اصلاح مواد نانو متخلخل سيليسي ﴿SBA-15﴾ و كاربرد آن جهت حذف نيترات از محلول هاي آبي

چكيده انگليسي :

Modification of Nanoporous Silica SBA 15 and Its Application for Nitrate Removal from Aqueous Solutions Marzieh Ghasemi M gh1011@yahoo com Date of Submission 06 04 2011 Department of Civil and Environmental Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Majid Sartaj msartaj@yahoo com Alireza Badiei abadiei@khayam ut ac ir Abstract Several nitrogen containing compounds such as nitrate have been found as common pollutants in drinking water Nitrate can cause several environmental problems Excessive amount of nitrate in water can stimulate eutrophication which is the term refers to abundance of aquatic plants growth of algae and depletion of dissolved oxygen Furthermore the presence of nitrate ions in drinking water is a potential public health hazard including infant methaemoglobinaemia Among current techniques for nitrate removal adsorption methods are promising because they allow simple and economical operation resulting in less sludge production and disposal problems On the other hand during the last two decades the so called mesostructured materials such as SBA 15 have received much attention due to their specific features like enormous surface area So the present wok is intended to study the adsorption of nitrate from aqueous solutions using modified SBA 15 At first SBA 15 was prepared and calcinated according to the synthesis strategy which has been introduced by Zhao and co workers Characterization techniques such as X Ray Diffraction and Adsorption Desorption Nitrogen were used to investigate physicochemical characteristics of SBA 15 X Ray Diffraction XRD patterns of prepared samples confirm the structure of the mesoporous materials The SBET and VTotal which were calculated using BJH and BET formula were respectively 659 14m2 g and 0 88cm3 g In order to modify the synthesized structures SBA 15 was introduced to solutions containing different amounts of Lanthanum precursor so different La SBA 15 mass ratios were prepared Initial experiments showed that nitrate removal was not effective for Lax SBA 15 In the next step adsorption of nitrate anions from aqueous solutions was investigated on ammonium functionalized SBA 15 This adsorbent was prepared via post synthesis grafting method using aminopropyltriethoxysilane followed by acidification in HCL solution The results showed that NH3 SBA 15 had a great nitrate adsorption capacity X Ray Diffraction XRD patterns of NH2 SBA 15 confirm the structure of the mesoporous materials The SBET and VTotal for NH2 SBA 15 were respectively 313 49m2 g and 0 41cm3 g According to further experiments equilibrium time were found to be 10 min for nitrate removal by this adsorbent and a good agreement of the experimental data with the second order kinetic model was observed for NH3 SBA 15 The values for the Langmuir R2 0 98 and Frendlich isotherm R2 0 92 constants indicate the adequacy of these isotherms model to explain the adsorption process by NH3 SBA 15 Extra experiments were done in order to find the effect of operating conditions such as initial nitrate concentration Adsorbent dose pH and temperature Experimental data showed that Increase in adsorbent dosage increased the percent removal of nitrate which is due to the increase in adsorbent surface area Increasing initial concentration also increased the qe which is the monolayer capacity of the adsorbent pH value did affect the nitrate removal significantly and the most effective

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اصلاح مواد نانو متخلخل سيليسي ﴿SBA-15﴾ و كاربرد آن جهت حذف نيترات از محلول هاي آبي

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