Competitive And Single Adsorption Of Arsenic And Phosphorus On La-MCM-41 Mesoporous Materials

In this study La doped mesoporous materials?La-MCM-41?,were hydrothermally synthesized and used to investigate the removal of arsenic and phosphorus by mesoporous materials under combined pollution conditions.The analysis methods including X-ray diffraction?XRD?,Brunauer-Emmett-Teller?BET?,and scanning electron microscope?SEM?were employed to pursue the change after the material were modified.Various factors such as pH,dosage and co-exist ions which affect As???and P adsorption were studied.The synchronous adsorption characteristics and competition discipline of As???and P were studied by adsorption kinetics experiment,adsorption equilibrium and regeneration experiments.Some conclusions can be drawn as follows:La doped MCM-41?La_xM41?was prepared by hydrothermal synthesis,a variety of analysis results show that La_xM41 had uniform hexagonal channels.The unmodified mesoporous materials has no absorption efficiency for As???and P,while the series of La-doped mesoporous materials?La_xM41?show great absorption efficiency for As???and P.The addition of La greatly improved the adsorption capacity of mesoporous materials for As???and P,and La_0.03-M41?La/Si=0.03?had the best adsorption effect.In the single adsorption system.The appropriate pH range for adsorption of As???and P is 4.0⁷.0.The effects of coexisting anions on As???and P adsorption is NO₃^-<Cl^-<F^-<SO₄^2-and SO₄^2-<CO₃^2-<SiO₃^2-<PO₄^3-respectively,and increase with the enhance of ionic strength.The Langmuir and Freundlich models were both used to simulate the sorption equilibrium,the results showed that the the Langmuir isotherm model fits much better than the Freundlich model.For kinetic study,the data could be described well by the second order dynamics equation.In the synchronous system.Freundlich models were both used to simulate the sorption equilibrium,the results showed that the the Langmuir isotherm model fits much better than the Freundlich model.For kinetic study,the data could be described well by the second order dynamics equation,and according to the Arrhenius equation,the adsorption activation energy of As???is slightly higher than P.The adsorption of As???and P was affected by the competition,which led to a large change in the adsorption amount,it was found that the adsorption capacity of As???and P by M3was 33.8 mg·g^-11 and 46.8 mg·g^-1,and P was in the dominant position under the condition of competitive adsorption.After adsorption,the adsorbent became rough,lower BET specific surface area and total pore volume and increased average pore diameter compared to the unmodified materials,and As???and P appeared in EDS spectra.According to adsorption data,the adsorption of As???and P is mainly through electrostatic and complexation attraction.And the adsorption capacity of As???and P decreased by15.55%and 14.8%after five Recyclability tests,but the adsorption capacity still maintained a high level,it shows that M3 is a promising adsorbent for As???and P removal.