Showing papers on "Activated alumina published in 2018"

Enhanced fluoride removal by La-doped Li/Al layered double hydroxides.

Abstract: In this study La intercalated Li/Al layered double hydroxide (LDH) was developed for efficient water defluoridation. The La-modified material, i.e., La doped Li/Al-LDH, exhibits more preferable fluoride adsorption than Li/Al-LDH in a broad pH range of 5–9, with the working capacity twice of the latter and seven times of magnitude higher than activated alumina. The fluoride removal kinetics is well fitted by pseudo-second order model, and the adsorption isotherm is well described by Freundlich model. Effect of pH and competing ions was examined during fluoride sequestration. The underlying mechanism for such enhanced adsorption of fluoride by La doped Li/Al-LDH was further revealed based on XPS and FTIR analysis. The presence of La and Al was found to be responsible for the satisfactory defluoridation of La doped Li/Al-LDH, and chloride replacement with fluoride occurred from both LDHs during fluoride adsorption. Also, the capacity of La doped Li/Al-LDH could be refreshed by alkaline solution (pH = 12) for cyclic runs. All the results implied that La doped Li/Al-LDH could serve as a potential adsorbent for efficient fluoride removal from water.

Adsorption of urea onto granular activated alumina: A comparative study with granular activated carbon

Abstract: This study investigated the ability of granular activated alumina to remove urea from wastewater through adsorption, and compared its performance with granular activated carbon. XRF, EDX, XRD, and ...

Insight into Optimization, isotherm, kinetics, and thermodynamics of fluoride adsorption onto activated alumina

Abstract: Investigation of essential technique to diminish the exceeded limit of fluoride in groundwater is the need of the hour due to severe adverse effects of fluoride on human health. The present study highlights the prospective of activated alumina, a defluoridating agent for the elimination of excess fluoride (F−) concentration from aqueous solution by using batch adsorption techniques. The adsorptive removal of fluoride was optimized by means of response surface methodology (RSM) considering the parameters in the range of pH (6-8), contact time (60-120 min), alumina dose (1-2 g), agitation speed (200-300 RPM), and temperature (25-45°C). The sorbent was instrumentally characterized to study the surface morphology and chemical composition by SEM (Scanning Electron Microscopy), EDX (X-ray Energy dispersive analysis) and XRD (X-ray Diffractometry). The optimized condition for the defluoridation procedure was obtained as pH 6, contact time 120 min, alumina dose 2 g, temperature 45°C, and agitation speed of 200 RPM gives 86.1% of fluoride removal. The equilibrium adsorption performances were studied and the data were fitted with both the Freundlich and Langmuir isotherms and showed Freundlich model was fitted well which signifies multilayer adsorption. The defluoridation method followed pseudo-second-order kinetics. Gibbs free energy showed that the process is feasible at all three operating temperatures. The statistical parameters proved the significance and applicability of the model for optimization of the defluoridation process using activated alumina as an adsorbent. Hence, alumina could be an eminent adsorbent for the defluoridation of wastewater. © 2017 American Institute of Chemical Engineers Environ Prog, 2017

Activated Alumina Granules with nanoscale porosity for water defluoridation

Abstract: Highly porous alumina granules have been processed by virtue of modified sol–gel method. Activated alumina (AA) granules were obtained through hydrolysis of aluminum nitrate controlled by ammonia in aqueous media and granules were formed in ammonia–paraffin oil bath. The prepared granules were found to be consisting of high porosity amorphous γ - alumina particles which were characterized by XRD, SEM, TEM, FT-IR and Brunauer–Emmett–Teller (BET) techniques. The material prepared via this method were found to be composed of nano-particles with an average grain size of 30 nm and a large BET surface area 447 m2/g which is very high compared with commercial alumina available in the market. The fluoride removal capacity of prepared granules with variation of fluoride dose has also been studied by employing AA in domestic candle type filters. It also shows better regeneration and reusability after ten cycles of usage. Fluoride removal from aqueous solution in continuous mode depends on adsorbent doses and initial concentration of fluoride.

Arsenic(V) Removal Using Activated Alumina: Kinetics and Modeling by Response Surface

Abstract: Arsenic(V) removal using activated alumina (AA) was carried out in batch mode and was modeled using response surface method. The Doehlert design of experiment (DOE) was used to model the ex...

Defluoridation of reject water from a reverse osmosis unit and synthetic water using adsorption

Abstract: Many parts of the world have excess fluoride in drinking water. At some locations, nitrate is also in excess. Hence, reverse osmosis (RO) units have been installed at several villages in India. Reverse osmosis is a good technique, but it has the disadvantage of discarding a considerable amount of the inlet water as a reject stream. This is an unsustainable way of using water. Two adsorbents, namely, a hybrid anion exchange resin embedded with zirconium oxide nanoparticles (HAIX-Zr), and activated alumina (AA) were used in column experiments. For water containing only F − , HAIX-Zr had a better capacity than AA. The same trend was observed with synthetic water samples containing other ions in addition to F - . However, for RO reject, the converse was true, and the capacities of AA and HAIX-Zr decreased significantly. For AA, the presence of a small concentration of HCO 3 − increased the uptake of F - by 100% compared to water containing only F - . For HAIX-Zr, the adsorption capacity decreased as the concentration of co-ions increased. The cost of treated water varied from 0.1–1.5/L (US $ 0.002–0.03/L) for AA and 0.2–11.5/L (US $ 0.004–0.23/L) for HAIX-Zr.

The Use of Activated Alumina and Magnetic Field for the Removal Heavy Metals from Water

Abstract: The objective of this work was to verify the granular activated alumina (AA) sorption properties, during the process of removing copper, lead and cadmium from water, and to monitor the impact of magnetic field (MF) on the effectiveness of removing copper, lead and cadmium from water. Activated alumina adsorption is known to be an effective and inexpensive technology for the removal of selenium and arsenic from water, and was suggested by EPA as a BAT for point-of-use applications. The removal of copper, lead and cadmium from water using AA and impact of magnetic field was reported to a lesser extent. Pilot tests showed that the use of AA sorption materials with MF impact could possibly decrease the copper, lead and cadmium content in the model water. The MF also had a positive effect on the efficiency of removal copper, lead and cadmium on AA. Increasing the efficiency of heavy metals removal in the samples exposed to magnetic field varied from 1.9% to 8.2% compared to the control samples.

Removal of fluoride from wastewater using HCl-treated activated alumina in a ribbed hydrocyclone separator.

Abstract: Excessive fluoride concentration in wastewater is a major health concern worldwide. The main objective of wastewater treatment is to allow industrial effluents to be disposed of without dan...

Removal of heavy metal ions by filtration on activated alumina-assisted magnetic field

Abstract: Magnetic field (MF), among others, influences more intense decomposition of many compounds, increases adsorption on the surface of the phase separation, as well as accelerates oxidation and reduction reactions. Therefore, they are used in the research as an aid for filtration process, which is one of the most popular stopping and separating processes for different components in different reservoirs. Beds usually function as an adsorbent, thus both filtration and adsorption processes are often. One of the inorganic sorbents that is used to remove metals and anions present in water is Al2O3. As part of this work, we investigated the use of a constant external MF as an elementary additional process to improve the filtration efficiency on activated alumina. The purpose of the study was to compare the effectiveness of the removal of elements (Fe, Mn, Cd, Cr, Cu, Pb, Zn, and Ni) from model aqueous solutions during the process of filtration assisted and not assisted by an MF on activated alumina. In addition, the purpose of the work was also to determine the influence of MF on the removal of these elements, as well as their affinity to physical properties of the adsorbate under the influence of MF. As a result of the experiment, it was proved that the MF support of the filtration on activated alumina for the removal of selected elements is more effective than the filtration without MF. Studies have shown that removal of individual metals occurs according to the following series of affinity toward alumina in magnetized samples: Pb > Mn > Ni > Zn > Cu > Fe > Cd > Cr.

Removal of Phosphorus from Leach Liquor of Steel Slag: Adsorption Dephosphorization with Activated Alumina

Abstract: Leaching dephosphorization is an effective way to remove the harmful element phosphorus from steel slags. In order to recycle the leach liquor, static phosphate adsorption with activated aluminum oxides was investigated in this work. It was demonstrated that, for an initial phosphorus concentration of 25.95 mg/L, a phosphorus removal rate of 88% and an adsorption capacity of 0.72 mg/g can be reached under the optimal conditions of adsorption time of 34 h, adsorbent dose of 40 g/L, pH of 6.3, and adsorbent particle size of 1.18–2 mm. The Freundlich model and pseudo-second-order-kinetic model can describe the adsorption process well. It was shown that adsorption of phosphorus on the surface of activated alumina particles was a multi-molecular-layer process whose kinetics was controlled by the adsorption reaction.

Removal of fluoride from wastewater using HCl-treated activated alumina in a ribbed hydrocyclone separator Part A Toxic/hazardous substances & environmental engineering

Abstract: Excessive fluoride concentration in wastewater is a major health concern worldwide. The main objective of wastewater treatment is to allow industrial effluents to be disposed of without danger to the human health and the natural environment. In this current study, experiments have been conducted to remove fluoride from aqueous solution using alumina and HCl (Hydrochloric acid) treated activated alumina in a continuous mode. A spiral rib was introduced in the cylindrical part of the conventional hydrocyclone to increase the performance, and the new hydrocyclone is dubbed as ribbed hydrocyclone. Experiments were carried out to analyze the performance of the ribbed hydrocyclone and compared the results with the conventional hydrocyclone of the same dimension. The efficiency of conventional and ribbed hydrocyclone at a slurry flow rate of 50 LPM (liter per minute) for the solid concentration of 1.4 wt% were 80% and 93.5% respectively. The cut size d₅₀ of the conventional and ribbed hydrocyclone was 18 µm and 13 µm respectively at a slurry velocity of 50 LPM. Fluoride removal efficiency using alumina and HCl-treated alumina was also investigated in a continuous mode by the ribbed hydrocyclone. Maximum fluoride removal efficiency was 49.5%, and 80% for alumina and HCl-treated alumina for the initial concentration of 10 mg/L at a slurry flow rate of 50 LPM.

Studies on performance characteristics of calcium and magnesium amended alumina for defluoridation of drinking water.

Abstract: Two variants of amended activated alumina named CMAA 650 and CMAA 850 were prepared using activated alumina (AA) granules. AA was successfully coated with calcium and magnesium in the form of calcium magnesium aluminum oxide (Ca0.965Mg2Al16O27), calcium aluminum oxide (Ca9(Al6O18)) and magnesium aluminum oxide (MgAl2O4). CMAA 850 had a highly crystalline porous leaf like structure and higher adsorption capacity than CMAA 650, with surface distribution of Ca & Mg at 30.96 and 3.29 wt% respectively. AA, CMAA 650 and CMAA 850 followed Langmuir and Temkin adsorption isotherms with maximum defluoridation capacity of 2.48, 2.61, and 2.74 mg/g respectively for treating a 10 mg/L of fluoride solution at neutral pH. CMAA 650 had a homogenous surface and CMAA 850 had a heterogeneous surface while both followed second order rate kinetics implying chemisorption. Fluoride adsorption equilibrium was attained in 120 min–180 min for all three adsorbents. Regeneration of CMAA 650 and CMAA 850 was carried out effectively by ultrasonication for 2 min using 1.5 M sodium hydroxide and after the second adsorption cycle, adsorption capacity dropped by 12.41% and 12.15% respectively. The adsorption capacity of CMAA 850 was unaffected in presence of other co-existing ions except that it got reduced by 21.4% in the presence of nitrate ions. No residual aluminum was detected in treated water samples of both CMAA 650 and CMAA 850. However, CMAA 850 was found to be more favorable with a higher capacity over a wider pH range of 4–9 for defluoridation of water.

Preparation and characterization and application of activated alumina (AA) from alum sludge for the adsorption of fluoride from aqueous solutions: new approach to alum sludge recycling

Abstract: Activated Alumina (AA) prepared from Alum Sludge (AS) was used in removal of fluoride from aqueous solutions. The capacity of AA in the adsorption of fluoride from water was found to be 17.75 mg/g. The maximum efficiency of fluoride adsorption was 96% at the optimum condition ( C = 5 mg/L, pH = 7, t = 20 min and adsorbent dosage = 5 g/L). Based on the results, it can be concluded that conversion of AS to AA can be a method for recycling of AS. Also AA can be used for adsorption of fluoride from aqueous solutions. So AS as a substance harmful to the environment turns into AA as a usable material in water treatment.

Factorial experimental design applied to adsorption of cadmium on activated alumina

Abstract: The effective removal of heavy metals from industrial wastewater is a very important issues for many countries. This paper examines the removal of cadmium ions from aqueous solutions and industrial effluents by adsorption on activated alumina. The Brunauer–Emmett–Teller (BET) specific surface area, pore diameter and pore volume of the activated alumina were 156.7 m 2 /g, 58.4 A and 0.23 cm 3 /g, respectively. Factorial experimental design was applied to evaluate the main effects and interactions among dose of activated alumina, initial cadmium concentration, pH of the solution and temperature. Analysis of variance, the F-test and the Student9s t -test shows that dose of activated alumina, initial cadmium ion concentration and temperature are the most significant parameters affecting cadmium ion removal and pH is the least significant parameter. Under optimal conditions, cadmium removal from industrial effluent samples was >98%. Furthermore, desorption and regeneration studies were carried out in order to evaluate the cost-effectiveness of activated alumina.

Activated alumina preparation and characterization: The review on recent advancement

Abstract: Aluminum and aluminum based material are significant industrial materials synthesis because of their abandonment, low weight and high-quality corrosion resistance. The most advances in aluminum processing are the ability to synthesize it’s under suitable chemical composition and conditions, a porous structure can be formed on the surface. Activated alumina particles (AAP) synthesized by the electrochemically process from aluminum have gained serious attention, inexpensive material that can be employed for water filtration due to its active surface. Thus, the paper present a review study based on recent progress and advances in synthesizing activated alumina, various techniques currently being used in preparing activated alumina and its characteristics are studied and summarized

A new green process to produce activated alumina by spray pyrolysis

Abstract: Abstract A green process that uses the spray pyrolysis method to prepare activated alumina is proposed in this research. The effects of spray temperature, carrier gas pressure, and AlCl3 solution concentration are experimentally investigated using pure reagents. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and specific surface area (BET) analyses. The results indicate that the spray temperature is the most important factor on the conversion ratio of alumina during the spray pyrolysis process. The conversion ratio of alumina achieved over 99% at the following optimal conditions: temperature of 1000°C, pressure of 0.3 MPa, and AlCl3 solution concentration of 10 wt%. The activated alumina with 8–20 nm particle size (γ-Al2O3+α-Al2O3) was prepared using the same process, which well met the requirement of the catalyst carrier. The green utilization of high-alumina fly ash and acid recycling can be achieved by using this process.

Removal of cadmium Cd(ii) and silver Ag(i) from aqueous solutions by nano activated alumina. part i: batch adsorption experiments

Abstract: The extent of removal of heavy metal ions cadmium Cd(II) and silver Ag(I) in single and binary system by adsorption on alumina has been investigated. Adsorption experiments were performed in batch technique from synthetic solutions using high purity nano activated alumina prepared in laboratory as adsorbent for heavy metals remove. Several experimental parameters that affect the extent of adsorption of the metal ions of interest have been investigated such as adsorbent dosage, concentration of the adsorbate, contact time, agitation speed and pH of the system under study. The equilibrium nature of the adsorption of the metal ions at different concentrations has been followed by Freundlich and Langmuir adsorption isotherms. Correlation coefficients (RR2) derived from these plots are (0.965) for cadmium Cd(II) and (0.966) for silver Ag(I). This work proposes a cost-effective method for the efficient removal of Cd(II) and Ag(I) from aqueous solutions. The conditions required for effective removal have been optimized.

Steam pre-reforming of natural gas over nanostructured Ni/12CaO–7Al 2 O 3 catalyst for hydrogen production: effect of support preparation method

Abstract: Calcium aluminate (12CaO–7Al2O3) powder was synthesized using three methods, viz. Pechini, coprecipitation, and a new novel facile decomposition route starting from activated alumina and calcium nitrate precursors, then used as a support to prepare a series of 31 wt%Ni/12CaO–7Al2O3 catalysts by deposition–precipitation method. The resultant catalysts were tested in steam pre-reforming of natural gas at 400–550 °C, low steam-to-carbon (S/C) molar ratio of 1.5, and atmospheric pressure. The obtained samples were characterized by Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), hydrogen chemisorption, and CO2–temperature-programmed desorption (TPD). Experimental results showed that the basicity and morphology of the supports depended significantly on the synthesis method. Calcium aluminate synthesized using the new decomposition procedure showed surface area of 6.23 m2 g−1, while the surface area of those prepared by the Pechini and coprecipitation method were 1.38 and 3.76 m2 g−1, respectively. The catalytic properties of the 31 wt%Ni/12CaO–7Al2O3 catalysts were strongly influenced by the support preparation approach. The highest specific surface area (about 230 m2 g−1), smallest Ni particle size (8.86 nm), and highest nickel dispersion (7.48%) were observed for the catalyst whose support was synthesized by the decomposition method. Even at high gas hourly space velocity (GHSV) of 2 × 105 mL $${\text{g}}^{ - 1}_{\text{catalyst}}$$ h−1, this catalyst exhibited around 100% C2H6 and C3H8 conversion at temperature above 500 °C. High catalytic stability during 60 h time on-stream was also shown. The TPO profiles of the spent catalyst demonstrated high resistance to carbon formation.

Métodos de remoção de íons fluoreto em água

Abstract: In view of growing evidence of natural and anthropic contamination by fluoride ion (F-) in several aquifers used for water supply, this paper analyzes the main types of available traditional and alternative treatments for its removal. The most applied method relies upon adsorption, mainly using activated alumina. However, new materials to replace the alumina have been studied in order to cheapen costs and increase the efficiency of treatment. Alternative materials that have been highlighted lately are the biochars – produced by calcination from many different types of biomass – and natural and synthesized nanoparticles. In addition to adsorption, there are other methods such as chemical and electrochemical treatments, use of membranes, and phytoremediation. However, the choice of the best method will depend upon the characteristics of each technique as well as of the water to be treated. In making a choice, it is necessary to take into account not only the cost and efficiency of the process, but also the waste generated by the treatment – such as the adsorbent material, slurries and liquid effluents concentrated with F- - and its proper disposed.

Comparative Studies of Fluoride Removal from Groundwater by Calcium Carbonate, Activated Alumina and Activated Punica granatum Ash

Abstract: Fluoride contamination of groundwater is a serious problem of the whole world as ingestion of excess fluoride through contaminated groundwater causes fluorosis. High level of fluoride intake through drinking water causes dental caries, skeletal fluorosis and decreases growth and intelligence [1]. It is estimated that about 80 % of diseases in the world are attributed to poor quality of drinking water and fluoride contamination in drinking water is responsible for 65 % cases of endemic fluorosis [2]. The permissible level of fluoride in drinking water for general good health set by WHO is considered to be 1.5 mg/L [3]. It has been reported that geological and anthropogenic factors are mainly responsible for fluoride contamination in groundwater [4]. Physiological conditions of rock like decomposition, dissociation and subsequent dissolution along with long residence time may be the responsible factors for fluoride leaching [5]. Further, various anthropogenic factors such as industrialization, urbanization and improper use of water resources are the main cause for enhancing the fluoride content of ground water in the developing countries. Various technologies such as precipitation [6], ion exchange [7], reverse osmosis [8], electro-dialysis [9] and adsorption [10] have been employed for fluoride removal from groundComparative Studies of Fluoride Removal from Groundwater by Calcium Carbonate, Activated Alumina and Activated Punica granatum Ash

Preparation and Characterization of Activated Alumina

Abstract: Activated alumina is a high surface area and highly porous form of aluminum oxide that can be employed for contaminant species adsorb from ether gases or liquids without changing its form. The research in getting this material has generated huge interested. Thus, this paper presented preparation of activated alumina from chemical process. Pure aluminum (99.9% pure) reacted at room temperature with an aqueous NaOH in a reactor to produce a solution of sodium aluminate (NaAlO2 ). This solution was passed through filter paper and the clear filtrate was neutralized with H2 SO4 , to pH 6, 7 or 8, resulting in the precipitation of a white gel, Al(OH)3·XH2O. The washed gel for sulfate ions were dried at 80 °C for 6 h, a 60 mesh sieve was to separate and sort them into different sizes. The samples were then calcined (burn) for 3h in a muffle furnace, in air, at a heating rate of 2 °C min–1 . The prepared activated alumina was further characterized for better understanding of its physical properties in order to predict its chemical mechanism.

Method for treating initial fluorine-containing rainwater by adopting magnetic flocculation-adsorption

Abstract: The invention discloses a coagulating sedimentation-adsorption method for treating initial fluorine-containing rainwater. The method comprises the steps that lime milk is added to adjust the pH to alkaline, aluminum salt coagulant and coagulant aid are added after calcium chloride and magnetic powder are added to mixed with the lime milk, and the fluorine-containing rainwater filtered by a multi-medium filter and a second-level activated alumina filter can be reused or discharged after reactive precipitation. According to the method, a stable and high-efficient method for treating the initialfluorine-containing rainwater is provided to aim at the present situation that fluoride content in the initial rain water produced by enterprises using villiaumite exceeds a standard, which can not meet the demand of environmental protection. The method is suitable for occasions where the concentration of fluoride in the initial fluoride-containing water does not exceed 200 mg/L, and the fluorideconcentration in effluent can be controlled at 1 mg/L.