Immobilization mechanism of Se oxyanions in geopolymer: Effects of alkaline activators and calcined hydrotalcite additive

2020 ◽  
Vol 387 ◽  
pp. 121994 ◽  
Author(s):  
Quanzhi Tian ◽  
Binglin Guo ◽  
Keiko Sasaki
Keyword(s):  
Calcined Hydrotalcite

The combined effect of CO2 and calcined hydrotalcite on one-coat limestone mortar properties

2021 ◽  
Vol 280 ◽  
pp. 122532
Author(s):  
David Suescum-Morales ◽  
David Cantador Fernández ◽  
José María Fernández ◽  
José Ramón Jiménez
Keyword(s):  
Combined Effect ◽  
Calcined Hydrotalcite

scholarly journals Sorption of aspartic and glutamic aminoacids on calcined hydrotalcite

SpringerPlus ◽  
2013 ◽  
Vol 2 (1) ◽  
pp. 211 ◽  
Author(s):  
Fabiano Silvério ◽  
Márcio José dos Reis ◽  
Jairo Tronto ◽  
João Barros Valim
Keyword(s):  
Calcined Hydrotalcite

Cannizzaro reactions over calcined hydrotalcite

2019 ◽  
Vol 174 ◽  
pp. 86-89 ◽  
Author(s):  
Bhojaraj ◽  
Pramod Harley ◽  
Michael Rajamathi
Keyword(s):  
Calcined Hydrotalcite

Removal of Anions from Solution by Calcined Hydrotalcite and Regeneration of Used Sorbent in Repeated Calcination-Rehydration-Anion Exchange Processes

1999 ◽  
Vol 64 (9) ◽  
pp. 1517-1528 ◽  
Author(s):  
František Kovanda ◽  
Eva Kovácsová ◽  
David Koloušek
Keyword(s):  
Anion Exchange ◽  
Sorption Capacity ◽  
Sorption Isotherms ◽  
Layered Crystal ◽  
Calcined Hydrotalcite ◽  
Capacity Evaluation ◽  
Exchange Processes ◽  
Sorption Ability ◽  
Subsequent Calcination ◽  
Rehydration Process

Synthetic hydrotalcite calcined at 350-550 °C was used for the removal of arsenate, chromate, and vanadate ions from water solutions. The initial anion concentrations were 0.002 mol l-1. The sorption isotherms were measured at 20 °C and at neutral pH. The Langmuir adsorption isotherm was used for the sorption capacity evaluation. The ability of the calcined hydrotalcite to remove the anions from solution decreased in the order of vanadate - arsenate - chromate. The hydrotalcite calcined at 450 °C exhibited the best sorption ability for all the anions. The sorbed anions were released by anion exchange in a carbonate-containing solution and the hydrotalcite after subsequent calcination was used again for the removal of anions. The repeating cycles calcination-rehydration-anion exchange gradually reduced the adsorption capacity of the hydrotalcite. The sorption capacity decreased by 50% after the first two cycles but it did not change significantly in the subsequent cycles. When chromate anions were adsorbed, the decrease in sorption capacity was not observed during repeated calcination-rehydration-anion exchange cycles. The change in the sorption capacity was influenced by the ability of calcined hydrotalcite to regenerate the layered crystal structure during the rehydration process.

Basicity and Porosity of a Calcined Hydrotalcite-Type Material from Nitrogen Porosimetry and Adsorption Microcalorimetry Methods.

ChemInform ◽  
2004 ◽  
Vol 35 (4) ◽  
Author(s):  
M. L. Occelli ◽  
J. P. Olivier ◽  
A. Auroux ◽  
M. Kalwei ◽  
H. Eckert
Keyword(s):  
Type Material ◽  
Adsorption Microcalorimetry ◽  
Calcined Hydrotalcite

scholarly journals Continuous isomerization of glucose to fructose using activated hydrotalcite catalyst: Effects of reaction conditions

2021 ◽  
Author(s):  
Sadra Souzanchi ◽  
Laleh Nazari ◽  
Venkat Kasanneni ◽  
Zhongchao Tan ◽  
Charles Xu
Keyword(s):  
Reaction Temperature ◽  
Flow Rate ◽  
Retention Time ◽  
Catalyst Activity ◽  
Tubular Reactor ◽  
Operating Conditions ◽  
Bet Surface Area ◽  
Isomerization Reaction ◽  
Catalyst Loading ◽  
Calcined Hydrotalcite

Isomerization of glucose to fructose was studied over activated hydrotalcite as a catalyst in a continuous-flow tubular reactor. The synthetic hydrotalcite (HT), calcined hydrotalcite (HT-C) and activated hydrotalcite (calcined-rehydrated hydrotalcite (HT-C-R)) were characterized by TGA, XRD, BET surface area, and FT-IR analyses. The effects of operating conditions, including reaction temperature and retention time (in terms of both catalyst loading and feeding flow rate) on the isomerization reaction, were investigated. Glucose conversion and fructose selectivity were found to be more strongly dependent on retention time than reaction temperature. The fructose yield was mostly dependent on the feeding flow rate, and its maximum value of 18% corresponded to the lowest flow rate of 0.5 ml/min. The regenerated hydrotalcite catalyst showed that the catalyst activity could be restored through the calcination-rehydration process, and it showed good potential for recycling and reusability.

scholarly journals Activity in the Photodegradation of 4-Nitrophenol of a Zn,Al Hydrotalcite-Like Solid and the Derived Alumina-Supported ZnO

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 702
Author(s):  
Raquel Trujillano ◽  
César Nájera ◽  
Vicente Rives
Keyword(s):  
Aqueous Solution ◽  
Microwave Irradiation ◽  
Photocatalytic Degradation ◽  
Hydrothermal Treatment ◽  
Layered Double Hydroxide ◽  
Mixed Oxide ◽  
Photocatalytic Performance ◽  
Ageing Treatment ◽  
Calcined Hydrotalcite ◽  
Double Hydroxide

A Zn,Al layered double hydroxide (LDH), with the hydrotalcite structure and the mixed oxide obtained upon its calcination at 650 °C, was tested in the adsorption and photocatalytic degradation of 4-Nitrophenol in aqueous solution. The Zn,Al LDH was fast and easily obtained by the coprecipitation method. Hydrothermal treatment under microwave irradiation was applied to compare the effect of the ageing treatment on the photocatalytic behavior. The efficiency of the synthetized solids was compared to that of a commercial ZnO. The ageing treatment did not improve the performance of the original samples in the degradation of 4-nitrophenol. The activity of the synthetized solids tested exceeded that observed for the reaction with commercial ZnO. The photocatalytic performance of the original non-calcined hydrotalcite is similar to that of commercial ZnO. The calcined hydrotalcite showed a better performance in the adsorption-degradation of the contaminant than ZnO, and its reusability would be possible as it recovered the hydrotalcite-like structure during the reaction.

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