سنتز نانو كريستال زئوليت هاي ZSM-5 و مورد ينيت به روش ميكروامولسيون-فراصوت و بررسي جذب+ pb2 توسط زئوليت ZSM-5 سنتز شده

چكيده انگليسي :

Synthesis of ZSM 5 and Mordenite zeolite nanocrystals using Microemulsion ultrasound technique and Study of its Adsorption by Pb 2 Homa Fardi Emamzadeh Hashemi Homa fardi@yahoo com Date of Submission 2013 12 24 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi K shams@cc iut ac ir Abstract Zeolites are porous crystalline materials with various attractive properties that are widely used in chemical process industries because of their adsorption capacity thermal stability ion exchange strong acidity high surface area and molecular sieving Today synthetic zeolites are used commercially more often than natural zeolites due to the purity of crystalline products and the uniformity of particles and pore sizes Short crystallization time has always been pursued from the commercial viewpoint since it is associated with high synthesis efficiency low energy consumption and thus low production cost Pore size of zeolite is a property that differs between different types of zeolites and improvement tuning of pore size of zeolites has recently received much attention Size of zeolite crystalline and uniformity of zeolite grains are properties that are significant in synthesis and application of these materials Uniform small sized zeolites show better catalytic and adsorptive properties than large sized ones because of increased surface area increased ion exchange capacity decreased diffusion limitations and improvement of mass transfer Crystal size distribution of zeolites is influenced by different parameters such as initial chemical composition of precursors the silicon and aluminum source temperature time of crystallization pH of solution processes of ageing stirring and use of surfactants during the synthesis of the zeolites Microemulsions usually consist of small droplets of water in oil or oil in water formed by the dispersion in continuous oil or water phases inside of a surfactant layer Microemulsions are generally prepared by using a surfactant a co surfactant an oil phase and water phase Under appropriate conditions a variety of reactants can be introduced into the nanometer sized aqueous domains for reaction leading to materials with controlled size and shape There are two advantages in using microemulsions as a medium for zeolite growth during the synthesis process On one hand the microemulsion with small aqueous domains can be viewed as micro nanoreactors for synthesis of zeolite nanocrystals and on the other hand the surfactant will coordinate to the crystallographic faces of the growing crystals and affect the growth of the zeolite crystals In this research project ZSM 5 and mordinite nanocrystals were synthesized using sodium silicate as the silica source and aluminum sulfate as the source of alumina via nanoemulsion ultrasound method and the effects of the pertinent parameters such as concentration of the surfactant concentration of the aluminosilicate gel and intensity of the ultrasound on nanostructural modifications were investigated Pb2 adsorption tests were performed to determine the effect of nanoemulsion ultrasound technique on adsorption property of ZSM 5 zeolite XRD SEM and FTIR were utilized to study and characterize crystal phases and crystalinity morphology of crystals and phase purity of ZSM 5 and mordenite prepared samples The celebrated Scherer equation was used to determine the crystalline size of samples Results show that the nanoemulsion ultrasound technique compared with the conventional hydrothermal synthesis allows rapid crystallization of both ZSM 5 and mordenite and leads into much smaller crystals and zeolite grains with smaller and uniform morphologies Results show that the crystals and grain sizes of ZSM 5 samples prepared by nanoemulsion ultrasound technique compared with samples produced via the conventional method are reduced to from 113 nm to 17nm and from 39 m to 1 5 m respectively These results for the case of mordenite ze

فردي امامزاده هاشمي، هما

سنتز نانو كريستال زئوليت هاي ZSM-5 و مورد ينيت به روش ميكروامولسيون-فراصوت و بررسي جذب+ pb2 توسط زئوليت ZSM-5 سنتز شده

ماده فعال سطحي , نانو امولسيون , امواج فراصوتي , هم دماي فرندليچ