和嶋 隆昌

Conversion of three different types of incineration ash, coal fly ash (CFA), paper sludge fly ash (PSFA) and industrial waste incineration fly ash (IWIFA) into useful materials using the alkali fusion method is attempted. The chemical and mineralogical compositions of these ashes differed. The order of Ca content in the ash was IWIFA&gt PSFA&gt CFA, while the Si and Al contents in the ashes were CFA&gt PSFA&gt IWIFA. CFA was mainly composed of quartz [SiO 2] and mullite [3Al2O32SiO2], PSFA mainly of gehlenite [Ca2Al2SiO7], anorthite [CaAl2Si2O8] and talc [Mg3Si 4O10(OH)2], and IWIFA mainly of portlandite [Ca(OH)2], halite [NaCl] and sylvine [KCl]. Zeolites (zeolite-X, -A, -P and hydroxysodalite), hydrogrossular (katoite), and calcite were synthesized from the ashes. With an increasing Ca content of the ash, the Si concentration in the solution decreased, and the main product phases changed from zeolite (aluminosilicate) to hydrogrossular (calcium aluminosilicate), and finally to calcite (calcium carbonate). The observed concentrations of Si, Al, and Na in the solution during the reaction explain the crystallization of these phases.

We attempted to develop a new process to remove NaCl content in seawater using natural zeolite. Na+ in seawater can be reduced by ion exchange of natural zeolite, and Cl- can be reduced by AgNO3 or calcined hydrotalcite. The two-step process, which comprised natural zeolite treatment and anion reduction treatment (AgNO3 or calcined hydrotalcite), was applied to remove NaCl from the seawater. The possibility of cultivation using the obtained solution for the growth test of radish sprouts was then examined. The latter did not grow in the seawater, the solution treated with natural zeolite, the solution treated with AgNO3 after zeolite treatment, and in the solution treated with natural zeolite after AgNO3 treatment, due to the high contents of Cl- and NO3 - remaining in these solutions. Radish sprouts also did not grow in the solution treated with calcined hydrotalcite because of high pH and high content of Na+ in the solution. By combination of anion reduction treatment using calcined hydrotalcite and zeolite treatment, radish sprouts can be grown in the prepared solution. © 2010 Taylor &amp Francis.

We attempted to prepare sulfur-impregnated adsorbent from coal for removal of heavy metals. A two-step process (pyrolysis and sulfur impregnation) was used. Raw coal was rapidly pyrolyzed to prepare char with a high specific surface area. It was sulfurized by H(2)S impregnation to obtain sulfur-impregnated char that could adsorb heavy metals. Pyrolysis char with high specific surface area can be obtained by rapid pyrolysis; sulfur can be added to rapid-pyrolysis char using H(2) gas. Sulfur-impregnated char was more effective for adsorption of Pb(2+), Cd(2+), and Zn(2+) than raw coal, rapid-pyrolysis char, and commercial charcoal.

火力発電所で排出される石炭灰フライアッシュとタービン用冷却水として使用される海水を利用した機能性物質の製造を目的として，アルカリ溶融石炭灰を原料とするゼオライト系吸着剤の調製を行い，調製条件の最適化を検討した。500°C でアルカリ溶融した石炭灰を前駆体，2倍に希釈した海水を原料として80°C，12時間反応した調製物のアンモニウムイオン交換能は4.6 mmol⁄g で，イオン交換水を原料とした調製物と同等であった。また，海水中では希釈の有無に関わらず6時間以上の反応でゼオライトX，ゼオライトA が生成したが，12時間以上の反応ではイオン交換能の低いヒドロキシソーダライトが生成したことから，生成物中のゼオライトAがヒドロキシソーダライトに転化したものであることが示唆された。以上より500°Cでアルカリ溶融した石炭灰と2倍希釈した海水を用い，80°Cで6∼12時間反応させれば，高い陽イオン交換能を有するゼオライトX系吸着剤が製造できることが明らかとなった。

The removal behavior of fluoride ions was examined in aqueous sodium fluoride solutions using a titanium hydroxide-derived adsorbent. The adsorbent was prepared from titanium oxysulfate (TiOSO4 center dot xH(2)O) solution, and was characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry-differential thermal analysis, Fourier transform infrared spectrum and specific surface area. Batchwise adsorption test of prepared adsorbent was carried out in aqueous sodium fluoride solutions and real wastewater containing fluoride ion. The absorbent was the amorphous material, which had different morphology to the raw material, titanium oxysulfate, and the specific surface area of the adsorbent (96.8 m(2)/g) was 200 times higher than that of raw material (0.5 m(2)/g). Adsorption of fluoride on the adsorbent was saturated within 30 min in the solution with 200 mg/L of fluoride ions, together with increasing pH of the solution, due to ion exchange between fluoride ions in the solution and hydroxide ions in the adsorbent. Fluoride ions were adsorbed even in at a low fluoride concentration of 5 mg/L; and were selectively adsorbed in the solution containing a high concentration of chloride, nitrate and sulfate ions. The adsorbent can remove fluoride below permitted level (< 0.8 mg/L) from real wastewaters containing various substances. The maximum adsorption of fluoride on the adsorbent could be obtained in the solution at about pH 3. After fluoride adsorption, fluoride ions were easily desorbed using a high pH solution. completely regenerating for further removal process at acidic pH. The capacity for fluoride ion adsorption was almost unchanged three times after repeat adsorption and desorption. The equilibrium adsorption capacity of the adsorbent used for fluoride ion at pH 3 was measured, extrapolated using Langmuir and Freundlich isotherm models, and experimental data are found to fit Freundlich than Langmuir. The prepared adsorbent is expected to be a new inorganic ion exchanger for the removal and recovery of fluoride ions from wastewater. (C) 2009 Elsevier B.V. All rights reserved.

We attempted to convert waste porcelain into crystalline zeolite-13X using the alkali fusion method. Waste porcelain is mainly composed of amorphous glass phase and crystalline phases such as quartz and mullite. Most of the amorphous and crystalline phases were converted into soluble phases by alkali fusion, and could be transformed into single zcolite-13X crystals with a high specific surface area (412 m(2)/g) and unique micropore diameter (13 angstrom). (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Thermodynamic and kinetic studies on the adsorption of Cs+ and Sr2+ by Na-exchanged clinoptilolite-rich zeolite rock from Akita (Northern Japan) were performed for the purpose of nuclear waste treatment. The thermodynamic parameters such as selectivity coefficient, thermodynamic equilibrium constant, and standard free energy of exchange were evaluated. These values indicated that the selectivity order was determined as Cs+ &gt Na+ &gt Sr2+. In order to discuss the adsorption mechanism of Cs+ and Sr2+ onto Na-exchanged clinoptilolite, the effective diffusion coefficients were calculated and two kinetic models, pseudofirst-order and pseudo-second-order kinetic model, were tested. For all systems studied, chemisorption seems significant in the rate-controlling step, and the pseudo-second-order kinetic model provided the best correlation of the experimental data. © 2009 Taylor &amp Francis.

Cryogenic adsorption is effective for the separative recovery of hydrogen isotopes of small concentrations from the bulk helium gas. The authors performed a screening test to find candidate adsorbents for the recovery of hydrogen isotopes from the bulk helium gas at liquid nitrogen temperature. The screening test indicates that a natural mordenite adsorbent has a quite high adsorption capacity for hydrogen under the helium atmosphere. The effect of the ion exchange for the natural mordenite on the adsorption capacity of hydrogen was also investigated using protium and silver as well. With regard to the adsorbent examined in the screening test, the adsorption characteristics of deuterium were also investigated For the adsorption of deuterium, it was found that the natural mordenite adsorbent have a high adsorption capacity. The isotope effect on the adsorption of hydrogen isotopes on the natural mordenite adsorbent is not large compared with the MS5A adsorbent.

地熱発電所において，地熱水から蒸気分離された後の還元水には，排水基準以上のAsやシリカスケールの問題を引き起こす多量のシリカが含まれている．本研究では,地熱資源有効利用システムの構築を目指し，無機陰イオン交換体であるハイドロタルサイトを用いて，地熱発電所で湧出する地熱水からのAsとシリカの同時除去に関する基礎的検討を行った．ハイドロタルサイトにより処理することで，Asとシリカを同時に減少させ，As濃度を排水基準の0.1mg/l以下に，シリカ濃度をシリカスケールの発生を防止できる100mg/l以下にすることができ，その除去率は25～80℃の温度範囲ではほとんど変わらなかった．焼成処理を行った焼成ハイドロタルサイトを用いることで，より効率的な除去が可能であることがわかった．また，除去処理後の残渣を60℃で乾燥することで，As・シリカはほとんど再溶出しなかった．

&nbsp;&nbsp;During quarrying, waste stone cake is discharged as industrial waste. In this study, we attempted to convert waste sandstone cake to zeolitic materials using alkali fusion method. By varying the experimental conditions different types of the product were obtained, e. g. zeolite-X, zeolite-P, hydroxysodalite, tobermorite, and nepheline. The siliceous minerals in the cake were transformed into soluble phases, while calcite remains in the solid after 24-agitation following alkali fusion. The optimum condition of zeolite-X synthesis in the product is that the mixed ratio of NaOH to the cake is 1.6, fusion temperature is 600&deg;C, and heating time at 80&deg;C is less than 12 h. The results of the sorption experiments suggest that the product can be applied in environmental field such as the removal of pollutant.<br>

紙のリサイクル工程では，製紙スラッジ焼却飛灰が産業廃棄物として発生する。本研究では，製紙スラッジ焼却飛灰の重金属捕集剤としての新たな有効利用法の開発を目的として，製紙スラッジ焼却飛灰の酸性重金属溶液浄化能について検討した。製紙スラッジ焼却飛灰を酸性重金属溶液に対して固液比1:100で添加することによって，酸性溶液は中和され，ほとんどの重金属は溶液中から沈殿除去された。Fe，Cr，Zn，Cd，Mn，Niの除去率は90%以上と高く，他の重金属もCu，Pbはそれぞれ89.6%，81.6%，Mo，Bはそれぞれ51.5%，58.5%除去された。処理後の残渣には，溶液中から沈澱除去された重金属の85～100%が固定化された。これらの結果より，産業廃棄物である製紙スラッジ焼却飛灰が酸性重金属溶液の浄化に適用できる性能をもつことが示唆された。

We attempted to make irrigation water from seawater with a simple treatment of natural zeolite. Cations contents in artificial seawater can be adjusted by the treatment of natural zeolite, and Na⁺ can be reduced, but high contents of Cl^- and SO₄^2-remains in the solution after treatment. With a simple two-step process using calcined hydrotalcite and natural zeolite, Cl^- and SO₄^2- in artificial seawater can be reduced by calcined hydrotalcite, and Na⁺ can be reduced by ion exchange with natural zeolite. The obtained solution was neutral, and includes the nutrients, K⁺, Mg²⁺, and Ca²⁺, and low levels of Na⁺ and Cl^-. Although Radish sprouts did not grow in artificial seawater, the solution treated with natural zeolite and the solution treated with calcined hydrotalcite, they could be grown in the solution treated with two-step process. These results suggest that it is possible to make a solution for irrigation water from seawater.

We describe the synthesis of zeolite-A using rice husk ash (RHA) as starting material. Synthesis comprised alkali activation at low temperature (<100 degrees C) using NaOH as reagent. We investigated the effect of experimental conditions on zeolite synthesis from RHA. The process was studied as a function of NaAlO2 addition, NaOH concentration, temperature, and reaction time. A stirred batch reactor was used under the following reaction conditions: SiO2/Al2O3 molar ratio, 1.7-2.8; NaOH concentration, 2-6 M; temperature, 50-80 degrees C; reaction time, 0-48 h. The obtained solids were identified by X-ray diffraction and characterized by scanning electron microscopy; specific surface areas and cation exchange capacity values were also determined. Concentrations of Si and Al in the solution were analyzed to monitor the reaction process. Single zeolite-A can be synthesized from RHA under all our experimental conditions. We proposed the formation mechanism of zeolite-A from RHA. The silicate ion dissolves in NaOH solution from RHA and reacts with aluminate in the solution to form aluminosilicate, from which zeolite-A crystals are generated. The high crystallinity was obtained rapidly when SiO2/Al2O3 ratio, NaOH concentration and temperate were high in this experimental conditions.

&nbsp;&nbsp;The leaching of potentially toxic elements or the generation of acidity from mine waste often creates significant environmental pollution. A great deal of research has been undertaken to find an effective solution to the problem of acid mine drainage. An attractive solution has been proposed, not only efficient but also economical, as it uses another waste material. The objective of this study was to investigate the feasibility of stabilizing acidic mine waste using alkaline industrial waste, paper sludge ash (PSA), produced by the pulp and paper industry, under laboratory conditions. By mixing mine waste with (PSA) (the weight ratio of mine waste to (PSA) is 10:4), the eluted solution became neutral, and the concentrations of almost all metals dropped below the Japanese effluent standard. The inhibition of acid mine drainage with addition of PSA is sustainable. Although Radish sprouts did not grow on mine waste, they could be grown on the waste mixed with PSA. These results suggest that it is possible to use PSA for the remediation of a mine waste site.<br>

BACKGROUND: This study aimed to investigate the synthesis of zeolites from paper sludge ash (PSA) with added diatomite to remove both NH4+ and PO43- for water purification. The PSA had low Si and significant Ca contents. Four types of diatomite: white (T-W) and brown (T-B) from deposits of marine origin in Takanosu, and white (S-W) and gray (S-G) from lacustrine deposits in Shonai, were added to NaOH solution to increase the Si content and thereby synthesize zeolites with high cation exchange capacity (CEC).RESULTS: The order of the amounts of Si extracted from the diatomite to the alkali solution was S-W > T-W = T-B > S-G, which correlates with the amorphous SiO2 content of diatomite. The original ash without addition of diatomite yielded hydroxysodalite with CEC of about 1.0mmol g(-1). For all samples, the addition of diatomite to the solution yielded zeolite-P with a higher CEC, but the addition of excess Si inhibited the synthesis of zeolite-P, and the CEC of the product was low. A product with high CEC including zeolite-P was obtained in a solution with around 500 mmol L-1 of Si concentration, and had the ability to remove both NH4+ and PO43-.CONCLUSION: Diatomite has the potential for used as an additive for the synthesis of high CEC zeolite from PSA. The product with zeolite-P exhibited relatively high CEC, capacity for NH4+ uptake, and the ability to remove PO43- by precipitation, which is preferable for water purification applications. (c) 2008 Society of Chemical Industry.

During quarrying, waste stone cake is discharged as industrial waste. In this study, we attempted to convert waste sandstone cake to zeolitic materials using alkali fusion method. By varying the experimental conditions different types of the product were obtained, e.g. zeolite-X, zeolite-P, hydroxysodalite, tobermorite, and nepheline. The siliceous minerals in the cake were transformed into soluble phases, while calcite remains in the solid after 24-agitation following alkali fusion. The optimum condition of zeolite-X synthesis in the product is that the mixed ratio of NaOH to the cake is 1.6, fusion temperature is 600 degrees C, and heating time at 80 degrees C is less than 12 h. The results of the sorption experiments suggest that the product can be applied in environmental field such as the removal of pollutant.

Paper sludge ash (PSA) typically has a low Si abundance and significant Ca content due to the presence of calcite fillers. Acid leaching with HCl was used to reduce the Ca content so that a zeolitic product with a high cation exchange capacity (CEC) could be synthesized. Zeolitic products were synthesized from raw ash and leached ash through reaction with 2.5 M NaOH solution at 80 degrees C. In the case of the original ash without acid leaching, the concentration of Al in the alkali solution always exceeded that of Si during the synthesis, and hydroxysodalite with a low Si/Al ratio (1: 1) was formed. In the case of the leached ash, the concentration of Si always exceeded that of Al during the synthesis, and zeolite-P with a higher Si/Al ratio (5: 3) was formed. Hydroxysodalite and zeolite-P crystallization was saturated after 6 h of reaction, and the product from leached ash had a higher CEC (approximately 150 cmol/kg) than that from original ash (approximately 40 cmol/kg). Both the decrease in the Ca phase in the leached ash and the corresponding increase in the Si and Al amorphous phases play an important role in zeolite synthesis.

We attempt to develop the process for making agricultural cultivation solution from seawater using natural zeolitc. Mordenitc-type zeolite obtained from lizaka mine in Japan indicated highest reduction of Na+. Radish sprouts did not grow using seawater, the solution treated with natural zeolitc, the solution treated with AgNO3 after zeolite treatment, and the solution treated with natural zeolite after AgNO3 treatment, due to the high contents of Cl' and NO3 remained in these solutions. By combination of anion reduction treatment using calcined hydrotalcite and zeolite treatment, radish sprouts can be grown in the prepared solution.

The leaching of potentially toxic elements or the generation of acidity from mine waste often creates significant environmental pollution. A great deal of research has been undertaken to find an effective solution to the problem of acid mine drainage. An attractive solution has been proposed. not only efficient but also economical, as it uses another waste material. The objective of this study was to investigate the feasibility of stabilizing acidic mine waste using alkaline industrial waste, paper sludge ash, produced by the pulp and paper industry, under laboratory conditions. By mixing mine waste with paper sludge ash (the weight ratio of mine waste to paper sludge ash is 10: 4), the eluted solution became neutral. and the concentrations of almost all metals dropped below the Japanese effluent standard. The inhibition of acid mine drainage with addition of PSA is sustainable. Although Radish sprouts did not grow on mine waste, they could be grown on the waste mixed with paper sludge ash. These results suggest that it is possible to use paper sludge ash for afforestation of a mine waste site.

Zeolites were synthesized from paper-sludge ash in different alkali solutions. The ash used in this study has a high-Ca content and a low abundance of Si, in part due to the presence of calcite that is used as a paper filler. The major minerals present in the ash are gehlenite (Ca2Al2SiO2) and anorthite (CaAl2Si2O8). Three kinds of alkali solutions (NaOH, KOH, and LiOH) at four different concentrations (1, 2, 3, and 4 M) were reacted with paper-sludge ash at 90 degrees C for 24 h. Powder X-ray diffraction showed that hydroxysodalite (Na6Al6Si6O24 center dot 8H(2)O) and zeolite Linde F (KAISiO(4)center dot 1.5H(2)O) had formed in NaOH and KOH solutions, respectively, and that anorthite had dissolved in these alkaline solutions, whereas gehlenite had remained unaffected. In the LiOH solution, both anorthite and gehlenite dissolved, and various minerals, including Li-ABW zeolite (Li4Al6Si6O16 center dot 4H(2)O), hydrocalumite [Ca2Al(OH)(6)(Cl, OH)center dot 3H(2)O], tobermorite [Ca5Si6O16(OH)(2)center dot 4H(2)O], katoite [Ca3Al2(SiO4)(OH)(8)], and portlandite [Ca(OH)(2)] formed. The products of mineral synthesis from paper-sludge ash by reaction in alkaline solutions strongly depend on the specific alkali present.

The objective of this study was to investigate the synthesis of zeolites from paper sludge ash, and to evaluate their applications for water purification to simultaneously remove NH4+ and pO(4)(3-) in aqueous solution. Paper sludge ash had a low abundance of Si and a significant Ca content, due to the presence of calcite that was used as paper filler. Na2SiO3 was added to the NaOH solution to increase Si content in order to synthesize zeolites with high cation exchange capacity. The original ash without addition of Si yielded hydroxysodalite with a cation exchange capacity of ca. 50 cmol/kg. Addition of Si to the solution yielded Na-PI (zeolite-P) with a higher cation exchange capacity (ca. 120 cmol/kg). The observed concentrations of Si and Al in the solution during the reaction explain crystallizations of these two phases. The product with Na-P1 could simultaneously remove NH4+ and Po-4(3-) from the solution 4 4 between pH 4 and 9.

An attempt was made to convert waste porcelain into zeolitic materials using a two-step alkali conversion. During the first step, under optimum conditions for both high Si extraction from the waste and residue with high cation exchange capacity (CEC), the concentration of Si extracted from the waste was ca. 26,000 mg/L, and the residue contained zeolitic (Na-Pl, and hydroxysodalite) materials and residual phases (quartz, and mullite), which had high CEC (170 cmol/kg). In the second step, Na-A, Na-X, and Na-P1 zeolites were synthesized from the extracted solution during the first step, with addition of aluminate solution. With increasing Si/Al molar ratio of the solution, the product phase changed from Na-A -> Na-X -> Na-P1, and the Si content increased in the solution. (c) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

On the Tsushima Island, a practical application of an ocean thermal energy conversion (OTEC) and desalination plant is expected due to the short of electric power and drinking water. In the present study, we made oceanographic observation in the area northwest of Tsushima Island on August, October and November in 2005 and July, August and October in 2006 to obtain physical and chemical data (water temperature, salinity, dissolved oxygen, nutrients and velocity of currents) and topographic data, which is necessary for designing the hybrid OTEC system.<BR>Approximate temperatures in the surface and deep seawaters (SSW and DSW, respectively) at about 170 m in depth were 28&deg;C and 5 &deg;C in August 2005, and 21&deg;C and 8 &deg;C in November. From the thermal data, OTEC was supposed to be active from August to October. The salinity in SSW and DSW were 31.0-31.8 31.8 PSU and below 34.2 PSU, respectively in August 2005; between depths of 30 and 50 m a drastic halocline was detected. The low salinity of SSW in summer suggests the influence of continental river waters. Dissolved oxygen in SSW and DSW in August 2005 were comparatively high (> 5.0 ml/1). Water quality showed drastic seasonal changes in SSW shallower than a depth of ca. 150 m, which may be the influence of continental river waters. On the contrary, DSW characterized by high salinity and low temperature was thought to be the cold water endemic to Sea of Japan. On an expected cold water pipe (CWP) (180-200 m in length, 1.7 m in diameter) designed for a seabased 1, 000 kW OTEC plant, the maximum bending moment was estimated to be larger than 3, 922 Nm. In the case of employing a land based OTEC plant at Cape Sao on the north of Tsushima Island, length of the CWP should be longer than ca. 9.5 km.

砕石場では, 砕石を製品化する際に産業廃棄物として砕石屑が発生する. 本研究では, 砂岩砕石屑の有効利用を目的として, 焼却灰からのゼオライト合成において代表的なアルカリ水熱法とアルカリ溶融法を用いて, 砕石屑からのゼオライト合成を試みた. アルカリ水熱法では砕石屑からのゼオライト合成は行えなかったが, アルカリ溶融法では砕石屑の大部分をゼオライトに転換できた. アルカリ溶融法で得られた生成物はゼオライトXとハイドロキシソーダライトを含み, 陽イオン交換能は約230cmol/kgと天然ゼオライトより高い能力を示した.

秋田県澄川地熱発電所では, 地熱水から蒸気分離された後の還元水に排水基準以上のAs (約13mg/l) が含まれているため, 還元井より地下に戻している. 本研究では, 地熱発電所の排ガス中に含まれるH₂Sガスを用いて, 地熱発電所で湧出する地熱水からAsを除去する排出物有効利用システムの構築を目指し, 人工的に発生させたH2Sガスを用いた地熱水中のAsの除去に関する基礎的検討を行った. pH 4以下の強酸性にした地熱水中に, H2Sガスを吹き込むことによりS2-を供給し, As濃度を排水基準の0.1mg/l以下にすることができた. また, H₂SガスによるAs除去法は, Al塩添加により地熱水中の過飽和シリカを除去した処理水に対しても, 地熱水と同等の効果を示し, 過飽和シリカ除去法との組み合わせが可能であることがわかった.

Paper sludge ash was partially converted into zeolites by reaction with 3 M NaOH solution at 90 degrees C for 24 h. The paper sludge ash had a low abundance of Si and significant Ca content, due to the presence of calcite that was used as a paper filler. Diatomite was added to the NaOH solution to increase its Si content in order to synthesize zeolites with high cation exchange capacity. Diatomite residue was filtered from solution before addition of ash. The original ash without addition of diatomite yielded hydroxysodalite with a cation exchange capacity ca. 50 cmol/kg. Addition of Si to the solution yielded Na-P1 (zeolite-P) with a higher cation exchange capacity (ca. 130 cmol/kg). 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 capacity for PO43- removal from solution as a function of Ca2+ content, suggesting the formation of an insoluble Ca-phosphate salt. The product with Na-P1 exhibits the ability to remove NH4+ as well as PO43- from solution in concentrations sufficient for application in water purification. Both NH4+ and PO43- removal showed little variation with pH between 5 and 9. Alternative processing methods of zeolite synthesis, including the addition of ash to an unfiltered Si-NaOH solution and addition of a dry ash/diatomite mixture to NaOH solution, were tested. The third process yielded materials with lower cation exchange capacity due to formation of hydroxysodalite. The second process results in a product with relatively high cation exchange capacity, and reduces the number of processing steps necessary for zeolite synthesis. (c) 2005 Elsevier B.V. All rights reserved.