和嶋 隆昌

In this study, Palm Kernel Shell (PKS) was gasified in a fixed-bed gasifier, using air as the gasifying agent. Whole apparatus including gasifier, material hopper, feeder, etc. were put inside a pressure vessel. Experiments were conducted at 0.1MPa, 0.3MPa, 0.5MPa, 0.7MPa. As a results, produced CO & tar amount showed to decreasing tendency with pressure increasing. Conversion rate to products within high heating value was also discussed.

A large amount of blast furnace slag, a by-product of the iron-making process, is generated annually. We attempted to convert blast furnace slag (BFS) into zeolitic materials using alkali fusion with ethylenediamine tetraacetate dihydrate (EDTA) chelation. Without addition of EDTA, a mixture of hydroxysodalite and calcite was synthesized. With EDTA addition, Ca&lt sup&gt 2+&lt /sup&gt ions were trapped by chelation in solution during agitation, then the chelation was promoted by heating at synthesis, and zeolite-A, zeolite-X and hydroxysodalite were synthesized.

The acrylonitrile butadiene styrene "ABS" resin is used in a variety of exterior and chassis electrical products, it have been contained brominated flame retardants to prevent fire accidients. If the resin (ABS) was thermally decomposed, the bromine compound was mixed in the pyrolysis oil. In this work, the fraction of acrylonitrile butadiene styrene "ABS" containing brominated flame retardants was pyrolyzed by using a reflux-condenser apparatus installation at 450 degrees C. And we used additives of sodium hydroxide "NaOH", calcium hydroxide "Ca(OH)(2)" and scallop shell. The total bromine compounds in product oil could be reduced from 296 mg/L to 27 mg/L by NaOH. (C) 2014 Published by Elsevier B.V.

Recovery of tantalum resource from used tantalum capacitor in electric equipment is important because the production of tantalum have not been stable for the price and the quantity. However, recovery of tantalum sintered compact from tantalum capacitor is difficult since the compact strongly covered with the flame retardant resin made of halogenated compounds (mold resin). In this study, steam gasification with sodium hydroxide was applied for recovery of tantalum sintered compact by destroying mold resin and stabilization of halogenated compounds in sodium hydroxide to prevent exhausting halogenated gas. Mold resin can be decomposed by steam gasification with NaOH to recover the sintered compact of tantalum. Furthermore, most halogen gas generated from decomposition of mold resin can be trapped in sodium hydroxide not to exhaust halogen gas. These results suggested that recovery process of tantalum sintered compact from the used condenser using steam gasification with sodium hydroxide is expected as a feasible way to recycle the rare metal in electric equipment. (C) 2014 The Authors. Published by Elsevier B.V.

Preparation of the adsorbent with lead removal ability using a sulfur impregnation was studied. Coal, palm shell, waste tire and diatomite, were used as raw materials. Raw material was mixed with K2S powder and then heated at 800 degrees C or 900 degrees C for 30 min in nitrogen to produce a sulfur-impregnated adsorbent. The sulfur-impregnated adsorbents prepared from coal, palm shell, waste tire and diatomite at 800 degrees C have lead removal property, and the order of lead removal ability is the adsorbent from coal = palm shell > waste tire > diatomite. The sulfur-impregnated adsorbent prepared from coal had a high sulfur content and high specific surface area. The adsorbent showed higher removal ability for lead ions from aqueous solution than zinc and cadmium ions in ternary Pb2+-Zn2+-Cd2+ solution. These results indicate that the sulfur-impregnated adsorbent has high selective adsorption ability for lead ions in aqueous solutions.

During the manufacture of recycled paper, paper sludge is discharged as an industrial waste. The amount of sludge discharged from manufacturing plants increases annually. In this study, the organic constituents, such as cellulose, in the sludge were converted into carbonaceous heavy metal absorbents using sulfur treatment, and its removal ability of lead from aqueous solution was examined. The sludge was treated with 5 M HCl to remove inorganic content, and then immersed in 1 M K2S solution to prepare sulfur-immersed sludge. The immersed-sludge was heated at 100-1000 degrees C for 1 hour in nitrogen gas to produce the sulfur-impregnated adsorbent by pyrolysis. The product obtained at 400 degrees C (Product400) has a high removal ability for lead ion, which has high specific surface areas and high sulfur content. The product400 shows the highest adsorption of lead from aqueous solution, and high selective removal for lead ions in low pH solution. (C) 2014 The Author. Published by Elsevier B. V.

Paper sludge, which is an industrial waste generated during the manufacture of recycled paper products, was converted into an effective phosphate (PO43-) sequestration agent through calcination and its removal behavior toward phosphate ion in aqueous solution was examined. Paper sludge contains mainly cellulose fibers and inorganic fillers together with coating materials such as calcite and kaolinite. The sludge was calcined at temperatures between 200 and 1000 degrees C for 6h. Crystalline phases originally present were altered at increasing temperatures (up to 800 degrees C) in the order kaolinite < calcite. An amorphous phase formed at 800 degrees C, and gehlenite formed at 1000 degrees C. Paper sludge calcined at 800 degrees C (PS-800), which has amorphous phases with high reactivity, removed the greatest amount of phosphate ion. The removal of phosphate by PS-800 was nearly constant in the equilibrium pH range of 5-12, and possessed high selectively for PO43- in solution with coexisting Cl-, NO3-, and SO42-. With increasing temperature of the aqueous solution, the kinetics of removal increased and the amount of phosphate removed was greater, which indicated that the removal reaction was an endothermic process. The main process responsible for sequestration of PO43- was the formation of brushite [CaHPO4 center dot 2H(2)O] by the reaction between labile Ca and PO43- in the solution. (C) 2013 Elsevier B.V. All rights reserved.

Paper sludge (PS) is generated as an industrial waste during the manufacture of recycled paper products, and amounts discharged globally are increasing annually. In this study, PS is converted into an effective sequestration agent for fluoride through calcination. PS contains mainly cellulose fibers and inorganic fillers together with coating materials such as calcite, kaolinite, and talc. The sludge was fired at temperatures between 200 and 1,000 A degrees C for 6 h. Crystalline phases originally present were altered at increasing temperatures (up to 800 A degrees C) in the order of kaolinite < calcite < talc. An amorphous phase was formed at 800 A degrees C, and gehlenite was formed at 1,000 A degrees C. The uptake of fluoride by these fired samples was investigated at room temperature. PS fired at 800 A degrees C shows a higher uptake of fluoride than that calcined at other temperatures. It also shows a high selective removal for fluoride in solutions containing chloride, nitrate, and sulfate. The main process responsible for fluoride sequestration is the formation of fluorite by reaction between labile calcium and fluoride in solution. The fluoride removal behavior fits a Freundlich isotherm model than Langmuir, and indicates the spontaneous nature of this reaction.

Ion exchange properties of five different Japanese natural zeolites in seawater were examined. Sodium ions could be reduced by all zeolites, although anions, Cl- and SO42-, in seawater showed barely changes. Natural zeolite desalination treatment mainly depends on the ion exchange between Na+, K+ and Mg2+ in seawater and Ca2+ in natural zeolite. This study found that mordenite is superior to clinoptilolite for use in Na+ reduction. Mordenite with high cation exchange capacity containing Ca2+ resulted in the highest Na+ reduction from seawater.

During the manufacture of recycled paper, paper sludge is discharged as an industrial waste. The amount of sludge discharged from manufacturing plants increases annually. In this study, the organic constituents, such as cellulose, in the sludge were converted into carbonaceous heavy metal absorbents using sulfur treatment. Paper sludge was washed with 5 M HCl solution to remove inorganic content, and then immersed in 1 M K2S solution for 24 h. After immersion, the sample was heated at 800 °C for 1 h under N2 atmosphere, and then cooled to room temperature to obtain the product. The sludge was mainly composed of inorganic content, such as calcite, kaolinite and talc, and organic content. Calcite was removed with acid washing and sulfur was impregnated into the sludge by immersing it into the K2S solution. The product with sulfur impregnation indicated higher removal abilities for lead and nickel than those without sulfur impregnation. © (2013) Trans Tech Publications, Switzerland.

The removal of lead ions from aqueous solutions was studied using a sulfur-impregnated adsorbent. Coal was mixed with K2S powder and then heated at 800 degrees C for 30 min in nitrogen to produce a sulfur-impregnated adsorbent. The sulfur-impregnated adsorbent prepared had a high sulfur content and high specific surface area. The adsorbent showed a high removal ability for lead ions, and a high removal ratio for lead ions in binary Pb2+-Na+ and Pb2+-Mg2+ solutions. This characteristics were similar to unitary Pb2+ solutions. These results indicate that the sulfur-impregnated adsorbent has a high selective adsorption ability for lead ions in aqueous solutions.

Zeolitic material including zeolite K-F (KAlSiO4 center dot 1.5H(2)O) with soil amendment properties was synthesized at 90 degrees C from paper sludge ash in KOH-NaOH and KOH-LiOH mixtures. The total alkali concentration in each solution was maintained at 4 mol/L and the relative amounts of the cationic species (K+/Na+ and K+/Li+) were varied. Zeolite K-F crystal could be obtained in KOH-NaOH solutions with Na/(Na + K) ratios lower than 0.5 or KOH-LiOH solutions with Li/(Li + K) molar ratios lower than 0.25, while hydroxysodalite (Na6Al6Si6O24 center dot 8H(2)O) and katoite (Ca3Al2(SiO4)(OH)(8)) were formed at other cation molar ratios in each mixture. The observed concentrations of Si and Al in the solution during the reaction explain the synthesis of reaction products with soil amendment properties. The properties of a product intended for K+ release depend on formation of an amorphous gel and zeolite K-F, while that for Ca2+ release depends on formation of an amorphous gel and calcium hydrate minerals, such as katoite. The formation of zeolite K-F in a KOH-LiOH solution with Li/(Li + K) ratio = 0.25 is faster than that in KOH alone and the product with good properties, high cation exchange capacity and high released amount of Ca2+, for soil amendment could be obtained. (C) 2012 Elsevier B.V. All rights reserved.

Paper sludge ash (PSA) was partially converted into zeolites by reaction with 3 M NaOH solution at 90 degrees C for 24 h. The PSA had a low abundance of Si and significant Ca content, due to the presence of calcite that was used as paper filler. Diatomite, which contains amorphous silica and dissolves easily in alkali solution, was mixed with the ash, and then added to the NaOH solution to increase its Si content during alkali reaction and thus synthesize zeolites with high cation exchange capacity (CEC). The original ash without addition of diatomite yielded hydroxysodalite with CEC ca. 0.5 mmol/g. Addition of diatomite to the ash yielded zeolite-P with a higher CEC (ca. 1 mmol/g). The observed concentrations of Si and Al in the solution during the reaction explain the crystallization of these two phases. The reaction products were tested for their adsorption capacity for nutrients from liquid fertilizer, such as K+, NH4+ and PO43-. The product with zeolite-P exhibits high ability to adsorb these nutrients from liquid fertilizer, which is desirable for application in soil improvement. [doi:10.2320/matertrans.ME201104]

We attempted to convert blast furnace slag into an adsorbent for phosphate removal using the alkali fusion method. The slag was mixed with NaOH powder (NaOH/Slag=1.6), and the mixture was heated at 600°C for 6 h to prepare the precursor, which was then stirred at room temperature in various aqueous solutions: distilled water, 1 M NaOH, 1 M NaCl, 1 M NaNO3, 1 M Na2CO3 and 1 M Na2SO4, to synthesize the adsorbent. Regardless of the reaction solution, products were synthesized, including hydrocalumite and calcite. Phosphate ions in solution were removed as calcium phosphate minerals using all obtained adsorbents. The PO 43- adsorption abilities of all products obtained and the solution pHs after removal were similar. The adsorbents could adsorb PO 43- selectively in the presence of F-, Cl -, Br, NO3- and SO42-. We have prepared a new inorganic adsorbent with high affinity for phosphate from wastewater. © 2011 Soc. Mater. Eng. Resour. Japan.

An inorganic cation exchanger was synthesized from waste sandstone cake using the alkali fusion method. We used two starting materials: one was the original cake and the other was leached cake, which was prepared from the original cake by acid-leaching with 1 M HCl solution. Each starting material was mixed with NaOH powder (the weight ratio of NaOH/sandstone = 1.6) and then heated at 600 degrees C for 1 h to make a fused material. This fused material was then added to distilled water and agitated for one day, then heated at 80 degrees C, 120 degrees C, and 160 degrees C for 8 h in reaction bombs under autogenous pressure in order to synthesize the cation exchanger. From the original cake, a mixture of zeolite-X and hydroxysodalite was synthesized at 80 degrees C, hydroxysodalite alone was synthesized at 120 degrees C, and a mixture of hydroxysodalite and tobermorite was synthesized at 160 degrees C. From the leached cake, zeolite-X alone was synthesized at 80 degrees C, a mixture of zeolite-X and hydroxysodalite was synthesized at 120 degrees C, and the hydroxysodalite alone was synthesized at 160 degrees C. By increasing the synthesis temperature, the cation exchange capacity (CEC) of the product from both cakes decreased, and at each synthesis temperature the product from the leached cake had a higher CEC than did the original cake. The product with the highest CEC was the zeolite-X alone synthesized from the leached cake at 80 degrees C, which had a CEC of 230 cmol/kg. (C) 2011 Elsevier Ltd and Techna Group Sri. All rights reserved.

It is imperative to establish the blanket technologies for realization of D-T fusion reactors. The neutron multiplier in the fusion reactor blankets plays one of the key roles with regard to breeding of tritium. Metallic beryllium has been considered as a primary candidate for the neutron multiplier, but it is highly reactive with water vapor and oxygen at high temperatures producing H 2 and BeO. Thus, it is necessary to develop more advanced neutron multipliers that are more chemically stable than metallic beryllium. One of the intermetallic compounds of beryllium and titanium, Be 12Ti, possesses high tolerance to water vapor and oxygen, low swelling property, and better compatibility with structural materials. Thus, it could be an alternative of metallic beryllium. However, few experimental data are available for this material, and thus more experimental studies need to be performed to evaluate its performance as a neutron multiplier. In this study, a Be 12Ti sample was fabricated by a new production route, plasmasintering method, and of which reactivity with O 2 and H 2O was examined. Experimental results suggest that the Be 12Ti sample prepared by the new production route possesses high resistance to oxidation by O 2 and H 2O. © 2012 Atomic Energy Society of Japan. All rights reserved.

Paper sludge ash (PSA) was partially converted into zeolites by reaction with 3M NaOH solution at 90°C for 24 h. The PSA had a low abundance of Si and significant Ca content, due to the presence of calcite that was used as paper filler. Diatomite, which contains amorphous silica and dissolves easily in alkali solution, was mixed with the ash, and then added to the NaOH solution to increase its Si content during alkali reaction and thus synthesize zeolites with high cation exchange capacity (CEC). The original ash without addition of diatomite yielded hydroxysodalite with CEC ca. 0.5 mmol/g. Addition of diatomite to the ash yielded zeolite-P with a higher CEC (ca. 1 mmol/g). The observed concentrations of Si and Al in the solution during the reaction explain the crystallization of these two phases. The reaction products were tested for their adsorption capacity for nutrients from liquid fertilizer, such as K +, NH 4+ and PO 43-. The product with zeolite-P exhibits high ability to adsorb these nutrients from liquid fertilizer, which is desirable for application in soil improvement. © 2012 The Japan Institute of Metals.

The deuterium-tritium (D-T) fusion reactor system is expected to provide the main source of electricity in the future. Large amounts of lithium will be required, dependent on the reactor design concept, and alternative resources should be found to provide lithium inventories for nuclear fusion plants. Seawater has recently become an attractive source of this element and the separation and recovery of lithium from seawater by co-precipitation, solvent extraction and adsorption have been investigated. Amongst these techniques, the adsorption method is suitable for recovery of lithium from seawater, because certain inorganic ion-exchange materials, especially spinel-type manganese oxides, show extremely high selectivity for the lithium ion. In this study, we prepared a lithium adsorbent (HMn2O4) by elution of spinel-type lithium di-manganese-tetra-oxide (LiMn2O4) and examined the kinetics of the adsorbent for lithium ions in seawater using a pseudo-second-order kinetic model. The intermediate, LiMn2O4, can be synthesized from LiOH.H2O and Mn3O4, from which the lithium adsorbent can subsequently be prepared via acid treatment., The adsorption kinetics become faster and the amount of lithium adsorbed on the adsorbent increases with increasing solution temperature. The thermodynamic values, δG0, δH0 and δS 0, indicate that adsorption is an endothermic and spontaneous process. © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research.

The slag was attempted to be converted into the adsorbent for phosphate removal from aqueous solution using the alkali fusion method. The slag was mixed with NaOH powder (NaOH / Slag = 1.6), and then the mixture was heated at 600 ? for 6 h to prepare the precursor. The precursor was stirred at room temperature in distilled water to synthesize the adsorbent, and the removal ability of the obtained adsorbent for phosphate from aqueous solution was investigated. The products, including hydrocalumite and calcite, were synthesized, and the removal efficiencies of the adsorbent for F- and PO43- showed higher than those of raw BF slag, especially removal of PO 43-are excellent (99 %), while the removal of Cl - , SO42-, NO3- and Br- was minor. The adsorbent could remove PO43-selectively in the co-existing solution of Cl-, NO3-, F -, SO42-and Br-.The equilibrium adsorption capacity of the adsorbent for PO43-was extrapolated using Langmuir and Freundlich models, and experimental data are found to fit Langmuir than Freundlich. The calculated maximum adsorption capacity of the adsorbent for PO43- is higher than other adsorbent reported previously. The high affinity of the adsorbent for PO 43-in aqueous solution was caused by the formation of hydroxyapatite [Ca5(PO4)3(OH)] and brushite [CaHPO4•2H2O]. The prepared adsorbent is expected to be anew inorganic adsorbent for the removal of phosphate ion from wastewater.

Recovery of tritium released into working areas in nuclear fusion plants is a key issue for safety. A large volume of air in the last confinement of fusion power plants should be processed by air cleanup system (ACS). In ACS, tritium gas is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents. This method can remove tritium effectively, whereas high throughput of air causes higher pressure loss in catalyst and adsorbent beds. The pressure loss can be reduced by replacing the packed bed of catalysts with the honeycomb catalysts. In this study, the oxidation experiments of hydrogen in humid gases over honeycomb-type catalysts were performed, and the influence of water vapor on the rate of catalytic oxidation was investigated. The result of the experiments suggests that the rate of catalytic oxidation decreases with increasing water vapor content and its influence varies depends on the temperature. It is also indicated the rate of oxidation substantially decreases at the lower temperatures even in the case where water vapor contents is considerably lower. Therefore, it is necessary to consider the decrease in the catalytic activity by coexistent water vapor.

Large amounts of tritium would be handled in D-T fusion power plants. Tritium is the radioisotope of protium, and is easily taken into the human body. With regard to nuclear fusion reactor facilities, the concept of multi-confinement system is applied to prevent tritium leaking to the environment. The last barrier to confine tritium is a building itself containing all equipment and facilities. If a severe accident takes place, tritium gas could leak into the facilities. In order to prevent tritium leaking to the environment, a secure air cleanup system (ACS) needs to be installed in the building. In ACS, the tritium gas, which leaks to rooms by an accident, is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents. This method can remove tritium effectively, whereas which has a problem related to large ventilation force required to overcome high pressure drop in catalyst and adsorbent beds. Ventilation force could be substantially reduced by applying honeycomb catalysts and adsorbents to ACS. We investigated applicability of honeycomb catalysts and adsorbents to ACS, performing a screening test for the performance of honeycomb catalysts and adsorbents.

For a large volume air cleanup system in nuclear fusion facility, honeycomb type oxidizing catalyst and absorbing dehumidifier offer a useful advantage in terms of their low pressure drop. In the present study the weight ratio of Pd catalyst on the metal honeycomb of Al-Cr-steel alloy were varied from 0.1 g/L to 4g/L. Catalyst was heated up to over 400 degrees C. with stepwise under flowing air containing hydrogen and methane, and their oxidizing reaction rate was evaluated Its catalytic activation energies were estimated to be about 36 kJ/mol for hydrogen and 100 kJ/mol for methane. Also it was appeared that the effectiveness of high Pd weight ratio catalyst and high temperature operation, and the limit of previous activation by hydrogen gas.

Lithium orthosilicate and lithium aluminate are the candidates of the breeder material of the tritium-breeding blanket. To enhance the rate of tritium release from these breeder materials, 0.2 wt.% of palladium was impregnated into the breeder materials by the incipient wet impregnation method. The lithium orthosilicate and the lithium aluminate pebbles with or without Pd were irradiated in the Kyoto university research reactor, and out-of-pile annealing experiments were performed. When the breeder materials were deposited with a catalytic additive, such as Pd the ratio of the tritium discharged in the molecular form of tritium (HT) increased. It was also found that the amount of the tritium discharged from the lithium orthosilicate pebbles with a catalytic additive at the low temperatures is greater compared with lithium aluminate. (C) 2011 Published by Elsevier B.V.

Recovery of tritium released into working areas in nuclear fusion plants is a key issue of safety. A large volume of air from tritium fuel cycle or vacuum vessel should be processed by air cleanup system (ACS). In ACS, tritium gas is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents. This method can remove tritium effectively, whereas high throughput of air causes high-pressure drop in catalyst and adsorbent beds. In this study, the applicability of honeycomb-type adsorbents, which offers a useful advantage in terms of their low-pressure drop, to ACS was examined, in comparison with conventional pebble-type adsorbent. Honeycomb-type adsorbent causes far less pressure drop than pebble-type adsorbent beds. Adsorption capacity of water vapor on a honeycomb-type adsorbent is slightly lower than that on a pebble-type adsorbent, while adsorption rate of water vapor on honeycomb-type adsorbent is much higher than that of pebble-type adsorbent. (C) 2011 Elsevier B.V. All rights reserved.

In the process of development of D-T fusion power reactors, recovery of tritium released into the last confinement system would be a key issue related to safety. If an accidental leakage of tritium takes place in a fusion power plant, a large volume of air should be detritiated with an air cleanup system (ACS). In ACS, tritium gas is converted to tritiated water vapor with a catalyst bed, and then which is recovered with an adsorption bed. In this study, the authors examined the applicability of honeycomb-type catalysts to ACS. A screening test of catalysts for oxidation of hydrogen and deuterium was performed using various honeycomb-type and pebble-type catalysts. Experimental results reveal that a honeycomb-type catalyst possesses a high oxidation performance for oxidation of hydrogen isotopes. Furthermore, the isotope effect on the oxidation of hydrogen isotopes over the honeycomb-type catalyst was thoroughly examined and quantified using tritium. (C) 2011 Published by Elsevier B.V.

Acid mine drainage (AMD) is a widespread environmental problem associated with working and abandoned mining operations. It results from the microbial oxidation of pyrite in the presence of water and air, affording an acidic solution that contains toxic metal ions. Pyrite microencapsulation, utilizing silica coating, is a novel approach for controlling AMD that has been shown to be very effective in controlling pyrite oxidation. The roles of the solution pH and silica concentration in the formation mechanism for the AMD-preventing coating were investigated. A silica coating can be formed from silica solution at pH 7, at which the amount of Fe eluted from pyrite into the solution is small. No coating was formed at other pH values, and the amounts of eluted Fe were larger than at pH 7, especially at pH 11. The silica coating forms from 2,500 to 5,000 mg/L silica solutions, but not from 0 or 1,000 mg/L silica solutions. The coating formation rate was slower in the 2,500 mg/L silica solution than in the 5,000 mg/L silica solution. The formation of silica coating on pyrite surfaces depends on three main steps: formation of Fe(OH)(3) on the surface of pyrite, reaction between Fe(OH)(3) and silicate in the solution on the pyrite surface, and growth of the silica layer on the first layer of silica. The best pH condition to enable these steps was around 7, and the silica coating formation rate can be controlled by the concentration of silica.

Adsorption of mercury from aqueous solution on sulfur-impregnated adsorbent has been studied. Raw coal was mixed with K2S powder, and then heated at 800-1000 degrees C for 30 min in nitrogen to produce sulfur-impregnated adsorbent. The sulfur content and specific surface area of the adsorbent were determined, and the ability of the adsorbent to adsorb mercury in aqueous solution was examined. With increasing temperature of sulfur-impregnation, specific surface area of the adsorbent increases, while sulfur content of the adsorbent is almost constant. The adsorbent obtained at 900 degrees C shows the highest and fastest adsorption of mercury from aqueous solution at 25 degrees C, and the elution extents of adsorbed mercury are negligible in distilled water and 10% in 0.1 M HCl solution, respectively. Adsorption kinetics was tested for pseudo-first order and pseudo-second order reactions, and the rate constants of adsorption for these kinetic models were calculated. Adsorption experiments demonstrate that the adsorption process corresponds to pseudo-second-order kinetic model than pseudo-first-order model. With increasing temperature of aqueous solution, the kinetics of adsorption becomes faster and the amount of mercury adsorbed on the adsorbent increases. The thermodynamic values, Delta G(0), Delta H-0 and Delta S-0, indicated that adsorption was an endothermic and spontaneous process. (C) 2011 Elsevier B.V. All rights reserved.

Paper sludge ash was converted into a zeolitic product with high cation exchange capacity (CEC) through acid leaching. The raw ash was treated with 1 M HCl, 1 M HNO3 and 1 M CH3 COOH solutions. Ca and Mg were more easily extracted from the ash than Si and Al, and the Ca extractions using HCl and HNO3 were higher than that from CH3 COOH. Element extractions and leachant pH in the HCl and HNO3 solutions were similar and steady state was achieved after 2 hours of leaching. A zeolitic product was synthesized from the 2-hour 1 M HCl ash leach by reaction of the residue with 2.5 M NaOH solution (80°C, 24 hours). Zeolite-A was synthesized from leached ash, and the CEC of the zeolite produced from leached ash (130 cmol/kg) was higher that that from raw ash (40 cmol/kg), and similar to that obtained when leaching ash for 24 hours. © 2010 Soc. Mater. Eng. Resour. Japan.

We examined the desalination treatment of seawater using AgNO3 and Pb(NO3)2 for the removal of anions, such as Cl-, Br-, and SO42- AgNO3 could remove Br- andCl- from seawater, while Pb(NO3)2 could remove SO42-, Br- and Cl-. The pH of solution treated with AgNO3 was constant at pH8.1, but the pH of the solution treated with Pb(NO3)2 decreased to acidic. The reactions of AgNO3 and Pb(NO3)2 with anions in seawater were rapid. Regardless of temperature of seawater, the time for anion removal by AgNO3 was almost same, while that by Pb(NO3)2 delayed with decreasing temperature of seawater.

Blast furnace (BF) slag, one of the byproducts of iron- and steel-making plants, was converted into a hydrocalumite-like compound using the alkali fusion method. The slag was transformed into the precursor with reactive phases via alkali fusion, after which the precursor was added to distilled water and stirred at room temperature to synthesize the product including a hydrocalumite-like compound. The effects of the mixed ratio of NaOH to the slag (NaOH/slag ratio), fusion temperature, ratio of precursor mass to distilled water volume (W/V ratio) and crystallization reaction time on the product phase were investigated, and the removal abilities of the obtained product for certain ions from aqueous solution was examined. Optimal conditions for hydrocalumite synthesis are a NaOH/slag ratio of 1.6, fusion temperature of 600 degrees C, W/V ratio of 125 g/L and reaction time of more than 24 h. The product could remove more NH4+, Sr2+, F-, PO43- and AsO43- than BF slag, while the removal of Cl-, SO42- and NO3- was almost zero. These results suggest that a hydrocalumite-like adsorbent able to remove pollutant ions in aqueous solution can be synthesized from BF slag via alkali fusion.

Tritium release in nuclear fusion power plants must be recovered as efficiently as possible in air cleanup system (ACS). In conventional ACS, the tritium gas is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents, whereas which has a problem related to large ventilation force required to overcome high pressure drop in catalyst and adsorbent beds. Honeycomb-type catalyst and adsorbent offer a useful advantage in terms of their low-pressure drop, and honeycomb-type adsorbent using sepiolite-binder is feasible ability for application of ACS. In this study, we examined adsorption characteristics of water vapor on the building material, zeolitic materials using sepiolite-binder, for honeycomb-type adsorbent by changing temperature and concentration of water vapor, in comparison with those for conventional pebble-type adsorbent, and the experimental data were evaluated using Langmuir and Freundlich isotherm models. Each type of adsorbent includes mainly zeolite-4A. Adsorption capacity of zeolitic materials for both adsorbents gradually decreased with decreasing partial pressure of water or increasing temperature, and experimental data are found to fit Langmuir than Freundlich. The maximum adsorption capacity of water vapor on zeolitic material for honeycomb-type adsorbent, which was calculated by Langmuir isotherm model, is comparable to that for pebble-type adsorbent, and heat of water adsorption on zeolitic material for honeycomb-type adsorbent was higher than that for pebble-type adsorbent. These results indicate that honeycomb-type adsorbent using sepiolite-binder is applicable to ACS. © 2011 The Japan Society of Plasma Science and Nuclear Fusion Research.

Lithium orthosilicate is one of the candidate materials of the tritium-breeding blanket of the D-T fusion reactors. Tritium is released via the exchange reaction with sweep gases containing hydrogen. It is expected that the isotope exchange reaction is promoted by adding noble metals that possess catalytic functions. Thus, palladium was deposited in a sample of lithium orthosilicate, and the effect of catalyst on the rate of isotope exchange reaction on the sample surface was examined. It was found that the isotope exchange reaction proceeds faster even at lower temperatures over the breeder materials with a catalytic additive and its activation energy can be considerably lowered. This result suggests that the isotope exchange reaction can be promoted by the deposition of catalytic metals. (C) 2010 Elsevier B.V. All rights reserved.

In D-T fusion power plants, large amounts of tritium would be handled. Tritium is the radioisotope of protium, and is easily taken into the human body, and thus the behavior of tritium accidentally released in fusion power plants should be studied for the safety design and radioprotection of workers. Therefore, it is necessary to investigate the behavior of tritium released into large rooms with objectives. since complex flow fields should exist in such rooms and they could influence the ventilation of the air containing released tritium. Thus, tritium release experiments were conducted using Caisson Assembly for Tritium Safety Study (CATS) in TPL/JAEA. Some data were taken for tritium behavior in the ventilated area and response of tritium monitors. In the experiments, approximately 17 GBq of tritium was released into Caisson with the total volume of 12 m(3), and the room was ventilated at the rate of 12 m(3)/h after release of tritium. It was found that placement of an objective in the vessel substantially affects decontamination efficiency. With regard to an experimental result, numerical calculation was performed and the experimental result and the result of numerical calculation were compared, which indicates that experimental results are qualitatively reproduced by numerical calculation. However, further R&D needs to be carried out for quantitative reproduction of the experimental results. (c) 2010 Published by Elsevier B.V.

For large volume air clean-up in nuclear fusion facilities, honeycomb-type adsorbents offer a useful advantage in terms of their low-pressure drop. In this study, two different honeycomb-type adsorbents (honeycomb-K and honeycomb-N) and pebble-type adsorbents were used as samples and the water vapor adsorption performance of each adsorbent was examined by changing temperature, concentration of water vapor and flow rate. The honeycomb-K and honeycomb-N adsorbents included zeolite-4A or zeolite-5A with a 50% clay binder and with a 15% sepiolite binder, respectively. The shapes of cells in honeycomb-K and honeycomb-N are triangles with 1 mm sides and squares with 1 mm sides, respectively, and the cell densities of the both adsorbents were 200 CPSI (cells/in.(2)). The adsorption capacity for water vapor on the honeycomb-K adsorbent was comparable to that on the pebble-type adsorbent, while the adsorption capacity on the honeycomb-N adsorbent was lower. The adsorption rates of honeycomb-K and honeycomb-N adsorbents were higher than that of the pebble-type adsorbent. The honeycomb-K adsorbent containing zeolite-5A showed a higher adsorption rate than that containing zeolite-4A. Thus, honeycomb-K containing zeolite-5A adsorbent could be applicable to air cleanup systems in terms of both adsorption capacity and rate. (C) 2010 Elsevier B.V. All rights reserved.

Geothermal water from geothermal plants often contains high levels of boron (B), above the Japanese effluent standard level. To establish an effective utilization system for geothermal resources, boron removal using non-calcined and calcined hydrotalcite was investigated using geothermal water from the Sumikawa geothermal plant in Japan. Calcined hydrotalcite removed large amounts of boron, and changed the solution pH to 12, while non-calcined hydrotalcite removed little boron. Calcined hydrotalcite are also more effectively removed from other anions including Si, As, F-, Cl-, and SO2-4. The concentrations of boron dropped to below the Japanese effluent standard level of 10mg L-1 with a 6 h treatment with calcined hydrotalcite. The ability of calcined hydrotalcite to remove boron from geothermal water was almost constant over the temperature range 25-80°C. © 2010 Taylor &amp Francis.

Waste sandstone cake, which is discharged as industrial waste, was converted into crystalline zeolite-X using alkali fusion. The cake was transformed into a soluble phase via alkali fusion, and then agitated in distilled water at room temperature to give an intermediate solid, followed by synthesis at 80 degrees C to give the final product. The effects of the agitation and synthesis times on the product phase were investigated with a view to obtaining a single crystalline zeolite-X. Hydroxysodalite was synthesized from the intermediate solid obtained without agitation, and with increasing agitation times for the intermediate solid, the amount of zeolite-X in the product increased, because of the increased Si content in the intermediate solid and the decrease of interference from impurities in the synthesis of zeolite crystals. The observed concentrations of Si and Al in the solution during the reaction explain the crystallization of the zeolite phase. The equilibrium adsorption capacity of the product for Sr2+ was almost the same as that of commercial zeolite-X in a low concentration Sr2+ solution, and the maximum adsorption capacity of the product, calculated using the Langmuir isotherm model, was 0.46 mmol/g. [doi:10.2320/matertrans.MH200905]