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Article
Determination of Mass Transfer Coefficient for Copper Electrodeposition by Limiting Current Technique.

Authors: Marwa H. Ibrahim --- Sarmad T. Najim
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2017 Volume: 20 Issue: 3 Pages: 666-672
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

An experimental study was conducted to investigate the mass transport behavior for electrochemical reduction of copper in the presence of 0.5M H2SO4 as supporting electrolyte by limiting current technique (LCT). The experiments were carried out via rotating cylinder electrode made of copper as cathode. The effects of various operating conditions: rotation rates 100, 200, 300, 400, and 500rpm, electrolyte temperatures 30, 45, and 60℃, and cupric ions concentration 250, 500, and 750 ppm on mass transfer rate were studied. It was observed that mass transfer coefficient based mainly on rotation rates, then temperature and finally cupric ions concentration. The electrodeposition of cupric ions was proved to be a mass control. The mass transfer coefficient for rotating cylinder electrode was correlated with the aid of dimensionless groups as follows:Sh = 0.236 Re^(0.664 ) Sc^0.356 And the above correlation is a good agreement with eisenberg equation.

تم اجراء دراسة تجريبية للتحقيق في سلوك انتقال الكتلة للاختزال الكهروكيمياوي للنحاس بوجود حامض الكبريتيك كمحلول داعم بواسطة تقنية التيار المحدد. لقد اجريت التجارب باستخدام القطب الاسطواني الدوار المصنوع من النحاس كقطب كاثود. وتم دراسة تأثير ظروف التشغيل المختلفة: معدل دوران 100, 200, 300, 400, و 500 دورة / دقيقة, درجات حرارة المحلول الالكتروليتي 30, 45, و60 درجة سيليزية, و تركيز ايونات النحاس 250, 500, و 750 على معدل انتقال الكتلة . لوحظ ان معامل انتقال الكتلة تعتمد بشكل اساسي على معدلات الدوران , ثم درجة الحرارة واخيرا تركيز ايونات النحاس. وقد اثبتت التجارب ان الترسيب الكهربائي للنحاس تحت سيطرة الكتلة. تم الحصول على معادلة تربط معامل انتقال الكتلة بمجموعة عديمة الوحدات: Sh= 0.236 〖Re〗^(0.664 ) 〖Sc〗^0.356


Article
Experimental Study for the Influence of Operating Parameters on Copper Electrorefining Process

Authors: Hayder M. Abbas --- Sarmad T. Najim
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2018 Volume: 19 Issue: 1 Pages: 21-27
Publisher: Baghdad University جامعة بغداد

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Abstract

Copper electrodeposition by electrorefining process in acidic sulfate media contains 40 g/l of cupric ions and 160 g/l of sulfuric acid was achieved to study the influence of the operating parameters on cathode purity, surface morphology, deposition rate, current efficiency and power consumption. These operating parameters and there ranges are: current density 200, 300 and 400 A/m2, electrolyte temperature 35, 50 and 65 oC, electrodes spacing 15, 30 and 45 mm and electrolyte residence time 6, 4 and 2 h were utilized. XRF, SEM and EDX analyses were attained to clarify the properties of the produced cathode.


Article
Prediction and Correlations of Residual Entropy of Superheated Vapor for Pure Compounds

Authors: Mahmoud O. Abdullah --- Sarmad T. Najim --- Shahad Z. Atta
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2012 Volume: 13 Issue: 2 Pages: 11-27
Publisher: Baghdad University جامعة بغداد

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Abstract

Prediction of accurate values of residual entropy (SR) is necessary step for the calculation of the entropy. In this paper, different equations of state were tested for the available 2791 experimental data points of 20 pure superheated vapor compounds (14 pure nonpolar compounds + 6 pure polar compounds). The Average Absolute Deviation (AAD) for SR of 2791 experimental data points of the all 20 pure compounds (nonpolar and polar) when using equations of Lee-Kesler, Peng-Robinson, Virial truncated to second and to third terms, and Soave-Redlich-Kwong were 4.0591, 4.5849, 4.9686, 5.0350, and 4.3084 J/mol.K respectively. It was found from these results that the Lee-Kesler equation was the best (more accurate) one compared with the others, but this equation is sometimes not very preferable. It was noted that SRK equation was the closest one in its accuracy to that of the Lee-Kesler equation in calculating the residual entropy SR of superheated vapor, but it was developed primarily for calculating vapor-liquid equilibrium and to overcome this problem, efforts were directed toward the possibility of modifying SRK equation to increase its accuracy in predicting the residual entropy as much as possible. The modification was made by redefining the parameter α in SRK equation to be a function of reduced pressure, acentric factor, and polarity factor for polar compounds in addition to be originally function of reduced temperature and n parameter –which is also function of acentric factor– by using statistical methods. This correlation is as follows: This new modified correlation decreases the deviations in the results obtained by using SRK equation in calculating SR when comparing with the experimental data. The AAD for 2791 experimental data points of 20 pure compounds is 4.3084 J/mol.K while it becomes 2.4621 J/mol.K after modification. Thus SRK equation after this modification gives more accurate results for residual entropy of superheated vapor of pure 20 compounds than the rest of the equations mentioned above.


Article
Experimental Investigation of Mass Transfer for Copper Reduction by Weight Difference Technique

Authors: Marwa H. Ibrahim --- Sarmad T. Najim سرمد طالب نجم
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2016 Volume: 17 Issue: 4 Pages: 105-111
Publisher: Baghdad University جامعة بغداد

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Abstract

An experimental analysis was included to study and investigate the mass transport behavior of cupric ions reduction as the main reaction in the presence of 0.5M H2SO4 by weight difference technique (WDT). The experiments were carried out by electrochemical cell with a rotating cylinder electrode as cathode. The impacts of different operating conditions on mass transfer coefficient were analyzed such as rotation speeds 100-500 rpm, electrolyte temperatures 30-60 ℃, and cupric ions concentration 250-750 ppm. The order of copper reduction reaction was investigated and it shows a first order reaction behavior. The mass transfer coefficient for the described system was correlated with the aid of dimensionless groups as follows:Sh = 3.77 〖Re〗^(0.533 ) 〖Sc〗^0.356 4075 < Re < 34088

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