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Article
Utilization of Thomas model to predict the breakthrough curves for adsorption and ion exchange

Authors: Shahlaa E. Ebrahim --- Yasmen A. Mustafa
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2010 Volume: 16 Issue: 4 Pages: 6206 -6223
Publisher: Baghdad University جامعة بغداد

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Abstract

Fixed bed sorption processes such as adsorption and ion exchange do not operate at steady state. The design equations are differential that usually require numerical methods to solve. Thomas gives a general analytical solution for these equations. It is based on second-order reaction kinetics and the assumption of Langmuir isotherm. Computer program for the solution of Thomas model was designed using MATLAB 7.0. Four sets of experimental data are tested to show the capability of Thomas model to predict the breakthrough curves for adsorption and ion exchange processes. These data represent the sorption of o-cresol from water by activated carbon, acetic acid from air by activated carbon, phenol from water by natural zeolite, and trichloroethylene from air by zeolite-5A.The results show that there are a good agreement between the experimental data and the model.

أن عمليات الامتزاز والتبادل الايوني للطور الثابت تكون متغيرة ، فالمعادلات الخاصة بالتصاميم هي معادلات تفاضلية تحتاج الى حلول بالطرق العددية.توماس استطاع أن يعطي حل عام تحليلي لهذه المعادلات مستندا على ديناميكية التفاعل من الدرجة الثانية ومعادلة لانكمير عند التوازن. تم اعداد برنامج رياضي لموديل توماس بأستخدام MATLAB 7.0 . أستخدمت اربعة نماذج من التجارب لغرض أظهار مقدرة موديل توماس للتنبأ بمنحنيات الامتزاز والتبادل الايوني. البيانات مثلت امتزاز الاورثوكريسول من الماء بواسطة الفحم المنشط ، وحامض الخليك من الهواء بواسطة الفحم المنشط، والفينول من الماء بواسطة الزيولايت، وثلاثي كلوروالاثلين من الهواء بواسطة الزيولايت. النتائج بينت ان هناك تطابق جيد بين البيانات العملية والموديل.


Article
Removal of Lead, Cadmium, and Mercury Ions Using Biosorption

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Abstract

The biosorption of Pb (II), Cd (II), and Hg (II) from simulated aqueous solutions using baker’s yeast biomass was investigated. Batch type experiments were carried out to find the equilibrium isotherm data for each component (single, binary, and ternary), and the adsorption rate constants. Kinetics pseudo-first and second order rate models applied to the adsorption data to estimate the rate constant for each solute, the results showed that the Cd (II), Pb (II), and Hg (II) uptake process followed the pseudo-second order rate model with (R2) 0.963, 0.979, and 0.960 respectively. The equilibrium isotherm data were fitted with five theoretical models. Langmuir model provides the best fitting for the experimental results with (R2) 0.992, 0.9987, and 0.9995 for Cd (II), Pb (II), and Hg (II) respectively. The effect of various influent adsorbates concentrations, and flow rates on the performance of fixed bed adsorber was found for the three heavy metals. A mathematical model was formulated to describe the breakthrough curves in the fixed bed adsorber for each component. The results show that the mathematical model provides a good description of the adsorption process for Cd (II), Pb (II), and Hg (II) onto fixed bed of baker’s yeast biomass.

Keywords

Biosorption --- yeast --- Cd --- II --- Pb --- II --- Hg --- II --- fixed bed --- mathematical model --- mass transfer coefficient.

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