Showing papers on "Activated alumina published in 2017"

Factors Governing the Performance of Bauxite for Fluoride Remediation of Groundwater.

Abstract: Globally, 200 million people drink groundwater contaminated with fluoride concentrations exceeding the World Health Organization's recommended level (WHO-MCL = 1.5 mg F-/L). This study investigates the use of minimally processed (dried/milled) bauxite ore as an inexpensive adsorbent for remediating fluoride-contaminated groundwater in resource-constrained areas. Adsorption experiments in synthetic groundwater using bauxites from Guinea, Ghana, U.S., and India as single-use batch dispersive media demonstrated that doses of ∼10-23 g/L could effectively remediate 10 mg F-/L. To elucidate factors governing fluoride removal, bauxites were characterized using X-ray fluorescence, X-ray diffraction, gas-sorption analysis, and adsorption isotherms/envelopes. All ores contained gibbsite, had comparable surface areas (∼14-17 m2/g), had similar intrinsic affinities and capacities for fluoride, and did not leach harmful ions into product water. Fluoride uptake on bauxite -primarily through ion-exchange- was strongly pH-dependent, with highest removal occurring at pH 5.0-6.0. Dissolution of CaCO3, present in trace amounts in India bauxite, significantly hindered fluoride removal by increasing solution pH. We also showed that fluoride remediation with the best-performing Guinea bauxite was ∼23-33 times less expensive than with activated alumina. Overall, our results suggest that bauxite could be an affordable fluoride-remediation adsorbent with the potential to improve access to drinking water for millions living in developing countries.

Adsorption of Arsenate by Nano Scaled Activated Carbon Modified by Iron and Manganese Oxides

Abstract: The presence of arsenic in water supplies is a major problem for public health and still concerns large parts of population in Southeast Asia, Latin America and Europe Removal of arsenic is usually accomplished either by coagulation with iron salts or by adsorption with iron oxides or activated alumina However, these materials, although very efficient for arsenic, normally do not remove other undesirable constituents from waters, such as chlorine and organo-chlorine compounds, which are the results of water chlorination Activated carbon has this affinity for organic compounds, but does not remove arsenic efficiently Therefore, in the present study, iron modified activated carbons are investigated as alternative sorbents for the removal of arsenic(V) from aqueous solutions In addition, modified activated carbons with magnetic properties can easily be separated from the solutions In the present study, a simple and efficient method was used for the preparation of magnetic Fe3(Mn2+)O4 (M:Fe and/or Mn) activated carbons Activated carbons were impregnated with magnetic precursor solutions and then calcinated at 400 °C The obtained carbons were characterized by X-ray diffraction (XRD), nitrogen adsorption isotherms, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier Transform Infrared Spectrometry (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements Their adsorption performance for As(V) was evaluated The iron impregnation presented an increase in As(V) maximum adsorption capacity (Qmax) from about 4 mg g−1 for the raw carbon to 1105 mg g−1, while Mn incorporation further increased the adsorption capacity at 1935 mg g−1

A Critical Review on Occurrence of Fluoride and Its Removal through Adsorption with an Emphasis on Natural Minerals

Abstract: Being the most reactive of all chemical elements and the lightest member of halogen group, fluorine is found in the environment as fluoride. Both natural and anthropogenic activities are responsible for fluoride contamination in groundwater. Fluoride has dual effect on human health. While lower concentration ( 1.5 mg/L) leads to skeletal fluorosis and even death. The present review paper is aimed at providing detailed occurrence of fluoride pollution around the globe and in India. Among the different defluoridation techniques to remove excess fluoride from contaminated drinking water at both community and domestic levels, adsorption is found to be very effective due to its technical feasibility, simple characteristics and comparative low-cost nature. Various adsorbents have been tested for their ability to treat fluoride contaminated water, viz., activated carbon, activated alumina, soil, clay and a variety of waste materials. Since fluoride pollution of drinking water is a major concern of poor people as they cannot afford to spend on purification of water, usage of low-cost natural mineral (natural mineral) as adsorbent for fluoride removal is one of the most essential issues in modern era. The present review bestows a detailed discussion on natural mineral as adsorbent used in defluoridation process with special emphasis on soil and low-cost clay minerals.

Aluminum hydroxide supported on zeolites for fluoride removal from drinking water

Abstract: BACKGROUND Problems of fluorosis are still affecting millions of people around the world including Ethiopia. Hence the need to find sustainable solutions is still worth investigating. In this study, commercial zeolite Y (ZY) and natural stilbite (STI) from Ethiopia are evaluated as support for aluminum hydroxide (AO) and studied for fluoride removal from aqueous solution. The composites (STI-AO) and (ZY-AO) are synthesized at different zeolite to AO ratios by modifying the procedure used for synthesizing AO, reported earlier. RESULTS The X-ray diffraction profiles show that zeolite structures are stable during modification processes. The Si/Al ratio of composites decreases as the amount of AO is increased due to increase in Al content. The PZC of STI, initially at 2.5, increased to 9.2 in STI-AO. Textural properties of ZY and ZY-AO proved to block certain microporosity by the AO. Optimum conditions to reduce an initial fluoride concentration of 10 mg L−1 to below the WHO guideline value of 1.5 mg L−1 were 2 g L−1 for the 2:1 systems and 4 g L−1 for the 6:1 systems. CONCLUSION Zeolite-AO composites have very good equilibrium fluoride adsorption capacity compared with most reported materials. Hence these materials can be considered alternative adsorbents for the removal of fluoride from drinking water. © 2016 Society of Chemical Industry

Alpha, Beta and Gamma Alumina as a catalyst -A Review

Abstract: Alpha (α), Beta (β) and gamma (ƴ) are the different phases of Alumina. The α- Alumina is also known as Nano alumina and is white puffy powder. The specific surface area is low, resistant to high temperature and inert, but it does not belong to activated alumina, and it has almost no catalytic activity. β- Alumina is hexagonal, with lamellar structure and the unit cell contains two alumina spinel based block. ƴ -Alumina is nano alumina and has high purity and excellent dispersion and high specific surface, with resistance to high temperature and inert, high activity. Porous, hence it is a kind of activated alumina and used as catalyst support and adsorbent. Aim is to use ƴ-alumina catalyst for Alkylation of phenol for Meta cresol selectivity. Literature survey indicates that its use has been studied for selectivity and yield of o cresol, 2,6 xylenol but not for meta selectivity for the reaction-Alkylation of phenol. Challenge is to develop Gamma Alumina/Modified Gamma alumina catalyst for the study of selectivity of Meta cresol in Alkylation of phenol.

Studies on the efficiency of grundwater treatment process with adsorption on activated alumina

Abstract: One of inorganic sorbents used in water treatment technology is activated alumina. It is recommended by the European Commission to remove inorganic impurities, such as arsenic, fluoride, selenium and silicates. The adsorbent is usually applied in a granular form, under flow conditions. It can become absorbent material, increasingly used due to the presence of arsenic beside iron and manganese in groundwater intakes. The aim of the study was to evaluate the effectiveness of groundwater treatment in the technological system containing adsorption on activated alumina. The experiment was performed on test model CE 581 manufactured by G.U.N.T. Hamburg, in which four treatment stages can be extracted. The first stage is used in a gravel filter of grain size 1–2 mm, in the second sand filter of grain size 0.4–0.8 mm. The third and fourth phase includes two adsorbers. The first adsorber comprises activated alumina (Al2O3) and the other comprises a granular activated carbon. The study was conducted at different speeds of filtration: 5, 10 and 15 m/h. In the raw water samples and the purified water samples after each treatment step the following parameters were determined: pH, O2 concentration, electrolytic conductivity, SO4 2-, concentration, NO3 concentration, PO4 3concentration, Clconcentration, color, turbidity, iron and manganese concentration, CODMn, total hardness, calcium hardness, magnesium hardness, content of dissolved substances. The conducted research indicates that optimum filtration rate for most pollution is 15 m/h. Moreover, the presence of activated alumina has contributed to increasing the efficiency of nitrate (V) and phosphate (V) ions removal.

Controllable growth of Na2CO3 fibers for mesoporous activated alumina ball modification towards the high-efficiency adsorption of HCl gas at low temperature

Abstract: To fundamentally solve the problem of chlorine corrosion in blast furnace gas (BFG) systems, a supported adsorbent is used for HCl removal at low temperature. In this paper, three alkaline substances, Ca(OH)2, NaOH, and Na2CO3, were separately coated on the surface of activated alumina balls (AABs) by wetness impregnation method, using the as-active components. These materials were measured by XRF, XRD, SEM, TEM, and N2 adsorption to characterize textural properties. The modification experiments indicated that Na2CO3 fibers can be obtained on the surface of AABs by adjusting the loading amounts, impregnation time, and drying conditions. The fibers' structure contributes to the gas phase diffusion in the product layer, greatly improving the conversion of Na2CO3 (>0.98). The highest value of HCl adsorption capacity reaches 3.56 mmol g−1 when the Na2CO3 loading amount is 20 wt%, five times the adsorption capacity of pure AABs. The kinetics of HCl removal by the Na2CO3 fiber-modified AABs is controlled by the interfacial chemical reaction.

The Forms of Fluoride in Antarctic Krill (Euphausia superba) Oil Extracted with Hexane and its Removal with Different Absorbents

Abstract: Krill oils (KOs) were prepared using different extraction methods (hexane and supercritical carbon dioxide), different materials (heat-dried krill powder, freeze-dried krill powder, and freeze-dried krill tail meat powder), and different standing times during hexane extraction. The fluoride concentrations in the KOs were positively correlated with the protein concentrations. Absorbents were employed to remove fluoride from KO. Activated clay achieved the highest fluoride removal rate (70.66%), followed by calcium oxide (14.49%), activated carbon (11.97%), calcium chloride (9.32%), activated alumina (0.94%), and chitosan (0.52%). Meanwhile, the protein removal rates of the above absorbents were positively correlated with the fluoride removal rates.

Preparation method of high-performance activated alumina ball

Abstract: The invention discloses a preparation method of a high-performance activated alumina ball The preparation method comprises the following steps: uniformly mixing 70 to 95 parts by weight of rho-alumina and 5 to 30 parts by weight of pseudo boehmite, and then putting a mixture in a balling pan for balling; spraying a bonding agent in a balling process, wherein the bonding agent is a desalting aqueous solution of organic acid/inorganic acid The rho-alumina is used as a main production raw material, and the use amount of the rho-alumina is 75 percent or above, so that the mechanical strength of the activated alumina ball is guaranteed, and the cost of the product is reduced; the high-quality pseudo boehmite is added in the rho-alumina, so that the specific surface area and the pore volume of the activated alumina ball are effectively improved; the inorganic acid and the organic acid are added in the bonding agent, so that the surface of the pseudo boehmite and an acid solution react to generate alumina sol with the viscosity, the bonding of the pseudo boehmite and the rho-alumina is guaranteed, and the wear of an activated alumina ball product is reduced

Effect of MnCl 2 deposition content on the textural properties of activated alumina and its elution performance for hydrogen isotopes

Abstract: By a solution impregnation method, three modified stationary phases were prepared by contacting activated alumina with MnCl2 at different MnCl2:Al2O3 molar ratios = 1:10, 1:5, 1:2.5, respectively. N2 sorption isotherms at 78 K were examined for the unmodified and modified samples, from which pore size distributions (PSD) of textural properties were derived with density function theory. Elution chromatographic tests of hydrogen isotopes were carried out at 78 K. The results indicated that both the microporous specific surface area (SSA) and the mesoporous SSA decline after modification, while the microporous SSA remains nearly unvaried among the modified ones. The chromatographic retention times as well as the bandwidths decline as the Mn content rises. The resolution of chromatographic peaks increases after modification, it remains unvaried and then decreases as the Mn content increases. The PSD of alumina SSA changed by the modification significantly influences the hydrogen isotopic elution chromatography.

Preparation method of alumina foamed ceramic with high specific surface area and strength

Abstract: The invention discloses a preparation method of alumina foamed ceramic with high specific surface area and strength. The preparation method comprises the following steps: (S1) weighing 30-50 parts of activated alumina powder, 3-8 parts of pseudo-boehmite, 37-65 parts of deionized water and 2-5 parts of inorganic acid in parts by weight; (S2) adding the pseudo-boehmite into the deionized water, stirring, and adding a proper amount of the inorganic acid, so as to obtain first pseudo-boehmite sol; (S3) weighing 5-20 parts of activated alumina powder, 2-4 parts of pseudo-boehmite, 73-92 parts of deionized water and 1-3 parts of inorganic acid in parts by weight; and (S4) adding the pseudo-boehmite into the deionized water, stirring, and adding a proper amount of the inorganic acid, so as to obtain second pseudo-boehmite sol. The preparation method has the characteristics that the firing temperature is low, the breaking strength is high, the volume density is low, the specific surface area is large, the activity of the foamed ceramic is high, and the like; and furthermore, the preparation process is simple, the cost is low, and the preparation method is suitable for large-scale promotion.

Improvement of User Friendliness of a Simple Domestic Defluoridation Unit Using Activated Alumina

Abstract: The user friendliness of an Activated Alumina (AA) based fluoride filter using a ceramic cartridge, and locally available food grade containers has been improved by using two ceramic cartridges. The ceramic cartridge serve the dual purposes of filtering out any suspended particles and providing enough contact time for the AA to absorb the fluoride from water. The fluoride filter has a flow rate of 3 lit./hr a marked improvement from 1.7 lit./hr. achieved with one ceramic cartridge. These filters have been tested in laboratory using fluoride contaminated ground water from a nearby village. The filter yielded a safe volume of 1300 lit. water (<1.5 ppm fluoride in outlet water) with a Specific Safe Water Yield of 520 mg/kg of AA and Fluoride Uptake Capacity of 863.2 mg/kg AA. The cost of the defluoridated water for the first cycle is Rs. 0.87/lit. which includes the cost of the filter and the AA. The recurring cost of operating the filter, if the AA is to be discarded after single use, is quite low at Rs. 0.22/lit. With a water usage of 20 litres per day for a family of four, no maintenance is required in form of regeneration of the AA bed before two months five days with an inlet fluoride conc. of 2.41 ppm. and Simplicity of design and easy fabrication makes this fluoride filter suitable for replication. Keywords: Activated Alumina, defluoridation, fluoride, filter

Application of modified activated alumina in wastewater defluorination

Abstract: The Invention introduces application of modified activated alumina in wastewater defluoreination. The gamma-type alumina has a grain size of 1-2mm. The activated alumina is applied according to the following steps: adding 0.2-0.4mol/L of NaOH solution the weight of which is 5-20 times that of alumina, and modifying for 1-2 hours; filtering to separate and wash solid and liquid; adding a H2SO4 solution the weight of which is 5-20 times that of alumina and has a concentration range of 0.15-0.5 mol/L, and modifying for 0.5-2 hours; separating solid and liquid, and washing; drying at a temperature not higher than 200 DEG C; roasting for 1.5-2.5 hours at 500+/-30 DEG C; adding modified alumina into fluorine-containing wastewater, reacting at 30+/-25 DEG C. The modified activated alumina has fluorine ion adsorbing efficiency being about 4 times that before modification, has high adsorption capacity and high adsorption speed, is simple and feasible to operate, and is suitable for industrial production.

Arsenic and Fluoride Removal by Iron Oxide and Iron Oxide/Alumina Nanocomposites: A Comparison

Abstract: The study provides a comparative analysis of As (III), As (V) and F removal by iron oxide nanoparticles and iron oxide/alumina nanocomposites. The nanoparticles were characterized by particle size, zeta potential and Scanning Electron Microscopic analysis which showed spherical iron oxide nanoparticles around ~200 nm and nanocomposites around ~300 nm. Batch sorption studies carried out at varying initial concentrations of As and F revealed an enhanced F and As sorption capacity for the nanocomposites. The sorption isotherm showed that the data for As (III), As (V) and F fitted best to Freundlich isotherm for both the type of nanoparticles. The maximum sorption capacity of the iron oxide nanoparticles for As (III) and As (V) at pH 7 were 909 μg/g and 3333 μg/g while the comparative qm values for the nanocomposites were 1000 μg/g and 2500 μg/g respectively. The maximum F sorption capacity of iron oxide nanoparticles was 1.47 mg/g while it was 4.82 mg/g for the nanocomposites. The preliminary results of the study showed that the nanocomposites can be promising adsorbents for both As and F removal in small scale water systems.

Chloropentafluorobenzene preparation method

Abstract: The invention relates to a chloropentafluorobenzene preparation method, and belongs to the field of chemical production processes. According to the chloropentafluorobenzene preparation method, mixed gas obtained by mixing chlorine with reaction gas contacts with a catalyst to perform chlorination reaction, and pentafluorobenzene and ethyl alcohol are mixed and then gasified to obtain the reaction gas. The catalyst is prepared by a method including the steps: dissolving anhydrous ferric chloride and auxiliaries in absolute ethyl alcohol to obtain solution; adding coconut shell activated carbon or activated alumina particles into the solution, soaking the coconut shell activated carbon or activated alumina particles, and drying solvents by distillation to obtain the catalyst. The auxiliaries are one or more of manganese chloride, copper chloride and zinc chloride. Compared with the prior art, the chloropentafluorobenzene preparation method has the remarkable advantages that yield is high, solvents are omitted, reaction is continuous, no solid waste and liquid waste are generated, and the method is greener and more environment-friendly as compared with other methods.

Characterization of Activated Alumina Production via Spray Pyrolysis

Abstract: A novel method was developed to prepare activated alumina via spray pyrolysis of aluminum chloride solution. In this paper, activated alumina was obtained by spray pyrolysis in tube furnace with aluminum chloride solution as raw materials in different temperatures. X-ray diffraction (XRD), scanning electron microscope(SEM) and the specific surface area analysis were used to characterize the spray pyrolysis products, respectively. XRD results showed that the crystal phase composition of activated alumina can be controlled through adjusting pyrolysis temperature. The crystal structure of γ-Al2O3 in the products conformed to the requirements of the index of activated alumina. Most of pyrolysis products were porous structure which the particle size was around 5 μm under scanning electron microscope. With the activated alumina were examined by specific surface area analysis, the products existed as inkbottle-shaped and parallel-plate pores. Pyrolysis products more conformed to the requirements of activated alumina after examined by XRD, SEM, and the specific surface area.

Equilibrium and Kinetic Mechanisms of Fluoride Ions Adsorption Onto Activated Alumina

Abstract: Equilibrium and Kinetic Mechanisms of Fluoride Ions Adsorption onto Activated Alumina Pricila Marin, Silvia P. D. Monte‐Blanco, Aparecido N. Módenes, Rosângela Bergamasco, Natália U. Yamaguchi, Priscila F. Coldebella, Rosa M. Ribeiro, Paulo R. Paraiso State University of Maringá. Brazil. Av. Colombo, 5.790 – Jd. Universitário, CEP 87020-900 Maringá, PR, Brazil. West Parana State University. Rua da Faculdade, 645 Jd. Santa Maria, CEP 85903-000 Toledo, PR, Brazil. UniCesumar University Center of Maringá. Av. Guedner, 1610 – Jd. Aclimação, CEP: 87050-900 Maringá, PR, Brazil. natalia.yamaguchi@unicesumar.edu.br

Preparation process for loaded catalyst used for concentrated RO water

Abstract: The invention discloses a preparation process for a loaded catalyst used for concentrated RO water. The loaded catalyst is composed of the following components in parts by weight: 88.7 to 91.3 parts of activated alumina particles with particle sizes of 2 to 4 mm, 1.2 to 1.5 parts of copper oxide, 4 to 7 parts of polyethylene glycol, 1.5 to 2 parts of polyvinyl alcohol, 0.8 to 1 part of titanium dioxide, 0.3 to 0.5 part of hydroxypropyl cellulose and 0.2 to 0.4 part of manganese dioxide. The preparation process comprises the following steps: mixing 88.7 to 91.3 parts of the activated alumina particles with the particle sizes of 2 to 4 mm with 1.4 to 1.6 parts of copper oxide, 0.8 to 1.2 parts of titanium dioxide, 4 to 7 parts of polyethylene glycol and 1.9 to 2.1 parts of polyvinyl alcohol in a stirring mixer, and subjecting the uniformly-mixed 1.4 to 1.6 parts of copper oxide, 0.8 to 1.2 parts of titanium dioxide, 4 to 7 parts of polyethylene glycol and 1.9 to 2.1 parts of polyvinyl alcohol to covering on the surface of the activated alumina particles. The loaded catalyst prepared by using the process provided by the invention has strong resistance to salt substances, can be normally used in wastewater with TDS no more than 8000 mg/L, and has the advantages of high catalyst activity, low cost and simple preparation method.

High-salt-tolerant ozone catalyst and preparation method thereof

Abstract: The invention discloses a high-salt-tolerant ozone catalyst. The high-salt-tolerant ozone catalyst comprises the following components in parts by weight: 88.7 to 91.3 parts of activated alumina particles with particle sizes of 2 to 4 mm, 1.4 to 1.6 parts of copper oxide, 0.8 to 1.2 parts of titanium dioxide, 4 to 7 parts of polyethylene glycol and 1.9 to 2.1 parts of polyvinyl alcohol. The high-salt-tolerant ozone catalyst is prepared through the following steps: mixing 88.7 to 91.3 parts of the activated alumina particles with the particle sizes of 2 to 4 mm with 1.4 to 1.6 parts of copper oxide, 0.8 to 1.2 parts of titanium dioxide, 4 to 7 parts of polyethylene glycol and 1.9 to 2.1 parts of polyvinyl alcohol in a stirring mixer, and subjecting the uniformly-mixed 1.4 to 1.6 parts of copper oxide, 0.8 to 1.2 parts of titanium dioxide, 4 to 7 parts of polyethylene glycol and 1.9 to 2.1 parts of polyvinyl alcohol to covering on the surface of the activated alumina particles so as to form catalyst parent spheres; and successively subjecting the catalyst parent spheres to drying and calcination so as to obtain the high-salt-tolerant ozone catalyst. The high-salt-tolerant ozone catalyst provided by the invention improves tolerance to high-salt substances, and maintains good effects on removal, decolorization, deodorization, toxic pollutant degradation of wastewater COD and on improvement of wastewater biodegradability.

Advanced treatment device used for up-to-standard discharge of high-salt sewage in petrochemical industry

Abstract: The invention discloses an advanced treatment device used for up-to-standard discharge of high-salt sewage in the petrochemical industry. The advanced treatment device comprises a catalytic oxidation pool, an oxidation stabilizing pool, a post-biochemical BAF pool, a clear water pool, a water collecting pool and a filter, wherein the catalytic oxidation pool, the oxidation stabilizing pool, the post-biochemical BAF pool and the clear water pool are successively connected through transmission pipelines; the catalytic oxidation pool is filled with ozone catalytic particles in a form of a fixed bed; the ozone catalytic particles are composed of the following components in parts by weight: activated alumina particles, copper oxide, titanium dioxide, polyethylene glycol and polyvinyl alcohol; and the ozone catalytic particles are prepared through the following steps: mixing the activated alumina particles with 1.4 to 1.6 parts of copper oxide, titanium dioxide, polyethylene glycol and polyvinyl alcohol in a stirring mixer, and subjecting the uniformly-mixed copper oxide, titanium dioxide, polyethylene glycol and polyvinyl alcohol to covering on the surfaces of the activated alumina particles so as to obtain catalyst parent spheres; and successively subjecting the catalyst parent spheres to drying and calcination so as to obtain a high-salt-resistant ozone catalyst. The advanced treatment device provided by the invention has the advantages of low operation cost, simple operation and stable operation, achieves the purpose of highly-efficient degradation of organic pollutants, and can realize advanced treatment and up-to-standard discharge of the high-salt sewage with low cost in the petrochemical industry.