7043

6585

كارشناسي ارشد

علوم خاك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1390

چهارده، 127ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

مهران شيرواني، حسين شريعتمداري

اميرحسين خوش گفتارمنش

17/7/91

مجيد افيوني، منوچهر حيدرپور

1396/09/19

كتابنامه

كشاورزي

مهندسي كشاورزي

ID6585

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Equilibrium Kinetic and Thermodynamic Studies of Zinc and Copper Sorption on Palygorskite and Sepiolite Parisa Khosravi p khosravikoocheksaraei@ ag iut ac ir March 2012 Department of Soil Science Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Assist Prof M Shirvani shirvani@cc iut ac irSupervisor Prof H Shariatmadari shariat@cc iut ac irAbstractIndustrialization and urbanization processes have resulted in environmental pollution through a widerange of chemicals over the past few decades and threat humans and other organisms health Heavymetals are the most important environmental pollutants that made soil and water polluted The mostcommon heavy metals in soil and wastewaters are zinc and copper Interactions between metal ions andsoil constituents can affect metal toxicity to plants and micro organisms and mobility to the groundwaters Sorption processes are the most significant chemical reactions of heavy metals in soil Due topresence of various clay mineral and organic matters in soil investigation of interaction between heavymetals and pure minerals can help to better understand the behavior of these metals in the soil This studyexamined interaction between zinc and copper with sepiolite and palygorskite as clay minerals that arefrequently found in arid and semiarid regions soils In order to determine sorption capacity of sepioliteand palygorskite for Zn and Cu based on isotherm models different concentrations of these ions wereequilibrated with the clays in 1 suspensions for 24 h Results showed that Langmuir and Freundlichmodels were the best models describing Cu sorption on sepiolite and palygorskite respectively Similarresults were obtained for Zn sorption on the minerals Considering the importance of thermodynamic datato determine the physicochemical behavior of copper and zinc in soil environment sorption of copper andzinc on sepiolite and palygorskite at four different temperatures 15 25 35 and 50 C were studied Negative values of Gibbs free energy changes and positive values of enthalpy changes refer tospontaneous and endothermic nature of copper and zinc sorption on sepiolite and palygorskite respectively Positive values of entropy changes of Cu and Zn sorption on the clay minerals are indicativeof system disorder increase due to structural changes Considering the thermodynamic parameters showedthat chemical sorption is probably the main mechanism of copper and zinc sorption on sepiolite butsorption of these metal ions by palygorskite is more physical and probably the diffusion is the keymechanism in this process In this study sorption kinetics of copper and zinc by sepiolite and palygorskitewas also investigated and the role of temperature on the quantity and rate of sorption was determined Several kinetic models were used to explain the rate constants of adsorption processes as affected bytemperature Elovich model was selected as the best model for describing Cu and Zn sorption kinetics onpalygorskite The Elovich parabolic and power function models indicated best fit for Zn sorption onpalygorskite in 15 25 and 35 C respectively Power function and parabolic models were selected as thebest models for describing sorption data of Zn and Cu on sepiolite Overall equilibrium kinetic andthermodynamic sorption parameters of Cu and Zn by palygorskite and sepiolite are greatly influenced bytemperature Key words Palygorskite Thermodynamic Zinc Sepiolite Kinetic Copper

مهران شيرواني، حسين شريعتمداري

اميرحسين خوش گفتارمنش

مجيد افيوني، منوچهر حيدرپور