The Application Of Glass Derived Hydroxyapatite (G-HAP) On Water Treatment

Environmental pollution has always been a threat to human health. Development of wastewater treatment technology not only is benefit for environmental protection but also promote industrial development and human society progress. Compared with traditional methods, hydroxyapatite, as a new environmental material, which has a lot of advantages such as high chemical activity, biological stability, easy to be regenerated and no secondary pollution et al., is of great practical significance for environmental protection and clean.In this paper, a kind of glass derived hydroxyapatite (G-HAP) powder is prepared which can remove fluoride and lead ions in aqueous solutions effectively. The results show that the G-HAP has better adsorption performance than commercial micro and nano hydroxyapatite under the same conditions. The adsorption capacity is 17.35mg/g and adsorption rate can reach 86.7% when 5g/L,<100μm HAP is added to the NaF solutions for 12h with the concentration of 100mg/L and the initial pH value of 6.72 at 35℃. The adsorption kinetics and isotherms for fluoride ions can be well fitted by the second order kinetic and the Freundlich isotherm model. The adsorption capacity is 399.99mg/g and adsorption rate can reach 99.99% when 5g/L,<100μm of the G-HAP powder is added to the Pb(NO3)2 solutions for 2h with the concentration of 2000mg/L and the initial pH value of 7 at 35℃. The adsorption kinetics for lead ions can be well fitted by the second order kinetic. The adsorption of the lead ions is dominated by ion exchange theory at higher pH above 3, by the dissolution-precipitation theory at the lower pH under 3.The porous G-HAP matrix is prepared by a salt sintering method. The results show that the matrix has best performance with porosity of 75.67% and compressive strength of 0.944MPa when the salt (sodium chloride)/<100μm glass powder mixed by volume ratio of 40:60 is sintered at 580℃for 15 minutes. The porous matrix can adsorb lead ions, copper ions, and copper-fluoride mixed ions effectively.The porous G-HAP matrix residue is conducted by toxicity dissolution experiment. The results show that the matrix after adsorption is fairly stable according to relevant state regulations.