سنتز نانو فتو كاتاليست هيبريدي دي اكسيد تيتانيوم- نانو لوله كربني و بررسي حذف رنگ هاي آزو

چكيده انگليسي :

88 Synthesis of Titanium Dioxide Carbon Nanotube Hybrid Nanophotocatalyst and Study on Removal of Azo Dyes Maryam Rajabi Vinicheh m rajabivinicheh@ce iut ac ir Date of Submission 10 04 2012 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Seyyed Mohammad Ghoreishi ghoreshi@cc iut ac ir Alimorad Rashidi rashidiam@ripi irAbstractAmong the methods for water and wastewater treatment and decreasing their contaminants photocatalyticdegradation by semiconductors is a new effective rapid and destructive technique for this purpose and TiO2is considered to be one of the best candidate photocatalysts On the other hand carbon nanotube inorganichybrid materials are a new class of functional materials that has gained tremendous interest in recent yearsdue to their exceptional optical mechanical electrical and thermal properties The main objectives of thispaper are synthesis of TiO2 CNT carbon nanotube hybrid investigation of pristine CNT coating with TiO2 photocatalytic appliction of this hybrid and the effect of CNT on synthesis and photocatalytic performance ofTiO2 TiO2 CNT hybrids were prepared via the sol gel process using pristine MWCNT and functionalizedMWCNT as templates titanium isopropoxide as organic titanium precursor and benzyl alcohol as surfactantand linking agent Also TiO2 was prepared in the same method without adding CNT and benzyl alcohol Inall cases heat treatment was carried out in order to remove any solvents and to crystallise the initialamorphous titania and obtain the desired crystalline phase The synthesized materials were characterized byXRD FE SEM UV Visible and FTIR XRD results revealed that the crystalline structure of pure TiO2 andTiO2 coated on the surface of MWNTs were anatase The anatase crystallite size for characteristic peak wasobtained equal to 20 7 10 8 and 8 3 for pure TiO2 TiO2 pristine CNT and TiO2 functionalized CNT respectively FE SEM confirmed the presence of a layer of TiO2 coating MWNTs with thickness in the rangeof 3 45 nanometer in both hybrids initial CNT diameters 10 30 nanometer It was demonstrated that theMWCNTs surface were decorated with well dispersed TiO2 nanoparticles FTIR confirmed the presence ofTi O band which indicated the formation of titania structure The UV Vis absorbance spectrum of theresultant pure TiO2 and TiO2 MWCNT hybrids extended to the whole UV Visible region and the hybridshad more absorbtion intensity at higher wavelengths in visible region than pure TiO2 In order to investigatethe photocatalytic activity photodegradation experiments were carried out using TiO2 and TiO2 functionalized CNT as photocatalysts and azo dye acid blue 92 aqueous solution at low concentration asmodel for organic contamination in wastewater The experimental results showed that photocatalysts had anegligible effect when they used on their own without UV light and adsorption was low With initial dyeconcentration 20 ppm the photocatalyst dosage 80 ppm and pH 7 35 and 48 3 decolourization wasobserved for TiO2 and TiO2 CNT hybrid respectively The effect of some parameters such as pH the amountof photocatalyst and initial dye concentration was also examined employing TiO2 functinalized CNT hybridas photocatalyst The effect of initial concentration was obtained with different initial concentrations 10 25ppm To study the effect of photocatalyst dosage the photocatalyst loading in the dispersion was variedbetween 40 120 ppm The effect of pH of the solution was examined in the pH range of 2 12 The bestresults for decolourization was obtained in acidic solution pH 2 initial dye concentration 15 ppm photocatalyst dosage 80 ppm and was equal to 93 5 after 120 min The amount of dye adsorbed was higherin acidic medium and decreased with increasing initial pH In different cases the semi log plot of dyeconcentration versus time was linear suggesting first order reaction First order reaction rate constant wascalculated equal to

رجبي وينيچه، مريم

سنتز نانو فتو كاتاليست هيبريدي دي اكسيد تيتانيوم- نانو لوله كربني و بررسي حذف رنگ هاي آزو

اسيد بلو92