New Understanding of Clay Minerals New Understanding of Clay - PowerPoint PPT Presentation

New Understanding of Clay Minerals New Understanding of Clay Minerals Sang-Mo Koh Geology and Geoinformation Division, KIGAM 2006. 11. 27

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 science Mineralogy 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 belongs to the family of phyllosilicates and contain continuous two-demensional 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 corner 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 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

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, pyrophyllie, 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 barrrier 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 mineral 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 Waste water purification (high adsorption capacity) - 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

New Field of Clay Minerals ? 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 ? Modification of Clay Minerals Organic chemicals are adsorbed on the clay surface. Compound of clay mineral and organic chemicals Pillared Clay

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 Benzyltrimethylammonium (BTMA) 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

Organo-montmorillonite Organo-montmorillonite BTMA HYAMINE BDTDA 300 BDTDA (Benzyldimethyltetradecylammonium) -MONTMORILLONITE -MONTMORILLONITE -MONTMORILLONITE Actual exchanged amount compared to CEC (%) N 30.84 27.9 16.27 14.9 14.1 250 20000 262% 239% 200 Hyamine 30.68 27.5 97% 16000 O O 16.02 N 14.0 150 INTENSITY (COUNTS / SECOND) 238% 213% 96% 29.51 12000 93% 100 27.3 15.94 14.1 BTMA (Benzyltrimethylammonium) 89% N 191% 199% 50 8000 78% 19.19 22.9 0 103% 60% 103% 0 50 100 150 200 250 300 350 400 450 40% 4000 Exchanging amount compared to CEC (%) 12.5 Non-treated Non-treated Na-montmorillonite 0 6 8 10 2 2 4 6 8 10 2 4 4 6 8 10 2 THETA