New Understanding of Clay Minerals New Understanding of Clay Minerals Sang-Mo Koh Geology and Geoinformation Division, KIGAM 2006. 11. 27
Clay & Clay Minerals Clay & Clay Minerals
Contents Contents Introduction Definition of clay and clay minerals Classification of clay minerals Structure of clay minerals Properties of clay minerals Utilization of clay minerals Organo-clay : Modified New field of clay minerals Nano-composite clay clay
Introduction
Field of Clay Mineralogy Field of Clay Mineralogy Quantitative chemistry Crystallography Geology Clay Mineralogy Soil Mineralogy science Physical chemistry
What is clay ? What is clay ? Definition Size terminology Size terminology Ceramics A very fine grained soil that is plastic when moist but hard when fired. Civil Decomposed fine materials with the size less than 5μm engineering in weathered rocks and soils Geology Sediments with the size less than 1/256mm (4μm ) Pedology All the materials with size less than 2μm in soils (ISSS) ISSS: International Society of Soil Science
What is clay mineral ? What is clay mineral ? Definition in Clay Mineralogy (Bailey, 1980) Clay minerals belong to the family of phyllosilicates and contain continuous two-dimensional tetrahedral sheets of composition T 2 O 5 (T=Si, Al, Be etc.) with tetrahedral linked by sharing three corners of each, and with the four corners pointing in any direction. The tetrahedral sheets are linked in the unit structure to octahedral sheets, or to groups of coordinating cations, or individual cations
Classification of clay minerals Classification of clay minerals Group Layer (x=charge per Subgroup Species type Definition in Clay Mineralogy (Bailey, formula unit) 1980) Kaolin~ Kaolin Kaolinite, dickite, halloysite, nacrite 1:1 serpentine Serpentine Chrysotile, lizardite, amesite x=0 Pyrophyllite~ Pyrophyllite Pyrophyllite talc Talc Talc x=0 Montmorillonite Montmorillonite, beidellite, nontronite (dioctaheral smectite) Smectite x=0.2-0.6 Saponite Saponite, hectorite, (trioctahedral smectite) Dioctaheral vermiculite Dioctaheral vermiculite Vermiculite x=0.6-0.9 Trioctaheral vermiculite Trioctaheral vermiculite Dioctaheral mica Muscovite, illite, glauconite, paragonite Mica 2:1 x=0.5-1.0 Trioctaheral mica Phlogopite, biotite, lepidolite Dioctaheral brittle mica Margarite Brittle mica x=2.0 Trioctaheral brittle mica Clintonite, anandite Dioctaheral chlorite donbassite Chlorite Di,trioctaheral chlorite Cookeite, sudoite x=variable Trioctaheral chlorite Chlinochlore, chamosite, nimite Palygorskite~ Sepiolite Sepiolite sepiolite Palygorskite palygorskite x=variable
Structure of clay minerals Structure of clay minerals Tetrahedron structure Definition in Clay Mineralogy (Bailey, 1980)
Structure of clay minerals Structure of clay minerals Definition in Clay Mineralogy (Bailey, Three ways of tetrahedral sheet 1980)
Structure of clay minerals Structure of clay minerals Octahedron structure Definition in Clay Mineralogy (Bailey, 1980)
Structure of clay minerals Structure of clay minerals Trioctahedral & dioctahedral sheet Octahedral sheet Six coordination number Divalent cations (Mg 2+ ) : Three of every octahedral sites are occupied : Trioctahedral Trivalent cations (Al 3+ ) : Two of every octahedral sites are occupied : Dioctahedral
Structure of 1:1 type clay minerals Structure of 1:1 type clay minerals 1:1 layer structure consists of a unit made up of one octahedral & one tetrahedral sheet, with the apical O 2- ions of the tetrahedral sheets being shared with the octahedral sheet. Kaolin and serpentine group
Structure of 2:1 type clay minerals Structure of 2:1 type clay minerals 2:1 layer structure consists of two tetrahedral sheet with one bound to each side of an octahedral sheet. Octahedral sheet Smectite, micas, pyrophyllite, and vermiculite etc.
Equipment for research of clay minerals Equipment for research of clay minerals SEM X-ray Diffractometer Thermal TEM Analyser FTIR EPM A Qualitative and quantitative analysis of clay minerals Study on the crystal structure Study on the mineral chemistry Study for the utilization of clay minerals
Properties of clay minerals Properties of clay minerals Permanent negative charge ( 2:1 clay minerals) - By isomorphic substitution in octahedral and tetrahedral site [ octahedral site: Al 3+ (Fe 3+ ) → Fe 2+ , Ca 2+ , Mg 2+ ] [ tertrahedral site: Si 4+ → Al 3+ , Fe 3+ ] pH dependent charge or edge charge (1:1 clay minerals) - Broken, structural defect (terraces, kinks, holes) - react with water molecules to form surface hydroxyl group aluminol and silanol functional group
Properties of clay minerals Properties of clay minerals Negative Charge : Cation Exchange Capacity (CEC) : High Adsorption Capacity of Heavy Metals & Cationic nuclides Mineral type CEC (cmol/kg) Kaolinite 3-15 5-10 Halloysite (2H 2 O) Halloysite 40-50 (4H 2 O) Zeolite 100-300 10-150 Diocahedral vermiculite Trioctahedral vermiculite 100-200 Chlorite 10-40 Biotite 10-40 Smectite 80-150
Properties of clay minerals Properties of clay minerals High Surface Area : high adsorption capacity Mineral type Surface area(cm2/g) EGME BET EGME Ethylene Glycol Monoethyl Ether Montmorillonite 35 ~ 48 810 Kaolinite 5 ~ 9 48 Halloysite 76-173 Atapulgite 50 ~ 83 Illite 89 ~ 112 193 Talc 2.4 ~ 5.8 7 Vermiculite 350 Hectorite 461 High Refractoriness : SK
Properties of clay minerals Properties of clay minerals High Viscosity Mineral type Viscosity (cP) : 10% solution Bentonite 10-30 Pyrophyllite 1-1.5 1-1.2 Kaolin Sericite 1-1.2 High Expansion & Swelling Colloidal property Hydrophyllic property : well dispersed in the water solution Very easily hydrated and dehydrated High plastic property : important property of ceramic materials
Classic Utilization Classic Utilization Ceramics : pottery, sanitary ware, refractory brick, tile etc. : kaolin, pyrophyllite, illite(sericite) Refractory Refractory Plastic Plastic Materials Materials Flux Material Flux Material Materials Materials Mixing, Molding, Molding, Mixing, Drying, Sintering Drying, Sintering
Classic Utilization Classic Utilization Filler : paper, plastic and rubber (kaolinite, pyrophyllite) Cosmetics : kaolinite, smectite, illite, talc Glass fiber : pyrophyllite, dickite Agricultural fertilizer : pyrophyllite, kaolinite etc. Civil engineering (water barrier & stablizer) : bentonite (smectite) Foundry : bentonite (smectite) Environmental barrier : backfill material of waste disposal site : artificial barrier of nuclear disposal site
Classic Utilization Classic Utilization Best Clay Minerals ? ? Best Clay Minerals for Environmental Remediation or Treatment for Environmental Remediation or Treatment
Bentonite Bentonite Industrial ore composed of smectite (mainly montmorillonite) Montmorillonite R + 0.33 (Al 1.67 Mg 0.33 )Si 4 O 10 (OH) 2 Expandable interlayer Exchangeable cations in interlayer high adsorption capacity Waste water purification - precipitation of phosphates - sorption of heavy metals - purification of sewage plants : nitrogen and ammonium gases Pre-purification Post-purification
Bentonite Bentonite Liner of Waste Disposal Site ( Prevention of leachate)
Bentonite Bentonite Nuclear Waste Disposal Site Radionuclide transport barrier : adsorption of nuclides
New Field of Clay Minerals
Recent New Field of Clay Minerals ? Recent New Field of Clay Minerals ? Modification of Clay Minerals Organoclay Pillared Clay Organo-modified clay Organic - - - - substances Na + - - + + + + OH - - Na OH OH Ca OH Ca OH OH OH - - OH OH H 2 O Na OH H 2 O - - + + + - - - Purified clay Preparation of (Ca-type clay) Nano-composite
What is Organoclay ? What is Organoclay ? Organic chemicals can be adsorbed on the clay Modification of Clay Minerals surface and interlayer. Compound of clay mineral and organic chemicals Pillared Clay It is manufactured by the reaction between clay and chemicals.
Organoclay Organoclay Modification of Clay Minerals Commonly used clay mineral : smectite Expandable Interlayer & high charge
Organo-modified minerals Organo-sericite Organo-zeolite Organo-montmorillonite Different mineral types Different surfactants (chemicals) Characteristics of organo-modified minerals manufactured by different minerals and chemicals
Organo-modified mineral Organo-modified mineral Three minerals Three Chemicals S 8000 S : Sericite C : Clinoptilolite M : Mordenite S Mo : Montmorillonite 10.05 (001) CT : Opal-CT Hyamine 1622 R S 5.03(002) 6000 S S S Intensity (counts / second) S S S S S S S C C C C C 4000 C M C M C M M C M M C Benzyldimethyltetradecylammonium (BDTDA) Mo Mo (005) 2000 12.5(001) Mo Mo (020) (006) CT Mo (002) 0 2 12 22 32 42 2 Theta Benzyltrimethylammonium (BTMA) 5 Å
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