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Removal of Hexavalent Chromium from Wastewater using Modified Multiwall Carbon Nanotubes
No full textA Master of Science thesis in Chemical Engineering by Tamara Georgesaleh Dokmaji entitled, “Removal of Hexavalent Chromium from Wastewater using Modified Multiwall Carbon Nanotubes”, submitted in December 2018. Thesis advisor is Dr. Taleb Ibrahim and thesis co-advisor is Dr. Mustafa Khamis. Soft and hard copy available.Recently, the interest and research on the removal of heavy metals from wastewater have dramatically increased due to the adverse effects they have on humans, flora and fauna. Chromium, which is a heavy metal, is the tenth most abundant element in the universe and naturally occurs in the form of hexavalent chromium [Cr(VI)] and trivalent chromium [Cr(III)]. In this thesis, an adsorption technique using modified multiwall carbon nanotubes (MWCNTs) is investigated for Cr(VI) removal from wastewater. The surface of the MWCNTs was modified with a cationic surfactant, cetyl trimethylammonium bromide (CTAB). Surface characterization was conducted using Fourier Transform Infrared spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), and Energy Dispersive X-ray Spectroscope (EDS) in which a thorough review of results revealed that MWCNTs modification with CTAB was successful. The optimum conditions for adsorption using MWCNTs-CTAB were determined. The optimum values in terms of adsorbent dosage, contact time, pH, and temperature were found to be 0.05 g, 25 min, 4.5, and 25 oC, respectively. Fitting equilibrium data using various isotherm models revealed that the adsorption of Cr(VI) on MWCNTs-CTAB follows a Langmuir isotherm model with maximum adsorption capacity of 27.78 mg/g and Langmuir adsorption capacity of 3.956 L/mg. In addition, kinetic parameters were also fitted on several models and the data revealed that MWCNTs-CTAB followed a pseudo- second order reaction model with rate constant 9.85*10-4 g/mg.min. A thermodynamic study showed that the proposed adsorption process is spontaneous, endothermic and the mode of adsorption is physisorption with Gibbs free energy of -1.3 kJ/mol at 25 oC. From this batch experimental study, it can be concluded that the removal of Cr(VI) from wastewater using MWCNTs-CTAB was successful and a removal efficiency of 98% was achieved at the selected optimum conditions.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Social Cohesion and Optimal Redistribution in Economies with Long-Run Growth
No full textWe suggest that as social cohesion improves, the macroeconomic gains from progressive redistribution decline. Social interactions facilitate diffusion of nonrival knowledge. The consequent bridging of the knowledge gaps makes learning cheaper for children with limited access to adults with high human capital and thereby lowers the optimal progressivity for a redistributive policy. If social cohesion exceeds a critical threshold then zero progressivity would be optimal. Numerically, a country with greater social cohesion finds smaller gains in growth, efficiency, and welfare from progressive redistribution over and above the gains from a Pigouvian subsidy that eliminates the inefficiency caused by knowledge externalities
Does Foreign Direct Investment Promote Economic Growth: An Empirical Analysis
No full textThis paper used time-series data to investigate the causal relation between foreign direct investment and economic growth in two MENA countries, namely Egypt and Jordan. The methodology used in this study follows Toda and Yamamoto (1995) procedure in order to test the Granger causality between economic growth and foreign direct investment. The empirical results reveal that only the FDI-led growth hypothesis exists in the case of both Egypt and Jordan
Membrane Bioreactor-Desalination Microbial Fuel Cell Hybrid System
No full textA Master of Science thesis in Chemical Engineering by Noora Hussein Adam Mukhtar entitled, “Membrane Bioreactor-Desalination Microbial Fuel Cell Hybrid System”, submitted in April 2018. Thesis advisor is Dr. Sameer Al-Asheh and thesis co-advisor is Dr. Ahmed A. Aidan. Soft and hard copy available.The microbial desalination fuel cell (MDFC) is an emerging desalination technology offering great promise of high salinity removal with zero energy input. Moreover, the membrane bioreactor (MBR) is of great reliability in treating domestic and industrial wastewater. The objective of this work is to introduce a hybrid system of a membrane bioreactor and a microbial desalination fuel cell for simultaneous wastewater treatment, seawater desalination and production of electricity. This hybrid system allows low cost resources, energy conservation and low sludge and carbon footprints. Synthetic wastewater, exoelectrogenic microorganisms (yeast) and substrate (glucose) were employed as the anode feed in the MDFC. Two system configurations with an immersed MBR and side-stream MBR have been proposed and compared. In addition, the hybrid system was studied under open circuit (no external load) and closed circuit modes (three different resistive loads). This research presents the success of the hybridization in comparison with a MDFC employing only yeast solution as the anolyte. In addition, it investigates the effect of some modifications namely, the cell size, solutions volume ratio and type of ion exchange membrane. Experimental tests revealed that a bench scale system of 350-ml chamber capacity can achieve higher salinity removal (+6%) and voltage production (+0.035 V) than its alternative 4500-ml chamber. Also, reducing the volume of seawater to anolyte and catholyte volumes by 29% accomplished higher desalination by 6% for the hybrid system removing almost 20% of the salts in 8 days. A total desalination rate (TDR) of 6.25 mg/hr, and a power density of 4.34×10-3 W/m3 are obtained using a 300-KΩ external resistance. On the other hand, a power density of 0.222 W/m3 and 4.69 mg/hr TDR are achieved using a 4-KΩ external load. Thus, the choice of external resistance involves a trade-off between desalination efficiency and power generation. With regards to wastewater treatment by the MBR, the system was evaluated in terms of total dissolved solids (TDS), total suspended solids (TSS), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD) and turbidity for the permeate water. The effluent quality enhanced by more than 50% except for the COD and BOD analyses. MDFCs are good alternatives to the energy intensive desalination methods.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
The Internet Dilemma: An Exploratory Study of Luxury Firms' Usage of Internet-Based Technologies
No full textSurprisingly, there exists a paucity of research examining the adoption of Internet-based technologies by luxury firms. This represents a major shortcoming in our understanding of how luxury firms maintain the image of their brand, sustain a personal link with customers, and retain an aura of exclusivity as they seek to provide their products and services to increasingly technologically-astute customers. Using content analysis, we present the findings of a qualitative investigation of 92 luxury firm websites across the categories of automobiles, fashion, jewelry, watches, and yachts. Study findings indicate that there are noticeable differences in website characteristics and functionality across sectors. Implications of the results are discussed, noting that decisions about using the Internet for branding and selling, one-way and two-way communications, as well as operational and innovative features, are driven by the characteristics of the products being offered. Avenues for future research are also offered
Ultrasound triggered release of Trastuzumab-conjugated immunoliposomes targeting breast cancer
No full textA Master of Science thesis in Chemical Engineering by Amal Elsadig Elamir Ahmed entitled, “Ultrasound triggered release of Trastuzumab-conjugated immunoliposomes targeting breast cancer”, submitted in December 2018. Thesis advisor is Dr. Ghaleb Husseini and thesis co-advisor is Dr. Rana Sabouni. Soft and hard copy available.Cancer is one of the deadliest diseases in this era. Since conventional treatment has many side effects, its use is limited, which augments the need for new smart drug delivery systems, such as nanocarriers, capable of shielding the healthy cells from the adverse side effects of chemotherapy. To this endeavor, liposomes are the most widely used and researched nanovehicles in the fight against cancer. They can be engineered to specifically target cancer cells by modifying their surface with targeting moieties. In this thesis, Trastuzumab was used as the targeting moiety for HER2-positive breast cancer. Once these drug-loaded liposomes reach the tumor, their release can be triggered using ultrasound, an external modality capable of accelerating the cytotoxic effects of the drug. The purpose of this study is to test the ultrasound-triggered release of calcein (a model drug) from immunoliposomes and compare it with the control (non-targeted) liposomes, under the utility of low-frequency ultrasound. The overall goal is to obtain an engineered immunoliposomes that specifically targets malignant tissue using acoustic power. The liposomes were categorized to be unilamellar vesicles (ULVs) with average radii of 89 nm and 101 nm for non-targeted liposomes and immunoliposomes, respectively. Next, the attachment of Trastuzumab was confirmed resulting in 9 Trastuzumab molecules per liposome. Low-frequency ultrasound (at 20 kHz) results showed the sono-sensitivity of both carrier types, with immunoliposomes being more acoustically sensitive, releasing 92% of the model drug, compared to 86% released from NH2 liposomes. Results also showed an increase in the release rate as the power density increased from 7.46 to 17.31 (mW/cm2). Finally, both types of liposomes were tested for their release kinetics, and results showed adherence to the Korsmeyer-Peppas model with an n > 0.45 which indicates a non-Fickian diffusion of the drug through the liposomal membrane. Statistical analysis showed that the release rate constants were significantly different at different power densities. Release rates (kkp) at 7.46 (mW/cm2) for immunoliposomes and NH2 liposomes were 2.098 x 102 and 2.094 x 102, respectively. Using ultrasound and targeted liposomes, we envision a drug delivery system capable of reducing the side effects of conventional chemotherapy.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Effects of Selected Ionic Liquids on the Vapor-Liquid-Equilibria of Water-2-Propanol System
No full textA Master of Science thesis in Chemical Engineering by Faisal Waleed Mohammed entitled, “Effects of Selected Ionic Liquids on the Vapor-Liquid-Equilibria of Water-2-Propanol System”, submitted in April 2018. Thesis advisor is Dr. Naif Darwish. Soft and hard copy available.Separation processes involving vapor and liquid phases represent a typical unit operation in most chemical industries, including distillation and absorption. A large fraction of the capital and operating costs is usually devoted to such operations. Owing to the unlikelihood of the complete separation of azeotropic mixtures by distillation, separation processes involving such mixtures remain one of the most pressing challenges in the chemical industry. Using inorganic salts is a common technique in handling azeotropic systems. However, issues such as corrosion and fouling render this technique ineffective. Recently, ionic liquids were introduced as azeotrope-breakers. In this work, the effect of two ionic liquids, i.e., 1-Butyl-1-methylpyrrolidinium chloride [BMPy][Cl], and 1-Butyl-1-methylpyrrolidinium trifluoromethanesulfonate [BMPy][OTf] on the vapor liquid equilibrium (VLE) of the (azeotropic) water + 2-propanol system is investigated. For this purpose, the corresponding binary VLE for water or 2-propanol with each of the two ionic liquids were experimentally measured and reported at 100, 75, and 50 kPa. Based on the observed boiling point elevation, it has been found that [BMPy][Cl] has a higher interaction with both solvents than [BMPy][OTf]. Furthermore, it has been found that [BMPy][Cl] has a higher interaction with water than with 2-propanol, while [BMPy][OTf] interacts with both solvents in a similar manner. The boiling point elevation was found to be independent of the pressure. Most importantly, [BMPy][Cl], at a mole fraction of 0.31in the liquid phase, was capable of completely eliminating the azeotrope of water + 2-propanol system. In contrast, [BMPy][OTf] shifted the azeotrope towards the alcohol-rich region, yet it was not able to completely remove the azeotrope of this system at the studied concentrations. Data were modelled with the non-random, two-liquid (NRTL) model, which could describe the experimental data, with a root mean square deviation (RMSD) less than 0.015 for the solvents’ activity coefficients in the binary systems. For the ternary systems, the RMSD for temperature was found to be less than 2 ºC. Thus, it is concluded that chloride based ionic liquids resemble good entrainers for the extractive distillation of the studied azeotrope.College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Improving the Efficacy of Anticancer Drugs via Encapsulation and Acoustic Release
No full textConventional chemotherapeutics lack the specificity and controllability, thus may poison healthy cells while attempting to kill cancerous ones. Newly developed nano-drug delivery systems have shown promise in delivering anti-tumor agents with enhanced stability, durability and overall performance; especially when used along with targeting and triggering techniques. This work traces back the history of chemotherapy, addressing the main challenges that have encouraged the medical researchers to seek a sanctuary in nanotechnological-based drug delivery systems that are grafted with appropriate targeting techniques and drug release mechanisms. A special focus will be directed to acoustically triggered liposomes encapsulating doxorubicin
Designing a Flexible and Reconfigurable Manufacturing System Considering a Circular Shaped Layout
No full textA Master of Science thesis in Engineering Systems Management by Awrad Khalid AlDuaij entitled, “Designing a Flexible and Reconfigurable Manufacturing System Considering a Circular Shaped Layout”, submitted in May 2018. Thesis advisor is Dr. Noha Mohamed Hassan Hussein. Soft and hard copy available.Production demands are constantly changing at a fast pace. The demand for a shorter life cycle and customized products makes it more difficult for factories to adapt. To stay competitive, factories need to be flexible in embracing those continuous changes. Since the second half of the last century, several advanced manufacturing systems have been developed to efficiently produce a variety of products. One of them is the Flexible Manufacturing System (FMS) that has the ability to produce different quantities of different varieties without the need to pause the production line, thus improving process efficiency and lowering production cost. FMS layout includes several arrangements of machines and material handling system and has a significant influence on routing flexibility, machine utilization, factory floor space area, responsiveness to change and productivity. In this research, a new FMS layout, composed of multiple circular loops, is proposed and compared to the traditional open field layout with rectangular loops and ladders. Face Centered Composite Design (FCCD) is applied to investigate the main and interaction effect of product quantity, variety and complexity, and layout design on system performance. The fourth categorical factor considered is the layout shape. Total production cost is used as a system performance metric. To determine this cost, a linear programming (LP) mathematical model is formulated. The model design attributes include cell layout, cell formation, machine capacities, constant and variable machine cost, lot splitting, and alternative process routings. Lingo software is used to solve the formulated optimization model which was validated by comparing it to test cases available in the literature. Response Surface Methodology (RSM) was used for modeling the responses. The main effect plots indicate that increasing the number of locations had the most significant influence on cost, followed successively by product and routing. Results reveal that proposed circular layout is more cost effective than the traditional rectangular open field layout with cost savings reaching 14 % and more when product variety and complexity is increased.College of EngineeringDepartment of Industrial EngineeringMaster of Science in Engineering Systems Management (MSESM