The Study On Adsorption Removal Of Antimony And Phosphate Using Iron Oxide Coated Sand

Iron oxide coated sand (IOCS) synthesized by heating iron salt solution was characterized through SEM/EDAX, XRD, FTIR and surface analyzer. It was found that the particle size, the pore diameter, and the particle porosity of the iron oxide were about 100nm, 2×10-9m～9×10-9m, and 0.11%, respectively. The BET special surface area of IOCS was 5 times that of uncoated sand. The dominate phase of iron oxide on IOCS was hematite (α-Fe2O3). OH- groups ,water molecule , Fe-OH and Fe-O band were also identified on FTIR spectra at 3439 cm-1 ,1630cm-1, 1067 cm-1and 537 cm-1, respectively.Adsorption of antimony and phosphate on IOCS were performed by batch experiments and pilot column experiments under different conditions. Significantly improving adsorptive removal of Sb and P on IOCS were observed in batch experiments compared with that on raw quartz sand. The removal efficiency of Sb was independent of pH in the range of 4~9 and could be up to 95%, while removal efficiency of P was dependent on pH with the highest removal efficiency (88%) achieved at neutral solution, and the lowest removal efficiency ( 32%) appeared under basic condition. Competitive ions of NO3-, Cl-, Mn2+, Cu2+ had little effects on the adsorptive efficiency, capacity and rate of Sb on the IOCS. The same competitive ions had the same effects for P as did for Sb on IOCS. However, when Sb was as competitive ion, competitive adsorption occurred and the adsorptive efficiency, capacity and rate of P were reduced. Under three different test temperatures of (283K, 293K, and 313K), the adsorptive capacity and rate of Sb and P were increased as temperature increased. The isothermal data for both Sb and P were well fitted to the Langmuir adsorption isotherm, and the kinetic data for Sb and P could be well described using the second order rate model and the pseudo-second order rate model, respectively. Experimental breakthrough curves for Sb and P adsorbing in IOCS packed columns belonged to logistic curves. The volume of treated water increased with the increase of EBCT when the concentration of effluent reaches the limiting permissible concentration. The quantities of Sb and P adsorbed on IOCS were decreased with the depth increasing, and a majority of adsorbed Sb and P were within 10cm of the upper column. Adsorptivity of IOCS could be recovered by 60% when using 0.1mol/L NaOH to regenerate, and the reuse/regeneration three times had little...