Activated alumina

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

Fabrication of Manganese-Supported Activated Alumina Adsorbent for Defluoridation of Water: A Kinetics and Thermodynamics Study

Abstract: Fluoride pollution frequently occurs in many underground drinking water sources due to discrepancies in the geological environment. To address this problem, a manganese-supported activated alumina (MnOOH-supported AA) adsorbent was proposed in the present study. The adsorbent was prepared with an impregnation method, then the morphology and microstructure were systematically characterized. Further, the adsorption kinetics and thermodynamics were systematically explored through static experiments to confirm the adsorption mechanism. The results showed that MnOOH was successfully loaded on the activated alumina (AA), and irregular and convex spinous structures were formed on the surface of particles. Compared with the AA, MnOOH-supported AA exhibited a significantly higher defluoridation rate, which has been doubled. The kinetic behavior of fluoride adsorption on MnOOH-supported AA was governed by the quasi-second-order kinetics model with regression coefficients of 0.9862, 0.9978 and 0.9956, respectively. The adsorption rate was mainly ascribed to the intra-particle diffusion. Additionally, the Freundlich isotherm equation fitted the adsorption thermodynamic process reasonably well compared with the Langmuir adsorption model. Specifically, the correlation coefficients were 0.9614, 0.9383 and 0.9852 at 25 °C, 35 °C and 45 °C, respectively. The adsorption–desorption isotherm plot was similar to the Type V isotherm. The whole fluoride adsorption was a spontaneous endothermic reaction, and controlled by chemical adsorption. These results demonstrated that MnOOH-supported AA as an alternative to the conventional AA showed promising potential for defluoridation in drinking water treatment.

Dependence of Adsorptive Capability for Lithium Ions in Molten Salt on Surface Properties of Activated Alumina

Abstract: It was reported in our previous work that activated alumina had been successfully applied to selective adsorption of lithium ions in molten NaNO3 at a high temperature. In the present work, the activated alumina samples were prepared by heat treatment of commercially available alumina sol at different temperatures. Their physical properties were measured, then their adsorption uptake of lithium ions were evaluated. Amorphous alumina showed higher adsorption uptake of lithium ions than any other phases of alumina and the uptake increased in proportion to the surface area of activated alumina. The lithium ion uptake per unit surface area varied slightly with the phase of alumina, implying that the surface microstructure of each activated alumina has a different adsorptive capability for lithium ions. Since the mean pore radius of each activated alumina sample was at least forty times larger than the ionic radius of lithium, it may be concluded that there is little effect of the pore size on adsorptive capabilities for lithium ions.

Process for purifying a gas stream containing N2O as an impurity

Abstract: Nitrous oxide separation from gas comprises use of a faujasite zeolite adsorbent having a specified silicon-aluminum ratio and specified potassium, sodium and calcium cation contents. Nitrous oxide (N2O) is separated from a gas stream using a faujasite zeolite adsorbent having an Si/Al ratio of 1-1.50 and containing less than 35% K , 1-99% Na and 1-99% Ca . Preferred Features: The process also includes removal of one or more impurities selected from H2O, CO2, H2 and hydrocarbons, especially ethylene, propane and/or methane, the H2O and CO2 being removed using an activated alumina particle bed. Separation is carried out by TSA at -40 to +80 degrees C, using an adsorption pressure of 10 -10 Pa and/or a desorption pressure of 5 x 10 -10 Pa, especially atmospheric pressure. The adsorbent is regenerated at 50-250 degrees C.

Activated alumina for adsorbing arsenate ion and adsorption treatment of arsenate ion from aqueous solution by using the same

Abstract: PROBLEM TO BE SOLVED: To provide adsorption material of arsenate ions by which arsenate ions are adsorbed and removed from water to low concentration of /l, BET specific surface area is >=100 m /g, pore volume of 0.2-10 μm pore radius measured by a mercury press-fitting method is >=0.04 cc/g and pore volume of 0.2-1 μm pore radius is >=0.02 cc/g, is used as the adsorbent.

Novel Adsorption and Desorption Chemiluminescence of 10,10′-Disubstituted 9,9′(10H,10′H)-Biacridinylidenes in Alumina Slurries

Abstract: 10,10′-Disubstituted 9,9′(10H,10′H)-biacridinylidene (1) has a novel chemiluminescence (CL) in an alumina slurry. The CL is yellowish green emissions I and II from the excited singlet state of adsorbed 1 onto alumina, 11*(ads), and blue emission III from the excited singlet state of 10-substituted 9(10H)-acridinone (2), 12*. In this study the effects of alumina activity and solvent polarity on the generation of those emitters were investigated and the mechanism was clarified: 1) 11*(ads) is generated by two-step electron transfers, the first electron transfer from 1 to O2 gives 1+•(ads) accompanied by adsorption of 1 and the following electron transfer from –OH and/or –O− on alumina to 1+•(ads) gives 11*(ads), and 2) 12* is generated from the reaction of 12+ and O2−•, both of which are formed during the reaction of emissions I and II. The two key compounds, 12+ and O2−•, were detected spectroscopically. O2−• in a slurry of 1, benzene, and highly activated alumina was found to be extremely stable and to ge...