Preparation Of Amion-modified Porous Silica And Adsorption Of The Heavy Metal Ions

The traditional adsorbent adsorption capacity is limited, and looking for a kind of newefficient adsorbent has becoming the research focus of the new adsorbent materials in thefield. Self loading ordered porous silica （Assembled periodic mesoporous silicates, APMSs） isa kind of mesoporous molecular sieves, highly ordered adjustable pore structure and moreuniform pore size distribution, but it is not ideal on adsorption of metal ion in the water, it isneeded surface functional modification, in order to improve the ablility of the adsorption ofheavy metal ions. Therefore, the regularly, resizable buffet loaded ordered porous silicawere prepared and the amine-modified APMSs has high adsorption capacity and selectivityP123was used as the template agent in this experiment, tetraethyl orthosilicate （TEOS）used as the silicon source, the mesoporous silica was prepared by the removal of the templateagent and for the raw material. To increase its adsorption properties of heavy metal ions in thesolution, the hydrothermal synthesis-post-graft preparing amine-modified porous silica werechoiced, and transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption and infrared spectroscopy were used to characterized the structures. By the methodof batch experiments, the adsorption time,initial pH value, adsorbent dosage and temperatureand other factors, combined with the aqueous solution in the Cu²⁺, Cd²⁺, Pb²⁺ adsorptionof Zeta potential and XPS analysis of its adsorption were discussed.（1）The3N-APMSs could be prepared by the method of copolymerization andpost-grafting. By XRD analysis, indicating that the the synthetic of APMSs is SBA-15. Thecopolymerization method is conducive to the amine groups in the pores of the self-loadingorientation Ordering. Two kinds of3N-APMSs through the copolymerization method bothhave a better adsorption capacity on Cu²⁺. The3N-APMSs on the adsorption of Cu²⁺wouldproduce a certain steric effect, but12hours later, both of theirs adsorption rate on Cu²⁺aremore than99.5%.0.01mol L-1EDTA and0.1mol L-1HCl solution are the3N-APMSsappropriate regenerant.（2） By the method of posting-graft hydrothermal synthesis method, amine-modifiedAPMSs are prepared. By the surface parameters, XRD and infrared spectroscopy shows thatAPMSs are SBA-15, the amine functionality has not changed the structure of APMSs, just play the role of modification.（3） N-APMSs,2N-APMSs and3N-APMSs adsorbtion of Cd²⁺adsorption rate is greaterthan the rate of adsorption of Pb²⁺. Three adsorbents reaction on Cd²⁺can equal in30minsbut absorbtion on Pb²⁺needs90min to reach equilibrium. After amine-modified, theadsorption capacity of Cd²⁺, Pb²⁺has significantly increased. With the increase of pH, theamine-modified APMSs adsorptio on Cd²⁺, Pb²⁺are increased. and become stable in pH=2.0or3.49. With the increase of the amount of adsorbents, the adsorbent of Cd²⁺adsorptionrate are increasing, and reach the equilibrium with the adsorbent dosage of7.5to20mg,butCd²⁺adsorption rates are reducing with the increasing of the amount of adsorbents, theabsorption of Pb²⁺can reach equilibrium between10to30mg. As the increase of Elevatedionic strength, the amount of adsorption of Cd²⁺, Pb²⁺is decreased.（4）The mount of adsorption of APMSs on Cd²⁺, Pb²⁺increased with initial concentrationincreasing and at high concentrations, the change becomes slowly and constant. Theadsorption isotherms can described by the Langmuir model, the adsorption process isendothermic and spontaneous process, the temparture incresing is good to the adsorption ofheavy metal ions in water.（5） The thermodynamic parameters ΔG0, ΔH0and ΔS0, calculations show that theadsorption process is endothermic and spontaneous process. The amino of modified APMSson adsorption mechanism of heavy metal ions include physical adsorption, ion exchangingand complexation reactions and process adsorption process. The polyamine modified APMSsis a kind of adsorbent of good adsorption capacity,and has broad application prospects.