Showing papers on "Activated alumina published in 2010"

Characteristics of Ammonia Adsorption on Activated Alumina

Abstract: Adsorption of ammonia was measured volumetrically on activated alumina at temperatures of (273, 298, and 323) K and gas pressures up to 108 kPa. It was found that the final adsorption amounts at the terminal pressure point were (3.13, 2.53, and 1.89) mmol·g−1 at (273, 298, and 323) K, respectively. The Langmuir, Freundlich, Sips, and Toth isotherm models were employed to correlate the adsorption isotherms. Ammonia diffusivities in these adsorbents at (298 and 323) K and at five different pressure points were calculated from the adsorption kinetic uptake curves by using a classical diffusion model. It was found that the average diffusivity values were (4.02·10−14 and 4.71·10−14) m2·s−1, respectively, at (298 and 323) K. The heat of adsorption values are between (−35.6 and −15) kJ·mol−1 for adsorption loadings between (1.3 and 2.3) mmol·g−1. The Gibbs energies were calculated as (−14.01, −13.23, and −9.07) kJ·mol−1 at (323, 298, and 273) K, respectively. The value of the entropy lies within (−65 to −3) J·mo...

Arsenic and Fluoride Removal Using Simple Materials

Abstract: Since many at risk to arsenic and fluoride contamination cannot afford or do not have access to modern, centralized water treatment facilities, simple and low-cost solutions must be found. Bone char, goethite coated sand (G-IOCS) and hematite coated sand (H-IOCS) were evaluated for treating water with elevated levels of arsenic and fluoride present individually or together. Results obtained were compared to conventional media used in developed countries; activated alumina and granular ferric oxide. Fluoride adsorption capacity was higher in bone char than in G-IOCS and H-IOCS. Fluoride removal was not affected by the presence of environmentally significant arsenic (III) and arsenic (V) concentrations. On a mass basis, bone char’s fluoride adsorption capacity was comparable to that of activated alumina both in the presence and absence of 0.25 mg/L of arsenic (III) and arsenic (V) in solution. Bone char also showed higher capacity to remove arsenic (III) and arsenic (V) from solution than both G-IOCS and H-...

Alkali metal cation doped Al-SBA-15 for carbon dioxide adsorption.

Abstract: Mesoporous aluminosilicate adsorbents for carbon dioxide were prepared by the grafting of aluminium into SBA-15 silica using an aqueous solution of aluminium chlorohydrate. As the ion exchange sites are primarily associated with the presence of tetrahedrally coordinated aluminium, extra-framework aluminium on the SBA-15 surface was inserted into the silica matrix by a treatment with an aqueous solution of NH(4)OH. Synthesized mesoporous aluminosilicate preserving all the characteristic features of a mesoporous molecular sieve was finally modified by the alkali metal cation exchange. To examine carbon dioxide adsorption on prepared materials, adsorption isotherms in the temperature range from 0 °C to 60 °C were measured. Based on the known temperature dependence of adsorption isotherms, isosteric adsorption heats giving information on the surface energetics of CO(2) adsorption were calculated and discussed. The comparison of carbon dioxide isotherms obtained on aluminosilicate SBA-15, aluminosilicate SBA-15 containing cations Na(+) and K(+) and activated alumina F-200 reveals that the doping with sodium or potassium cations dramatically enhances adsorption in the region of equilibrium pressures lower than 10 kPa. Therefore, synthesized aluminosilicate adsorbents doped with Na(+) or K(+) cations are suitable for carbon dioxide separation from dilute gas mixtures.

The role of denitrification on arsenite oxidation and arsenic mobility in an anoxic sediment column model with activated alumina.

Abstract: Arsenite (As(III)) is the predominant arsenic (As) species in reducing environments. As(III) is less strongly adsorbed than As(V) at circumneutral pH conditions by common non-iron metal oxides in sediments such as those of aluminum. Therefore, oxidation of As(III) to As(V) could contribute to an improved immobilization of As and thus help mitigate As contamination in groundwater. Microbial oxidation of As(III) is known to readily under aerobic conditions, however, the dissolved oxygen (O₂) concentration in groundwater may be limited due to the poor solubility of O₂ and its high chemical reactivity with reduced compounds. Nitrate (NO₃⁻), can be considered as an alternative electron acceptor, which can support oxidation of As(III) to As(V) by denitrifying bacteria. In this study, two up-flow sediment columns packed with activated alumina (AA) were utilized to demonstrate the role of denitrification on the oxidation of As(III) to As(V) and its contribution to improved As adsorption onto AA. One column was supplied with NO₃⁻(C1) and its performance was compared with a control column lacking NO₃⁻(C2). During most of the operation when the pH was in the circumneutral range (days 50-250), the release of arsenic was greater from C2 compared to C1. The effluent As concentrations started increasing on days 60 and 100 in C2 and C1, respectively. Complete breakthrough started on day 200 in C2; whereas in C1, complete breakthrough was never achieved. The effluent and solid phase As speciation was dominated by As(V) in C1, indicating the occurrence of As(III) oxidation due to NO₃⁻; whereas in C2, only As(III) was dominant. This study illustrates a bioremediation or natural attenuation process based on anoxic microbial NO₃⁻-dependent oxidation of As(III) to more readily adsorbed As(V) as a means to enhance the immobilization of As on alumina oxide particles in subsurface environments.

Method for removal of selenium contaminants from aqueous fluids

Abstract: Aqueous fluid polluted with selenium contaminants is mixed with or passed through an adsorbent material selected from: (i) nanoparticles or colloids of oxides or hydroxides of transition metals or of aluminum, or mixtures thereof, or (ii) porous carbon, activated carbon, aluminum oxide or hydroxide, activated alumina, mineral clay, zeolite, or mixtures thereof in granular, particles or powder form, loaded with nanoparticles or colloids of oxides or hydroxides of transition metals or of aluminum, or mixtures thereof, to yield aqueous fluid purified from selenium

Removal of Arsenic(V) from Aqueous Solutions by Lanthanum‐loaded Zeolite

Abstract: A new adsorption process for the removal of As(V) ion from aqueous solutions is studied in this paper using lanthanum-loaded zeolite. The removal efficiency of different adsorbents, activated alumina and activated carbon are obtained in the study for comparison. The results show that lanthanum-loaded zeolite is an effective adsorbent for the removal of As(V) from aqueous solutions. Then, the pH effect and regeneration of modified zeolite on the As(V) removing efficiency are also assessed. It functions with a wide range of pH (2–8). After adsorption, zeolite adsorbed with As(V) ions can be regenerated successfully with 1M NaOH. Based on the data obtained, an adsorption mechanism and the possible complex structure are tentatively presented. Compare to other adsorbents, easy availability of this adsorbent, excellent adsorption capacity, wide optimum pH range, and regeneration are expected to be utilized in practical operations.

Removal of Fluoride Using Thermally Treated Activated Alumina

Abstract: In this study, sorption characteristics of thermally treated activated alumina (AA) for fluoride were investigated. Sorption experiments have been conducted in equilibrium and kinetic batch conditions. Also, effects of solution pH and anions on fluoride removal have been observed. The properties of thermally treated ( ) activated alumina (AA700) and untreated activated alumina (UAA) were compared using field-emission scanning electron microscope, energy-dispersive spectrometry, X-ray diffractometer (XRD) analysis, and Brunauer-Emmett-Teller (BET) analysis. From the experiments using AA thermally treated at different temperatures (100, 300, 500, ), it was found that at high fluoride concentrations (50, 100, 200 mg/L) the sorption capacity of thermally treated AA increased with increasing thermal treatment temperature. At an initial fluoride concentration of 200 mg/L, the sorption capacity of AA700 was 3.67 times greater than that of UAA. The BET analysis showed that the specific surface area of UAA was about 2 times larger than that of AA700. The XRD analysis indicated that UAA was composed of both boehmite (AlOOH) and bayerite () while AA700 was . The reason that fluoride sorption capacity of AA700 increased despite of decrease in specific surface area compared to UAA could be attributed to the change of crystal structure. The kinetic sorption test showed that fluoride sorption to AA700 arrived at equilibrium after 24 h. The equilibrium test demonstrated that the maximum sorption capacity of AA700 was 5.70 mg/g. Additional batch experiments indicated that fluoride sorption to AA700 was the highest at pH 7, decreasing at both acidic and basic solution pHs. Also, fluoride sorption to AA700 decreased in the presence of anions such as phosphate, nitrate, and carbonate. This study demonstrated that thermal treatment of AA at high temperature could increase its sorption capacity for fluoride.

Method for preparing ethyl acetate by using alumina supported phosphotungstic acid as catalyst

Abstract: The invention discloses a method for preparing ethyl acetate by using alumina supported phosphotungstic acid as a catalyst, which is characterized by comprising the following steps of: dissolving phosphotungstic acid in distilled water to prepare solution of which the concentration is between 0.031 and 0.062 mol/L at room temperature, immersing an activated alumina support into the solution for 1 hour, calcining the immersed alumina support at the temperature of between 120 and 200 DEG C for 2 to 6 hours, and stirring the calcined alumina support once at intervals of between 20 and 30 minutes in the process of calcination, wherein the phosphotungstic acid content of the prepared catalyst is between 5 and 10 percent; and catalyzing acetic acid and ethanol to prepare ethyl acetate by adopting the prepared catalyst and the technology of reactive rectification under the reaction condition that the feed molar ratio of the acetic acid to the ethanol is 1:1, the reaction temperature is 150 DEG C, the reflux ratio is between 1 and 2, and the rate of feed is between 20 and 60 mL/hour. The method simplifies the flow process, reduces equipment cost and operating cost, and increases the process conversion rate and the yield of products.

Pore surface fractal analysis of PEG and La(III)-doped mesoporous alumina obtained by the sol-gel method

Abstract: Active porous alumina was prepared via a sol-gel method and sub- jected to thermal treatment in the temperature range 500-1200 °C. The addition of lanthanum effectively inhibited the surface area loss of the aluminas. Fractal analysis from nitrogen adsorption isotherm was used to study the pore surface roughness of alumina samples with different chemical compositions (PEG, PEG and lanthanum) and calcinations conditions in terms of the surface fractal di- mension, d. The Mahnke and Mogel (MM) model was used to determine the value of d of La(III)-doped alumina. Following the MM model, the d value of the activated aluminas increased as the calcination temperature increased from 500 to 700 °C but decreased after calcination at 1000, 1100 and 1200 °C. The addition of polyethylene glycol (PEG 5600) to the boehmite sol reduced the surface fractal of the activated alumina due to the heterogeneous distribution of the pores. With increasing La(III) concentration from 0.015 to 0.045 mol La(III)/ /mol Al(III), the d value of La-modified alumina samples decreased, indicating a smoother surface. The obtained PEG+La-doped boehmite sol can be used as a precursor dispersion for the deposition of mesoporous alumina coatings on stain- less steel foil, by the spray pyrolysis method.

Preparation of high temperature-resistant active aluminum oxide

Abstract: The invention relates to a method for preparing fireresistant activated alumina. A liquid phase counter-titration precipitation method is adopted; a sodium aluminate solution and a nitric acid solution are used as raw material; organisms are used as a pore expanding agent; a rare earth oxide is used as a stabilizing agent; the alumina with large specific surface area and good fireresistant performance is prepared by adopting the liquid phase counter-titration precipitation method. The rare earth oxide content in the alumina is between 0.1 and 10 wt percent; an alumina solid is treated for 5 hours in the atmosphere of 700 DEG C; the specific surface area of the alumina solid is more than 350m /g; the average pore volume is 0.3122 mL/g; the average aperture is 5.23 nm; and the aperture distribution range is between 3 and 12 nm. The alumina solid is treated for 5 hours in the atmosphere of 1100 DEG C; and the specific surface area of the alumina solid is more than 150 m /g. The method has the characteristics of low production cost, simple process, large specific surface area, even aperture distribution and good high-temperature thermal stability.

Field studies on defluoridation using magnesium oxide

Abstract: By far the most serious natural groundwater-quality problem in India derives from high fluoride, arsenic and iron concentrations. Fluoride removal from contaminated groundwater is practiced by pump and treat method; treatment is generally accomplished by addition of an aluminium sulfate–lime mixture to the pumped water or by permeating water through column of activated alumina. A magnesium-oxide-based method (termed the IISc method) has been developed to remove fluoride from drinking water. The IISc method relies upon the precipitation–sedimentation–filtration technique. Magnesium oxide addition to the contaminated groundwater removes fluoride ions through chemical reactions. The alkaline pH induced by magnesium oxide addition is neutralised by the addition of sodium bisulfate solution to the treated water. Interference from bicarbonate ions towards pH neutralisation is minimised by the addition of lime and calcium chloride solution to the untreated water. The IISc method has several advantages: chemicals...

Device system for removing fluoride and arsenic from drinking water for urban and rural families

Abstract: The utility model provides a device system for removing fluoride and arsenic from drinking water for urban and rural families The device system comprises an activated carbon filter with a quartz sand filter layer and also comprises an activated alumina filter, wherein a ring-shaped partition plate is arranged inside the sealed container of the activated alumina filter, an integrated dedicated filtering head is arranged on the central hole of the partition plate, gaps are distributed on the arc-shaped part of the filtering head, a water outlet is formed at the lower part of the filtering head, an activated alumina filtering layer is arranged on the surface of the filtering head, a water inlet and a backwashing drainage port are arranged on the top of the container, a backwashing water inlet is arranged on the left side surface of the container below the partition plate, a water outlet is arranged on the right side surface of the container below the partition plate, a washing drainage port is arranged at the bottom of the container, and the water outlet of the activated carbon filter is communicated with the water inlet of the activated alumina filter The device system is economically efficient and practical and provides the healthy drinking water to the urban and rural families

Removal method of iodine mixtures from aqueous solution

Abstract: PURPOSE: A method for eliminating an iodine mixture from an aqueous solution is provided to effectively remove the iodine without a separate oxidation or reduction reaction process for making the iodine mixture into a single ion state and to completely eliminate the iodine from radioactive waste liquid. CONSTITUTION: A method for eliminating an iodine mixture from an aqueous solution includes a step of adsorbing a mixture selected from iodide ion(I^-), iodate ion(IO3^-) and iodine using an adsorbate selected from activated alumina, the activated alumina in which Ag are dipped, and activated charcoal. The method comprises the following steps: a step of absorbing the iodate ion from acidic activated alumina and the acidic activated alumina in which Ag are dipped; step of absorbing the iodide ion selected from basic activated alumina and the basic activated alumina in which Ag are dipped; and a step of absorbing the iodine using the activated charcoal.

Adsorbent for nonaqueous secondary battery, porous membrane for nonaqueous secondary battery, separator for nonaqueous secondary battery, and nonaqueous secondary battery

Abstract: PROBLEM TO BE SOLVED: To provide a technology of improving cycle characteristics in consideration of reaction with HF and adsorption of HF. SOLUTION: An adsorbent for a nonaqueous secondary battery is hydrogen fluoride mixed in the nonaqueous secondary battery, the adsorbent having a specific surface area of 300-1,000 m 2 /g and being amorphous activated alumina particles. COPYRIGHT: (C)2011,JPO&INPIT

Catalytic Degradation of Organic Pollutants by Packing Activated Alumina in High Voltage Pulsed Discharge Electric Field

Abstract: To increase the removal rate of organic substance in high voltage discharge process,activated alumina and beading were added between the electrodes with gas aeration in the submerged flow state.The removal rate of phenol increased with adding activated alumina and increasing the applied voltage.Oxygen flowing into the discharge region would promote the removal of phenol obviously.The polarization was more intense with activated alumina filled in the reactor,so more reactive species would be produced.Nevertheless,the enhanced electric field was unconspicuous with beading.The energy consumption of discharge between the electrodes by adding activated alumina was less than discharge in bubbles.The phenol degradation and the discharge condition could be improved by adding activated alumina between the discharge electrodes,which reduced the energy consumption and increased the energy utilization efficiency.

Behavior of Phosphorus Adsorption from Aqueous Solutions on Modified Activated Alumina

Abstract: In the study, activated alumina was modified by calcium chloride, and after modification the phosphorus removal from aqueous solution increased by 13% or so. Then the activated alumina with and without treatment were subjected to characterization by the methods of the BET and SEM, and the adsorption characteristics of modified activated alumina were further studied at different contact time, pH values, adsorbent dosage levels and initial phosphorus concentration. Moreover, the equilibrium adsorption data for phosphorus were better fitted to Langmuir adsorption isotherm, and it means that the uptake of phosphorus preferably followed the monolayer adsorption process.

Method for removing oxygen-containing compounds from crude hydrocarbon and method for producing purified hydrocarbon

Abstract: PROBLEM TO BE SOLVED: To provide a method for removing oxygen-containing compounds such as ether compounds and alcohol compounds from a crude hydrocarbon, and to provide a method for producing a purified hydrocarbon by the method. SOLUTION: There are provided the method for removing oxygen-containing compounds from the crude hydrocarbon containing the oxygen-containing compounds as impurities, characterized by bringing the crude hydrocarbon into contact with an adsorption column (i) filled with a hybrid type adsorbent comprising a mixture of activated alumina with zeolite, and then bringing the crude hydrocarbon into contact with an adsorption column (ii) filled with a zeolite-based adsorbent. COPYRIGHT: (C)2010,JPO&INPIT

Fluoride Adsorption onto a Ce-La Binary Hydroxide Adsorbent as Recovery of Ceria Glass Polishing Wastes

Abstract: The adsorption of fluoride onto a Ce−La binary hydroxide adsorbent, herein referred to as CLH adsorbent, was studied under various pH values, adsorbent dose, contact time, and the presence of major anions. In the pH range of 4 to 8, the fluoride adsorption onto CLH reaches a maximum, then decreases with further increasing of pH. A considerably higher adsorption capacity (77.4−89.5 mg g-1) was maintained until the solution pH was up to 8 compared with that of the commercially available activated alumina; indicative of the CLH material should be effective to fluoride removal for major fresh water supplies. The effect of contact time was dependent on the initial fluoride concentration but adsorption equilibriums were reached after 120 min under the initial concentrations of 10 and 25 mg L-1, whereas a residual F- concentration of HCO3- ≥ SiO32- > SO42- > Cl-, NO3-.

Compare Study of a New Type Adsorbent and 2 Traditional Adsorbents on Their Efficiency for As (V) Adsorption

Abstract: Iron coated zeolite is made and its adsorption characteristics are compared with activated alumina and zero-valent iron to get further understand of the new adsorbent. The results show that iron coated zeolite removes As(V) in the similar with that by activated alumina with removal rate of 50% in first 5min's adsorption but slower after 60 mins' adsorption and faster than that by zero-valent iron during the whole adsorption process. Iron coated zeolite sorption fits Langmuir model the best. Capacities of activated alumina, iron coated zeolite and zero-valent iron for As(V) adsorption are 7.3mg/g, 3.9mg/g and 3.3 mg/g, respectively. XRD analysis shows that main components on the surface of the used iron coated zeolite in this paper is FeOOH. To improve the adsorption efficiency of iron coated zeolite, diameter of the zeolite should be decreased and iron should be coated more tightly on the zeolite.

Kinetics of humics removal from water and wastewater using granular activated carbon, iron-coated activated alumina, and beta ferric oxihydroxide.

Abstract: Application of kinetic models to represent the removal of humic substances from water and wastewater was investigated. An adsorbate–adsorbent system was represented by humic substances and three adsorbents, namely granular activated carbon (GAC), iron-coated activated alumina (AAFS), and ferric oxihydroxide in its beta form. The Elovich, internal diffusion, and external diffusion models were considered. The first model represents fairly well the experimental data for GAC and AAFS. The intraparticle diffusion model applies well for the second stage (stage 2) of adsorption only. Reliable diffusion coefficients were estimated for GAC and beta ferric oxihydroxide. A different phenomenon occurred with AAFS, as adsorption seemed to follow a second stage instead of stage 3, which was attributed to the flaking of the coating, thus generating more bare surface. As a result, the dominant mechanism on AAFS varies, starting with the adsorption being limited by internal diffusion, then diffusion accompanied b...

Cigarette filter tip filtered by activated alumina ball and coconut shell activated carbon

Abstract: The utility model provides a cigarette filter tip filtered by an activated alumina ball and coconut shell activated carbon. The cigarette filter tip comprises a hollow transparent plastic pipe (1), aceramic filter (2), a white activated alumina ball (3), high-quality coconut shell activated carbon (4), a spiral filter element (5), a gas guiding device (6) and a mouthpiece (7). The middle pore ofthe gas guiding device and the four pores on the lower end surface of the spiral filter element are combined to form four jet flow passages.Part of oily substance in the cigarette is firstly trapped on the inner wall of the transparent plastic pipe, and then the rest most part of oily substance is secondly trapped by the activated alumina ball and the high-quality coconut shell activated carbon with strong adsorption and purifying functions, thereby effectively filtering off nicotine, cigarette tar oil and other impurities. The ceramic filter (2) is formed by four uniform micro-pores. When fluid flows through the micro-pores, the suspended substances, the colloidal particles and the organic substances are trapped on the surface of the filtering medium. Various physical effects are generated when the fluid flows through the micro-pores to achieve the effects of mechanical screening purification or diffusion, fluidization and the like.

Corundum material prepared from waste activated alumina and preparation method thereof

Abstract: The invention provides a corundum material prepared from waste activated alumina and a preparation method thereof. The raw material for preparing the corundum material from the waste activated alumina consists of waste activated alumina; the preparation method is realized by taking the waste activated alumina as the raw material. The corundum material is not only beneficial to waste utilization and overcomes the serious pollution of the waste activated alumina to the environment, but also produces products with high added value and a pollution-free high-quality refractory material, saves the production cost and has obvious economic benefits and popularization and application values.

The Experiment Study of Nitrobenzene Polluted Groundwater by Catalytic Oxidation

Abstract: The catalytic ozonation which treated nitrobenzene in extracted groundwater with high concentration was studiedThe experiment showed that the optimization of catalysts was that the manganese nitrate and iron nitrate were dissolved to dip the activated alumina in 10 percent of mass concentration, the ratio of manganese to iron was 2:1, the calcination temperature was 450°C with six hours The catalyst was characterized by SEM-EDS too; Adsorption of catalyst, air stripping, increasing concentration, temperature and pH all had effect on this reaction system When pH was 9,temperature was 25 °C and catalyst dosage was 30g/L, the removal rate of nitrobenzene could reach 688%