The high-density siliciclastic minerals (e.g. zircon) in the coarse fractions (>44 mm, informa... more The high-density siliciclastic minerals (e.g. zircon) in the coarse fractions (>44 mm, informally known as grit) of the mined Georgia kaolins are potential and significant sources of the rare-earth elements (REE). The abundances and provenance of the REE signature have not been studied extensively for the Georgia kaolins. The objective of the present study was, therefore, to define the contribution of these heavy minerals (e.g. zircon) to the REE inventory of the coarse fractions of Georgia kaolins. Heavy-mineral subfractions separated from the coarse fractions contained 1647 mg/kg REE from the Jeffersonville Member of the Lower Tertiary Huber Formation and 5012 mg/kg REE from the Buffalo Creek Kaolin Member of the Upper Cretaceous Galliard Formation, respectively. These heavy-mineral subfractions were enriched 10–100 times in the heavy rare-earth elements (HREE, Gd—Lu,), Hf, and Zr relative to the concentrations of these elements in Upper Continental Crust. The heavy-mineral subfractions comprised 5% of the coarse fractions (grit) of these two kaolin-producing formations. The heavy-mineral subfractions consisted of zircon, anatase, rutile, kaolinite, and minor amounts of muscovite, trace ilmenite, and staurolite. The large concentrations of REE were obtained by separating the dense heavy minerals from the coarse fraction (grit) obtained during the typical production of kaolin-group minerals (kaolinite) from kaolin ore. The amount of zircon (estimated from the 6–11 wt.% Zr) and the absence of monazite did not explain the high concentrations of REE in the heavy-mineral subfractions. The large amounts of REE could have resulted from the sorption of REE released during weathering reactions, or from the presence of small amounts (0.025 wt.%) each of monazite and xenotime in addition to the presence of zircon. This heavymineral subfraction represented a novel domestic resource of extractable REE, especially the HREE, of a grade as high as 0.50 wt.% total REE.
It is my sincere pleasure and honor to introduce Professor Sridhar Komarneni as the recipient of ... more It is my sincere pleasure and honor to introduce Professor Sridhar Komarneni as the recipient of the 2011 Marilyn and Sturges W. Bailey Distinguished Member Award of The Clay Minerals Society. This is the highest honor bestowed by the Society and is awarded solely for scientific eminence in clay mineralogy (in its broadest sense) as evidenced by the publication of outstanding original scientific research and by the impact of this research on the clay sciences. Dr. Komarneni is currently a Distinguished Professor of Clay Mineralogy in the Materials Research Institute as well as the Department of Crop and Soil Sciences and an Adjunct Professor of Civil and Environmental Engineering at Pennsylvania State University. Dr. Komarneni received his B.S. degree from the Andhra Pradesh Agricultural University, India, with the highest rank, followed by an M.S. degree in Soil Chemistry from the Indian Institute of Agricultural Research in New Delhi. After completion of his M.S. degree, Dr. Komarneni joined none other than M.L. Jackson at the University of Wisconsin for his Ph.D. I recall reading an interview with Dr. Jackson in which he mentioned Dr. Komarneni as his smartest Ph.D. student ever. He also had an association with Dr. S.W. Bailey as a student: in two graduate-level X-ray Crystallography classes and when Dr. Bailey served as a co-advisee for his dissertation. Dr. Komarneni continued working with Dr. Jackson for two years after the completion of his Ph.D. and then moved to Pennsylvania State University to work with Dr. G.W. Brindley and then with Dr. Rustom Roy at the Materials Research Laboratory. In essence, Dr. Komarneni has worked with several of the great minds in clay mineralogy. He moved to the rank of Associate Professor in 1984 and was promoted to full professor in 1987. Dr. Komarneni’s seminal scholarly contributions span several research areas. First, he has made fundamental contributions to the field of clay mineralogy where he has investigated the atomic architecture and nanostructure of clay minerals using a variety of techniques, including solid-state nuclear magnetic resonance spectroscopy and transmission electron microscopy. He has shown creative excellence in the design and synthesis of novel clays, which are expected to have a tremendous impact in the provision of clean drinking water worldwide through filtration as well as soil remediation. He has developed several novel synthetic clays and characterized the kinetics and equilibrium thermodynamics of their ion-exchange behavior. These novel clays are useful in drinking-water filters for elimination of toxic metals, as well as in the separation of radioactive Ra, Sr, and Cs from contaminated sites and waste waters. His publications in Science and Nature in this area have received world-wide publicity in news media such as The New York Times, The Wall Street Journal, and the London Financial Times. This research was referred to as ‘‘Mighty Mica’’ in the publication: Innovations by Environmental Health Perspectives, Journal of the National Institute of Environmental Health Sciences. Second, he has made original contributions in the field of solidification of nuclear and other hazardous waste. Dr. Komarneni’s research on nuclear-waste disposal spans the entire field, i.e. from the design and synthesis of new clays for ion separations, to ceramic waste forms, to backfills, and to studies of glass/ceramic waste-rock interactions. Clays and Clay Minerals, Vol. 60, No. 3, 338 339, 2012.
... In this context, erionite from Shoshone, California, and mordenite from Lovelock, California,... more ... In this context, erionite from Shoshone, California, and mordenite from Lovelock, California, appear to be the only suitable candidates for further modifications to achieve ideal shape of the ... DA Cadenhead) Academic Press, New York, 1975, p. 1 8 Hoss, H. and Roy, R., Beit. ...
Abstract Various aluminophosphate and silicoaluminophosphate molecular sieves were treated with m... more Abstract Various aluminophosphate and silicoaluminophosphate molecular sieves were treated with methanolic HCl to see its effectiveness as an alternative route for removing organic template molecules from molecular sieves. Both calcined and methanolic HCl-treated samples were characterized by X-ray powder diffraction and water adsorption-desorption isotherm measurements. The effectiveness of methanolic HCl in the removal of template molecules was found to be dependent on the pore size of the molecular sieves; that is, the template molecules were extracted effectively in sieves having a pore size ≥6 A. This method is not effective for molecular sieves with a pore size
ABSTRACTAluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO... more ABSTRACTAluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO-5, SAPO- 11, SAPO-17, SAPO-20) molecular sieves of varying pore sizes (3–8 Å) were synthesized and their water adsorption and desorption properties were studied. Water sorption isotherms of AlPO4 molecular sieves were characterized by unusual isotherm shapes, that is, little or no initial adsorption followed by extreme adsorption leading to volume filling by hydrogen bonding and cooperative interaction in micropores, apparently due to the nonpolar nature of pore surfaces coupled with weak (reversible upon evacuation) chemisorption of water, and hysteresis loops extending to very low pressures. Although micropore filling in AlPO2's and isostructural SAPO's was completed almost at the same relative pressure (p/po), SAPO's exhibited less extreme adsorption isotherms as a result of their slightly more polar nature of pore surfaces compared to AlPO4's. Neither AlPO4apos;s nor...
A series of microporous silica gels were synthesized by hydrolyzing tetramethylorthosilicate (TMO... more A series of microporous silica gels were synthesized by hydrolyzing tetramethylorthosilicate (TMOS) with varying amounts of water. No catalyst or alcohal was added. The gels were characterized by water sorption isotherms, the BET nitrogen surface area measurements, and differential thermal analysis. Although the gelation time for all H2O/TMOS molar ratios (R) was approximately the same (about 3 hr), the pore-size (pore diameter) and sorption capacity were found to be minimum in the R range 4.96–5.37 but increased with both increasing and decreasing R. Water sorption isotherms measured at 25°C after degassing at 200°C of gels prepared with R = 4.96–5.37 exhibited moderate Type I (Brunauer classification) isotherm which changed to intermediate between Type I and Type IV with decreasing or increasing R. These results indicated that the amount of organic or water which was not utilized in the reaction and the degree of cross-linking apparently played a role for the observed variations i...
ABSTRACTA kaolin was hydrothermally treated with various amounts of NaOH and KOH at 150°C for 15 ... more ABSTRACTA kaolin was hydrothermally treated with various amounts of NaOH and KOH at 150°C for 15 min to chemically aggregate the kaolin plates in a structured configuration. X-ray powder diffraction analysis indicated that kaolin was the only crystalline phase present. Chemical analyses showed that about 0.25 - 1.1 % Na2O and 1.2 - 5.0 % K2O were trapped in the solid phase depending on the reaction conditions. Mercury porosimetry indicated a highly porous nature with pore volumes of 0.3 - 1.4 ml/g and median pore sizes of 0.06 - 0.3 μm. Scanning electron micrographs showed that the aggregation was achieved by surface modification and random association (edge to edge and face to edge, face to face) of the particles. Measurement of light scattering coefficient of the coating showed an increase of ∼350% in scattering compared to that of the precursor kaolin. These materials are useful in imparting highly opacifying properties to paper and paint. They are also potentially useful as cata...
ABSTRACTTruly nanocomposite materials that are stable to about 400 to 700°C can be prepared by in... more ABSTRACTTruly nanocomposite materials that are stable to about 400 to 700°C can be prepared by intercalating oxides or metal clusters of about 0.4 to 2.0 nm in between ∼1.0 nm layers of smectite clays. Both the chemistry and size of intercalates (pillars) can be varied to introduce unique catalytic, molecular sieving, dehumidifying and adsorption properties in these materials. The intercalated clays also provide opportunities to prepare compositionally and stoichiometrically diverse nanocomposite precursors to high temperature structural and electronic ceramics. Although montmorillonite is the most widely used host, further designing in properties can be achieved by using other members of smectite family having subtle crystal chemical and compositional variations, such as beidellite, nontronite, saponite or hectorite. The sol-gel chemistry involving the preparation of positively charged mono- or multiphasic solution-sol or colloidal-sol particles is a viable approach to introduce ch...
The high-density siliciclastic minerals (e.g. zircon) in the coarse fractions (>44 mm, informa... more The high-density siliciclastic minerals (e.g. zircon) in the coarse fractions (>44 mm, informally known as grit) of the mined Georgia kaolins are potential and significant sources of the rare-earth elements (REE). The abundances and provenance of the REE signature have not been studied extensively for the Georgia kaolins. The objective of the present study was, therefore, to define the contribution of these heavy minerals (e.g. zircon) to the REE inventory of the coarse fractions of Georgia kaolins. Heavy-mineral subfractions separated from the coarse fractions contained 1647 mg/kg REE from the Jeffersonville Member of the Lower Tertiary Huber Formation and 5012 mg/kg REE from the Buffalo Creek Kaolin Member of the Upper Cretaceous Galliard Formation, respectively. These heavy-mineral subfractions were enriched 10–100 times in the heavy rare-earth elements (HREE, Gd—Lu,), Hf, and Zr relative to the concentrations of these elements in Upper Continental Crust. The heavy-mineral subfractions comprised 5% of the coarse fractions (grit) of these two kaolin-producing formations. The heavy-mineral subfractions consisted of zircon, anatase, rutile, kaolinite, and minor amounts of muscovite, trace ilmenite, and staurolite. The large concentrations of REE were obtained by separating the dense heavy minerals from the coarse fraction (grit) obtained during the typical production of kaolin-group minerals (kaolinite) from kaolin ore. The amount of zircon (estimated from the 6–11 wt.% Zr) and the absence of monazite did not explain the high concentrations of REE in the heavy-mineral subfractions. The large amounts of REE could have resulted from the sorption of REE released during weathering reactions, or from the presence of small amounts (0.025 wt.%) each of monazite and xenotime in addition to the presence of zircon. This heavymineral subfraction represented a novel domestic resource of extractable REE, especially the HREE, of a grade as high as 0.50 wt.% total REE.
It is my sincere pleasure and honor to introduce Professor Sridhar Komarneni as the recipient of ... more It is my sincere pleasure and honor to introduce Professor Sridhar Komarneni as the recipient of the 2011 Marilyn and Sturges W. Bailey Distinguished Member Award of The Clay Minerals Society. This is the highest honor bestowed by the Society and is awarded solely for scientific eminence in clay mineralogy (in its broadest sense) as evidenced by the publication of outstanding original scientific research and by the impact of this research on the clay sciences. Dr. Komarneni is currently a Distinguished Professor of Clay Mineralogy in the Materials Research Institute as well as the Department of Crop and Soil Sciences and an Adjunct Professor of Civil and Environmental Engineering at Pennsylvania State University. Dr. Komarneni received his B.S. degree from the Andhra Pradesh Agricultural University, India, with the highest rank, followed by an M.S. degree in Soil Chemistry from the Indian Institute of Agricultural Research in New Delhi. After completion of his M.S. degree, Dr. Komarneni joined none other than M.L. Jackson at the University of Wisconsin for his Ph.D. I recall reading an interview with Dr. Jackson in which he mentioned Dr. Komarneni as his smartest Ph.D. student ever. He also had an association with Dr. S.W. Bailey as a student: in two graduate-level X-ray Crystallography classes and when Dr. Bailey served as a co-advisee for his dissertation. Dr. Komarneni continued working with Dr. Jackson for two years after the completion of his Ph.D. and then moved to Pennsylvania State University to work with Dr. G.W. Brindley and then with Dr. Rustom Roy at the Materials Research Laboratory. In essence, Dr. Komarneni has worked with several of the great minds in clay mineralogy. He moved to the rank of Associate Professor in 1984 and was promoted to full professor in 1987. Dr. Komarneni’s seminal scholarly contributions span several research areas. First, he has made fundamental contributions to the field of clay mineralogy where he has investigated the atomic architecture and nanostructure of clay minerals using a variety of techniques, including solid-state nuclear magnetic resonance spectroscopy and transmission electron microscopy. He has shown creative excellence in the design and synthesis of novel clays, which are expected to have a tremendous impact in the provision of clean drinking water worldwide through filtration as well as soil remediation. He has developed several novel synthetic clays and characterized the kinetics and equilibrium thermodynamics of their ion-exchange behavior. These novel clays are useful in drinking-water filters for elimination of toxic metals, as well as in the separation of radioactive Ra, Sr, and Cs from contaminated sites and waste waters. His publications in Science and Nature in this area have received world-wide publicity in news media such as The New York Times, The Wall Street Journal, and the London Financial Times. This research was referred to as ‘‘Mighty Mica’’ in the publication: Innovations by Environmental Health Perspectives, Journal of the National Institute of Environmental Health Sciences. Second, he has made original contributions in the field of solidification of nuclear and other hazardous waste. Dr. Komarneni’s research on nuclear-waste disposal spans the entire field, i.e. from the design and synthesis of new clays for ion separations, to ceramic waste forms, to backfills, and to studies of glass/ceramic waste-rock interactions. Clays and Clay Minerals, Vol. 60, No. 3, 338 339, 2012.
... In this context, erionite from Shoshone, California, and mordenite from Lovelock, California,... more ... In this context, erionite from Shoshone, California, and mordenite from Lovelock, California, appear to be the only suitable candidates for further modifications to achieve ideal shape of the ... DA Cadenhead) Academic Press, New York, 1975, p. 1 8 Hoss, H. and Roy, R., Beit. ...
Abstract Various aluminophosphate and silicoaluminophosphate molecular sieves were treated with m... more Abstract Various aluminophosphate and silicoaluminophosphate molecular sieves were treated with methanolic HCl to see its effectiveness as an alternative route for removing organic template molecules from molecular sieves. Both calcined and methanolic HCl-treated samples were characterized by X-ray powder diffraction and water adsorption-desorption isotherm measurements. The effectiveness of methanolic HCl in the removal of template molecules was found to be dependent on the pore size of the molecular sieves; that is, the template molecules were extracted effectively in sieves having a pore size ≥6 A. This method is not effective for molecular sieves with a pore size
ABSTRACTAluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO... more ABSTRACTAluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO-5, SAPO- 11, SAPO-17, SAPO-20) molecular sieves of varying pore sizes (3–8 Å) were synthesized and their water adsorption and desorption properties were studied. Water sorption isotherms of AlPO4 molecular sieves were characterized by unusual isotherm shapes, that is, little or no initial adsorption followed by extreme adsorption leading to volume filling by hydrogen bonding and cooperative interaction in micropores, apparently due to the nonpolar nature of pore surfaces coupled with weak (reversible upon evacuation) chemisorption of water, and hysteresis loops extending to very low pressures. Although micropore filling in AlPO2's and isostructural SAPO's was completed almost at the same relative pressure (p/po), SAPO's exhibited less extreme adsorption isotherms as a result of their slightly more polar nature of pore surfaces compared to AlPO4's. Neither AlPO4apos;s nor...
A series of microporous silica gels were synthesized by hydrolyzing tetramethylorthosilicate (TMO... more A series of microporous silica gels were synthesized by hydrolyzing tetramethylorthosilicate (TMOS) with varying amounts of water. No catalyst or alcohal was added. The gels were characterized by water sorption isotherms, the BET nitrogen surface area measurements, and differential thermal analysis. Although the gelation time for all H2O/TMOS molar ratios (R) was approximately the same (about 3 hr), the pore-size (pore diameter) and sorption capacity were found to be minimum in the R range 4.96–5.37 but increased with both increasing and decreasing R. Water sorption isotherms measured at 25°C after degassing at 200°C of gels prepared with R = 4.96–5.37 exhibited moderate Type I (Brunauer classification) isotherm which changed to intermediate between Type I and Type IV with decreasing or increasing R. These results indicated that the amount of organic or water which was not utilized in the reaction and the degree of cross-linking apparently played a role for the observed variations i...
ABSTRACTA kaolin was hydrothermally treated with various amounts of NaOH and KOH at 150°C for 15 ... more ABSTRACTA kaolin was hydrothermally treated with various amounts of NaOH and KOH at 150°C for 15 min to chemically aggregate the kaolin plates in a structured configuration. X-ray powder diffraction analysis indicated that kaolin was the only crystalline phase present. Chemical analyses showed that about 0.25 - 1.1 % Na2O and 1.2 - 5.0 % K2O were trapped in the solid phase depending on the reaction conditions. Mercury porosimetry indicated a highly porous nature with pore volumes of 0.3 - 1.4 ml/g and median pore sizes of 0.06 - 0.3 μm. Scanning electron micrographs showed that the aggregation was achieved by surface modification and random association (edge to edge and face to edge, face to face) of the particles. Measurement of light scattering coefficient of the coating showed an increase of ∼350% in scattering compared to that of the precursor kaolin. These materials are useful in imparting highly opacifying properties to paper and paint. They are also potentially useful as cata...
ABSTRACTTruly nanocomposite materials that are stable to about 400 to 700°C can be prepared by in... more ABSTRACTTruly nanocomposite materials that are stable to about 400 to 700°C can be prepared by intercalating oxides or metal clusters of about 0.4 to 2.0 nm in between ∼1.0 nm layers of smectite clays. Both the chemistry and size of intercalates (pillars) can be varied to introduce unique catalytic, molecular sieving, dehumidifying and adsorption properties in these materials. The intercalated clays also provide opportunities to prepare compositionally and stoichiometrically diverse nanocomposite precursors to high temperature structural and electronic ceramics. Although montmorillonite is the most widely used host, further designing in properties can be achieved by using other members of smectite family having subtle crystal chemical and compositional variations, such as beidellite, nontronite, saponite or hectorite. The sol-gel chemistry involving the preparation of positively charged mono- or multiphasic solution-sol or colloidal-sol particles is a viable approach to introduce ch...
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