Modification of Natural Clays and Their Applications in the Remediation of Selected Contaminants from Aqueous Media

تنقية وتطوير الطين الطبيعي قد تكون من المداخل المهمة للحصول على مواد مُمتزَّة منخفضة التكلفة وفعالة للسيطرة على تلوث المياه. في هذه الدراسة تمت تنقية عينات من الطين الطبيعي، من المغرب ومن السودان، عن طريق التبادل الأيوني مع محلول كلوريد الصوديوم. ثم تطويرها بإدخال (intercalation) بروميد ثنائي ديسيل ثنائي مثيل الأمونيوم بين طبقات الطين، ثم تشخيصها بالطرق المختلفة، ثم دراسة فعاليتها كمواد مُمتزَّة منخفضة التكلفة لإزالة الزرنيخ الثلاثي، وصبغة الميثايلن الأزرق، وصبغة الكريستال البنفسجي، وصبغة الكونغو الحمراء، والفينول، والنترات. أوضحت نتائج طريقة بروناور-إيميت-تيلر وصور المجهر الإلكتروني النافذ أن عينات الطين عبارة عن مواد مسامية، مكونة من تجمعات مرنة لها شكل الألواح، وتصل مساحة سطحها إلى (23 و (128م2/غم، للعينة النيلية والعينة المغربية على التوالي. بينما أظهرت نتائج تحليل العينات بجهاز حيود الأشعة السينية أن عينة الطين السوداني تتكون من معادن السميستايت (smectite) والإليت (illite)، بينما تتكون عينة الطين المغربي من معادن الإليت والكاولينيت (kaolinite). تم التأكد من نجاح عملية التطوير بمقارنة نتائج تحليل عينات الطين قبل وبعد التطوير، باستعمال جهاز الأشعة تحت الحمراء. أظهرت عينة الطين المغربي المُنقاة Na-MO كفاءة عالية في إزالة: الزرنيخ الثلاثي وصبغتي الميثايلن الأزرق والكريستال البنفسجي، من المحاليل المائية في مدى الأس الهيدروجيني 9–10.8، حيث وصلت قيمة امتزاز الزرنيخ الثلاثي القصوى إلى 233.1 ملغم/غرام. من جهة أخرى فقد وُجد أن عملية إمتزاز الميثايلن الأزرق عملية طاردة للحرارة بينما عملية إمتزاز الكريستال البنفسجي مصحوبة بامتصاص للحرارة. أبدت العينتان (Surf-NI) و (Surf-MO) قدرة عالية على إزالة صبغة الكونغو الحمراء من المحاليل المائية مقارنة مع العينة (Na-MO)، حيث كانت قيم الإمتزاز القصوى 91.7 و 83.3 و 5.8 ملغم/غم لكل من (Surf-NI) و (Surf-MO) و (Na-MO)، على التوالي. هذه النتائج تبين بوضوح أن تنقية وتطوير الطين الطبيعي يمكن أن تساهم في إنتاج ممتزات عالية الكفاءة ومنخفضة التكلفة تصلُح لإزالة الأصباغ من المياه الملوثة. من جهة أخرة فقد أظهرت العينتان (Surf-NI) و (Surf-MO) كفاءة إمتزاز متماثلة عند استعمالهما لإزالة الفينول من المياه وذلك عند نفس الظروف التجريبية. وقد أوضحت الدراسات الحرارية أن عملية إمتزاز الفينول عملية تلقائية ماصة للحرارة، مصحوبة بزيادة في الأنتروبيا، مما يعكس قدرة كلتا المادتين على إزالة الفينول. النتائج الإجمالية لهذه الدراسة أوضحت أن تنقية وتطوير الطين الطبيعي تسهم بشكل كبير في زيادة كفاءته الامتزازية بالتالي يمكن استعماله كمادة مُمتزَّة قليلة التكلفة للسيطرة على تلوث المياه. إجراء دراسات إضافية باستعمال نمط العمود (column mode) لتقييم كفاءة الطين الطبيعي المطور على إزالة الملوثات المذكورة أو غيرها من الملوثات الكيميائية الأخرى من أهم توصيات هذه الدراسة

Improving the Productivity and Energy Efficiency by a Heat Treatment Method Applied to Aluminum Forged Parts

In industrial applications, hot forging of AA6082 alloy is carried at 480°C. After the hot forging operation parts are cooled down to room temperature and heated again up to 540°C for solution heat treatment and artificially aged. Heating-cooling-heating cycles leads to energy and time loss in production, and have long-termenvironmental and economic impacts. Mass production of aluminum parts for applications in various industries (automotive, aerospace etc.) requires a process with higher productivity. The aim of this study was to provide time and energy efficiency by combining hot forging and solution treatment processes into a single operation. AA6082 billets were forged at 540°C for 7.5, 15 and 30 minutes in order to achieve simultaneous solution treatment. Billets were then water quenched and artificially aged. Mechanical properties (hardness, tensile strength) as well as microstructure of samples were investigated. Required mechanical properties were achieved on the samples forged and treated at 540°C for 15 and 30 minutes

Uterine rupture: A review of 15 Cases at Bandier maternity hospital in Somalia

Background: Uterine rupture is a deadly obstetrical emergency endangering the life of both mother and fetus.Objective: To determine the frequency of ruptured uterus at Bandier Hospital and to elicit possible causes and type of management. Methods: It was cross sectional and hospital based descriptive study implemented during a time period of six months (July – December 2013) in Bandier maternity hospital and a total of 15 women presented with rupture uterus during the period of the study were included.Results: There were 15 cases of ruptured uterus out of a total of 2142 deliveries. Incidence of uterine rupture was found to be 0.7%. The mean age of women was 30.03 ± 4.55 years. Concerning risk factors for rupture uterus, 10 (66.7%) had previous uterine surgery, obstructed labor was found in 33.3%, and oxytocin was used in 46.7% of respondents. Repair was done for 8 (53.3%), 3 (20.6%) of respondents underwent total abdominal hysterectomy and 4 (26.7%) were ended by subtotal hysterectomy. Conclusions: Previous uterine surgery, obstructed labour and improper use of oxytocin increase the risk of uterine rupture in this study. Half of the patients underwent hysterectomy

Artımlı Sac Şekillendirme Yönteminin Sayısal Analizinde Açık Adım Ve Kapalı Adım Sonlu Eleman Yöntemi Çözümlerinin Karşılaştırmalı Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Sacın belirli bir pot çemberine bağlanarak bir şekillendirme ucu vasıtası ile değişik noktalardan uygulanan kuvvet ile (bu kuvvetin oluşturduğu lokal plastik deformasyonlar yolu ile) şekillendirilmesi yöntemine Artımlı Sac Şekillendirme (ASŞ) tekniği denmektedir. İşlem çoğunlukla sayısal kontrollü (CNC) dik işleme tezgahlarında gerçekleştirilmektedir. ASŞ, özellikle şekillendirme sırasında bir kalıp gerektirmemesi ve bu sebeple hem maliyetinin düşük olması hem de üretim esnekliği sağlaması açısından prototip ve/veya konsept üretim benzeri düşük adetli üretimler için uygun bir imalat yöntemidir. Artımlı sac şekillendirme işlemi, seçilen parça geometrisine göre uzun süren bir yöntemdir. Ayrıca şekillendirme sırasında parçanın çeperleri istenenden fazla incelebilmekte ya da yırtılabilmektedir. Bu sebeplerden dolayı, imalat öncesinde ilgili geometrinin üretiminde seçilen takımyolu ve diğer parametrelerin sayısal bir ortamda denenerek etkinliğinin ve doğruluğunun tespit edilmesi önem arz etmektedir. Bu durum, bu çalışmanın temel motivasyonunu oluşturmaktadır. Bu çalışmada, kesik koni ve kare piramit şekillerine sahip iki ayrı parça geometrisi için öncelikle belirlenen takımyolları sonlu elemanlar yöntemi kullanılarak açık adım (explicit) ve kapalı adım (implicit) analizler ile incelenmiştir. Takımyolları üç değişik şekillendirme ucu çapı için (5mm, 10mm ve 15mm) hazırlanmıştır. Hazırlanan takımyolları MATLAB programı vasıtası ile oluşturulan bir arayüz dosyası ile ABAQUS sonlu elemanlar yazılımına girdi olarak verilmiştir. Ayrıca malzemenin detaylı simülasyona yönelik mekanik özellikleri hassas şekilde tespit edilmiş ve bu bilgiler de ilgili sonlu elemanlar yöntemi programına malzeme kartları olarak yerleştirilmiştir. Çalışmada analizleri yapılan parçaların daha sonra imalatları gerçekleştirilmiş ve imal edilen parçalar üzerinden optik ölçüm yöntemi ile hem geometrik bilgi (ölçüler ve toleranslar) hem de genleme değerleri elde edilmiştir. Optik ölçümler için GOM-Atos ve Argus optik ölçüm sistemleri kullanılmıştır. Belirli bir kesit boyunca ölçümler karşılaştırıldığında gerek açık adım gerekse kapalı adım çözümlerinin oldukça iyi sonuçlar verdiği görülebilir. Ancak çözümler kalınlık değişmesi açısından karşılaştırıldığında kapalı adım çözümlerin açık adım çözümlerine göre çok daha iyi sonuç verdiği değerlendirilmektedir. Anahtar kelimeler: artımlı sac şekillendirme, sonlu eleman yöntemi, kalıpsız şekillendirm

Improving the Productivity and Energy Efficiency by a Heat Treatment Method Applied to Aluminum Forged Parts

In industrial applications, hot forging of AA6082 alloy is carried at 480°C. After the hot forging operation parts are cooled down to room temperature and heated again up to 540°C for solution heat treatment and artificially aged. Heating-cooling-heating cycles leads to energy and time loss in production, and have long-termenvironmental and economic impacts. Mass production of aluminum parts for applications in various industries (automotive, aerospace etc.) requires a process with higher productivity. The aim of this study was to provide time and energy efficiency by combining hot forging and solution treatment processes into a single operation. AA6082 billets were forged at 540°C for 7.5, 15 and 30 minutes in order to achieve simultaneous solution treatment. Billets were then water quenched and artificially aged. Mechanical properties (hardness, tensile strength) as well as microstructure of samples were investigated. Required mechanical properties were achieved on the samples forged and treated at 540°C for 15 and 30 minutes

Adsorption thermodynamics of cationic dyes (methylene blue and crystal violet) to a natural clay mineral from aqueous solution between 293.15 and 323.15 K

Wastewater from dyestuff production is one of the main water pollutants. Several methods have been applied for the remediation of contaminated water. Currently, adsorption using a cheap, abundant, and environmental-friendly adsorbent such as natural clay is the simplest and most useful method. This study aimed to determine the enthalpies of adsorption of the organic cationic dyes, methylene blue (MB) and crystal violet (CV), from polluted water onto a natural clay mineral. Early on, we performed mineralogical and textural analyses of a clay sample using various techniques, namely X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller analysis, Fourier-transform infrared spectroscopy, and differential scanning calorimetry, before and after adsorption. The experimental results showed that this adsorbent is a mesoporous and non-swelling clay with illite and kaolinite as the major components. The effects of various parameters such as contact time, pH, and temperature were examined. The experimental data were analyzed using the linear forms of the Langmuir and Freundlich isotherm models and showed a good fit with the Langmuir equation for MB adsorption. Thermodynamic parameters such as the changes in Gibbs free energy, enthalpy, and entropy were determined from batch experiments. Results revealed that the adsorption of MB onto illitic clay was endothermic, while that of CV was an exothermic and spontaneous process. Keywords: Adsorption, Cationic dyes, Illitic clay, Temperature effect, Enthalpies of adsorptio

An organified mixture of illite-kaolinite for the removal of Congo red from wastewater

Congo red (CR), an anionic dye, is very harmful to the environment and should be removed via an easy and inexpensive technique. The adsorption of CR from an aqueous solution onto a mixture of illite-kaolinite clay minerals and surfactant-modified illite-kaolinite was investigated at different temperatures. The characterization of the raw clay mixture and the organified sample was confirmed with X-ray diffraction, FTIR spectroscopy, nitrogen gas adsorption at 77 K and transmission electronic microscopy techniques. Factors influencing the adsorption such as pH, adsorbent dosage and temperature were tested. The thermodynamic parameters ΔG°, ΔH° and ΔS° have been calculated, and it was found that the adsorption is exothermic in nature. The isotherm data were fitted by the linear form of the Langmuir and Freundlich models and showed a good fit with the Langmuir approach. The maximum adsorption capacity of surfactant-modified clay (83 mg/g) was found to be around 14 times higher than that of unmodified clay. Kinetic studies of CR on illite-kaolinite and organified illite-kaolinite were evaluated by pseudo-first-order and pseudo-second-order models

Adsorption thermodynamics of cationic dyes (methylene blue and crystal violet) to a natural clay mineral from aqueous solution between 293.15 and 323.15 K

Wastewater from dyestuff production is one of the main water pollutants. Several methods have been applied for the remediation of contaminated water. Currently, adsorption using a cheap, abundant, and environmental-friendly adsorbent such as natural clay is the simplest and most useful method. This study aimed to determine the enthalpies of adsorption of the organic cationic dyes, methylene blue (MB) and crystal violet (CV), from polluted water onto a natural clay mineral. Early on, we performed mineralogical and textural analyses of a clay sample using various techniques, namely X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller analysis, Fourier-transform infrared spectroscopy, and differential scanning calorimetry, before and after adsorption. The experimental results showed that this adsorbent is a mesoporous and non-swelling clay with illite and kaolinite as the major components. The effects of various parameters such as contact time, pH, and temperature were examined. The experimental data were analyzed using the linear forms of the Langmuir and Freundlich isotherm models and showed a good fit with the Langmuir equation for MB adsorption. Thermodynamic parameters such as the changes in Gibbs free energy, enthalpy, and entropy were determined from batch experiments. Results revealed that the adsorption of MB onto illitic clay was endothermic, while that of CV was an exothermic and spontaneous process. Keywords: Adsorption, Cationic dyes, Illitic clay, Temperature effect, Enthalpies of adsorptio