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Showing papers on "Activated alumina published in 2005"


Journal ArticleDOI
TL;DR: In this paper, the dependence of the adsorption of fluoride on the pH of the solution has been studied to achieve the optimum pH value and a better understanding of the adorption mechanism.

532 citations


Journal ArticleDOI
TL;DR: These results indicate that As forms inner-sphere bidentate binuclear surface complexes on all five adsorbent surfaces and improved the understanding of As bonding structures on adsorptive media surfaces and As leaching behavior for different adsorbents.
Abstract: Arsenic leachability in water treatment adsorbents was studied using batch leaching tests, surface complexation modeling and extended X-ray absorption fine structure (EXAFS) spectroscopy. Spent adsorbents were collected from five pilot-scale filters that were tested for removal of arsenic from groundwater in Southern New Jersey. The spent media included granular ferric hydroxide (GFH), granular ferric oxide, titanium dioxide, activated alumina, and modified activated alumina. The As leachability determined with the Toxicity Characteristic Leaching Procedure (TCLP, 0.1 M acetate solution) was below 180 μg L-1 for all spent media. The leachate As concentration in the California Waste Extraction Test (0.2 M citrate solution) was more than 10 times higher than that in the TCLP and reached as high as 6650 μg L-1 in the spent GFH sample. The EXAFS results indicate that As forms inner-sphere bidentate binuclear surface complexes on all five adsorbent surfaces. The As adsorption/desorption behaviors in each media...

100 citations


Journal ArticleDOI
TL;DR: Since 1997, over 135 well-head arsenic removal units have been installed in remote villages in the Indian state of West Bengal bordering Bangladesh, and every component of the arsenic removal treatment system including activated alumina sorbent is procured indigenously.

95 citations


Journal ArticleDOI
TL;DR: The oxide-based supported catalysts with high specific surface area were produced in one step through combination of the impregnation and solution combustion synthesis approaches and it was demonstrated that the developed approach may be used to produce different types of oxide- based supported catalyts, including perovskites.
Abstract: The oxide-based supported catalysts with high specific surface area (>200 m2/g) were produced in one step through combination of the impregnation and solution combustion synthesis approaches. As a model system, iron oxide was selected, which was loaded on different porous supports including α-Al2O3, γ-Al2O3, and ZrO2, as well as activated alumina. It was shown that for the former three cases the specific surface areas of the supported catalysts are about or below the surface areas of the support. However, for the activated Al2O3 this characteristic significantly increases compared to that of the support. It was demonstrated that the developed approach may be used to produce different types of oxide-based supported catalysts, including perovskites.

83 citations


Journal ArticleDOI
TL;DR: In this article, the pore size change in the course of methane decomposition over activated carbons indicates that the catalytic reaction occurs mainly in the micropores of active alumina.

78 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined arsenic sorption to amorphous and granular media oxides at various levels of silica, calcium and pH, and closely monitored the progress of sorption in these systems.
Abstract: Arsenic can be effectively removed from water by sorption to amorphous or granular iron or aluminum oxides. however, silica is known to interfere with arsenic sorption at pH >7.5. The goal of this work was to examine arsenic sorption to amorphous and granular media oxides at various levels of silica, calcium and pH, and to closely monitor the progress of sorption in these systems. At pH 8.5, calcium dramatically increased arsenic sorption to amorphous iron hydroxide in the presence of silica over relatively short reaction times, but the effects gradually disappeared over longer reaction times. Additionally, batch tests indicated that activated alumina granular media was more sensitive to silica interference than granular ferric hydroxide. However, relatively low levels of calcium could reduce silica interference to arsenic sorption onto activated alumina. While future confirmation research is needed, severe silica interference can occur in practice due to exclusion of arsenate from interstitial granular media pores.

50 citations


Journal ArticleDOI
TL;DR: A novel method for the removal of inorganic arsenic(III) (As(III), monomethylarsonate (MMA), and dimethylarsinate (DMA) from aqueous media, which involves the combined use of TiO2-photocatalyst and an adsorbent, which has a high ability of As(V) adsorption, under photo-irradiation.

42 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of water and NaOH on the hydrogenation of 2-ethylanthraquinone (eAQ) over alumina supported 2% Pd/Al2O3-A and 12% Pc/Al 2 O3-B catalysts was studied.
Abstract: The effect of water and NaOH was studied on the hydrogenation of 2-ethylanthraquinone (eAQ) over alumina supported 2% Pd/Al2O3-A and 12% Pd/Al2O3-B catalysts The hydrogenation was performed in a fixed-bed reactor by circulating the eAQ solution (the concentration of eAQ was 60 g/dm3) at 50 °C and 5 bar hydrogen pressure The egg-shell catalysts were prepared by the precipitation of palladium hydroxide onto the support A (activated alumina, preimpregnated with NaH2PO4) or support B (alumina containing 10% SiO2, and preimpregnated with Na2SiO3) Prior to the hydrogenation, the catalysts were dried and pre-treated with water vapour or NaOH solution The effect of water and NaOH on the amount of active quinones (eAQ and 2-ethyl-5,6,7,8-tetrahydroanthraquinone, H4eAQ) and in particular the role of such reagents in the consumption of aromatic hydroquinone eAQH2, the primary product of the quinone system of eAQ reduction was examined The saturation of the phenyl rings in eAQH2 produces H4eAQH2, which is a reactive compound and the hydrogenolysis of the C−O bond in the tautomerized eAQH2 leads to other degradation products Water and NaOH influence the hydrogenation of C O and the hydrogenolysis of C−O bond but have no effect on the hydrogenation of the aromatic rings The increase in activity in the former C O to C−OH reduction did not depend of alumina A and B as well as the type of reagent (NaH2PO4 or Na2SiO3) introduced to alumina during the catalyst preparation These reagents however, influenced the course of degradation processes Water when introduced to the catalyst exhibited unprofitable effect on maintenance the activity of catalyst during the hydrogenation run Such an unprofitable role is related to influence of water on the course of reactions yielding degradation products

41 citations


Journal ArticleDOI
TL;DR: Evaluating the potential of an anaerobic microbial consortium to biologically mobilize arsenate (As(V)) adsorbed onto activated alumina (AA), a common adsorbent used for treating arsenic in drinking water found it confirmed that VFA, present in landfill leachates, served as an electron donating substrate supporting enhanced rates of As(V) reduction to As(III).

38 citations


Journal ArticleDOI
15 Jul 2005-Talanta
TL;DR: A rapid and sensitive method for the on-line separation and pre-concentration of inorganic arsenic in water samples is described and good agreement was obtained with the values from spiked experiments.

34 citations


Journal ArticleDOI
TL;DR: In this paper, a laboratory study showed that manganese amended activated alumina (MAA), prepared by calcining (400°C) manganESE acetate-impregnated activated aluminina, showed promise as a more effective medium for use in small municipal drinking water systems or point of use treatment, for removing arsenic [As(III) and As(V)] from groundwater.
Abstract: In a laboratory study, manganese amended activated alumina (MAA), prepared by calcining (400°C) manganese acetate-impregnated activated alumina, showed promise as a more effective medium than activated alumina (AA) for use in small municipal drinking water systems or point-of-use treatment, for removing arsenic [As(III) and As(V)] from groundwater. Batch adsorption/oxidation kinetic tests indicated that in fixed-bed operation, with a bed flowthrough time of 10–20 min , MAA would be a more effective medium than AA in removing arsenic [As(V), As(III), and As(III) and As(V) (present together)] from groundwater. In three cycles of downflow column test [bed depth 200 mm ; bed flowthrough time 20 min ; influent arsenic 1.0–0.6 mg∕L As(III) and 0.4 mg∕L As(V)], breakthrough bed volumes at the World Health Organization guideline value of 0.01 mg∕L for arsenic in drinking water were 580, 550, and 485, and 825, 770, and 695, respectively, for AA and MAA. During regeneration (backwashing with a sodium hydroxide solu...

Journal Article
TL;DR: The results indicate that the adsorption process is favored at pH 9.5, which is close to the optimum conditions for the best adsorbent formation.
Abstract: Removal of nickel ions from industrial effluents has been studied using activated alumina prepared by the galvanic oxidation of aluminum metal at ambient temperature as the adsorbent. The effect of various factors, such as initial concentration of nickel, contact time, dose of adsorbent and pH of the solution has been investigated. Batch and column type of adsorption studies have been made. The results indicate that the adsorption process is favored at pH 9. The adsorption data were fitted with suitable adsorption isotherm. The optimum conditions for the best adsorption have been evaluated for the following factors: dosage, contact time, pH, initial concentration of nickel ions and temperature. The process of regeneration of the adsorbent has also been studied.

Patent
30 Mar 2005
TL;DR: In this article, a system containing two or more beds of activated alumina can use one bed to remove siloxanes from biogas while one or more of the other beds are being regenerated.
Abstract: Biogas released from landfills and sewage treatment plants is freed of siloxane contaminants by passing the biogas through a bed containing activated alumina, which absorbs the siloxanes. When the activated alumina becomes saturated with siloxanes, the absorption capability of the activated alumina can be recovered by passing a regeneration gas through the bed of activated alumina. A system containing two or more beds of activated alumina can use one bed to remove siloxanes from biogas while one or more of the other beds are being regenerated.

Journal ArticleDOI
TL;DR: In this paper, the removal of natural organic matter (NOM) by four different granular sorbent media, activated carbon, an anion exchange resin, activated alumina and granular ferric hydroxide, respectively, was investigated.
Abstract: The removal of natural organic matter (NOM) by four different granular sorbent media, activated carbon, an anion exchange resin, activated alumina and granular ferric hydroxide, respectively, was investigated. Isotherm data, kinetic parameters and column breakthrough curves were determined. Adsorption analysis was applied to describe sorption equilibria, and the film-homogeneous surface diffusion model was used to predict NOM uptake in fixed-bed columns. The results show that NOM adsorption by activated carbon and activated alumina could be modelled quite well by the approach used. NOM uptake by the anion exchange resin could be predicted with respect to capacity while two kinetic parameters were obviously not sufficient to describe the rate of uptake correctly. NOM adsorption by granular ferric hydroxide proved to be a very slow process that could not be predicted using parameters derived from batch data.

Journal ArticleDOI
TL;DR: Langmuir isotherm model best represents the experimental data for As(III) in activated alumina and Freundlich model in activated carbon and it is observed that k was independent of concentration of As( III).
Abstract: Equilibrium adsorption isotherms of As(III) were obtained from the experimentally generated data on activated alumina and activated carbon at temperature 303 K and pH 7.4. The isotherm for As(III) on activated alumina was typically of Brunauer Type – I but in the case of activated carbon equilibrium capacity seems to be increasing with increase in concentration. Langmuir isotherm model best represents the experimental data for As(III) in activated alumina and Freundlich model in activated carbon. Model parameters such as saturation capacity of adsorbent qs, Langmuir constant b, and Freundlich constants K and n were determined. Saturation adsorption capacity of As(III) in activated carbon was much higher than that in activated alumina. Overall effective mass transfer coefficient k was determined using uptake rate method. It is observed that k was independent of concentration of As(III). Values of k for both the adsorbents are of the order of 10−2 min−1.

01 Sep 2005
TL;DR: In this paper, the authors used modified activated alumina with iron compounds (AAFS-50) for household water treatment in rural areas, and the results showed that the results were compatible with both Freundlich and Laungmuier models.
Abstract: Considering contamination of drinking water to arsenic in some villages ofIran. In order to develop a simple method for household water treatment in rural areas, efficiency of modified activated alumina with iron compounds- a product of Alcan Company with trade name of AAFS-50- was studied Equilibrium batch experiments were carried out using shaker incubator and arsenic was analyzed with SDDC method. Effects of initial concentration of arsenic, adsorbent dose, oxidation state of arsenic, pH and oxidation with chlorine on adsorption were studied. Correlation coefficient of Freundlich and Laungmuier isotherms for As(V) and As(III) were 0.964 , 0.991 and 0.970, 0.978 respectively . These results show that adsorption of arsenic on modified activated alumina is compatible with both models specially Laungmuier models. Removal efficiency of As(V) at 0.5 ,1 and 2 hr increased with doubling the adsorbent dose from 44.8 to 72%, 69.6 to 90.8 and 92.4 to 98% ; respectively. Experiments using different concentrations of arsenic showed that adsorption of arsenic on activated alumina are a first order reaction that is, rate of reaction is dependent on intial; concentration of arsenic. Removal efficiency for concentration of 0.250 mg/L of arsenic, with increasing of reaction time from 15 min to 60 min, increased 1.54 times and reached from 61% to 94%. During 2hrs, removal of As(V) and As(III) were 96% and 16% respectively. Using 1.5 mg/L Chlorine as oxidant agent, removal of As(III) was increased to 94%. In the case of pH effect, rate of adsorption increased for arsenite, with increasing of pH to 8 and decreased with more increasing, so that adsorption at pH 14 was equal to pH 2. For arsenate, the most adsorption was observed at pH between 6 to 8 . These results show that by using the studied activated alumina, there will not be need for adjustment of pH and the activated alumina used in this study could have application as a safe adsorbent for removal of arsenic from drinking water in simple household treatment systems in form of adsorptive column.

Journal ArticleDOI
TL;DR: In this article, the surface water on concrete materials consists of physically adsorbed water, chemically adorned water, and structural water as in the case of porous adsorption materials, and it is shown that concrete is easily contaminated with tritiated water.
Abstract: The concrete materials are used as the partition wall of the tritium handling facilities. It is important to grasp the tritium behavior in the concrete wall for radiation safety. It is considered in this study that the surface water on the concrete materials consists of physically adsorbed water, chemically adsorbed water and structural water as in the case of porous adsorption materials. The adsorption capacity due to physically and chemically adsorption isotherms observed in this study shows that the amount of water adsorption on the cement paste is a quarter of the amount adsorbed onto the surface of activated alumina or molecular sieves 5A (MS-5A). It shows that concrete is easily contaminated with tritiated water.

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the ability of passive flux meters (PFM) to estimate arsenic in groundwater using activated alumina, which displayed a Freundlich adsorption isotherm with respect to arsenic in solution.

Journal ArticleDOI
TL;DR: In this article, mesoporous activated alumina was prepared by a surfactant-templating route and the alumina layers were deposited on FeCrAl metallic substrates by an in situ hydrothermal method.

Patent
20 Apr 2005
TL;DR: In this paper, the utility model relates to a secondary lithium cell cathode, which comprises cathode active materials and water absorbents dispersed in the active materials, wherein the water absorbent has strong water absorbability of dewpoint below-56 DEG C, which can completely adsorb moisture remained in the process of the preparation of a primary lithium cell and soaked by the gas permeability of water molecules when in use.
Abstract: The utility model relates to a secondary lithium cell cathode, which comprises cathode active materials and water absorbents dispersed in the cathode active materials, wherein the cathode active materials comprise carbon materials, such as graphite, carbon filament, carbon nanotubes, etc; in addition, transitional metal or oxide of the transitional metal can be also adopted, such as tin and oxide of the tin; the water absorbent comprises a lithiation molecular sieve, activated carbon, activated alumina, silica gel, calcia, calcium sulphate, etc, and the water absorbent has strong water absorbability of dewpoint below-56 DEG C; the water absorbent can completely adsorb moisture remained in the process of the preparation of a secondary lithium cell and soaked by the gas permeability of water molecules when in use, which can prevent lithium cell poisoning As a consequence, the service life of the secondary lithium cell is enhanced The utility model also relates to a secondary lithium cell using the same cathode


Journal ArticleDOI
TL;DR: In this paper, the removal efficiency of a biotrikling filter was evaluated under different operating conditions, where Activated Alumina (AA) was used as the immobilization matrix for Thiobacillus denitrificans in the biotrickling filter.
Abstract: Nitrogen dioxide (NO2) removal efficiency of a biotrikling filter was evaluated under different operating conditions. Activated alumina (AA) was used as the immobilization matrix for Thiobacillus denitrificans (T. denitrificans) in the biotrickling filter. Batch studies were conducted to find out the degradation kinetics of nitrate and nitrite for a concentration range of 600–10,000 mg/L expressed as nitrogen. Nitrite exhibited maximum degradation rate followed by nitrate. Electron acceptor in the form of NO2 gas showed least removal efficiency. Bio-kinetic parameters for T. denitrificans, by utilizing nitrate and nitrite as electron acceptors, were also evaluated. The μmax (Maximum specific growth rate) and YT (Yield coefficient) values for T. denitrificans in the presence of nitrate and nitrite were 1.03 h−1, 0.275 and 0.63 h−1, 0.1316 respectively. Column study was conducted to find the adsorption and desorption potential of activated alumina. The adsorbed NO2 from AA could easily be desorbed using distilled water with an efficiency of 76±0.8%. Once fed batch studies were conducted to evaluate the NO2 removal efficiency by a biotrickling filter. With an influent NO2 gas concentration of 2,735 ppm, the reactor could achieve a removal efficiency of 99% within 2 min from gas phase and within 96 h from the liquid phase, with an average biomass concentration of 200 mg/g of AA. The mechanism of NO2 gas removal in the biotrickling filter seems to be the dissolution of NO2 in water to form NO 3 − , conversion of NO 3 − to NO2 −, and finally to N2 gas.

01 Jan 2005
TL;DR: In this paper, the ability of clay membranes to retain arsenic was investigated at different initial arsenic concentrations and ionic strengths controlled by sodium chloride, and the influence of applied pressure and the permeate flux on arsenic removal efficiency was also examined.
Abstract: While many treatment technologies are available for arsenic removal from drinking water including coagulation/filtration, lime softening, activated alumina adsorption, ion exchange, and membrane processes, most of these approaches are expensive and more suitable for large water systems. In this study, membranes made of low-cost clay minerals were explored for arsenate removal. Montmorillonite, kaolinite, and illite were selected for membrane preparation. Feed water spiked with arsenate was pumped through the compacted clay membranes and the effluent was collected at the lower pressure side for arsenic analysis. The ability of clay membranes to retain arsenic was investigated at different initial arsenic concentrations and ionic strengths controlled by sodium chloride. The influence of applied pressure and the permeate flux on arsenic removal efficiency was also examined. The results indicated that a greater than 90% of arsenic rejection could be achieved for water with 50-100 μg/l of arsenate using the clay membranes. The required pressure for clay membrane filtration was, however, significantly higher than that of synthetic organic membranes.

Journal ArticleDOI
TL;DR: In this paper, the effect of the silica modulus of water glass, functional additives, and mechanical activation of the filler on the composition of a fireproof composite is described, at temperatures up to 700°C one can decrease thermal diffusivity by the formation of a heat-insulating layer frothed by water vapor dehydrated from water glass.
Abstract: The effect of the silica modulus of water glass, functional additives, and mechanical activation of the filler on the composition of a fireproof composite is described. At temperatures up to 700°C one can decrease thermal diffusivity by the formation of a heat-insulating layer frothed by water vapor dehydrated from water glass. Within the high-temperature range heat-insulating properties are improved by the synthesis of nepheline in the reaction between sodium silicate and alumina. Mechanical activation of alumina improves this effect. Introduction of carbamide and boric acid additives improves the fireproof properties of the gaseous medium.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the production of activated alumina from aluminum hydroxide-based waste from the Seydisehir Eti Aluminum Works and found that the results showed that aluminum hydoxide based waste could be converted to activated alumine effectively by using a combination of acid and heat activation processes.

Patent
21 Apr 2005
TL;DR: In this paper, a fluorine-containing waste water is passed through an activated alumina packed column to adsorb and remove fluorine and an inorganic alkali solution (A), water (B), and a metallic sulfate solution (C) are passed through the column in this order for reclaiming the activated aluminium whose adsorption capacity has been decreased.
Abstract: PROBLEM TO BE SOLVED: To provide a fluorine-containing waste water treatment method which employs activated alumina as an adsorbent and improves the reclaiming method of the activated alumina whose adsorption capacity has been decreased. SOLUTION: The fluorine-containing waste water is passed through an activated alumina packed column to adsorb and remove fluorine. Subsequently, an inorganic alkali solution (A), water (B), and a metallic sulfate solution (C) are passed through the column in this order for reclaiming the activated alumina whose adsorption capacity has been decreased. COPYRIGHT: (C)2005,JPO&NCIPI

Journal ArticleDOI
Zhou Rui1, Zhou Yan1, Hu Kai1, JI Zhen-ping1, Cheng Gong-zhen1 
TL;DR: In this paper, three different spin-lattice relaxation times (T1) of water were obtained in activated alumina-water slurry system, which indicate that there exist three states of water: bound water, pore water and bulk water.
Abstract: Three different spin-lattice relaxation times (T1) of water were obtained in activated alumina-water slurry system, which indicate that there exist three states of water: bound water, pore water and bulk water. The chemical shift (δH) decreases as the amount of water added to the system increases due to the differences in contribution of these three states of water in the samples. TheδH value for adsorbed water decreases nearly linearly andT1 increases with elevating temperature, which result from the decrease in the content of bound water by the increase in thermal motion.

Patent
21 Apr 2005
TL;DR: In this paper, a method for producing a fluorinated ether comprises reacting a ≥ 2C fluorinated olefin having at least one fluorine atom with a ≥ 1C alcohol in the presence of a potassium fluoride/activated alumina, potassium hydroxyide or activated alumina or sodium hydroxide/activated aluminina solid catalyst supporting potassium fluoride, potassium hydroxides or sodium hyroxide on activated alumnina.
Abstract: PROBLEM TO BE SOLVED: To provide a method for producing a hydrofluorocarbon (HFE) which is promising as a substitute for CFC, HCFC, HFC or PFC due to its relatively small stratosphere ozone-depleting capacity and global warming capacity by using, as a raw material, a substance available on an industrial scale or a substance producible from a raw material available on an industrial scale. SOLUTION: This method for producing a fluorinated ether comprises reacting a ≥2C fluorinated olefin having at least one fluorine atom with a ≥1C alcohol in the presence of a potassium fluoride/activated alumina, potassium hydroxyide/activated alumina or sodium hydroxide/activated alumina solid catalyst supporting potassium fluoride, potassium hydroxide or sodium hydroxide on activated alumina. COPYRIGHT: (C)2007,JPO&INPIT


Patent
10 Aug 2005
TL;DR: In this paper, the authors describe a process for continuous precipitation of aluminum hydroxide with pseudoboehmit structure from basic aluminum sulfate solution by neutralization with alkali reagent, filtration, autoclave treatment, and washing of precipitate with chemically desalted water, drying, and final heat treatment.
Abstract: FIELD: inorganic compounds technologies. ^ SUBSTANCE: invention relates to production of activated alumina appropriate as catalyst carrier for petrochemical and organic synthesis, in particular as reforming catalyst carrier. Process comprises continuous precipitation of aluminum hydroxide with pseudoboehmit structure from basic aluminum sulfate solution by neutralization with alkali reagent, filtration, autoclave treatment of resulting aluminum hydroxide precipitate in aqueous ammonia solution at pH 10.0-11.0 of reaction mixture, 135-145°C, and agitation time 1.0-2.0 h, washing of precipitate with chemically desalted water, drying, and final heat treatment. ^ EFFECT: improved quality of activated alumina and reduced consumption of water in washing of final product. ^ 2 cl, 1 tbl