The poly(ethyleneimine) (PEI)-functionalized organic-inorganic hybrid silica was prepared by a hydrothermal-assisted surface grafting technique. Static adsorption experiment results showed that PEI-functionalized hybrid silica had high static adsorption capacity of 68.1 mg g À1 , which was 1.3 times as much as that of the sorbents by conventional heating method. PEI-functionalized hybrid silica displayed stable adsorption ability for Pb(II) ions in the range of pH 4-8. An equilibrium state was reached within 30 min. Freundlich and Langmuir adsorption isotherm models were used to fit the equilibrium data, and it was found that the Langmuir adsorption model provided good fit. Kinetic studies indicated that the adsorption followed a pseudo-second-order model. Various thermodynamic parameters, such as ΔG o , ΔH o and ΔS o , were evaluated with results indicating that this system was a spontaneous and endothermic process. The results indicated that PEIfunctionalized hybrid silica could be employed as an effective material for the adsorption of Pb(II) ions from aqueous solutions.

The new compound Ag12(OH)2(H2O)4KNa (P2Mo5O23)2 is synthesized by the liquid diffusion method at the interface between an ethanolic AgNO3 solution and an aqueous solutions of Na2MoO4 and NaH2PO4 (pH 3 for both solutions, 25 °C, 2 weeks; 35% yield).