Showing papers on "Activated alumina published in 2007"

Adsorption of Fluoride from Water Solution on Bone Char

Abstract: The effects of solution pH and temperature on the adsorption of fluoride onto bone char made from cattle bones were investigated in this work. It was found that the maximum adsorption took place at pH 3 and the adsorption capacity decreased nearly 20 times augmenting the pH from 3 to 12. This behavior was attributed to the electrostatic interactions between the surface of bone char and the fluoride ions in solution. The adsorption capacity was not influenced by temperature in the range from 15 to 35 °C. A comparison of fluoride adsorption capacities among several adsorbents revealed that the adsorption capacity of the bone char was 2.8 and 36 times greater than those of a commercial activated alumina (F-1) and a commercial activated carbon (F-400). The adsorption capacity is considerably dependent upon the physicochemical properties of the bone char surface and the solution pH.

Use of ArsenXnp, a hybrid anion exchanger, for arsenic removal in remote villages in the Indian subcontinent

Abstract: Many of the arsenic removal units operating in remote villages of West Bengal, India now use a hybrid anion exchanger (HAIX) which are essentially spherical anion exchange resin beads containing dispersed nanoparticles of hydrated ferric oxide (HFO). HAIX, now commercially available as ArsenX np , offers a very high selectivity for sorption of oxyanions of arsenic due to the Donnan membrane effect. The sorption columns used in the field for removal of arsenic are either single column or split-column design. The sorption columns allow flow of atmospheric oxygen, thereby promoting oxidation of dissolved Fe(II) species of arsenic-contaminated raw water to insoluble Fe(III) oxides or HFO particulates. Apart from the usual role played by the sorbents like ArsenX np or activated alumina towards arsenic removal, HFO particulates also aid in the treatment process. Each unit is attached to a hand-pump driven well and capable of providing arsenic-safe water to three hundred (300) households or approximately one thousand villagers. No chemical addition, pH adjustment or electricity is required to run these units. On average, every unit runs for more than 20,000 bed volumes before a breakthrough of 50 μg/L of arsenic, the maximum contaminant level in drinking water in India, is reached. In addition to arsenic removal, significant iron removal is also achieved throughout the run. Upon exhaustion, the media is withdrawn and taken to a central regeneration facility where 2% NaCl and 2% NaOH solution are used for regeneration. Subsequently, the regenerated resin is reloaded into the well-head sorption column. Following regeneration, the spent solutions, containing high arsenic concentration, are transformed into solids residuals and contained in a way to avoid any significant arsenic leaching. Laboratory investigations confirmed that the regenerated ArsenX np is amenable to reuse for multiple cycles without any significant loss in capacity.

Extraction of Chlorpyrifos and Malathion from Water by Metal Nanoparticles

Abstract: The nanoparticles of gold and silver in solution state and supported over activated alumina are effective systems for the quantitative removal of chlorpyrifos and malathion, two common pesticides found in surface waters of developing nations, from water. In the solution phase, these pesticides adsorb onto the nanoparticles' surfaces and upon interaction for a long time, the nanoparticles with adsorbed pesticides precipitate. In contrast, complete removal of these pesticides occurs when contaminated water is passed over nanoparticles supported on alumina. A prototype of an on-line filter was made using a column of activated alumina powder loaded with silver nanoparticles and the device was used for pesticide removal for extended periods. We believe that the method has great technological potential in drinking water purification, especially using silver nanoparticles.

Adsorption of disperse dye by various adsorbents

Abstract: Laboratory investigations of C.I. Disperse Red 60 adsorption on molecular sieves, activated alumina, granular activated carbon (GAC), diatomite and sawdust were conducted. The effectiveness of those adsorbents for pollutant removal and color reduction of disperse dye was examined and compared with that of powdered activated carbon (PAC). It was found that the activated alumina has only 61% COD (chemical oxygen demand) removal efficiency in comparison with that of PAC while those of molecular sieves, GAC and diatomite are much lower. In terms of color removal, activated alumina and molecular sieves are as effective as PAC while GAC, diatomite and sawdust are much less effective. The monolayer Langmuir isotherm was found to represent well the measured adsorption data and the constant parameters of the adsorption isotherms were determined for all adsorbents. The simplified mass transfer model proposed previously was also used for estimating the mass transfer coefficients using the initial adsorption data for several adsorbents

Removal of boron dissolved in water

Abstract: The study aimed to investigate boron adsorption on activated carbon, activated carbon impregnated with different substances, activated alumina, zirconium dioxide and silica-aerosil. The removal of boron from water was carried out in static and dynamic systems. Isotherms for boron adsorption from model aqueous solutions on various adsorbents were applied and Langmuir constants were calculated. The results indicate that the application of the impregnants increases the ability of activated carbon to adsorb boron. The first removal of boron using activated carbon impregnated with mannitol compared favorably with other impregnants. © 2007 American Institute of Chemical Engineers Environ Prog 26:71–77, 2007.

Boron Removal from Wastewater Using Adsorbents

Abstract: In the present study, boron adsorption on activated alumina and activated carbon impregnated with calcium chloride, tartaric acid and mannitol was investigated. The adsorbate in question was the wastewater from the chemical landfill in Tarnowskie Gory of 25-70 mg l−1 boron content. The removal of boron from the above-described wastewater was examined in the static (batch) and dynamic (column) experiments. The static experiments were carried out to assess boron adsorption isotherms, based on which the most efficient adsorbent as well as the rough resin load was determined. On the basis of the dynamic experiment results, the boron adsorptive capacities of the examined resins were deduced. It was concluded that the use of the impregnants increased the ability of activated carbon to adsorb boron. Granulated activated carbon WG-12 impregnated with mannitol was found to be the most promising for the boron removal from wastewater of the Chemical Wastewater Plant in Tarnowskie Gory.

Screening of Commercial Sorbents for Removal of Fluoride in Synthetic and Groundwater

Abstract: Numerous methods have been described employing various materials for fluoride removal due to the risk of high fluoride dosing for human health. There is a broad collection of commercial products for adsorption applications. The materials most recommended are activated alumina and bone char. Nineteen commercial sorbents were screened for fluoride removal in static experiments, with synthetic water and groundwater from the city of Aguascalientes (Mexico), where some wells contain up to 15 mg l−1 of fluoride. Removal efficiency of aluminas and activated carbons with a uniform particle diameter of 0.63 mm was compared. Four materials leading to a final concentration of 1 mg F l−1 were selected, pretreated, and characterized (X-ray diffractometry, infrared spectroscopy, titration, methylene blue and nitrogen adsorption) for further investigation. Adsorption rate constant was determined and obeyed a pseudo-first order equation. Fluoride removal was clearly improved after the conditioning procedure and was highe...

Removal of phenol by activated alumina bed in pulsed high-voltage electric field.

Abstract: A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe 2+ . The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/ LF e 2+ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation.

Characterization of Commercial Ceramic Adsorbents and its Application on Naphthenic Acids Removal of Petroleum Distillates

Abstract: The mixture of carboxylic acids present in petroleum oil and directly responsible for its acidity and corrosiveness in liquid phase during the refine process is denominated "naphthenic acids". These acids are also present in distilled fraction of petroleum, causing several problems in final products quality. A possible way to remove the carboxilic acids from petroleum distilled fractions is the adsorption in porous materials. However, the results obtained until now indicate that ion exchange resins would be the best adsorbents for this process, which would probably increase its cost. In this work, two commercial adsorbents (clay and activated alumina) were characterized by a set of physical-chemistry techniques and evaluated concerning their capacity of removing naphthenic acids from a light petroleum fraction. It was verified the influence of a thermal treatment previous to the adsorption in its physical-chemistry characteristics and its properties. A high reduction of the TAN values was verified in the residual oils from both adsorbent, although there was a competition among all the compounds present in the light oil fraction for the adsorption sites, which can be probably related to the thermal pre-treatment. These results were related to corrosion yield experiments, and it was observed that the adsorbent pretreatment also affected the reduction in corrosion yields for both alumina and clay.

Iron and manganese amended activated alumina - A medium for adsorption/oxidation of arsenic from water

Abstract: In a laboratory study, iron and manganese amended activated alumina (IMAA) showed promise as an effective medium for removing arsenic [As(III) and As(V)] from groundwater. Batch adsorption/oxidation kinetic test indicated that the effectiveness of the IMAA medium was due to in situ oxidation of As(III) to As(V) and higher adsorption of As(V) by the medium. A home arsenic removal unit, containing 4 L of IMAA or AA and operated at 6 L/h, produced 2400 L and 2340 L or 1392 L and 1320 L of water in two cycles of runs when the influent arsenic concentration was 1.0 mg/L [0.6 mg/L of As(III) and 0.4 mg/L of As(V)]. The IMAA medium should be subjected to field trials to assess the long-term effects on performance, such as loss of medium capacity, attrition of the iron and manganese coating, fouling by organics, and pH and competing ion effects. © IWA Publishing 2007.

Integrated Liquid-Phase Sintering of Glass-Alumina Functionally Graded Materials

Abstract: The sintering mechanism of glass-alumina functionally graded materials (G-A FGMs) at 710°C prepared by a novel rapid prototyping manufacturing (RP&M) technology was studied. An integrated kinetics equation was established for the initial 20 minutes. Linear shrinkage is due to the integrated working of both viscous flow of the glass particles and gravitation of the effective activated alumina grain boundaries towards the equilibrium state. The driving force for gravitation of the activated alumina grain boundaries originates from the coactions of passive flow of the alumina particles during viscous flow of the glass particles and the compressive stress formed during cooling. In the middle 10 minutes, the sintering process follows the solution-precipitation mechanism. Confirmed by Scanning Electron Microscope (SEM) and the line scanning Energy Dispersive Spectrum (EDS), a layer of Si-Al eutectic of about 1.04µm on the alumina surface is formed. Then the alkali and alkali earth ions in the glass phase diffuse through this layer and precipitate on the surface. Additionally, the dissolved Al ions can easily transport through the eutectic layer and precipitate in the glass matrix due to the effect of Si in the glass matrix.

Removal of phenol by activated alumina bed in pulsed high-voltage electric field

Abstract: 为在搏动的高电压的电场在水的 solution-activatedalumina 床上移开污染物质的新进程为试验性的结果显示了的酚 underdifferent conditions.The 的移动被调查有 increasingapplied 电压的移动率的增加，解决方案的增加的 pH 价值，通风，并且补充说当空气通风流动率是 1200 ml/min 时， Fe2+.The 移动率 ofphenol 能到达72.1%，并且88.2%当 0.05 mmol/LFe2+was 在条件下面增加了进解决方案时

Catalyst material for cleaning exhaust gas component and particulate filter with the same catalyst material

Abstract: PROBLEM TO BE SOLVED: To provide a catalyst material for cleaning exhaust gas component which can improve cleaning performance for exhaust gas components (including HC, CO and particulates) and has improved heat resistance. SOLUTION: The catalyst material for cleaning exhaust gas component comprises activated alumina, a ZrNd-based conjugated oxide which contains Zr and Nd, and a rare earth metal M other than Ce and Nd, wherein primary particles of the ZrNd-based conjugated oxide are dispersively carried on the surface of secondary particles of activated alumina and the primary particles of the ZrNd-based conjugated oxide contain ZrO 2 at a proportion of ≥55 mol% and COPYRIGHT: (C)2009,JPO&INPIT

Argon-blowing narrow brick

Abstract: The invention discloses a continuous-casting flame-proof argon-blowing brick, which comprises the following steps: blending electro-melting zirconium-corundum, electro-melting zirconium mullite, activated alumina powder, electro-melting alumina, chromic oxide powder and additive according to weight percentage; pre-mixing; stirring; moulding; drying; sintering; obtaining the product with brushing-proof, etching-proof and excellent air permeability.

Adsorption of NaCl Vapor at Elevated Temperature on Mineral Adsorbents

Abstract: Some mineral adsorbents were selected to remove NaCl vapor at elevated temperature. Results indicate that the activated alumina is the best adsorbent with the highest sodium compound content, under conditions of 1123 K, a gas velocity of 16 L/min, an adsorption time of 5 h, and a NaCl concentration of 0.13 mg/L. Results show that sodium compound content is dependent on the microporous structure and the chemical constitutes of the adsorbent, but the extent of the effects varies with each adsorbent. Results of XRD and SEM indicate that physical adsorption exists in the NaCl vapor-capture mechanism of the activated alumina. Its kinetics results indicate that both chemical adsorption and physical adsorption exist, and the adsorption process of the activated alumina is controlled by both the chemical adsorption control and the product-layer-diffusion control of physical adsorption.

The chromatographic purification of inorganic salts on activated alumina

Abstract: Solutions of zinc, cadmium, manganese, magnesium, calcium, strontium and barium salts and of ammonium and sodium tungstates have been freed from trace impurities of iron, copper, silver and lead by one passage through a column packed with activated alumina. In most cases, the contamination in the resulting solutions is below the limits of polarographic or photometric analysis.

Method for removing palladium

Abstract: PROBLEM TO BE SOLVED: To provide a commercial method for removing palladium, by which the palladium that is contained in an organic reaction product solution using a palladium catalyst and may cause problems in the fields of medicines, agrochemicals, electronic materials, and the like can be removed with an inexpensive adsorbent in a simple operation. SOLUTION: This method for removing the palladium comprises treating a solution after an organic reaction using a palladium catalyst with activated alumina. Namely, the method for removing the palladium is characterized by treating the solution after the organic reaction using the catalyst containing a phosphorous ligand and a palladium compound with the activated alumina having a specific surface area of 50 to 400 m 2 per g. COPYRIGHT: (C)2009,JPO&INPIT

Method for producing phosphorus-containing activated alumina

Abstract: PROBLEM TO BE SOLVED: To provide a method for producing phosphorus-containing activated alumina which is excellent in hydrothermal stability, hardly causes the phase transition to boehmite-form alumina hydrate by hydrothermal treatment, and hardly causes the phase transition to α-alumina by heat treatment, and is reduced in the lowering of the specific surface area by the treatment. SOLUTION: This method for producing phosphorus-containing activated alumina comprises the steps of reacting a soluble aluminum salt aqueous solution with a basic aqueous solution in the presence of a soluble carboxylic acid to form 2-15 wt.%, in terms of alumina, of pseudo-boehmite alumina hydrogel, washing the alumina hydrogel to remove by-produced salts and reduce the alkali metal content in alumina to ≤1.0 wt.%, in terms of oxides, then adding a phosphorus component and an organic polymer acid to washed alumina hydrogel, heating and aging, adjusting the moisture content of the aged slurry to a value enabling extrusion molding, extrusion-molding it into a desired shape, drying the molded article and firing the dried article at 400-800°C for 0.5-10 h. The resultant phosphorus-containing activated alumina product has a rate of the phase-transition to α-alumina by the hydrothermal treatment of 20% or less and has a specific surface area of 300-600 m 2 /g. The decreasing rate of the specific surface area by the hydrothermal treatment is 20% or less. COPYRIGHT: (C)2008,JPO&INPIT

Pore Structure Control of Activated Alumina

Abstract: Influences of pH value swing, hydrothermal treatment and the surfactants addition on the pore structure of activated alumina were studied. The results indicated that pH value changes in alternative way could be beneficial to the preparation of pseudoboehmites with large, uniform crystalline sizes and high crystallinities, hydrothermal treatment favored the migration of aluminum atoms and promoted crystal growth, while surfactants could insert into layers of pseudoboehmite, decreasing the tendency in collapsing of layers and shrinking of capillarys upon calcinations, so pore structure of alumina could be controlled effectively. Hydrothermal treatment and pH value swing could shift the micropore distribution of alumina to macroporous direction, and decreased surface areas; the surfactants addition could shift the micropore distribution of alumina to microporous direction, and increase surface areas. The high-porosity alumina carriers were obtained with surface areas (≤150 m2·g-1 )and surface areas (≥250 m2·g-1). The coordinated states of aluminum species were investigated too, and it was found that aluminum atoms were in 4-coordinated and 6-coordinated states mainly, the addition of surfactants and hydrothermal treatment could remarkably influence the ratio of 4-coordinated Al to 6-coordinated Al.

Kinetics of MoO3 thermal desorption from the surface of mechanically activated alumina

Abstract: We have studied the kinetics of molybdenum trioxide desorption from the alumina surface after mechanical activation of Al2O3 + MoO3 mixtures. Mechanical activation has been shown to considerably inhibit MoO3 thermal desorption. The apparent rate constant and activation energy of the process have been evaluated.

Bio‐Regeneration of Desulfurization Adsorbents by Selected P. delafieldii R‐8 Strains

Abstract: Adsorption properties of different adsorbents such as reduced NiY, AgY, alumina, 13X, and activated carbon were studied with dibenzothiophene (DBT) and naphthalene as model compounds. The desorption of DBT was carried on thermo gravimetric-differential thermal analysis (TG-DTA). The interaction of DBT with different adsorbents follows the sequence: activated carbon > reduced NiY > AgY > activated alumina > 13X. The bio-regeneration of these adsorbents was studied with P. delafieldii R-8 as desulfurization strains. Adding P. delafieldii R-8 cells can improve DBT desorption from adsorbent AgY. The desorption of DBT from adsorbents by bioregeneration of adsorbents follows the sequence: 13X > alumina > AgY > reduced NiY > activated carbon. The presence of naphthalene can decrease the desorption of sulfur compounds. The adsorption capacity of AgY decreases for the first time recycling and then changes little. The decrease of the adsorption capacity is due to the loss of Ag+ ions.

Comparation of Adsorption Properties of Glyphosate on Resins and Activated Aluminas

Abstract: Adsorption of glyphosate by NDA-88 and D301 resins and two activated alumina were carried out through static experiments.The effect of NaCl on adsorption was also studied.Experimental results indicate that in the selected range of temperature and concentration,the four adsorption systems all fit the Langmuir model.Low temperature benefits resin adsorption while high temperature favors adsorption on alumina.In the absence of NaCl,resin adsorption capacity is higher than alumina(except Al-1 at 323 K).However,dramatic decrease in adsorption capacity was observed for both resins upon addition of 0.5% or more NaCl into the solution containing glyphosate.