Showing papers on "Activated alumina published in 2013"

Dehydration of Ethanol to Ethylene

Abstract: This article is an up-to-date review of the literature available on the subject of ethanol to ethylene. The process of ethanol to ethylene has broad development prospects. Compared with the process of petroleum to ethylene, ethanol dehydration to ethylene is economically feasible. Researchers have been redirecting their interest to the ethylene production process, catalysts, and reaction mechanisms. A fluidized bed reactor, together with a wear-resistant, efficient, and stable catalyst will be the focus of future research that includes a deep understanding of the large-scale activated alumina catalyst and the molecular sieve catalyst used, and will promote the development of the ethanol dehydration to ethylene process and provide strong support for the market competiveness of the process.

Enhanced Removal of Fluoride by Polystyrene Anion Exchanger Supported Hydrous Zirconium Oxide Nanoparticles

Abstract: Here we fabricated a novel nanocomposite HZO-201, an encapsulated nanosized hydrous zirconium oxide (HZO) within a commercial porous polystyrene anion exchanger D201, for highly efficient defluoridation of water. HZO-201 exhibited much higher preference than activated alumina and D201 toward fluoride removal when competing anions (chloride, sulfate, nitrate, and bicarbonate) coexisted at relatively high levels. Fixed column adsorption indicated that the effective treatable volume of water with HZO-201 was about 7-14 times as much as with D201 irrespective of whether synthetic solution or groundwater was the feeding solution. In addition, HZO-201 could treat >3000 BV of the acidic effluent (around 3.5 mg F(-)/L) per run at pH 3.5, compared to only ∼4 BV with D201. The exhausted HZO-201 could be regenerated by NaOH solution for repeated use without any significant capacity loss. Such attractive performance of HZO-201 resulted from its specific hybrid structure, that is, the host anion exchanger D201 favors the preconcentration of fluoride ions inside the polymer based on the Donnan principle, and the encapsulated nanosized HZO exhibits preferable sequestration of fluoride through specific interaction, as further demonstrated by XPS spectra. The influence of solution pH, competitive anions, and contact time was also examined. The results suggested that HZO-201 has a great potential in efficient defluoridation of groundwater and acidic mine drainage.

Removal of Fluoride from Drinking Water Using Modified Immobilized Activated Alumina

Abstract: The study describes the removal of fluoride from drinking water using modified immobilized activated alumina (MIAA) prepared by sol-gel method. The modification was done by adding a specific amount of alum during the sol formation step. The fluoride removal efficiency of MIAA was 1.35 times higher as compared to normal immobilized activated alumina. A batch adsorption study was performed as a function of adsorbent dose, contact time, stirring rate, and initial fluoride concentration. More than 90% removal of fluoride was achieved within 60 minutes of contact time. The adsorption potential of MIAA was compared with activated charcoal which showed that the removal efficiency was about 10% more than the activated charcoal. Both the Langmuir and Freundlich adsorption isotherms fitted well for the fluoride adsorption on MIAA with the regression coefficient R2 of 0.99 and 0.98, respectively. MIAA can both be regenerated thermally and chemically. Adsorption experiments using MIAA were employed on real drinking water samples from a fluoride affected area. The study showed that modified immobilized activated alumina is an effective adsorbent for fluoride removal.

Alumina/Iron Oxide Nano Composite for Cadmium Ions Removal from Aqueous Solutions

Abstract: Magnetic alumina nano composite (MANC) was prepared for combination of the adsorption features of nano activated alumina with the magnetic properties of iron oxides to produce a nano magnetic adsorbent, which can be separated from the medium by a simple magnetic process after adsorption. MANC was characterized using XRD, SEM, TEM, EDX and surface area (BET). Quantum design SQUID magnetometer was used to study the magnetic measurement. The present study was conducted to evaluate the feasibility of MANC for the removal of cadmium ions from aqueous solutions through batch adsorption technique. The effects of pH, adsorbent dose, temperature, contact time and initial Cd2+ concentration on cadmium ions adsorption were studied. Equilibrium data were fitted to Langmuir, Freundlich and Temkin isotherms. The equilibrium data were best represented by the Langmuir isotherm. The kinetic data were fitted to pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models, and it was found to follow closely the pseudo-second-order model. Thermodynamic parameters were calculated for the Cd2+ ion-MANC system and the positive value of ΔH° showed that the adsorption was endothermic in nature. Furthermore, a single-stage batch adsorber was designed for the removal of Cd2+ ions by MANC based on the equilibrium data obtained.

Synthesis of nano- alumina powder from impure kaolin and its application for arsenite removal from aqueous solutions

Abstract: Adsorption is considered a cost-effective procedure, safer to handle with high removal efficiency. Activated alumina is the most commonly used adsorbent for the removal of arsenic from aqueous solutions. However, activated alumina has a low adsorption capacity and acts kinetically in a slow manner. An ideal adsorbent should have a high surface area, physical and/or chemical stability and be inexpensive. To meet this requirement, nanomeso porous γ-alumina with a high surface area (201.53 m2/g) and small particle size (22–36 nm) was prepared from inexpensive kaolin as the raw material, by precipitation method. The research results showed that adsorbent has the high adsorption capacity (for initial arsenite concentration up to 10 mg/L, in which 97.65% recovery was achieved). Optimal experimental conditions including pH, initial arsenite concentration and contact time were determined. Langmuir, Freundlich and Dubinin– Radushkevich isotherm models were applied to analyze the experimental data. The best interpretation for the experimental data was given by Langmuir adsorption isotherm equation and the maximum arsenite adsorbed by synthesized nano γ–alumina (qe) was found to be 40 (mg/g).

Synthesis, characterization and application of lanthanum-impregnated activated alumina for F removal

Abstract: Elevated fluoride (F) in groundwater presents an obvious environmental concern. Adsorption using activated alumina (AA) is currently the best available technology for F removal, despite its low efficiency, pH dependence, and aluminium (Al) release. The motivation for our study is to synthesise a new F adsorbent by impregnating commercially available granulated AA with lanthanum oxide (LAA), and to explore its F adsorption mechanism on the molecular scale. Five cycles of lanthanum impregnation on AA followed by calcination at 573 K increased the La content up to 19.1% and the F removal from 18.1% by pristine AA to 92.4% by LAA. The SEM, TEM, XRD, TGA, and EXAFS results demonstrated that the 5–20 nm thin flakes of LaOOH on LAA were in an amorphous form, with 7.6 oxygen atoms around each La. This LaOOH layer was uniformly distributed inside the micropores of the 1–3 mm AA granules. LAA exhibited four fold higher F adsorption capacity than AA in the pH range 3.9 to 9.6, with substantially reduced Al release. The ability to regenerate and reuse LAA makes it an attractive sustainable material. Multiple complementary spectroscopic analyses demonstrated that ligand exchange between F and surface hydroxyl groups is the mechanism for F adsorption on LAA. Our work improves the understanding of F interaction with metal oxides on the molecular scale and presents an alternative solution for elevated F water treatment.

Kinetics, equilibrium and thermodynamics of ciprofloxacin hydrochloride removal by adsorption on coal fly ash and activated alumina

Abstract: In this study, performance of two different adsorbents namely, activated alumina (AA) and coal fly ash (CFA) have been examined for the removal of an antibiotic Ciprofloxacin hydrochloride (CPH) from its aqueous solution. Batch adsorption experiments were conducted to study the effect of various operational parameters such as pH, initial antibiotic concentration, adsorbent dose, and temperature on the adsorption process. The optimal pH for CPH adsorption was found to be 4. The adsorption kinetics was evaluated at different initial antibiotic concentrations and temperatures. Kinetics of adsorption, in all cases, followed pseudo-second-order rate equation for both the adsorbents. Adsorption of CPH was well described by Freundlich isotherm. Thermodynamic analysis unveiled the feasibility, spontaneity, and endothermic nature of overall adsorption process at higher temperatures. Values of ΔG° for CFA and AA are −0.029 and −2.714 kJ/mol, respectively, at 328 K. The corresponding values for ΔH° are 6.572...

Arsenic (III) adsorption on iron acetate coated activated alumina: thermodynamic, kinetics and equilibrium approach.

Abstract: The adsorption potential of iron acetate coated activated alumina (IACAA) for removal of arsenic [As (III)] as arsenite by batch sorption technique is described. IACAA was characterized by XRD, FTIR, EDAX and SEM instruments. Percentage adsorption on IACAA was determined as a function of pH, contact time and adsorbent dose. The study revealed that the removal of As (III) was best achieved at pH =7.4. The initial As (III) concentration (0.45 mg/L) came down to less than 0.01 mg/L at contact time 90 min with adsorbent dose of 1 g/100 mL. The sorption was reasonably explained with Langmuir and Freundlich isotherms. The thermodynamic parameters such as ΔG 0 , ΔH 0 , ΔS 0 and E a were calculated in order to understand the nature of sorption process. The sorption process was found to be controlled by pseudo-second order and intraparticle diffusion models.

Desiccant based honeycomb chemical filter and method of manufacture thereof

Abstract: The present invention provides a desiccant based honeycomb chemical filter comprising a matrix formed of a substrate having a desiccant generated in situ or deposited thereon, said desiccant being selected from the group consisting of metal silicates, silica gel, molecular sieves, activated alumina, activated carbon or hydrophobic zeolite, and any mixture thereof, said substrate being further impregnated with one or more of an oxidizing agent, or an alkali metal hydroxide, or strong or weak acid(s), or reducing agents.

Removal of Fluoride Ion from Aqueous Solution

Abstract: High concentrations of fluoride in drinking water had caused widespread fluorosis. A simple, precise, rapid and reliable technique has been developed for removal of fluoride in drinking water. The innovative technique employs activated alumina for defluoridation of drinking water. Alumina is inert in nature, hence it is safe to use and handle. The innovation in regeneration of alumina makes the technique cost effective. The reliability of the newly developed technique has been established by analyzing spiked water samples of high concentrations of fluoride (upto 50 ppm) and levels of fluoride has been brought down to less than 1 ppm. The method is superior to currently employed techniques and is recommended to the laboratories where a huge volume of water is to be defluoridated.

Oxidation catalyst for purifying diesel engine waste gas and preparation method of oxidation catalyst

Abstract: The invention relates to an oxidation catalyst for purifying diesel engine waste gas and a preparation method of the oxidation catalyst, in the technical field of automobile tail gas treatment. The catalyst comprises cordierite honeycomb ceramic or metal serving as a carrier and an active coating containing activated alumina, composite oxide, a molecular sieve and precious metal. The preparation method comprises the steps of mixing, stirring and ballmilling pseudo-boehmite, alumina and composite oxide in deionized water, adding the molecular sieve and a precious metal solution to prepare a coating feed solution, coating the coating feed solution on the carrier, and obtaining the oxidation catalyst through drying and roasting. The diesel oil oxidation catalyst has a better purifying effect on CO (Carbonic Oxide), HC (Hydrocarbon Compounds) and SOF (Soluble Organic Fractions), and as composite oxide containing Mn is added, the oxidation temperature of NO (Nitric Oxide) is reduced, and the catalyst has a better low-temperature oxidation property.

Method for preparing catalyst for hydrogenating pyridine compound and application thereof

Abstract: The invention discloses a method for preparing a catalyst for hydrogenating a pyridine compound. The method comprises the following steps of: 1, pre-treating activated carbon; 2, preparing a precursor solution; 3, immersing the activated carbon by the precursor solution; 4, reducing, washing and drying to obtain the catalyst. The invention also discloses another method for preparing the catalyst for hydrogenating a pyridine compound, which comprises the following steps of: 1, pre-treating alumina; 2, preparing a precursor solution; 3, immersing the alumina by the precursor solution, drying, roasting and reducing to obtain the catalyst. According to the catalyst prepared by the invention, the activated carbon or activated alumina is used as a carrier, noble metal ruthenium and auxiliary metal element are loaded and highly dispersed on the carrier, and the granularity of ruthenium metal particles in the catalyst is 30nm-80nm. The prepared catalyst is suitable for catalytically hydrogenating pyridine compounds to synthesize piperidine compounds, the conversion rate of the catalytic hydrogenation reaction is high, and the production cost for the piperidine compounds can be greatly reduced.

Optimization and Kinetics of Furfural Oxidation to Furoic Acid Over Alum-impregnated Activated Alumina

Abstract: In the present investigation, oxidation of furfural was carried out using alum-impregnated activated alumina, which led to the formation of 2-furancarboxylic acid (furoic acid). Operational parameters such as catalytic ratio were varied from 1 to 9%, temperature from 40 to 70°C, initial concentration from 0.1 to 0.5 m and time from 0.5–7.5 h, and were optimized using Box–Behnken design. The Fisher F-value of 55.10 confirmed that the second-order regression model used for prediction of results was satisfactory. By using the reaction scheme proposed, rate constants at various reaction temperatures were determined. Activation energy and frequency factor corresponding to the reaction were also calculated.

Defluoridation Of Drinking Water Using Activated Alumina

Abstract: Excess fluoride (F-) in drinking water poses a health threat to millions of people around the world. In the present work, activated alumina (AA) has been used as an adsorbent. Data obtained from batch experiments were fitted to the (i) pseudo-first order, (ii) pseudo-second order, and (iii) Langmuir kinetic model. Model (ii) performed better than model (i), and fitted the data well. However, the rate constant for adsorption ka had to be varied as a function of the initial concentration of F- in the liquid phase c0. A more satisfactory approach is provided by Langmuir model, which fitted the data reasonably even though ka was independent of c0. Shreyas (2008) developed a model for the batch adsorption of F- onto porous pellets of AA. Some errors were detected in his computer program were corrected. The parameters of the model were estimated by fitting predictions to data. The parameter values suggest that the adsorption process is likely to be diffusion limited. Column experiments were conducted as follows. The pellets were soaked in deionized water for a time ts before they were loaded into columns. A feed solution having a fluoride concentration cf = 3 mg/L was fed to column and the concentration of F- in the exit stream ce was measured at regular intervals. Breakthrough was deemed to have occurred when ce exceeded the permissible limit (= 1 mg/L). Constant values of the bed height H, and the empty bed contact time tc were used in the experiments. The volume of treated water V, scaled by the volume of the bed Vb, varied strongly with the soaking time ts, with a maximum at ts = 24 h. To understand the possible reasons for this behaviour, XRD, FESEM, and FTIR were used to characterize the surface of AA. Though the concentrations of the surface hydroxyl groups may influence the adsorption of F-, FTIR studies show there is no direct correlation between V/Vb and the concentrations of these groups. The FESEM and XRD studies indicate that fresh AA consists mainly of boehmite, which gradually converted to gibbsite during soaking. For fixed values of H and tc, the dimensionless volume of treated water V/Vb was a maximum at D = 45 mm. This behaviour may be caused by wall effects for small values of D and by occurrence of quasi-static regions near the wall for large values of D. The cost of treated of water was Rs. 0.42/L. It decreased slightly to Rs. 0.37/L after one regeneration cycle, but increased to Rs. 0.41/L after two cycles. The volume of treated water after two regeneration cycles was 595 L/kg. The concentration of Al3+ ions ca in the treated water increased and exceeded the permissible limit of 0.2 mg/L as the number of regeneration cycles increased. The concentration of F- in regeneration effluent cre was in the range 32-70 mg/L. The effluent was subjected to solar distillation, leading to a distillate whose fluoride concentration F- was in the range 9-12 mg/L. The distillate can be discharged into the public sewers, as the permissible limit is 15 mg/L.

Arsenate removal from water by adsorption with magnetic nanoparticles (γ-Fe2O3)

Abstract: Arsenic is a poisonous and carcinogenic heavy metal that exists naturally on the earth’s crust, from where it can leach into the groundwater – a common water source worldwide. Therefore, arsenic-rich areas pose the risk of chronic exposure, which is prevented by removing arsenic from water using various technologies. Adsorption with conventional adsorbents, as activated alumina and iron-based adsorbents, is commonly applied for arsenic removal. This study introduces a nanoscale adsorbent, maghemite-magnetic nanoadsorbent, for arsenic removal. The overall aim of the study was to compile fundamental information on novel maghemite nanoparticles and their suitability for arsenic removal from water with laboratory—scale batch experiments. The study was conducted with three kinds of maghemites: sol-gel, mechanochemical, and commercial maghemite. Sol-gel maghemite was the main research target; the others were studied for reference. The research consisted of the preparation of maghemite nanoparticles and their characterization, the study of adsorption kinetics, an investigation of arsenate adsorption properties on maghemite, a determination of the adsorption mechanism, and the evaluation of maghemite stability and regeneration properties. The results indicated the applicability of sol-gel maghemite for arsenic removal by adsorption. The reasons are several: sol-gel maghemite synthesis is fast, convenient to work with and produces repeatedly high-quality particles, adsorbs arsenate satisfactorily, and there is no need for preliminary treatments prior to adsorption experiments: it is easy to handle and separate via an external magnet, it maintains its initial arsenate uptake capacity after six regeneration cycles, and it is stable, which are important factors for cost-effectiveness. And it produces only a small amount of “arsenate-maghemite” waste. Moreover, sol-gel maghemite is competitive with activated alumina in adsorbent properties. Both adsorbents need careful monitoring due to pH control, interference of other ions, and regeneration. Activated alumina can remove slightly more arsenate than sol-gel maghemite, but sol-gel maghemite is more stable, forms less waste, and is separated simply and rapidly by external magnet. ; Arseeni on myrkyllinen ja karsinogeeninen raskasmetalli, jota esiintyy kallio- ja maaperassa. Sielta arseenia voi liueta pohjaveteen, joka on yleinen juomaveden lahde maailmanlaajuisesti. Arseenipitoisilla pohjavesialueilla kroonisen altistumisen riski on merkittava ja altistumisen estamiseksi arseenia poistetaan juomavedesta erilaisilla tekniikoilla. Adsorptio perinteisilla adsorbenteilla, kuten aktivoidulla alumiinilla ja rautapohjaisilla adsorbenteilla, on yleisesti kaytossa oleva arseenin poistomenetelma. Tassa tutkimuksessa esitetaan nanomittakaavan adsorbentti – maghemiitti – magneettinen nanoadsorbentti – arseenin poistoon. Tutkimuksen tavoitteena oli koota perustietoa uudesta maghemiittinanohiukkasesta ja sen soveltuvuudesta arsenaatin (As(V)), poistoon vedesta laboratoriomittakaavan kokeilla.…

Merits and Demerits of different technologies of defluoridation for drinking water

Abstract: The problem of excess fluoride in ground water was detected in many states of India as early as 1930s.Till 1999 as many as 17 states have been identified with the problem of excess fluoride in ground water sources. After view of problems related fluorosis many methods used for removal of excess of fluoride from drinking water in India. In this paper compile all the merits and demerits of some defluoridation methods including Nalgonda method, Activated Alumina, bone char, fly ash, brick and reverse osmosis methods etc.

Cr -activated alumina glass-ceramic for agricultural greenhouse and its preparation method and use

Abstract: The invention discloses a Cr -activated alumina glass-ceramic for an agricultural greenhouse and its preparation method and use. The Cr -activated alumina glass-ceramic is obtained by doping 1-10wt% of a mixture of Al2O3 and Cr2O3 in a low-melting point glass material, wherein the mixture of Al2O3 and Cr2O3 comprises 0.1-1mol% of Cr2O3. The Cr -activated alumina glass-ceramic can realize selective absorption and permeation of light. The Cr -activated alumina glass-ceramic can be used for the agricultural greenhouse, has a long service life, solves the problem that a film-type light replacement product produces pollution and waste, and is in accordance with development tendency of a light conversion material for plant growth.

Silica removal from coal seam gas brine using activated alumina

Abstract: This study reports using activated alumina for the removal of silica from coal seam gas (CSG) associated water. Spectroscopic and analytical characterization confirmed the presence of both reactive-dissolved and nonreactive-particulate silica in a number of aqueous streams at a CSG water treatment facility. The removal of these silica species from brine produced at the facility by activated alumina (AA) was the focus of the study. In addition to being an adsorbent for dissolved silica, activated alumina columns were found to be a filter for particulate silica. The surface characterization of spent adsorbent by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) confirmed adsorption of silica onto activated alumina.

Water filtration system using hybrid nano carbon, silver, iron and aluminium oxide

Abstract: The present invention relates to a filter for filtering water comprising carbon nanospheres from the pyrolytic combustion of a carbonaceous material such as plant material which are activated with silver nitrate, activated alumina and/or ferrous oxide.

Study on phosphate removal and recovery by activated alumina

Abstract: Activated alumina was studied for removing phosphate from water, and the recovery of adsorbed phosphate on activated aluminum oxide was also tested. Phosphate solution was prepared using distilled water, tap water and Luoshijiang River water, respectively. All the phosphate adsorption tests using activated alumina were proved to be well fitted with Langmuir isotherm and the respective maximum adsorption amount were 20.88, 32.15 and 29.85 mg x g(-1), respectively. The presence of electrolyte in water could be a positive factor for phosphate removal. As the pH value of phosphate solution became lower the Zeta potential of activated alumina increased, which could enhance the phosphate removal efficiency of activated alumina. The recovery tests indicated that NaOH (0.1 mol x L(-1)) solution could almost completely extract the phosphate adsorbed by activated alumina.

Gas dryer for electric machine

Abstract: PROBLEM TO BE SOLVED: To obtain a gas dryer for the inside of an electric machine, which keeps manufacturing costs low by a simple configuration, which can reduce management items, and which can secure safety.SOLUTION: Desiccant containers 3a and 3b, the insides of which are filled with activated alumina 2a and 2b, are provided in parallel, and a gas channel is formed via either of them. When the gas channel is formed via the desiccant container 3a, a control device 12 acquires the result of detection performed by a weight sensor 11a. When the degree of a decrease in the dehumidification capacity of the activated alumina 2a reaches a value equal to/higher than a predetermined value, an inlet-side switching three-way valve 7 and an outlet-side switching three-way valve 8 are switched by an actuator 13, and the gas channel is formed via the desiccant container 3b. Additionally, the desiccant containers 3a and 3b can also be provided with air blowers 14a and 14b for drying the activated alumina 2a and 2b, respectively.