remove heavy metal ions from the waste water and the soil.However,HA powders are not convenient for recycling,limiting its practical application.This paper proposed a method in which HA will obtains the magnetic property by combining with Fe3O4 magnetic nanoparticles.The combined power is convenient to recycle under the additional magnetic field.Taking Ca(NO3)2·4H2O and(NH4)2HPO4 aqueous solution as the precursor,and also a high concentration of sodium dodecyl sulfate(SDS)as the template,the nano-HA may be prepared by the hydrothermal method.The X-ray diffraction,scanning electron microscopy(SEM),Fourier Transform Infrared Spectroscopy(FTIR),and other methods were used to characterize the nano-HA.The results show that the rodlike nano-HA distributed uniformly.When pH is 7,a small amount of CaHPO4(DCP)is generated with mixed phases;When the p H is 11,the pure HA can be prepared.Compared with the sintering condition under 80?and 600?,the powder obtained by 600? has a higher crystallinity and larger grain size.With FeCl2.4H2 O and FeCl3.6H2 O as the precursor,and NaOH as precipitant,the nano ferroferric oxide(Fe3O4)was synthesized by coprecipitation process.The powers were characterized by XRD,SEM and so on.The results indicate thatnano-sized Fe3O4 magnetic particles are obtained.Particles distribute uniformly and the agglomerate phenomenon is not obvious.In this dissertation,the magnetic Fe3O4/HA composite particles were prepared by two ways.One is mechanical mixing method and another is in situ synthesis method.XRD,SEM,powder magnetic adsorption test were used to analyze it.The results show that the magnetic Fe3O4/HA composite particles can be obtained by the two methods.By mechanical mixing method the power's aggregation is relatively serious,and with the increase of Fe3O4 content,the aggregation becomes more obviously.The particle size distributed uniformity by in situ synthesis method.With the mass ratio between Fe3O4 and HA changing from 1:1 to 1:3,the crystallinity of the powder is the higher,powder dispersion is better,and grain size is bigger.With the reaction temperature increasing from 60 ? to 120 ?,the crystallinity becomes higher and the crystalline size becomes larger.When the reaction temperature reaches 180 ?,the Fe3O4 was oxidized to Fe2O3,which leads to the power losing magnetism.The adsorption experiments of HA,Fe3O4,and the magnetic Fe3O4/HA composite particles to heavy metal Cu2+ ions were investigated.The concentration of Cu2+ ions is 20mg/L.The results show that the magnetic Fe3O4/HA composite particles by the two methods all have the ability to remove Cu2+ ions.The removal efficiency of magnetic Fe3O4/HA by in-situ is more higher than by the mechanical mixing one and may reaches over 95%.Compareing the adsorption capacity of the powers by the two methods,the one prepared by in-situ is 9.54mg/g and higher than by the mechanical mixing one.Therefore,the adsorption property of magnetic Fe3O4/HA producted by in situ is better than that by mechanical mixing magnetic. |
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