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Article
Determination of Volumetric Mass Transfer Coefficient in Fixed Bed Adsorption

Authors: Farah Y. Al-Kaisy --- Adi A. Al-Hemiri عادل احمد عوض
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2007 Volume: 8 Issue: 2 Pages: 23-27
Publisher: Baghdad University جامعة بغداد

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Abstract

This work was conducted to determine the volumetric mass transfrr coefficient (Ky.a) injixed bed adsorption using hexane-benrene mixture by adsorption onto a fixed bed of white silica gel.Benzene concentration was measured by gas chromatography. The effect of fred flow rate and initial concentration of benzene in hexane-benzene mixture on the volumetric mass transfer coefficient and on the adsorption capacity of silica gel was investigated.In general, the volumetric mass transfrr coefficient increases with increasing hexane flow rate, and with increasing initial concentration of beniene in the mixture. The ultimate value of (Ky. a) was at 53 mI/ of hexane flow rate with benzene initial concentration of (653 wt. %,), and it was (99.4 kg/m3.s).The adsorptive capacity of silica gel increases with decreasing hexane flow rate, as with increasing initial concentration of benzene in the mixture. The best adsorptive capacity of the imported silica gel (100 g of imported silica gel yielded 120 ml of benzene-free effluent) was achieved with the grade (1.18-5 mm) in size at a hexane flow rate 15 m


Article
HYDRODESULFURIZATION OF THIOPHENE OVER CO-MO/AL2O3 CATALYST USING FIXED- AND FLUIDIZED-BED REACTORS

Authors: Saad Hanash Ammar --- Abdul Halim A-K Mohammed
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2011 Volume: 17 Issue: 1 Pages: 92-102
Publisher: Baghdad University جامعة بغداد

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Abstract

The present work reports a direct experimental comparison of the catalytic hydrodesulfurization of thiophene over Co-Mo/Al2O3 in fixed- and fluidized-bed reactors under the same conditions. An experimental pilot plant scale was constructed in the laboratories of chemical engineering department, Baghdad University; fixed-bed unit (2.54 cm diameter, and 60cm length) and fluidized-bed unit (diameter of 2.54 cm and 40 cm long with a separation zone of 30 cm long and 12.7 cm diameter). The affecting variables studied in the two systems were reaction temperature of (308 – 460) oC, Liquid hourly space velocity of (2 – 5) hr-1, and catalyst particle size of (0.075-0.5) mm. It was found in both operations that the conversion increases with increasing of reaction temperature, slightly decreases with increasing of liquid hourly space velocity and not affected by particle size. Also a kinetic analysis was performed for thiophene hydrodesulfurization reaction in fixed bed reactor and the results indicate that the reaction kinetics are not affected by pore and film diffusion limitations. The results of the comparison between the two reactors indicate that a low conversion was obtained in a fluidized bed than in fixed bed over the range of conditions studied. The lower conversion can be attributed to the gas that bypasses the bed in the form of bubbles or channels.

تم في هذا البحث دراسة تفاعل هدرجة الثيوفين لازالة الكبريت بوجود عامل مساعد صلب وهو الكوبولت – مولبيديوم المحمل على الالومينا.وذلك في نوعين من المفاعلات وهما المفاعل ذو الطبقة الثابتة والمفاعل ذو الطبقة المميعة. تم بناء منظومتين ريادية مكونة من مفاعل الطبقة الثابتة (ذو قطر 2,54 سم وطول 60 سم) ومفاعل الطبقة المميعة (ذو قطر 2,54 سم مطول 40 سم) الهدف من هذا الدراسة هو مقارنة اداء كل من هذين المفاعلين تحت نفس الضروف من درجة حرارة (308 -460) مه وسرعة حجمية (2-5) سا-1، وحجم جسيمة العامل المساعد (استخدمت ثلاث مديات لحجم جسيمة العامل المساعد:(0,075 – 0,15) ملم, (0,15 – 0,3) ملم, (0,3 – 0,5) ملم, بالاضافة للحجم الاصلي (1 (2 – 5) ملم).اظهرت النتائج في تجارب المفاعل ذو الطبقة الثابتة تأثر التحول كثيرا بتغيير درجة حرارة التفاعل حيث يزداد التحول بزيادة درجة الحرارة ويتأثر قليلا بتغيير السرعة الحجمية ولا يتأثر بتغيير حجم جسيمة العامل الساعد. كذلك ضهرت نتائج مشابهة في تجارب المفاعل ذو الطبقة المميعة. استنتج من هذه النتائج ان حركية تفاعل هدرجة الثيوفين بوجود العامل المساعد الكوبلت - موليبيديوم المحمل على الالومينا لا تتأثر بمقاومة الانتشار الداخلي لجسيمة العامل المساعد (داخل المسامات) وكذلك لا تتأثر بمقاومة الانتشار الخارجي للجسيمة (الانتشار الغشائي).بصورة عامة وبمقارنة الاداء بين المفاعلين, اظهرت النتائج حصول تحول اقل في المفاعل ذو الطبقة المميعة عنه في المفاعل ذو الطبقة الثابتة وذلك بسبب مرور قسم من الغاز المتفاعل الداخل خلال فقاعات او قنوات في طور الفقاعات ولا يمر على العامل المساعد في الطور المستحلب في المفاعل ذو الطبقة المميعة.


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 SO2 in Dry Fluidized and Fixed Bed Reactors using Granular Activated Carbon

Authors: Neran K. Ibrahim --- Omar A. Jabbar
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 14 Pages: 3019-3037
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Flue gas desulfurization process has been studied using granular activated carbon in bubbling fluidized bed reactor. For the sake of comparison, fixed bed configuration has been also studied at the same operating conditions. The effect of temperature 30 . T . 80 oC, inlet SO2 concentration 500 . Co . 2000 ppm, and flue gas flow rate 2.5 .Q . 30 ./min were investigated. The results showed that the SO2 removal efficiency increases with increasing reaction temperature up to 80 oC. Also, it was noted that the removal efficiency decreases with increasing the inlet SO2 concentration within the range of temperatures studied. The effect of flue gas flow rate on the desulfurizationactivity was in two ways; an increase in the removal efficiency with increasing gas flow rate was observed below flow rate = 7.5 ./min, while a decrease in the efficiency was observed upon any increment in the gas flow rate beyond the 7.5 ./min. The results of fluidized bed reactor were used to obtain an empirical correlation and the experimental results were well correlated with the proposed formwith a correlation coefficient, (R) =0.989. A reaction rate equation was proposed for the oxidative desulfurization and the activation energy was obtained using differential analysis of integral reactor technique. The resulted value of apparent activation energy was 2.981 kJ/mol.


Article
Removal of Lead and Copper Ions onto Granular Activated Carbon in Batch and Fixed Bed A Dsorber
ازالة الرصاصوالنحاس باستخدام الكاربون المنشط الحبیبي بواسطة الامنزاز في عملیة دفعیة والامتزاز في عمود الحشوة الثابتة

Authors: Abbass H. Sulaymon --- Balasim A. Abid --- Jenan A. Al Najar
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2009 Volume: 27 Issue: 12 Pages: 2336-2351
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The adsorption of lead and copper ions onto granular activated carbon (DARCO20-40 mesh) in a single component system has been studied using fixed bed adsorbers.A film-pore diffusion model has been developed to predict the fixed bed breakthroughcurves for the two metal ions. This model takes account both external and internalmass transfer resistance as well as axial dispersion with non-linear isotherm. Theeffects of flow rate, bed height and initial metal ion concentration has been studied.Batch adsorber experiments were conducted to estimate the parameters required forfixed bed model, such as adsorption equilibrium isotherm constants the external masstransfer coefficient and pore diffusion coefficient by fitting the experimental data withtheoretical model. The batch isotherm experimental data was correlated usingLangmuir and Freundlich isotherm models. The adsorption isotherm data follow theLangmuir model better than Freundlich model. The pore diffusion coefficient wasobtained using pore diffusion model for batch adsorber by matching between theexperimental data and predicted data from the model. The results show that the filmporediffusion model used for fixed bed adsorber provide a good description of theadsorption process for adsorption of metal ions Pb(II) and Cu(II) onto activated carbonin fixed bed adsorber.

تم درسة ازالة الرصاص والنحاس بواسطة الامتزاز على الكاربون المنشط الحبيبي فيعملية دفعية وفي عمود الحشوة الثابتة. في عملية الامتزاز باستخدام الحشوة الثابتة تماستنباط موديل رياضي لايجاد منحنيات الاختراق. الموديل ياخذ بنظر الاعتبار المقاومةالخارجية والمقاومة الداخلية لانتقال المادة وكذلك الانتشار المحوري مع استخدام معادلة غيرخطيةلتمثيل حالة الاتزان لنظام ثابت الحرارة. تم اجراء الامتزاز في عملية دفعية لايجاد ثوابتالاتزان, معامل الانتقال الخارجي ومعامل الانتشار داخل الحبيبات من خلال مطابقة النتائجالعملية مع النتائج المستحصلة من الموديل النظري. تم مطابقة النتائج العملية المستحصلة منتجربة الاتزان مع النتائج النظرية المستحصلة من عدد من علاقة الانزان لنظام ثابت الحرارةووجد أن النتائج العملية تتبع معادلة لانكماير بصورة جيدة. معامل الانتشار الحبيبي تم الحصول عليه من خلال مطابقة النتائج العملية في عملية دفعية مع النتائج المستحصلة منالموديل الرياضي لعملية دفعية. النتائج العملية في تجربة الحشوة الثابتة اظهرت بان الموديلالرياضي المستخدم لتمثيل الامتزاز في الحشوة الثابتة يعطي وصفا جيد لعملية امتزازالرصاص والنحاس باستخدام الكاربون المنشط كحشوة ثابتة.


Article
Adsorption of Methyl Green Dye onto Bamboo in Batch and Continuous System

Author: Ahmed Adnan Atshan احمد عدنان
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2014 Volume: 15 Issue: 1 Pages: 65-72
Publisher: Baghdad University جامعة بغداد

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Abstract

Adsorption techniques are widely used to remove certain classes of pollutants from waters, especially those that are not easily biodegradable. Dyes represent one of the problematic groups. The removal of methyl green from waste water using bamboo was studied in batch and continuous system. In batch system equilibrium time and adsorption isotherm was studied at different concentrations (5, 10, 15, 20, 25 and 30 ppm) and 50 mg weight of adsorbent. Langmuir and Freundlich equations were applied for adsorption isotherm data. Langmiur equation was fitted better than Freundlich equation (R2=0.984 for Langmuir equation).The maximum percentage dye removal obtained 79.4% and adsorption capacity was 15.5 mg/g. For continuous system the breakthrough curve was studied at different bed depths (1, 2 and 4 cm), different concentrations (5 and 10 ppm), and different flow rates (5 and 10 ml/min).


Article
Batch and Fixed-Bed Modeling of Adsorption Reactive Remazol Yellow Dye onto Granular Activated Carbon
النمذجة الرياضية لامتزاز الصبغة الصفراء الفعالة باستخدام الفحم المنشط في تجارب الوجبة و تجارب الحشوة الثابتة

Authors: DhaferFaza Ali ظافر فزع علي --- Waleed Mohammed Abood وليد محمد عبود --- Mohammed Sadeq Salman محمد صادق سلمان
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2014 Volume: 20 Issue: 8 Pages: 156-176
Publisher: Baghdad University جامعة بغداد

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Abstract

In this work, the adsorption of reactive yellow dye (Remazol yellow FG dye) by granular activated carbon (GAC) was investigated using batch and continuous process. The batch process involved determination the equilibrium isotherm curve either favorable or unfavorable by estimation relation between adsorption capacity and concentration of dye at different dosage of activated carbon. The results were fitted with equilibrium isotherm models Langmuir and Freundlich models with R2value (>0.97). Batch Kinetic study showed good fitting with pseudo second order model with R2 (0.987) at contact time 5 h. which provesthat the adsorption is chemisorptions nature. Continuous study was done by fixed bed column where breakthrough time was increased at flow rates (21.67, 12.5 and 6 ml/min) and initial dye concentration (80, 40, 20 and 10 mg/l) were decreased and bed depth was increased (5, 10, 15 and 20 cm). The adsorption data were fitted to the fixed-bed adsorption mathematical models Thomas and Yoon-Nelson models. The results fitted well to the Thomas and Yoon-Nelson models with correlation coefficient, R2≥ 0.944. Average relative error ARE% was applied to examine the theoretical and experimental results.

في هذا البحث تم امتزاز الصبغة الصفراء الفعالة باستخدام الفحم المنشط الحبيبي خلال تجارب وجبية و مستمرة حيث تضمنت التجربة الوجبية عملية تحديد منحني التوازن عند ثبوت درجة الحرارة وبيان هل نوعه مفضل ام غير مفضل من خلال احتساب علاقة مابين سعة الامتزاز وتركيز الصبغة المتبقية في المحلول بعد الامتزاز بعد استخدام اوزان مختلفة من الفحم المنشط حيث وضحت النتائج مطابقة مع موديل لانكمير بقيمة مربع معامل ارتباط اكثر من 97% في حين تطابقت تجارب تغيير زمن التلامس عند ثبوت الحجم مع موديل سيدو ذا المرتبة الثانية بقيمة مربع معامل الارتباط 98.7% في اقصى زمن تلامس مقداره 5 ساعات والذي يثبت ان طبيعة الامتزاز بين الصبغة والفحم المنشط هو امتزاز كيمياوي. التجارب المستمرة من خلال استخدام حشوة ثابتة عند عدة متغيرات مثل معدل جريان محلول الصبغة من الاعلى الى الاسفل بمقدار ( 6 , 12.5 , 21.67) مل/دقيقة و عند تغيير تركيز الصبغة ( 10 , 20 , 40 ,80 ) ملغم/لتر وعند عمق حشوات ( 5 , 10 , 15 , 20) سم واحتساب منحني الانكسار ومقارنة النتائج مع موديلين ثوماس و يوون نيلسون و احتساب معدل الخطاء بين النتائج النظرية والعملية .


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.


Article
INCREASING THE ADSORPTION SURFACE AREA OF ACTIVATED CARBON

Authors: Shahlaa E. Ebrahim --- Abbas H. Sulaymon
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2008 Volume: 14 Issue: 3 Pages: 2700-2717
Publisher: Baghdad University جامعة بغداد

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Abstract

Experiments were carried out to study the effect of various activated carbon-glass beads weight ratios, influent phenol concentrations, flow rate and bed depth on the performance of fixed bed adsorption column. The equilibrium data and interparticle diffusion coefficients obtained from separate experiments in a batch adsorber were fitted with theoretical model. The effect of adding different weight ratios of an inert solid material to the adsorbent bed in the adsorption process of phenol onto activated carbon was carried out. Adding 5 wt % glass beads to the activated carbon bed reduces the amount of activated carbon by 5% and increases the operating time by 80%.. Increasing the glass beads from 10 wt % and above makes the adsorption process inefficient compared with 0 wt % glass beads. A mathematical model was achieved to describe the mass transfer kinetics in a fixed bed column. The results show that the mathematical model includes external mass transfer and pore diffusion using nonlinear isotherms, provides a good description of the adsorption process for phenol in fixed bed adsorber.


Article
Competitive Adsorption of Furfural and Phenolic Compounds onto Activated Carbon in Fixed Bed Column

Authors: KAWTHER W. AHMED --- ABBAS H. SULAYMON
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2007 Volume: 13 Issue: 3 Pages: 1721-1736
Publisher: Baghdad University جامعة بغداد

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Abstract

For a multicomponent competitive adsorption of furfural and phenolic compounds, a mathematical model was built to describe the mass transfer kinetics in a fixed bed column with activated carbon. The effects of competitive adsorption equilibrium constant, axial dispersion, external mass transfer and intraparticle diffusion resistance on the breakthrough curve were studied for weakly adsorbed compound (furfural) and strongly compounds (parachlorophenol and phenol). Experiments were carried out to remove the furfural and phenolic compound from aqueous solution. The equilibrium data and intraparticle diffusion coefficients obtained from separate experiments in a batch absorber, by fitting the experimental data with theoretical model. The results show that the mathematical model includes external mass transfer and pore diffusion using nonlinear isotherms, provides a good description of the adsorption process for furfural and phenolic compounds in fixed bed adsorber.

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