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دراسة حركية وثرموديناميكية لامتزاز صبغة اخضر ملكيت على سطح البنتونايت والبنتونايت المعدل العراقي == Kinetic and thermodynamic study for adsorption Malachite Green dye on the surface bentonite and bentonite modified Iraqi
Author name:
عمر كريم نجم
Supervisor name:
تقي الدين عبد الهادي حمدان
General topic:
Chemistry
Specific topic:
Chemistry
Degree:
Master
University:
University of Baghdad
Language:
Arabic
University location:
Baghdad
First pages:
25T1823 - p.pdf
Abstract:
In this study a new prepared composite polymeric - clay material through growing the polymer (Ethylene terephthalate) among the layers of the crystal level (001) of bentonite. This process characterized using (FT - IR) spectroscopy and X - ray diffraction (X - RD), the surface prepared morphology was studied using atomic force microscope (AFM) and scanning electron microscope )SEM(, and it was compared with the original bentonite.The results showed that the growth of polymer was accord among clay layers leads to the separation of the linked layers of the (001) crystal plane in a manner leads to isolate they in the form of two - dimensional flakes their structural units are the layers of silica tetrahedral and alumina octahedral.The prepared surface was used to study of the adsorption of dye (Malachite Green) from water at the temperatures (293,298,303,308,313K), the study included kinetic study thermodynamic process and for purpose of comparison adsorption was studied in the same previous conditions on the surface of the modified bentonite .contact time measurements showed that the adsorption of (Malachite Green) on bentonite and modified bentonite takes the values on the surface of bentonite (30 min) at (293,303,313 K) and (45 min) when (298,308 K) and on the surface of modified bentonite takes (120,60,50,45,60 min) at (298,303,308,313, 293 K) respectively.Used non - linear model (exponential form of Lagergreen equation) in the kinetic study of adsorption on the two surfaces, the results showed that the non - linear model gives a more comprehensive description of the kinetics of adsorption and allowed to take cases fluctuating around an equilibrium point within theaccounts and gives more sense for the value of the amount of the adsorbent (????e) at equilibrium on the both surfaces. The general result of kinetic studies show that the adsorption rate constant of the first order on the surface of bentonite was larger from that on the modified surface (adsorption on the surface of bentonite faster), also, the amount of adsorption (????e) values on the surface of bentonite be the largest from which on the modified surface in all temperatures.It was calculated the activation energies (Ea.) and frequency factors (A) by Ahrens’s equation for the adsorption of (Malachite Green) on both surfaces were as follow because closure of the polymer to adsorption sites. the sense that the presence of polymer worked to reduce the chance of collision leading to adsorption.The treatment thermodynamic functions of adsorption were treated by three stages Certified on constant equilibrium and concentrationThe first stage : When concentrations low describe the balance of the process of adsorption at the initial stages.The second stage : When concentration of a particular be similar to factor distribution between stages (Hnry).The third stage : When the maximum concentration of a particular, according to model Langmuir describes thermodynamic the adsorption on the basis of the proportion of adsorption for concentration saturation.As it found that the enthalpy (Δ????) be (Endothermic) on surfaces and in temperatures all, Δ????????????????<Δ???????????????????? because the bentonite surface is heterogeneous, and state Δ???????? because saturate most of these pores by adsorbate particles, Δ???????? the enthalpy value is biggest because the adsorption get in to depth pores for adsorption surface and need to high energy, but the surface modified low because the adsorption process is slow.Δ????0 ????????????<Δ????0 ???????????????? because the adsorbent particle that carried into the surface increases the likelihood arranges particle adsorbent (Malachite Green), Δ???????? ????????????>Δ???????? ???????????????? because the polymer work on random, Δ???????? ????????????<Δ???????? ???????????????? because of the number of adsorption sites than causing an increase in the arrange particles (Malachite Green).We note values Δ???? are more spontaneuos on the surface of bentointe from modified at all stage, and less spontaneuos process the decrease in number of sites vacancies at the evolution of adsorption of stage start to the growth and then finish.
