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A review of Alumina: Most abundant and productive material of the mother
nature
KAYAALP UmayPAPOUTSOGLOU Dimitra
January 2012
Supervisors: AYRAL Andre; andre.ayral@iemm.univ-montp2.fr
BACCHIN Patrice ; bacchin@chimie.ups-tlse.fr January 26, 2012
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1. Introduction
Ceramics:
‘’The art and science of making and using solid articles which have as their essential component, and are composed in large of inorganic nonmetallic materials.’’ Kingerly
‘’All high-temperature chemistry and physics of nonmetallic materials, and the techniques of forming products at high temperatures.’’ Mitchell
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1. Introduction
Aluminum is the most abundant metal in the earth's crust and the third most element in the earth's crust, after oxygen and silicon.
Aluminum is too reactive to be found pure. Bauxite (mainly aluminum oxide) is the most important ore.
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1. Introduction
The following information has been gathered:
occurrence in nature
mineralogical characteristics
mechanical, thermal, chemical and colloidal properties
alumina membranes fabrication
modules and industrial applications
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2. Nomenclature
Figure 1: Dehydration Sequence Of Alumina Hydrates In Air
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3. Structure And Mineralogical Properties
Crystal structure is the main factor controls the properties of alumina
In general, the phases of alumina are produced by pseudomorphic dehydration
Pseudomorphosis is of considerable importance because of its effect on surface area of the intermediate phase structures, and on crystal size and size distribution
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3. Structure And Mineralogical Properties
Alumina is widely used as a catalyst or catalyst support in many heterogeneous catalytic processes owing to its high surface area, superior chemical activity and low cost.
Resistance to: softening swelling and disintegration when immersed in water or other
liquids thermal shock and corrosion
The ability to return to the original highly adsorptive from by a suitable thermal regenerative treatment
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4. Mechanical – Thermal Properties
Alumina has remarkable mechanical properties in comparison with conventional porcelains and other single oxide ceramics
The interest in mechanical – thermal properties lead to several applications such as possible substitution of alumina ceramics for refractory metal parts in air-bone equipment, or fabrication forms.
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4. Mechanical – Thermal Properties
Mechanical properties
Tensile Strength (MPa) 173 117
Bending Strenght Mpa 413 307 Modulus of Elasticity (E) X 108 MPa 26.8 21.27 Compressive Strenght Mpa 3733 1600 Modulus of Ridity(G) X 108 MPa 11.3 8.67 Hardness on the mohs scale 9
Thermal properties
Melting point OC2051±9.7
Boiling Point OC3530
± 200 January 26, 2012
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5. Chemical Properties
Chemical reactions of alumina of general ceramic interest include the resistance to attack of sintered alumina by various reagents, particularly at high temperatures.
Finely divided alumina is rapidly dissolved by HF, hot concentrated H2SO4, mixtures of these acids, ammonium fluoride, molten alkali bisulfates or pyrosulfates, and by concentrated HCl, especially when under pressure.
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Alumina membranes are constantly growing area. In the Figure 3, it can be seen that, the publication numbers are highly increasing parallel with the membrane research especially during recent years.
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6. Alumina Membranes
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6. Alumina Membranes
Excellent mechanical strength
Tolerance to solvents, as well as pH, oxidation,
Can be used at significantly higher temperatures
Have better structural stability
Can be backflushed
Less cost
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6. Alumina Membranes
Highly selective
Permeable / Selective ( based on pore size and dist.)
Durable
Hydrophilic to maximize flow and minimize fouling
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6. Alumina Membranes
Table 2 : Selected commercial Alumina Membranes
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6.1. Macroporous Membranes
Usage: Filtration , diffusion, dispersion rolls, inkpads for fingerprinting
Anodizing of pure aluminum most common path Anodizing well controlled process and provides
homogenous pore distribution The preparation of regular pore arrays typically
involves electrolytic polishing and multiple anodising steps or even mechanical pre-texturing.
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6.1. Macroporous Membranes
Macroporous alumina membranes also can be made from particles or discontinuous fibers by the use of a binder or by sintering .
Silica, vitreous glass and also phosphate are widely used binders in the refractory and ceramic industry
This method is generally used to produce alumina microfiltration filters, which contain larger pores and supports for ultrafiltration membranes, which contain smaller pores
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6.2. Mesoporous Membranes
Figure 4: Preparation procedure of boehmite sol
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6.2. Mesoporous Membranes
Figure 5: Schematic drawing of the rapid gelation processing, 1 - nozzle, 2 - atomizing sol and 3 -substrate.
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Mesoporous -alumina membranes are formed by dip-γcoating a porous substrate in a Boehmite ( -AlOOH) γprecursor sol, will be treated by heat and sintering steps.
The quality and properties of the membrane depend on the dispersion rheology and quality of the Boehmite sol and the dip-coating process as well
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6.2. Mesoporous Membranes
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6.3. Microporous Membranes
A conventional path to synthesis microporous membranes is slipcasting.
In the slipcasting method, a porous support is usually made first by conventional ceramic processing techniques to provide rigid structure with relatively large pore size for slip deposition.
The ability to consistently produce high quality alumina membranes on a commercial scale has been the key to wider acceptance of ceramic membranes as a separation tool.
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7. Membrane ModulesTubular mode / Multichannel / Monolithic
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Schematic side-view of membrane module consisting of multi-channel
elements [Remigy, 2007]
Cross-section of a monolithic multi-
channel membrane element [Hsieh et al.,
1998]
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Composite or anisotropic / Multilayer
Schematic representation of Polypeptide films formed inside pore walls of a thin anodic alumina membrane
[Duran H. et al., 2004]
7. Membrane Modules
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Honeycomb mode
(a) AnoporeTM alumina membrane with honeycomb pore size distribution
(b)Commercial version of honeycomb alumina membrane by Lianyungang Highborn Technology Co., Ltd
7. Membrane Modules
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Kerasep® alumina membrane module
•Alumina/Titanium oxide layers•7-84 channels•Pore size>0.8μm•Compact•d<1178mm •P>80bar•Θ>80oC•pH 0-14
Bulk fermentation / Milk and dairy products / Beverages (beer, wine, water, fruit juice)
7. Membrane Modules
8. Applications
Adsorption layer of alumina
Microfiltration – Ultrafiltration
Crossflow filtration – High Crossflow velocity
Transmembrane pressure : driving force of operation
Concentration of soluble molecules and suspended solids &
Clarification by removing suspended solids
Pretreatment process
8.1 Liquid phase separation (LPS)
1. Environmental
Ions removal from wastewater (Cr, F, Ar)
Eg. Microporous Alumina membrane for Heavy metals removal in petrochemical industry
Oil Recovery
2. Food/Beverage
Clarification of juices
Eg. Pretreatment prior ion exchange/chromatography of clarified juice
Filtration of sugar cane juice
Alcoholic beverages
3. Pharmaceutical
Fermentation broths clarification Eg. Recovery of antibiotics
Fungal cells ultrafiltration
Eg. microfiltration of biological media, such as human red blood cells
Lysozyme ultrafiltration, Penicillin recovery
ECN industry demonstration of inorganic membrane module for liquid phase separation [ecn.nl]
In a wide range of wastewaters, alumina membranes assumed to be suitable for Ar(V) and Cr (III) removal
γ-Al2O3/α-Al2O3, mesoporous alumina / Calcium doped alumina / Composite membranes
Concentration of arsenic ions decreased from 1ppm in 5ppb
Flocculation was used as a pretreatment / for the treatment of the stone cutting wastewater
Example:
Pagana et al., 2008 : Composite γ-Al2O3 membranes made by sol–gel method
Pilot system for Cr(III) and Ar(V) removal
Ar(V) 2 stages adsorption – ultrafiltration process in series
Cr(III) 1 adsorption-ultrafiltration parallel process
8.1 LPS / As (V) – Cr (III) Removal
8.1 LPS / As(V) – Cr (III) Removal
Flow diagram of the Cr (III) removal process [Pagana et al., 2008]
Conclusion: Adsorption-ultrafiltration ion process using ceramic membranes may offer a low cost effective alternative arsenic and chromium purification technology basically in terms of membrane stability, applied pressure and product flux with the additional advantage of being suitable for small local units
8.2 Gas Phase Separation (GPS)
1. Carbon Dioxide Capture
CO2/N2 separation
H2/CO2 separation
2. Hydrocarbons separation
Acetone recovery
Propane separation
Alcoholic beverages
3. Catalytic reactors
VOCs oxidation
Methane to ethane reaction
INSIDE Céram membrane by TAMI industry [tami-industries.com]
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Alumina membrane are used in combination with catalysts or used for catalyst recovery in a wide range of applications
Example: Saraco et al., 1999 / University of Saragoza Chem. Eng.Lab.
Pt/Al2O3 and perovskite-containing membranes
Using hydrogenation reactions over Pt/Al2O3 catalysts in membrane module
Purification (by catalytic combustion) of air streams containing volatile organic compounds (VOCs) in low concentrations
Membrane would be expected to give high contact efficiency in the reaction of diluted streams
Conclusion: The membrane performed very efficiently in the combustion of VOCs at low temperatures, although at the expense of a significant pressure drop.
8.2 GPS /VOCs removal
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Schematic of a multi tube membrane module for H2 and CO2 separation [Diriz
et al., 2007]
Applications of membrane reactors [Coronas et al., 1999]
8.2 GPS /VOCs removal
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Nanotechnology / Composite structures Modifications Sensitive active layers Alumina Catalysts/ Surface Adsorption Nanofiltration Gas separation Lower Cost (10 times > Polymeric, Remigy, 2004)
Lower Fragility / Fouling/ Cracking
Application of ceramic membranes in fields “traditionally” dominated by polymeric
membranes!
9. Perspectives
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Acknowledgements
We would like to express our sincere thanks to
EM3E for its support
Prof.A.Ayral, Prof.P.Bacchin and A.Julbe for their advices
EM3E GROUP FOR THIS FIRST… HARD SEMESTER!
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Goodbye France!