¦¡-fe <sub> 2 </ Sub> O <sub> 3 </ Sub>, ¦Ãal <sub> 2 </ Sub> O <sub> 3 </ Sub>, Sio <sub> 2 </ Sub> Interfacial Chemistry Of Single Nanoparticles And Its Hybrid System Behavior

Fe₂O₃,Al₂O₃ and SiO₂ are common substances in soil. The physical, chemical reactions occurring on the surfaces of Fe₂O₃, Al₂O₃ and SiO₂ such as acid-base, adsorption, desorption, complexation, precipitation, dissolution, flocculation, and others largely determine the destination of pollutants in water and soil. However, the impurities, contained in a multi-component system such as soil vary from region to region, taking natural soil as the object to study the fundamental properties of the solid-liquid interface is lacking of representitive characterestic. Synthetic silica, iron oxide, alumina nano-materials are pure and their composition, structure can be controlled. Characteristics of their micro structure and composition can change their metal ions adsorption capacities and selectivities. Therefore, study of adsorption properties of synthetic Fe₂O₃, Al₂O₃ and SiO₂ can provide better data on the adsorption of complex systems and the basic theories for rational use of industrial waste.In this paper,α-Fe₂O₃,γ-Al₂O₃ and SiO₂ nano-particles were prepared from the precursors of TEOS, aluminum nitrate, ferric nitrate by sol– gel and precipitation methods, and in some cases in combination with using templates. The synthetic samples were characterized by TEM, XRD, N2 adsorption/desorption and IR methods. The results showed that the preparedα-Fe₂O₃,γ-Al₂O₃ and SiO₂ all have large specific surface areas.Fe₂O₃ were prepared from the precursors of Fe³⁺ nitrate, chloride and sulfate. The zero-valent iron was synthesized by the reduction of iron (â…¡) salts using NaBH4. The nano-iron oxides were synthesized by the reaction of nano zero-valent iron with hydroxide of alkali metal (LiOH, NaOH, KOH). The products were characterized by advanced XRD, BET, IR, TEM techniques. The result shows that the surface area of iron oxide prepared using nitrate, chlorate and sulfate salts as precursor are in the order of NO3- > Cl- >SO42-.respectively, i.e. the anti-sintering property is in the same order. According to solution chemistry reaction, the testing results and reaction mechanism of samples were evaluated using Medusa software;as Li⁺, Na⁺, K⁺ radius increases, the corresponding surface area of Fe₂O₃ prepared is increasing gradually.At length, the surface acid-base and complexation behaviors of heavy metal ions as well as concerning equilibrium constants in the aqueous suspensions ofα-Fe₂O₃,γ-Al₂O₃,SiO₂ and their mixed systems were systematically studied by potentiometric titration technique in combination with computer calculation using constant capacitance model (CCM). The experimental results and calculations revealed that the surface chemical reactions in the mixed system were not the same as the sum of their individual single system but possessing complicated mutual interaction among them. The surface chemical reaction models and relevant equilibrium constants in the mixed system were established as follows: forα-Fe₂O₃/γ-Al₂O₃ mixed system≡XOH⁺H⁺≡XOH²⁺ log K1=4.04≡XOH≡XO-+H⁺ log K2=-9.20 forα-Fe₂O₃/γ-Al₂O₃/SiO₂ mixed system≡XOH⁺H⁺≡XOH²⁺ log K1=4.23≡XOH≡XO-+H⁺ logK2=-8.41The surface complexation models and constants of Cu²⁺,Pb²⁺,Zn²⁺ in the mixed system can be well described by following reaction: inα-Fe₂O₃/γ-Al₂O₃ mixed system≡XOH⁺M²⁺≡XOM++H⁺ with log K of -2.50, -2.25, -3.75 where M represents Cu²⁺, Pb²⁺, Zn²⁺ respectively. inα-Fe₂O₃/γ-Al₂O₃/SiO₂ mixed system≡XOH⁺M²⁺≡XOM++H⁺ with log K of -2.20, -1.90, -3.20 where M represents Cu²⁺, Pb²⁺, Zn²⁺ respectively.