Showing papers on "Activated alumina published in 2008"

Adsorption characteristics of As(V), Se(IV), and V(V) onto activated alumina: Effects of pH, surface loading, and ionic strength

Abstract: Arsenic, selenium, and vanadium are major anionic elements of concern in drinking water. This research investigated the adsorption characteristics of As(V), Se(IV), and V(V) onto a commercial activated alumina (AA) under different pH, surface loading, and ionic strength conditions using batch systems. The results indicated that the adsorption of these elements was significantly affected by pH and the surface loading. However, ionic strength generally did not impact their adsorption, indicating that the electrostatic effect on the adsorption of these elements was relatively not important compared to surface chemical reactions. A speciation-based adsorption model was used to simulate the adsorption of As(V), Se(IV), and V(V) by activated alumina and to determine the adsorption constants of different element species. This model can satisfactorily predict the adsorption of these elements in a broad pH range from 1.5 to 12 and a wide surface loading range from 1.0 to 50 mg/g activated alumina for different sorbent concentrations, using the same set of adsorption constants.

Adsorption Equilibrium and Kinetics of Water Vapor on Different Adsorbents

Abstract: Water vapor needs to be removed from many industrial streams using, for example, adsorption processes. Equilibrium and kinetic data are essential for the design of these adsorption processes. In this work, the adsorption equilibrium isotherms of water vapor were measured at 303 K by a gravimetric system on three commercial adsorbents, an activated carbon, an activated alumina, and a zeolite. The zeolite sample presented the highest capacity at low relative pressures, while at pressures near saturation the higher amount adsorbed was obtained on the alumina sample. The experimental points obtained for the activated carbon and the zeolite were fitted with the Virial isotherm while the n-layer BET equation was used in the fitting of the alumina data. The adsorption kinetics was evaluated through the analysis of breakthrough curves obtained at the same temperature for different feed humidity values. The fixed bed behavior was described using an isothermal model that includes axial dispersion and external (film...

Fluoride removal from water solution by adsorption on activated alumina prepared from pseudo-boehmite

Abstract: The adsorption of fluoride from a water solution on an activated alumina prepared from pseudo-boehmite was investigated in this work. The activated alumina was characterized to determine its physicochemical and textural properties. It was found that the fluoride adsorption capacity of the activated alumina was considerably dependent upon the solution pH and diminished considerably with increasing solution pH from 4 to 11. The effect of the pH was attributed to the electrostatic interactions between the surface of the activated alumina and the fluoride in solution. The activated alumina was dissolved at pH lower than 4. It was not possible to ascertain the effect of the temperature on the adsorption of fluoride because the adsorption capacity increased and then decreased while the temperature was augmented from 15 to 25 °C and from 25 to 35 °C, respectively. The adsorption equilibrium was not reversible at pH of 5 but was reversible at pH of 11. The solution pH was a very important factor in desorbing fluoride and more mass of fluoride was desorbed increasing the solution pH. The adsorption of fluoride on activated alumina was mainly due to both electrostatic attraction and chemisorption mechanisms, but not to ion exchange.

Method for adsorption of phosphate contaminants from water solutions and its recovery

Abstract: Aqueous fluid polluted with phosphate contaminants is mixed with or passed through an adsorbent material selected from: (i) particles of oxides or hydroxides of transition metals, aluminum oxides or hydroxides, TiO2, or mixtures thereof, or (ii) particules of activated carbon, activated alumina, aluminum oxide, activated TiO2, TiO2, mineral clay, zeolite, or an ion exchanger loaded with nanoparticles of oxides or hydroxides of transition metals, aluminum oxides or hydroxides or TiO2, or mixtures thereof, to yield aqueous fluid purified from phosphate. The adsorbent material is further regenerated by increasing the pH of the adsorbent sludge, concentrated phosphate solution or a phosphate crystal slurry is recovered as well.

Catalyst-supported particulate filter

Abstract: In a particulate filter, a catalyst layer containing Pt-carried activated alumina particles, CeZr-based mixed oxide particles and ZrNd-based mixed oxide particles is formed, the proportion of the total amount of the CeZr-based mixed oxide particles and the ZrNd-based mixed oxide particles in the total amount of the Pt-carried activated alumina particles, the CeZr-based mixed oxide particles and the ZrNd-based mixed oxide particles is 10% to 60% by mass, both inclusive, and the mass ratio of the CeZr-based mixed oxide particles to the ZrNd-based mixed oxide particles is 20/80 to 80/20, both inclusive. This configuration enhances the particulate burning property and the low-temperature exhaust gas conversion efficiency.

Purification process of fluorine-based solvent-containing solution

Abstract: To provide a purification process where a fluorine-based solvent can be obtained at a high purity by relatively small equipment without using a distillation apparatus. A purification process of a mixed solution containing a fluorine-based solvent which is a process for purifying a fluorine-based solvent from a mixed solution containing a fluorine-based solvent, a water-soluble organic solvent contaminant, an organic contaminant and an ion contaminant, the process comprising: step (1): washing the mixed solution with water to obtain a first treated solution in which the water-soluble organic solvent concentration is reduced to 0.01 wt% or less, step (2): treating the first treated solution with activated carbon to obtain a second treated solution in which the organic contaminant concentration is reduced to 20 ppb or less, step (3): treating the second treated solution with activated alumina to obtain a third treated solution in which the fluoride ion contaminant is reduced to 10 ppb or less, and step (4): treating the third treated solution with a particle removing filter to obtain a fluorine-based solvent in which the number of particles of 0.1 μm or more is 10 particles/mL or less.

Activated alumina: defluoridation of water and household application - a study

Abstract: In fluoride endemic areas, especially small communities with staggered habitat, defluoridation of potable water supply is still a problem. In this respect household defluoridation techniques with attendant regeneration would be more appropriate and the present study is directed towards development of point-of-use domestic candletype filters for removal of fluoride from water employing activated alumina (AA) which is a proven material for defluoridation. Batch sorption kinetic studies employing activated alumina for sorptive removal of fluorides from water were conducted and observed to be dependent on various system parameters like contact time, pH, dose and ionic environment. Down-flow column studies further demonstrated the practical applicability and effectiveness of activated alumina in removing fluorides from an initial fluoride concentration of 5.0 mg FL -1 at a flow rate of 955 L/h/m 2 to the permissible limits of < 1.0 mg FL -1 . Experimental studies were also conducted to investigate the household applicability of activated alumina for removal of fluorides by filling the candles of domestic (candle) water filters with AA and found to be effective. Further, regeneration studies (cyclic adsorption ‐ desorption studies) indicated that the spent AA may be regenerated and this would offset the overall cost of fluoride removal.

Microwave inducing catalyst and method for preparing the same

Abstract: The present invention relates to a microwave inducing catalyst and the preparation method thereof. The preparation method of the catalyst is that: the nitrate of rare earth element is loaded onto the activated alumina after activation by using impregnation method, and then the rare earth element is made to exist on the surface of the activated alumina in the mode of oxide through the heat treatment under certain temperature, making the activated alumina modified from the rare earth element; then transition metal nitrate is loaded onto the surface of the activated alumina after modification by using impregnation method; due to the existence of the rare earth element oxide, the transition metal oxide crystals after heat treatment can be more equably distributed on the surface of the activated alumina, and the supported catalyst is finally made. The catalyst has the advantages of good solid-liquid separability in water treating process, higher stability than the conventional activated carbon system and stronger inducing catalytic activity, which solves the problem that the microwave inducing catalytic and oxidation technology is difficult to be industrialized on wastewater treatment.

Exothermal Water Release from Pseudoboehmite Gels and Their Mechanically Treated Analogs Caused by Activated Hydrogen

Abstract: Exothermal differential thermal analysis (DTA) effects for water release have been observed both for mechanically activated alumina gels, which may contain residual nitrate, and for strongly amorphisized AlO(OH) gels at comparably low temperatures (150−350 °C) under hydrogen. The observations are based on an investigation combining thermal analysis (TA), on-line coupled to mass spectrometry (MS), with ESR spectroscopy. This allowed the identification and quantification of trapped NO2 molecules as well as to follow the mechanically and thermally induced changes of the Al−O−H matrix via the contained (or doped) Fe3+ impurities. The appearance of the exothermal DTA effects is related not only to a strong mechanical activation and the access of hydrogen during the thermal treatment but also to the interaction of hydrogen with metallic platinum, for exampel, as crucible material or as metal powder. This interaction is discussed to be the origin of the chain start of the radical reaction between H2 and NO2 yiel...

Primary Study of Fluoride Removal from Aqueous Solution by Activated Ferric Hydroxide

Abstract: A novel adsorbent-activated ferric hydroxide adsorbent (AFe) was synthesized by reaction of FeCl3 with NaOH with additive of PVA. Adsorption experiments of fluoride at different concentrations and pH were carried out on AFe and activated alumina (AA). The results showed that AFe performed very well for F adsorption, Its adsorption capacity was 10 times of that of AA at 5 mg/L equilibrium level. The AFe also showed wider adaptive range to pH change and disturbing ions. The result shows the potential application of the adsorbent for effective F removal from drink water.

Determination of trace lithium in uranium compounds by adsorption on activated alumina using a micro-column method.

Abstract: A novel method using a micro-column packed with active alumina as solid phase was proposed for separation of trace lithium from uranium compounds prior to determination. The method is based on a preliminary chromatographic separation of the total amount of uranium. This separation involves passing the solution containing sodium carbonate through active alumina and then eluting the trace lithium retained by the solid phase with a solution of sulfuric acid. Two modes, off-line and on-line micro-column preconcentration, were performed. In conjunction with atomic absorption spectrometry, this on-line preconcentration technique allows a determination of lithium at 10-9 level. Both off-line and on-line mode operation conditions were investigated in separation and determination of trace lithium by micro-column method (length of column bed, flow rate, etc.). The adsorption capacity of activated alumina was found to be 343 µg g-1 for lithium. Under the optimal operation condition, the detection limit (DL) of on-line preconcentration corresponding to three times the standard deviation of the blank (S/N = 3) was found to be 1.3 ng mL-1 and the RSD of this method is 3.32% (n = 5). The on-line calibration graph was linear over the range 20 - 200 ng mL-1. A good preconcentration factor 820 was achieved by experiment under the on-line mode. The developed method was applied to the analysis of trace lithium in nuclear grade uranium compounds.

Equilibrium Analysis for Batch Studies of Adsorption of Fluoride in Water using Activated Alumina R and D 651-X

Abstract: Fluoride is one of the accumulative toxin. The batch adsorption studies were undertaken to asses the suitability of commercial available adsorbent activated alumina. From the earlier work, it was evident that the large surface area, higher acidity and good mechanical properties are requisites for the choice of suitable adsorbent. The most promising adsorbent used for defluoridation purpose is activated alumina. Among the various types of activated alumina, the type of activated alumina chosen for present study is UCIL R and D 651-X. To test its performance for defluoridation, the static studies have aimed at investigation of rate at which adsorption occurs under the varying condition of the major parameters of adsorption, viz. pH, dose of adsorbent, rate of stirring, contact time and initial adsorbate concentration on fluoride removal efficiency were studied and optimized by batch procedure, in which mixture of known concentration of fluoride solution continuously agitated and samples were taken at appropriate times, have been used in all experiments. The optimum sorbent dose was found 3.5g/L by varying the dose of adsorbent from 0 to 5 g; equilibrium was achieved in 100 min for the optimum pH. It has been observed that the optimum pH range for adsorption is between 6 to 7, by varying pH from 2 to10 and enhanced adsorption was obtained at pH 6.5. Maximum fluoride removal was observed to be 96% at optimum conditions. Freundlich as well as Langmuir isotherms were plotted and constants of isotherms were determined.

Method for removing hydrofluoric acid and organic fluorides from a fluid stream

Abstract: A method is provided for removing HF and organic fluorides from fluid streams in which the fluoride species exist as impurities and, in particular, from hydrocarbon fluid streams containing no more than about 1.0% by weight total fluorides. The method consists of first contacting the fluid stream first with a nonpromoted alumina and then with an adsorbent consisting essentially of activated alumina that has been treated with a promoter material selected from the oxides and phosphates of alkali metals and alkaline earth metals, and mixtures thereof. This is preferably accomplished by providing a suitable absorber vessel charged with the adsorbent in a fixed bed, and then contacting the fluoride-contaminated fluid through the fixed bed.

Filter for water purifier including organic germanium and thereof method

Abstract: A filter for water purifier comprising organic germanium is provided to allow users to drink water comprising organic germanium by heating a porous adsorbent to expand pores of the adsorbent, adsorbing organic germanium onto the expanded pores, coating ethyl cellulose on the organic germanium-adsorbed adsorbent, and using the resulting adsorbent in the filter for the water purifier, thereby eluting organic germanium into purified water, and a manufacturing method of the filter is provided. A filter for water purifier comprising organic germanium comprises organic germanium adsorbed onto a porous adsorbent and coated with an insoluble polymer. A manufacturing method of a filter for water purifier comprising organic germanium comprises: an adsorption process for adsorbing organic germanium onto a porous adsorbent, the adsorption process comprising steps of (1) heating a porous adsorbent at 70 to 150 deg.C for 1 to 2 hours, (2) dissolving organic germanium into distilled water, (3) mixing the organic germanium-dissolved water of the step(2) with the heated porous adsorbent of the step(1), and (4) drying the organic germanium-dissolved water mixed in the step(3) at 25 to 100 deg.C for 12 to 24 hours; and a coating process comprising the steps of (5) dissolving an insoluble polymer into ethyl alcohol and adding distilled water into the dissolved solution to prepare an insoluble polymer coating solution, (6) coating the organic germanium-adsorbed porous adsorbent of the step(4) with the insoluble polymer coating solution, and (7) drying the coated porous adsorbent of the step(6) at 70 to 80 deg.C for 12 to 24 hours. Further, the porous adsorbent is one selected from activated carbon, zeolite, silica, activated alumina and clay.

Composite type zeolite drier and method for making the same

Abstract: The invention discloses a composite type zeolitic drying agent and preparing method, which comprises the following steps: allocating 67-89 wt slope zeolite, 11-26 wt activated alumina, 8-15 wt micro void calcium silicate and 7-12 wt silica gel; grinding the zeolite to 200 order powder; mixing with the activated alumina, micro void calcium silicate and the silica gel; blending with proper water; preparing to small ball body with grain diameter at 1.5-2mm; drying or air-drying with water content at 10%-25%; roasting with microwave oven; getting the product. This invention possesses strong moisture absorption ability, which can be used to food, tea, medicine and so on aspects.

Process and apparatus for purification of fluorine-based solvent-containing solution and cleaning apparatus

Abstract: To provide a purification process where a fluorine-based solvent can be obtained at a high purity by relatively small equipment without using a distillation apparatus. A purification process of a mixed solution containing a fluorine-based solvent which is a process for purifying a fluorine-based solvent from a mixed solution containing a fluorine-based solvent, a water-soluble organic solvent contaminant, an organic contaminant and an ion contaminant, the process comprising: step (1): washing the mixed solution with water to obtain a first treated solution in which the water-soluble organic solvent concentration is reduced to 0. 01 wt% or less, step (2): treating the first treated solution with activated carbon to obtain a second treated solution in which the organic contaminant concentration is reduced to 20 ppb or less, step (3): treating the second treated solution with activated alumina to obtain a third treated solution in which the fluoride ion contaminant is reduced to 10 ppb or less, and step (4): treating the third treated solution with a particle removing filter to obtain a fluorine-based solvent in which the number of particles of 0. 1 μ m or more is 10 particles/mL or less.

Regenerating Method for Activated Alumina Used in Regenerating Working Fluid of Hydrogen Peroxide

Abstract: A regenerating method for activated alumina used in regenerating working fluid of hydrogen peroxide comprises the following steps: adding deactivated alumina discharged from a regenerating bed for working fluid of hydrogen peroxide into a reactor through the top of the reactor and settling by gravity, oxidizing atmosphere entering into the reactor from the bottom of the reactor and running upwardly, then discharging exit gas and regenerated alumina through the discharge port on the top and discharging device on the bottom of the reactor respectively. The method is economic, environment-protective, safe, low-costly. The regenerated alumina will not poison palladium catalyst.