Synthesis Of Mesoporous Silicon Aluminum And Ferric Oxides Through The Improved EISA Method

Mesoporous silica and complex have been prepared through the EISA method. Based on the EISA method, the NH₃·H₂O-EISA method was designed to control the hydrolysis rate of inorganic salts, through which, Al₂O₃ and Fe₂O₃ mesostructured materials were synthesized and mechanism was discussed.Mesoporous silica SBA-16 was prepared through the EISA method. Eosin Y/mesoporous SiO₂ complex was synthesized through the incorporation of Eosin Y in the system of preparing mesoporous silica. The results show that PL intensity of complex increase with the increase of Eosin Y and is much stronger than that of pure Eosin Y, which is attributed to decrease of the PL self-abruptly effect vanishing by the Eosin Y anchored in mesoporous silica structure. CdS with flower-like morphology was synthesized through the electro-deposition on the SBA-16 film/ITO substrate. Cd2+ and S₂O₃^2- could not diffuse into the mesopore and have reaction because the mesopore are less than 5 nm. CdS was grown on the surface of electrode with good PL property.For the preparation of ordered mesoporous Al₂O₃, aluminum alcoxides were often used as inorganic precursors, while inorganic salts were used as precursors. Long reaction time was needed and the hydrolysis rate was difficult to control. The NH₃·H₂O-EISA method was designed to control the hydrolysis rate. Mesoporous alumina materials with wormhole-like or 2D hexagonal mesopore structures have been synthesized using AlCl3·6H₂O as inorganic precursor and tri-block copolymer P123 or F127 as structure-directing agent through the designed NH₃·H₂O-EISA method. The results show thatγ-Al₂O₃ mesoporous material with 2D hexagonal mesopore structure and narrow pore size distribution has been obtained when calcination temperature is raised to 700 oC. The pore size is 7.6 nm, BET surface area is 200 m²Â·g^-1 and pore volume is 0.38 cm³Â·g^-1.Uniform and transparent mesoporous alumina thin film with tunable mesopore structures (2D hexagonal and 3D Fm3m cubic) have been synthesized in F127-EtOH-NH₃·H₂O-salts (EsNs) system by changing the aging time of the sol through the NH₃·H₂O-EISA method. Mesoporous materials have narrow pore size distribution, relatively large BET surface area and highly ordered mesopore structures. According to the results of experiments, the rule of mesopore structures'change was found and formation mechanism of ordered mesoporous alumina thin films with tunable mesopore structures is proposed. The ability to easily control the mesophases of alumina layers within a short time provides distinct advantages over previously reported synthesis procedures. In our strategy, formation mechanism of the synthesized mesoporous alumina thin films with tunable mesopore structures was summarized as follows: Hydrogen bond may be formed between EO of surfactant and NH₃·H₂O, which controls the dissociation rate of NH₃·H₂O. The hydrolysis of inorganic precursors can be controlled to provide relatively smaller aluminum oxo-clusters, which offer probability for assembly with surfactants; The EISA method belongs to LC template mechanism and volatile solvents evaporate at some temprerature and relative humidity, which makes the micelles assemble to different structures and surfactant can have assembly with aluminum oxo-clusters to form different mesostructures; There is strong interaction between surfactant and aluminum oxo-clusters which makes mesophase keep with removal of surfactant. Mesoporousγorα,δ-Al₂O₃ can be obtained through changing calcination temperature.Using the NH₃·H₂O-EISA method, Fe(NO3)3·9H₂O instead of aluminum inorganic salts as inorganic precursor and F127 as structure-directing agent, wormlikeα-Fe₂O₃ were synthesized. The particle size is 17.36³3.57 nm, BET surface area is 20.08⁴5.11 m²Â·g^-1 and film thickness is 360.5³70.1 nm The study shows that crystalline particle size of samples increases, BET surface area decreases and film thickness increases with the increase of calcined temperature. The formation mechanism was discussed. The study shows the NH₃·H₂O-EISA method has general application in controlling hydrolysis rate of inorganic salts. The samples under different calcined temperature were tested to remove heavy metal ion [Cr (VI)]. The removal capacity of samples is 4.30⁵.03 mg·g(Cat.)^-1,which was better than that of commercialα-Fe₂O₃ [0.70 mg·g(Cat.)^-1]. The better performances are attributed to relatively higher surface area and porous structure of wormlikeα-Fe₂O₃, which provide novel materials in water treatment.