The Research On Preparation And Adsorption Property Of Organic Modification Hydroxyapatite

In recent years, with the increase of the environmental protection consciousness ofpeople, the treatment of heavy metal pollution in the waste water has become a hot topic. Forexample, heavy metals from both industrial wastewater and domestic sewage are affecting thehealth of human directly or indirectly with different degrees. Nowadays, the developedmaterials for the removal of heavy metals existed many issues, such as high cost, poorremoval effect, serious pollution in the regeneration process and so on. Therefore, newmaterials with low cost, environment friendly and high-efficiency for removing heavy metalsare in urgent need of development.Naco-hydroapatite（HA） is a new environment function material which acquired greatattention in research with special crystal structure and the characteristics of high surface area,small particle size, simple preparation process and so on for the past few years. However, thedisadvantages of lower adsorption capacity and slower adsorption rate limited the applicationof it. In order to make the HA refining, homogenize, activation and improve the adsorptionproperty and harsh adsorption condition and expand the application scope, modificationresearch of HA has been carried out in rescent years.In this research, Nano HA was firstly synthesized by microemulsion-sol-gel methodthrough making the sol system of calcium nitrate, phosphate, ammonia water and ethanolsolubilized in the oil one of Triton X-100/n-amyl alcohol/cyclohexane. The synthesizedpowders were combined characterized by thermogravimetric/different thermal analysis（TG/DSC）, X-ray diffraction（XRD）, fourier transform infrared spectroscopy（FT-IR）, scanningelectron microscopy （SEM） and energy dispersion spectrum analysis（EDS） and the resultshowed that nano HA prepared by microemulsion-sol-gel method present the morphologies ofplate-like, sphere-like and rod-like. The particle size of HA is narrow and about in100nm orso. A small amount of CaHPO4was formed when the pH is9and it would be decomposedinto Ca₂P₂O₇at the temperature of700℃.When the pH value achieved to11, pure HA was acquired. With the improvement of calcination temperature, particle size and degree ofcrystallinity increase. Pure powders don’t decompose even at1000℃.Modification research of HA was carried out by using different organic polymermaterials as polyving akohol（PEG）, polyacrylamide（PAM） and stearic acid（SA） and themodified powders were also characterized by XRD、SEM、FTIR and so on. The result showedthat the modified HA by PEG belonged to physical modification. PEG improved thedispersive power of powders and the crystal structure was not destroyed. On the contrary, themodified HA by PAM and SA both belonged to chemical modification. As to the PAMmodified HA powders, the morphology is snowflake，the diffraction intensity of crystalsurface in the crystal structure was markedly changed and the hydrophilic ability enhancedand could be dispered in the water. As to the SA modified HA powders, the particles getlonger and the hydrophobic ability enhanced.The adsorption performance study and the discussion of adsorption mechanism of nonmodification and modification of the HA powders for the heavy metal Cu²⁺ion were carriedout. The result showed that the HA powders prepared by microemulsion-sol-gel method havestronger adsorption ability for Cu²⁺. The removal ability of organic modified HA is better thanthe unmodified HA. The chemical modified HA has stronger adsorption ability for Cu²⁺thanthe physical modified one and the removal rate can reach over ninety-eight percents. Theadsorption for Cu²⁺of HA powders and PEG-HA meets the secondary adsorption dynamicsand is mainly for the ion exchange. The adsorption for Cu²⁺of PAM-HA and SA-HA ismainly chelation therapy, ion exchange and internal diffusion.