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Emile Hideki Ishida - One of the best experts on this subject based on the ideXlab platform.
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Hydrothermal preparation of Tobermorite incorporating phosphate species
Materials Letters, 2012Co-Authors: Hirotaka Maeda, Emile Hideki Ishida, Toshihiro KasugaAbstract:Abstract Slurries of quartz, slaked lime, and sodium dihydrogen phosphate containing hydrochloric acid as the solvent were hydrothermally treated to prepare Tobermorite incorporating phosphate species. X-ray diffraction and X-ray fluorescence analyses showed that Tobermorite with a trace of phosphate species formed after the treatment. The sizes of plate-like Tobermorite depended on the sodium phosphate additive and solvent. There were almost no effects observed of the additive and solvent on the morphology of Tobermorite. Sodium and/or phosphate species promoted the transformation from calcium silicate hydrate gel as the precursor to Tobermorite. Phosphate species were introduced into the Tobermorite structure, resulting in the distortion of its structure.
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Preparation of porous poly(l-lactic acid)/Tobermorite composite membranes via electrospinning and heat treatment
Journal of Materials Science, 2011Co-Authors: Tatsuya Okuyama, Hirotaka Maeda, Emile Hideki IshidaAbstract:A novel poly(l-lactic acid) (PLLA)/Tobermorite composite porous membrane for use as filter materials was synthesized by electrospinning a mixture of Tobermorite modified by poly(dialyldimethylammoniumchloride) (PDDA) and PLLA. X-ray diffraction patterns of the sample indicated the existence of Tobermorite in the sample. Scanning electron micrographs of the sample showed that the nonwoven membrane consists of a few microscopic fibers despite the existence of Tobermorite particles. This was due to repulsive force and surface tension. However, no Tobermorite particle was exposed at its fiber surface. Thermal analysis showed PLLA of the sample pyrolyzed with two steps of weight loss (44% at around 170 °C and 34% at around 270 °C). Heat treatment of the sample at 130 and 250 °C led to crystallization of a part of amorphous PLLA in the fiber and elimination of the remaining amorphous PLLA, respectively. After the treatment, the membrane maintained its porous structure and was coated with Tobermorite particles at the fiber surface.
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Hydrothermal synthesis of aluminum substituted Tobermorite by using various crystal phases of alumina
Journal of the Ceramic Society of Japan, 2011Co-Authors: Hirotaka Maeda, Kazuki Abe, Emile Hideki IshidaAbstract:Slurries of quartz and slaked lime containing various crystal phases of alumina were hydrothermally reacted to synthesize aluminum-substituted Tobermorite. X-ray diffraction results confirmed the formation of aluminum-substituted Tobermorite during the reaction. The aluminum species were substituted at the Q2 or Q3 sites in Tobermorite. The amount of aluminum substituted in the Tobermorite depended on the reactivity of alumina. The Tobermorite formed showed fiber- and plate-like morphologies. The reactivity of the alumina used as an additive influenced the substitution site and the amount of aluminum substituted into the Tobermorite structure, resulting in controlling its morphology.
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Precipitation mechanism of Al‐substituted Tobermorite using hydrothermal reaction
2010Co-Authors: Kazuki Abe, Hirotaka Maeda, Emile Hideki IshidaAbstract:We examined the addition of different crystal phases of alumina (α‐Al2O3, γ‐Al2O3) to slurries consisting of quartz and slaked lime for synthesis of Al‐substituted Tobermorite. XRD results showed that Al‐substituted Tobermorite formed after the reaction. It was clear that two kinds of Al‐substituted Tobermorite synthesized using different alumina crystal phases shows different morphologies. The difference in the reactivity of the Al2O3 had an influence in the hydrothermal reaction environment. The coordination number and chemical bonding‐state of Al caused the different morphology of the Tobermorite.
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influence of additions of coal fly ash and quartz on hydrothermal solidification of blast furnace slag
Cement and Concrete Research, 2008Co-Authors: Zhenzi Jing, Toshiyuki Hashida, Nakamichi Yamasaki, Emile Hideki IshidaAbstract:Abstract Blast furnace water-cooled slag (BFWS) has been solidified hydrothermally with Tobermorite formation. The experimental results showed that the addition of fly ash and quartz was favorable to the formation of Tobermorite, and the strength development of solidified body depended on both of the Tobermorite formation and filling degree of formed Tobermorite in the spaces between BFWS particles. The fly ash added appeared to have a higher reactivity than the quartz used during the initial hydrothermal processing due to the higher solubility of glassy phase in fly ash. The Tobermorite formation seemed to be very sensitive to the fly ash content, e.g., the addition of fly ash 10–20 mass% was favorable to Tobermorite formation, while the excessive addition of fly ash (> 20 mass%) appeared to impede the Tobermorite formation. The excessive addition of quartz was also shown to exert a negative effect on the Tobermorite formation, which causes strength deduction.
Hirotaka Maeda - One of the best experts on this subject based on the ideXlab platform.
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Improving the biocompatibility of Tobermorite by incorporating calcium phosphate clusters.
Bio-medical materials and engineering, 2017Co-Authors: Hirotaka Maeda, Tomoyuki Tamura, Toshihiro KasugaAbstract:BACKGROUND In our earlier work, Tobermorite containing calcium phosphate (CP) clusters (CP-Tob) was hydrothermally prepared in the CaO-SiO2-P2O5-H2O system for biomedical applications. OBJECTIVE CP-Tob was used to investigate the influence of CP cluster incorporation on its biocompatibility. METHODS Tobermorite samples with and without CP clusters were hydrothermally prepared at 180°C for 40 h. The biocompatibility, structure, and density of states of the Tobermorite samples were investigated by experimental and first principles methods. RESULTS The amounts of lysozyme and bovine serum albumin adsorbed on CP-Tob were higher than those on Tobermorite without CP clusters. Cluster incorporation caused a decrease in the solubility, resulting in the enhancement of the cell compatibility. The calculated results indicated that incorporating clusters, which interact with the silicate units of Tobermorite, led to a change of the density of states of Tobermorite. CONCLUSIONS Incorporation of CP clusters in Tobermorite led to improvement of the biocompatibility evaluated by biological and computational analyses.
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Hydrothermal preparation of Tobermorite incorporating phosphate species
Materials Letters, 2012Co-Authors: Hirotaka Maeda, Emile Hideki Ishida, Toshihiro KasugaAbstract:Abstract Slurries of quartz, slaked lime, and sodium dihydrogen phosphate containing hydrochloric acid as the solvent were hydrothermally treated to prepare Tobermorite incorporating phosphate species. X-ray diffraction and X-ray fluorescence analyses showed that Tobermorite with a trace of phosphate species formed after the treatment. The sizes of plate-like Tobermorite depended on the sodium phosphate additive and solvent. There were almost no effects observed of the additive and solvent on the morphology of Tobermorite. Sodium and/or phosphate species promoted the transformation from calcium silicate hydrate gel as the precursor to Tobermorite. Phosphate species were introduced into the Tobermorite structure, resulting in the distortion of its structure.
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Preparation of porous poly(l-lactic acid)/Tobermorite composite membranes via electrospinning and heat treatment
Journal of Materials Science, 2011Co-Authors: Tatsuya Okuyama, Hirotaka Maeda, Emile Hideki IshidaAbstract:A novel poly(l-lactic acid) (PLLA)/Tobermorite composite porous membrane for use as filter materials was synthesized by electrospinning a mixture of Tobermorite modified by poly(dialyldimethylammoniumchloride) (PDDA) and PLLA. X-ray diffraction patterns of the sample indicated the existence of Tobermorite in the sample. Scanning electron micrographs of the sample showed that the nonwoven membrane consists of a few microscopic fibers despite the existence of Tobermorite particles. This was due to repulsive force and surface tension. However, no Tobermorite particle was exposed at its fiber surface. Thermal analysis showed PLLA of the sample pyrolyzed with two steps of weight loss (44% at around 170 °C and 34% at around 270 °C). Heat treatment of the sample at 130 and 250 °C led to crystallization of a part of amorphous PLLA in the fiber and elimination of the remaining amorphous PLLA, respectively. After the treatment, the membrane maintained its porous structure and was coated with Tobermorite particles at the fiber surface.
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Hydrothermal synthesis of aluminum substituted Tobermorite by using various crystal phases of alumina
Journal of the Ceramic Society of Japan, 2011Co-Authors: Hirotaka Maeda, Kazuki Abe, Emile Hideki IshidaAbstract:Slurries of quartz and slaked lime containing various crystal phases of alumina were hydrothermally reacted to synthesize aluminum-substituted Tobermorite. X-ray diffraction results confirmed the formation of aluminum-substituted Tobermorite during the reaction. The aluminum species were substituted at the Q2 or Q3 sites in Tobermorite. The amount of aluminum substituted in the Tobermorite depended on the reactivity of alumina. The Tobermorite formed showed fiber- and plate-like morphologies. The reactivity of the alumina used as an additive influenced the substitution site and the amount of aluminum substituted into the Tobermorite structure, resulting in controlling its morphology.
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Precipitation mechanism of Al‐substituted Tobermorite using hydrothermal reaction
2010Co-Authors: Kazuki Abe, Hirotaka Maeda, Emile Hideki IshidaAbstract:We examined the addition of different crystal phases of alumina (α‐Al2O3, γ‐Al2O3) to slurries consisting of quartz and slaked lime for synthesis of Al‐substituted Tobermorite. XRD results showed that Al‐substituted Tobermorite formed after the reaction. It was clear that two kinds of Al‐substituted Tobermorite synthesized using different alumina crystal phases shows different morphologies. The difference in the reactivity of the Al2O3 had an influence in the hydrothermal reaction environment. The coordination number and chemical bonding‐state of Al caused the different morphology of the Tobermorite.
Nichola J. Coleman - One of the best experts on this subject based on the ideXlab platform.
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Tobermorite ion-exchanger from paper recycling ash and waste glass
2018Co-Authors: Michael Rivett, Victoria K. Elmes, Nichola J. ColemanAbstract:A Tobermorite (Ca5(Si)6O16(OH)2.4H2O) and its Al-substituted counterpart are layer-lattice cation-exchangers that are of interest with respect to their applications in nuclear and hazardous wastewater treatment [1-3]. In 2015, the European Declaration on Paper Recycling reported that 71.5% of all paper consumed in Europe was recycled, corresponding to 1.2 million tonnes more than their 70% target [4]. Waste paper recycling ash (PRA) arising from this activity contains reactive calcium aluminosilicate phases that can be used for the hydrothermal synthesis of Tobermorite when stoichiometrically adjusted with additional silicate-bearing reagents [1]. Waste soda-lime-silica container glass (SCG) has also been used as a partial feedstock for the preparation Tobermorite in alkaline media [2]. This research tested the feasibility of a one-step synthesis of Tobermorite from a combination of PRA and SCG under alkaline hydrothermal conditions at 100 °C. Reaction products were analysed by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). This study also evaluated the Cs+ cation-exchange capacity (CEC), selective Cs+ distribution coefficients (Kd, from Na+ and Ca2+ background solutions) and the uptake kinetics of Cd2+ and Pb2+ by the waste-derived Tobermorite product
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Aspects of the in vitro bioactivity and antimicrobial properties of Ag+- and Zn2+-exchanged 11 Å Tobermorites
Journal of materials science. Materials in medicine, 2009Co-Authors: Nichola J. ColemanAbstract:11 A Tobermorite, Ca5Si6O16(OH)2 · 4H2O, is a layer lattice ion exchange mineral whose potential as a carrier for Ag+ and Zn2+ ions in antimicrobial, bioactive formulations has not yet been explored. In view of this, the in vitro bioactivity of Ag+- and Zn2+-exchanged 11 A Tobermorites and their bactericidal action against S. aureus and P.aeruginosa are reported. The in vitro bioactivity of the synthetic unsubstituted Tobermorite phase was confirmed by the formation of bone-like hydroxycarbonate apatite (HCA) on its surface within 48 h of contact with simulated body fluid. The substitution of labile Ag+ ions into the Tobermorite lattice delayed the onset of HCA-formation to 72 h; whereas, the Zn2+-substituted phase failed to elicit an HCA-layer within 14 days. Both Ag+- and Zn2+-exchanged Tobermorite phases were found to exhibit marked antimicrobial action against S. aureus and P.aeruginosa, two common pathogens in biomaterial-centred infections.
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Ag+- and Zn2+-exchange kinetics and antimicrobial properties of 11 Å Tobermorites
Journal of the European Ceramic Society, 2009Co-Authors: Nichola J. Coleman, Alistair H. Bishop, Samantha E. Booth, John W. NicholsonAbstract:Abstract Ag + - and Zn 2+ -exchanged zeolites and clays have been used as coatings and in composites to confer broad-spectrum antimicrobial properties on a range of technical and biomedical materials. 11 A Tobermorite is a bioactive layer lattice ion exchanger whose potential as a carrier for Ag + and Zn 2+ ions in antimicrobial formulations has not yet been explored. In view of this, batch Ag + - and Zn 2+ -exchange kinetics of two structurally distinct synthetic 11 A Tobermorites and their subsequent bactericidal action against Staphylococcus aureus and Pseudomonas aeruginosa are reported. During the exchange reactions, Ag + ions were found to replace labile interlayer cations; whereas, Zn 2+ ions also displaced structural Ca 2+ ions from the Tobermorite lattice. In spite of these different mechanisms, a simple pseudo-second-order model provided a suitable description of both exchange processes ( R 2 ≥ 0.996). The Ag + - and Zn 2+ -exchanged Tobermorite phases exhibited marked bacteriostatic effects against both bacteria, and accordingly, their potential for use as antimicrobial materials for in situ bone tissue regeneration is discussed.
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Interactions of Cd(II) with waste-derived 11 Å Tobermorites
Separation and Purification Technology, 2006Co-Authors: Nichola J. ColemanAbstract:Paper recycling gives rise to significant volumes of secondary waste materials which undermine its economic and environmental sustainability. In response to this problem, a waste combustion ash arising from newsprint recycling has been evaluated as a feedstock material for the hydrothermal synthesis of Al-substituted 11 angstrom Tobermorites. Highly crystalline Tobermorite (NRR-H2O) was obtained from a stoichiometrically optimised mixture of newsprint recycling residue, sodium silicate and calcium oxide, whereas a less well-ordered product (NRR-NaOH) was acquired when sodium hydroxide was also incorporated into the reagent mixture. Structural disorder within the Tobermorite lattice was found to accelerate the kinetics of Cd2+ for Ca2+ ion exchange although had little impact on the total number of available exchange sites per unit formula. The Langmuir isotherm model provided a suitable description for the steady state uptake of Cd2+ by both Tobermorite specimens under single metal ion batch sorption conditions, from which, maximum adsorption capacities of 167 and 179 mg g(-1) were obtained for NRR-NaOH and NRR-H2O, respectively. (C) 2005 Elsevier B.V. All rights reserved.
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synthesis structure and ion exchange properties of 11 a Tobermorites from newsprint recycling residue
Materials Research Bulletin, 2005Co-Authors: Nichola J. ColemanAbstract:Abstract Al-substituted 11 A Tobermorites were obtained from stoichiometrically adjusted mixtures of newsprint recycling waste, sodium silicate and calcium oxide via hydrothermal synthesis at 100 °C. Hydrothermal processing in water yielded a highly crystalline 11 A Tobermorite product with a Cs + cation exchange capacity of 85 meq 100 g −1 and selective Cs + distribution coefficient of ∼5500 cm 3 g −1 . Conversely, a product of inferior crystallinity was obtained from hydrothermal synthesis in alkaline liquor whose Cs + ion exchange capacity and selective Cs + distribution coefficient were found to be 66.3 meq 100 g −1 and ∼700 cm 3 g −1 , respectively. Silicate chain configuration was found to have a modest impact on the number of cation exchange sites per unit cell, whereas the influence of structural defects on selectivity was more pronounced. The structures and ion exchange credentials of both 11 A Tobermorite products corresponded well with those of their essentially phase-pure counterparts.
Rashmi Shrivastava - One of the best experts on this subject based on the ideXlab platform.
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sr2 uptake and leachability study on cured aluminum substituted Tobermorite opc admixtures
Cement and Concrete Research, 2001Co-Authors: O.p. Shrivastava, Rashmi ShrivastavaAbstract:Abstract Synthetic calcium silicate hydrate (C-S-H), which is similar to 1.1 nm Tobermorite mineral, has demonstrated capacity to selectively pick up Sr 2+ cations from mixed cationic solutions in the presence of 1000 times concentration of Na + , K + , Ca 2+ and Ba 2+ ions. The selective uptake of Sr 2+ from mixed cationic solution has been quantified as distribution coefficient ( K d ) and decontamination factor ( D f ). The mass balance data have been generated from the solution analysis for Ca 2+ ⇆Sr 2+ system after equilibration. The data show that ratio of the amount of Sr 2+ incorporated in the matrix to the amount of Ca 2+ released from the Tobermorite is approximately equal to 1:1. The position of Al and Si in the aluminum-substituted Tobermorite has been characterized by 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. Because 1.1 nm Tobermorite is a powder, experiments were carried out on monolithic samples solidified with various amounts of ordinary portland cement (OPC). Leach rate studies were performed to study the retention power of Sr 2+ in these monoliths. The leach rate of Sr 2+ decreases drastically due to the addition of 10–40% of Tobermorite to the OPC. The Sr 2+ retention capacity is expressed in terms of meq/100 g of exchanger. The leach rate studies show that Sr 2+ retention by various Tobermorite containing OPC blocks increases with increasing weight percentage of this 1.1-nm Al-substituted Tobermorite, which may be used as an additive to make the waste form.
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Sr2+ uptake and leachability study on cured aluminum-substituted Tobermorite–OPC admixtures
Cement and Concrete Research, 2001Co-Authors: O.p. Shrivastava, Rashmi ShrivastavaAbstract:Abstract Synthetic calcium silicate hydrate (C-S-H), which is similar to 1.1 nm Tobermorite mineral, has demonstrated capacity to selectively pick up Sr 2+ cations from mixed cationic solutions in the presence of 1000 times concentration of Na + , K + , Ca 2+ and Ba 2+ ions. The selective uptake of Sr 2+ from mixed cationic solution has been quantified as distribution coefficient ( K d ) and decontamination factor ( D f ). The mass balance data have been generated from the solution analysis for Ca 2+ ⇆Sr 2+ system after equilibration. The data show that ratio of the amount of Sr 2+ incorporated in the matrix to the amount of Ca 2+ released from the Tobermorite is approximately equal to 1:1. The position of Al and Si in the aluminum-substituted Tobermorite has been characterized by 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. Because 1.1 nm Tobermorite is a powder, experiments were carried out on monolithic samples solidified with various amounts of ordinary portland cement (OPC). Leach rate studies were performed to study the retention power of Sr 2+ in these monoliths. The leach rate of Sr 2+ decreases drastically due to the addition of 10–40% of Tobermorite to the OPC. The Sr 2+ retention capacity is expressed in terms of meq/100 g of exchanger. The leach rate studies show that Sr 2+ retention by various Tobermorite containing OPC blocks increases with increasing weight percentage of this 1.1-nm Al-substituted Tobermorite, which may be used as an additive to make the waste form.
O.p. Shrivastava - One of the best experts on this subject based on the ideXlab platform.
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sr2 uptake and leachability study on cured aluminum substituted Tobermorite opc admixtures
Cement and Concrete Research, 2001Co-Authors: O.p. Shrivastava, Rashmi ShrivastavaAbstract:Abstract Synthetic calcium silicate hydrate (C-S-H), which is similar to 1.1 nm Tobermorite mineral, has demonstrated capacity to selectively pick up Sr 2+ cations from mixed cationic solutions in the presence of 1000 times concentration of Na + , K + , Ca 2+ and Ba 2+ ions. The selective uptake of Sr 2+ from mixed cationic solution has been quantified as distribution coefficient ( K d ) and decontamination factor ( D f ). The mass balance data have been generated from the solution analysis for Ca 2+ ⇆Sr 2+ system after equilibration. The data show that ratio of the amount of Sr 2+ incorporated in the matrix to the amount of Ca 2+ released from the Tobermorite is approximately equal to 1:1. The position of Al and Si in the aluminum-substituted Tobermorite has been characterized by 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. Because 1.1 nm Tobermorite is a powder, experiments were carried out on monolithic samples solidified with various amounts of ordinary portland cement (OPC). Leach rate studies were performed to study the retention power of Sr 2+ in these monoliths. The leach rate of Sr 2+ decreases drastically due to the addition of 10–40% of Tobermorite to the OPC. The Sr 2+ retention capacity is expressed in terms of meq/100 g of exchanger. The leach rate studies show that Sr 2+ retention by various Tobermorite containing OPC blocks increases with increasing weight percentage of this 1.1-nm Al-substituted Tobermorite, which may be used as an additive to make the waste form.
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Sr2+ uptake and leachability study on cured aluminum-substituted Tobermorite–OPC admixtures
Cement and Concrete Research, 2001Co-Authors: O.p. Shrivastava, Rashmi ShrivastavaAbstract:Abstract Synthetic calcium silicate hydrate (C-S-H), which is similar to 1.1 nm Tobermorite mineral, has demonstrated capacity to selectively pick up Sr 2+ cations from mixed cationic solutions in the presence of 1000 times concentration of Na + , K + , Ca 2+ and Ba 2+ ions. The selective uptake of Sr 2+ from mixed cationic solution has been quantified as distribution coefficient ( K d ) and decontamination factor ( D f ). The mass balance data have been generated from the solution analysis for Ca 2+ ⇆Sr 2+ system after equilibration. The data show that ratio of the amount of Sr 2+ incorporated in the matrix to the amount of Ca 2+ released from the Tobermorite is approximately equal to 1:1. The position of Al and Si in the aluminum-substituted Tobermorite has been characterized by 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. Because 1.1 nm Tobermorite is a powder, experiments were carried out on monolithic samples solidified with various amounts of ordinary portland cement (OPC). Leach rate studies were performed to study the retention power of Sr 2+ in these monoliths. The leach rate of Sr 2+ decreases drastically due to the addition of 10–40% of Tobermorite to the OPC. The Sr 2+ retention capacity is expressed in terms of meq/100 g of exchanger. The leach rate studies show that Sr 2+ retention by various Tobermorite containing OPC blocks increases with increasing weight percentage of this 1.1-nm Al-substituted Tobermorite, which may be used as an additive to make the waste form.
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Cesium selectivity of (Al+Na)-substituted Tobermorite
Cement and Concrete Research, 1994Co-Authors: O.p. Shrivastava, Sridhar KomarneniAbstract:Several synthetic Tobermorites with different levels of [Al+Na] substitution were prepared from two different types of starting materials and their cation exchange and cesium selective properties were investigated. The substituted Tobermorites were found to have high cation exchange capacities and very high selectivities for Cs[sup +] ion. Cesium selectivity of the substituted Tobermorites was demonstrated in the presence of divalent cations such as Ca[sup 2+], Mg[sup 2+], Ba[sup 2+] and univalent cations such as Na[sup +], K[sup +] and Li[sup +] which are one hundred times more concentrated than the cesium ion. The uptake of Cs is maximum in the presence of highly hydrated Mg[sup 2+] and Li[sup +] ions whereas it is minimum in the presence of less hydrated K[sup +] and Ba[sup 2+] ions due to steric limitations of the Tobermorite structure.