Search for: nanoporous-silica
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    Study of Micropollutants Adsorption from Water by Nanoporous Silica Aerogels

    , M.Sc. Thesis Sharif University of Technology Abdoli, Majid (Author) ; Bastani, Daruoosh (Supervisor) ; Bargozin, Hassan (Co-Advisor)
    Phenolic compounds are important environmental pollutants that the removal and separation of them from the water and industrial wastewater especially in the oil industry is essential before entering the environment. In the present study, the removal efficiency of the adsorbent silica aerogel 4-Chlorophenol and 4-Bromophenol as phenolic compounds from aqueous solution was surveyed. In this research, the effects of various factors such as contact time, pH, and initial concentration of the pollutant and the adsorbent on the adsorption were studied. It was observed that there is a large amount of adsorption in acidic pH and this amount increases by incrementing the concentration of the... 

    Study of 131I Adsorption Behavior on Nanoporous Silicates Modified with Elements of Ag, Cu, Zn, Ni

    , M.Sc. Thesis Sharif University of Technology Rohani, Ramezan (Author) ; Sayf Kordi, Ali Akbar (Supervisor) ; Sepehrian, Hamid (Supervisor)
    One of the common methods used for treatment of gaseous radioactive wastes in nuclear waste management is adsorption process. Nanoporous materials have found great utility as sorption media because of their large internal surface area and more adsorption sites than other adsorbents, which caused the increasing attention of researchers to use them in the nuclear waste management. Hence in this study, the surface of nanoporous silicates of SBA-15 and MCM-41 modified with d-block elements of the periodic table such as silver, copper, zinc and nickel by wet impregnation method. After characterization by different techniques such as X-ray diffraction, nitrogen gas porosimetry, Fourier... 

    Studies on the recovery of uranium from nuclear industrial effluent using nanoporous silica adsorbent

    , Article International Journal of Environmental Science and Technology ; Volume 9, Issue 4 , October , 2012 , Pages 629-636 ; 17351472 (ISSN) Sepehrian, H ; Samadfam, M ; Asadi, Z ; Sharif University of Technology
    Springer  2012
    In this paper, the sorption of uranium onto nanoporous silica adsorbent in the presence of nitrate, sulfate, chloride, fluoride and phosphate was studied. The effect of contact time between the nanoporous sorbent and aqueous solution, pH and initial concentration of uranium was also investigated. Uranium sorption onto nanoporous silica adsorbent is a very fast process as sorption rate increases with pH increment. Optimum pH for uranium sorption was 4-8. Experimental sorption isotherm is successfully described by Langmuir and Freundlich models. The results obtained by batch experiments showed that the presence of high concentration of nitrate, sulfate, chloride and phosphate anions alone had... 

    Vanadium–Schiff base complex-functionalized SBA-15 as a heterogeneous catalyst: synthesis, characterization and application in pharmaceutical sulfoxidation of sulfids

    , Article Research on Chemical Intermediates ; Volume 42, Issue 12 , 2016 , Pages 8201-8215 ; 09226168 (ISSN) Taghizadeh, M. J ; Karimi, H ; Sadeghi Abandansari, H ; Sharif University of Technology
    Springer Netherlands 
    VO2(picolinichydrazone) complex as a catalyst was stabilized on a SBA-15 mesoporous silica as a catalytic support by using (3-chloropropyl)triethoxysilane as a connector. SBA-15 is nanoporous and has a high ratio of surface area to volume. The immobilization of a metal–Schiff base complex to the surface area of SBA-15 can improve its catalytic effects by increasing the catalytic surface area. Unlike homogeneous catalysts, heterogeneous catalysts can be recovered and reused several times without any significant loss of catalytic activity. A vanadium–Schiff base complex-functionalized SBA-15 was synthesized by covalency connected by a pre-synthesised VO2(picolinichydrazone) complex to... 

    Persistent superhydrophilicity of sol-gel derived nanoporous silica thin films

    , Article Journal of Physics D: Applied Physics ; Volume 42, Issue 2 , 2009 ; 00223727 (ISSN) Ganjoo, S ; Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    In this investigation, sol-gel synthesized nanoporous silica thin films, annealed at different temperatures, with long time superhydrophilic property have been studied. Two kinds of sol-gel silica thin films were fabricated by dip-coating of glass substrates in two different solutions; with low and high water. The transparent coated films were dried at 100 °C and then annealed in a temperature range of 200-500 °C. The average water contact angle of the silica films prepared with low water content and annealed at 300 °C measured about 5° for a long time (6 months) without any UV irradiation. Instead, adding water into the sol resulted in silica films with an average water contact angle...