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Activated alumina

About: Activated alumina is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 31090 citations.


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TL;DR: In this article, the authors studied the desulfurization of diesel fuel by different layered adsorbents and regeneration of the latter in a fixed-bed unit operated at ambient temperature and pressure.
Abstract: Desulfurization of a commercial diesel fuel by different layered adsorbents and regeneration of the latter were studied in a fixed-bed unit operated at ambient temperature and pressure. In general, a layered bed consisting of 12 wt % activated carbon, 22 wt % of activated alumina (Selexsorb CDX), followed by Cu(I)−Y, activated carbon/Selexsorb CDX/Cu(I)−Y, is capable of producing 41 cm3 of desulfurized diesel fuel/g of adsorbent. The matrix is capable of processing 27 cm3 of deep-desulfurized diesel with a weighted average content of 76 ppbw S. These low-sulfur fuels are suitable for fuel cell applications. For layered-bed regeneration, it was determined that calcination of the adsorbed sulfur moieties with air at 350 °C followed by autoreduction of the copper species recovered all of the original desulfurization capacity when activated aluminas are used as a guard layer. Solvent elution experiments indicate that carbon tetrachloride and N,N-dimethylformamide are suitable solvents to recover all of the ad...

125 citations

Journal ArticleDOI
TL;DR: A new technique based on the combination of an activated alumina column and an electrochemical system for fluoride removal from water is reported in this article. But it is not shown that it is more efficient than the former in removing fluoride from water.

125 citations

Journal ArticleDOI
TL;DR: In this paper, a surface complex formation model was used to describe the removal of fluoride by activated alumina, and the intrinsic constants, pKa1int and pKa2int, are 4.2 and 10.5, respectively, in 0.05 M NaClO4, and density of Bronsted acid sites is approximately 5.6×1013/cm2.
Abstract: Fluoride removal by activated alumina, Type F‐1, depends primarily on the pH and surface loading. The optimal pH for fluoride removal is approximately 5. However, at pH<6.0, the aluminum (III) dissolved from activated alumina reacts with fluoride ions and forms alumino‐fluoro complexes. These complexes are unstable in neutral or alkaline pH regions. Consequently, the role of pH in minimizing alumina dissolution as opposed to maximizing fluoride removal must be considered. An alkalimetric titration method was used to determine the surface acidity of the activated alumina. The intrinsic constants, pKa1int and pKa2int, are 4.2 and 10.5, respectively, in 0.05 M NaClO4, and the density of Bronsted acid sites is approximately 5.6×1013/cm2. A surface complex formation model was used to describe the removal of fluoride by activated alumina. These reaction mechanisms can be identified as a surface complex formation involving Al¯OH and Al¯OH2+. Polynuclear surface complex may be formed at high surface loading.

114 citations

Journal ArticleDOI
TL;DR: In this article, a newly identified sorbent that, in terms of composition, is a specialty chelating polymer with immobilized Cu(II) present at the sorption sites is presented, which shows higher selenite and arsenate selectivities over competing sulfate ions.
Abstract: The need for selective sorption of trace concentrations of toxic Se(IV) and As(V) oxyanions, especially in the presence of competing high concentrations of sulfate ions, is well recognized. In this regard, previous investigators have shown the advantages as well as shortcomings of the fixed-bed sorption process when activated alumina or strong-base polymeric anion exchangers are used as sorbents. The present study reports the sorption behaviors of a newly identified sorbent that, in terms of composition, is a specialty chelating polymer with immobilized Cu(II) present at the sorption sites. Experimental results with the new sorbent show higher selenite and arsenate selectivities over competing sulfate ions. Anion exchange accompanied by Lewis acid-base interactions are the underlying reasons for the new sorbent’s enhanced affinities toward arsenates and selenites. In several ways, the new sorbent can complement the shortcomings of activated alumina and other strong-base anion exchangers.

114 citations

01 Jan 1998
TL;DR: In this article, column studies were conducted at the University of Regina to examine oxidation with KMnO 4 followed by filtration using manganese greensand and ironoxide coated sand to examine the removal of arsenic from drinking water; these results were compared with the data from ion exchange studies.
Abstract: The current United States maximum contaminant level for arsenic in drinking water is set at 50 μg/l. Because of the cancer risks involved, Canada has already lowered the maximum contaminant level to 25 μg/l; the United States Environmental Protection Agency is reviewing the current allowable level for arsenic with a view of lowering it significantly. Various treatment methods have been adopted to remove arsenic from drinking water. These methods include 1) adsorption-coprecipitation using iron and aluminum salts, 2) adsorption on activated alumina, activated carbon, and activated bauxite, 3) reverse osmosis, 4) ion exchange and 5) oxidation followed by filtration. Because of the promise of oxidation-filtration systems, column studies were conducted at the University of Regina to examine oxidation with KMnO 4 followed by filtration using manganese greensand and iron-oxide coated sand to examine the removal of arsenic from drinking water; these results were compared with the data from ion exchange studies. These studies demonstrated that As (III) could be reduced from 200 μg/l to below 25 μg/l by the manganese greensand system. In the case of manganese greensand filtration, addition of iron in the ratio of 20:1 was found necessary to achieve this removal.

114 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202218
202118
202031
201941
201839