البحث — المستودع الرقمي العراقي

نتائج البحث: 25 من أصل 347

استخلاص الزيوت العطرية من قشور الحمضيات باستعمال التقطير البخاري بمساعدة المايكرويف == Extraction of Essential Oils From Citrus By - Products Using Microwave Steam Distillation

اسم المؤلف: سارة جبير صالح

اسم المشرف: ابتهال كريم شاكر

الموضوع العام: الهندسة الكيمياوية

السنة: 2014

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: يهدف هذا البحث الى استخلاص الزيت العطري من ثلاثة انواع من قشور الحمضيات (البرتقال, الليمون, اللالنكي) بطريقتين : التقطير البخاري والتقطير البخاري بمساعدة المايكرويف.ودراسة تاثير عوامل الاستخلاص : (وزن القشور, وقت الاستخلاص,طاقة المايكرويف ونوع قشور الحمضي | The main objectives of this research is to extract essential oil from : orange( citrus sinensis), lemon( citrus limon) and mandarin( citrus reticulata) peels by two methods : steam distillation (SD) and microwave assisted steam distillation (MASD), study the effect of extraction conditions : weight of the sample( 398.56g, 281.8g, 116.76g), extraction time, microwave power( 135W, 265W, 445W) and citrus peel type( orange, lemon, mandarin) on oil yield and compare the results of the two methods, the resulting essential oil was analyzed by Gas Chromatography (GC).Essential oils are highly concentrated substances used for their flavor and therapeutic or odoriferous properties, in a wide selection of products such as foods, medicines and cosmetics. Extraction of essential oil is one of the most time and effort consuming process. Microwave - assisted extraction is a green technique for the extraction of natural products. (MASD) was better than (SD) in terms of rapidity, energy saving and yield. (MASD) gave higher yield than (SD) with shorter extraction time, yield of orange oil extracted by (MASD) was (1.150%) in (35min.) compared to (1.095%) in (45min.) by (SD) process, same results obtained for lemon and mandarin. It was found that the optimal microwave power was (135W) and the yield was : (1.150%, 1.115%, 0.940%) for orange, lemon and mandarin respectively, (MASD) increased extraction temperature in short time and to a higher level compared to (SD).It was found that the optimal weight was (398.56g) and the yield in (SD) was : (1.095%) and MASD (1.091%) for orange oil, same results obtained for lemon and mandarin.The best citrus peel type which gave the highest yield was orange followed by lemon then mandarin in both processes.Limonene is the most abundant component in citrus essential oil, (GC) analysis showed that the amount of limonene increased in low microwave power with long extraction time for mandarin oil it was (84.3891% at 135W in 60min.), while for (SD) it was (83.0271% in 75min.) and decreased with increasing microwave power for orange oil it was (80.9661% at 265W in 35min.) while for (SD) it was (83.2189% in 45min.), (SD) was more convenient to give high amount of limonene because of the graduate temperature rise, while in microwave extraction exposure to low microwave power for long time would give complete recovery and better quality of essential oil.

تثبيط تاكل الحديد الكاربوني الواطئ في حامض الكبريتيك باستعمال كحول البولي فينيل ومستخلص نبات PIPER LONGUM == Corrosion Inhibition of Low Carbon Steel In Sulfuric Acid By PVA And Piper Longum Extracts

اسم المؤلف: اياد بهاء الدين احمد

اسم المشرف: ماجد ابراهيم عبد الوهاب | ابرائيل سركيس يارو

الموضوع العام: الهندسة الكيمياوية

السنة: 2014

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: دكتوراه

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: The inhibitive power of Polyvinyl Alcohol (PVA) and the synergistic effects added on the inhibition power of PVA by two types of Piper Longum (PL) Ethanol Extracts (PLEXT) were investigated toward the corrosion of carbon steel in (0.2N) H2SO4 solution in the temperature range (30 - 60?C) and PVA concentration range (150 - 2000 PPM).The corrosion rate measurements were carried out using the following two standard corrosion measurements techniques.1. Weight loss technique was applied on carbon steel plates to evaluate inhibition efficiency in presence and absence of these inhibitors.2. Electrochemical Techniques were used to validate and support inhibition efficiencies found in weight loss techniques.A detailed study of the experimental methods and results is reported for each test conducted.The weight loss results showed that PVA could serve as a corrosion inhibitor but its inhibition power was found to be low for the corrosion of carbon steel in the acidic media.It was shown that the inhibition efficiency for (PVA) decreased with increasing temperature at a given PVA concentration. On the other hand it was shown that at given temperature the inhibition efficiency of (PVA) was increased with increasing of PVA concentration until a PVA concentration of 2000 ppm PVA was reached then only a slight decrease in inhibition efficiency was observed when increasing PVA concentration further.The Maximum inhibition efficiency reached was about 71 % at 30?C & 2000 ppm (PVA) concentration, calculated by the weight loss techniques.In order to improve the inhibition efficiency of PVA, by adding 6 ml/l of ethanol extracts of piper longum (PL) to a liter of the acid solution in presence of concentrations of PVA 150,500,1000.1500, and 2000 ppm at temperatures (30,40,50, and 60?C) was investigated.Weight loss results showed a jump in inhibition efficiency (% IE) value of the modified inhibitor mixture compared with the presence of PVA alone at all (PVA) concentrations for temperature range considered in this investigation.This study demonstrated the extra inhibition power added by the (PL) fruit extracts to the organic polymer (PVA) used. Maximum inhibition efficiencies recorded were approximately 95% for Piper Longum Extract Number two (PLEXT2) at 30?C and 2000 ppm PVA.The kinetic and thermodynamic parameters regarding the adsorption process of inhibitors used was calculated.It was found that the changes corrosion rates correlates well with the Arrhenius equation in absence and presence of inhibitors.The Results showed that the adsorption of the polymer and the plant extract follows Langmuir adsorption isotherms and the adsorption of the inhibitor molecules on the metal surface is mainly physical, nevertheless the adsorption is believed to be slightly deviated from the Langmuir model at 30?C.Electrochemical analysis of the corrosion process of carbon steel in an electrochemical corrosion cell was investigated using 3 - Electrode corrosion cell coupled with a potentiostat interfaced with a computer which assisted polarization data interception and interpretation.Polarization technique was used to obtain polarization data which was recorded for carbon steel in 0.2N H2SO4 solutions in presence and absence of the inhibitors investigated. Electrochemical runs were done in the (PVA) concentrations of 150, 1000, and 2000 PPM and a temperatures of 30, 40, 50, and 60?C.Tafel slopes, Corrosion currents, and corrosion rates were calculated from polarization curves by Tafel extrapolation method. Results showed corrosion rate trends similar to findings by the weight loss method. It was indicated also that the corrosion of carbon steel in 0.2N H2SO4 is highly activity controlled.Results revealed that the inhibition action is occurring at both anodic and cathodic sites on the metal surface so that both corrosion reactions were affected, so that the composite inhibitor could be considered as mixed - type inhibitor.Electrochemical results confirmed that (PLEXT2) was more efficient as inhibition improvement additive to (PVA) than (PLEXT1) at all experimental conditions range encountered in this study.The highest inhibition efficiency recorded using Tafel polarization method was 83% obtained at 30?C and 2000 ppm of PVA with 6 ml/l PLEXT2.

تحضير الكاربون المنشط من نوى التمر باستخدام كاربونات البوتاسيوم كعامل منشط في ازالة صبغة المثيلين الزرقاء == Preparation of Activated Carbon From Date Stones By K2Co3 Activation For Methylene Blue Dye Adsorption

اسم المؤلف: اسماء فاضل عباس

اسم المشرف: مثنى جبار احمد

الموضوع العام: الهندسة الكيمياوية

السنة: 2014

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

ازالة الكادميوم من المياه الملوثة بالترسيب الكهروكيمياوي باستخدام حزمة من الانابيب الفولاذية متحدة المركز == Removal of Cadmium From Wastewater By Electro - Deposition On Stainless Steel Concentric Tubes Bundle

اسم المؤلف: انس بديوي سلمان

اسم المشرف: عباس حميد سليمون | بسمة عباس عبد المجيد

الموضوع العام: الهندسة الكيمياوية

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: دكتوراه

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: تم دراسة انتقال الكتلة الخاص بايونات الكادميوم الثنائية الى سطح اسطوانة دوراة مصنوعة من مادة الفولاذ المقاوم للتاكل (كقطب كاثود) بواسطة قياس التيار المحدد لتفاعل اختزال ايونات الكادميوم الكاثودي في محلول كبريتات الصوديوم بتركيز مولار باستخدام خلية ثلاثية | 1 - Mass transfer of Cd+2 ions to a smooth stainless steel rotating cylinder electrode was studied by measuring the limiting current for the cathodic reduction of Cd+2 in 0.5 M sodium sulphate supporting electrolyte by three electrodes cell with stainless steel rotating cylinder electrode working in hydrodynamic voltammetry mode. The studied parameters were electrolyte pH (4, 5, 6 and 7), initial Cd+2 concentrations (50, 100, 200, 300 and 400 ppm) and rotation rates (100, 150, 200 and 250 rpm). Cadmium ions' reduction potential for mass transfer control conditions was found to be - 0.13 V. Diffusion coefficient was determined and correlated with the bulk concentration of Cd+2 in sodium sulphate solution. The increase in pH was found to enhance the mass transfer coefficient and this effect diminishes nearly at pH=7, and the experimental data were well fitted by an empirical dimensionless correlation among the Sherwood number, Reynolds number and Schmidt number. The obtained correlation was : Sh=0.047 ?Re?^0.769 ?Sc?^0.356 For (8015.519 < Re < 20587.07) Reduction potential obtained via the voltammograms constructed by the rotating cylinder cell was applied for the two pilot scale units in order to keep the process under mass transfer control conditions. Parameters studied in these units are : initial cadmium concentration, pH, and electrolyte flow rate. The first pilot scale unit was an electrochemical reactor with smooth stainless steel concentric tubes, and the second one was an electrochemical reactor with stainless steel mesh concentric cylinders.2 - For the stainless steel smooth concentric tubes cathode, mass transfer coefficient was calculated and correlated with initial concentration.Effect of pH on mass transfer coefficient was studied and correlated, and it was found that the effect of pH was found to be completely negligible at pH=7.On the other hand, effect of flow rate on mass transfer coefficient was studied and correlated. Performance of the reactor was analyzed by introducing figures of merit for fractional conversion, specific energy consumption, space time yield and normalizes space velocity. The experimental data were correlated in a dimensionless expression as flows : Sh=0.804?Re?^0.632 ?Sc?^(1/3) For 254 < Re < 1018.3 - For the stainless steel mesh concentric cylinders was adjusted to work under mass transfer control conditions by applying the reduction potential obtained in hydrodynamic voltammetry experiments.Effect of initial cadmium concentration, pH and solution flow rate was studied and analyzed. Mass transfer coefficient was correlated with these studied parameters.Similar to smooth cathode, the mesh cathode showed a negligible response to pH at pH=7.Noticeable enhancement in mass transfer coefficient was investigated by the action of flow rate, and the mass transfer coefficient was correlated with the solution flow rate.The mesh cathode showed a higher conversion than that adopted by the smooth cathode, and showed lower cumulative current efficiency than that of smooth cathode.Mesh cathode showed specific energy consumption, space time yield and normalized space velocity higher than that for the smooth cathode.Experimental data for the mesh reactor were correlated in a dimensionless relation as follows : Sh=1.898?Re?^0.514 ?Sc?^(1/3) For 235 < Re < 943 Cadmium ions reduction reaction was found to follow a first order reaction with respect to Cd+2 concentration, and reaction rate constant was predicted under different operating conditions.