Gjergj Dodbiba
The University of Tokyo, Systems Innovation, Faculty Member
- Separation Techniques, Recycling, LCA, Separation processes, Membrane Technology, Recycled Materials, and 18 moreProcess Optimization, Separation, Bioprocess/ Biochemical Engineering, Biofuel, Chemical and Biological Engineering, Reaction engineering, Reaction Mechanisms, Systems Innovation, Physical Chemistry, Mineral Processing, Mineral Resources, Minerals, Wastewater Treatment, Waste Management, Solid Waste Management, Water and wastewater treatment, Waste recycling, and Rare Metals(Process Optimization, Separation, Bioprocess/ Biochemical Engineering, Biofuel, Chemical and Biological Engineering, Reaction engineering, Reaction Mechanisms, Systems Innovation, Physical Chemistry, Mineral Processing, Mineral Resources, Minerals, Wastewater Treatment, Waste Management, Solid Waste Management, Water and wastewater treatment, Waste recycling, and Rare Metals)edit
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In this work, properties of a magnetorheological (MR) fluid, prepared by dispersing a mixture of two types of carbonyl iron powders (CIPs) of different sizes, in an ionic liquid (N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium... more
In this work, properties of a magnetorheological (MR) fluid, prepared by dispersing a mixture of two types of carbonyl iron powders (CIPs) of different sizes, in an ionic liquid (N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate) that is stable from 9°C to ca. 300°C, have been investigated. At first, the random packing density of the mixture was computed as function of mixing ratio of
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ABSTRACT Properties of a magnetorheological (MR) fluid synthesized by dispersing a mixture of two carbonyl iron powders (CIP) in an ionic liquid have been investigated. At first, mixtures of CM (d50 = 7 μm) and HQ (d50 = 1.1 μm) CIP... more
ABSTRACT Properties of a magnetorheological (MR) fluid synthesized by dispersing a mixture of two carbonyl iron powders (CIP) in an ionic liquid have been investigated. At first, mixtures of CM (d50 = 7 μm) and HQ (d50 = 1.1 μm) CIP powders, prepared at the same solid weight fraction but at various weight fractions of large particles, were dispersed in the ionic liquid (N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate), which is stable even at high temperature. Then, the magnetic clusters of the synthesized MR fluids were observed by using an optical microscope, whereas the magnetorheological properties were investigated by using a bi-cylindrical viscometer. Each apparatus was equipped with a magnetic field generator to create a uniform magnetic field. After finding the most suitable mixing ratio of powders, a new batch of MR fluid was synthesized by the addition of surfactant (ETC-7) to enhance its stability. Finally, the properties of the MR fluid with or without addition of surfactant were compared. The experimental results showed that the MR fluid with 60 wt% fraction of large particles exhibited the highest MR response.
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The heat convection, which can be provided from a magneto-rheological (MR) fluid, is a useful process in converting heat from high to low temperature and vice versa. In this work, the property and preparation of liquid gallium-based MR... more
The heat convection, which can be provided from a magneto-rheological (MR) fluid, is a useful process in converting heat from high to low temperature and vice versa. In this work, the property and preparation of liquid gallium-based MR fluid is presented. The prepared MR fluid disperses micron-sized iron or nicked metal powders in liquid gallium ( Ga ). In this experiment, supercooling of MR fluid was investigated in order to obtain the condition under which the liquid state can be kept below the melting point. Moreover, the viscosity and elasticity of the prepared MR liquid were measured as a function of magnetic flux density. Finally, it was demonstrated that liquid Ga is a useful base for preparing a new type MR fluid.
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ABSTRACT The feasibility study on the accelerated mineral carbonation reveals that the addition of ammonia was important in the simplified two-step carbonation reaction, and that micro-bubbling and gas inflow speed were main factors for... more
ABSTRACT The feasibility study on the accelerated mineral carbonation reveals that the addition of ammonia was important in the simplified two-step carbonation reaction, and that micro-bubbling and gas inflow speed were main factors for the reactions. The efficiency of CO2 uptake was 33.9% in the first step of carbonation process and increased to 58.6% in the second step. Calcium carbonate was obtained as product of Ca conversion up to 56.6% as a maximum conversion, through first and second carbonations. In the mineralogical analysis of ash, XRD pattern showed that, as carbonation proceed, the peaks of Ca(OH)2 and CaClOH disappeared, and intensity of CaCO3 peaks increased. Finally, scanning electron microscopy analysis also indicated that the fly ash particles became more crystalline with agglomeration by further carbonation using ammonia. The process suggested in this study could be applied in the eco-industrial parks.
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The demand for lithium-ion batteries has been increasing due to the increasing demand for laptop computers, cellular phones, automobiles, etc. The positive electrode of the lithium-ion secondary battery is mainly made of lithium oxides... more
The demand for lithium-ion batteries has been increasing due to the increasing demand for laptop computers, cellular phones, automobiles, etc. The positive electrode of the lithium-ion secondary battery is mainly made of lithium oxides well as cobalt, nickel, manganese, etc. Thus, an effective recycling method not only would collect cobalt and lithium, but also would enable the separation of other materials from the spent batteries. In this work, a novel processing flow sheet is put forward and its efficiency is evaluated. The aim was to obtain pure fractions of various constituents.
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In this work, FeMB (M = Nb, V) nanoparticles were first reported to be synthesized by a chemical method, from reduction of FeCl2, NbF5 (and NH4VO3) using NaBH4 as a reducing agent in aqueous solution. A new temperature sensitive... more
In this work, FeMB (M = Nb, V) nanoparticles were first reported to be synthesized by a chemical method, from reduction of FeCl2, NbF5 (and NH4VO3) using NaBH4 as a reducing agent in aqueous solution. A new temperature sensitive functional fluid was then prepared by dispersing silica coated FeNbVB nanoparticles in liquid gallium. The result shows that the FeNbVB nanoparticles
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Abstract Particle geometry is important for designing and optimizing physical separation, a material processing technique employed in many areas. Particle geometry is usually analyzed by sieving, an indirect method for particle size... more
Abstract Particle geometry is important for designing and optimizing physical separation, a material processing technique employed in many areas. Particle geometry is usually analyzed by sieving, an indirect method for particle size calculation. Moreover, other particle geometry parameters, such as aspect ratio, circularity, and cross-section area are sometimes calculated through visual analysis. It is important to note that the image processing method for simultaneously calculating several particle geometry parameters is challenging. This paper introduces a novel particle geometry algorism that simultaneously calculates several particle geometry parameters, including the shape factor that can be applied for modeling several physical separation methods. For evaluating the result of the image processing method, a sample of waste electric appliances was subject to a sieving experiment. After comparing the results of the image processing and sieving experiment, it was found that the size error width between image processing and sieving was promotional to the value of aspect ratio and circularity. Finally, considering the particle geometry of the sample, a general conceptual flowsheet was put forward to select the most suitable treatment method.
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ABSTRACT Magnetorheological suspension (MRS) dispersing spherical several gm of iron particles in the low vapor pressure of dimethylpolysiloxane has been prepared. Yield stress has been proportional to square of magnetic field intensity... more
ABSTRACT Magnetorheological suspension (MRS) dispersing spherical several gm of iron particles in the low vapor pressure of dimethylpolysiloxane has been prepared. Yield stress has been proportional to square of magnetic field intensity and increases as containing larger volume fraction of iron particles and using solvent that is more viscous. The plastic viscosity increased linearly as a function of volume fraction of iron particles. The burst pressure of MRF seal is related on the dispersed iron particle size. The burst pressure is related on the magnetization curve in the MRS dispersing less than several gm of iron particles. On the other hand, the surface tension of solvent influences on the burst pressure in the MRS dispersing more than several gm of iron particles. Also the burst pressure is affected on the seal gap. In the large gap, the burst pressure in stationary condition adds the pressure by the yield stress of MRS. However, in the small gap the burst pressure of rotating condition is almost the same as that of stationary condition because the arranged iron particles cannot be reconstructed in a small gap. The larger viscosity of solvent and volume of iron in MRS increases the burst pressure.