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Title of article :
A comparative study between chloride and calcined carbonate hydrotalcites as adsorbents for Cr(VI)
Author/Authors :
Carriazo، نويسنده , , D. and del Arco، نويسنده , , M. and Martيn، نويسنده , , C. and Rives، نويسنده , , V.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2007
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Abstract :
Hydrotalcite-type solids with different metal ions within the layers (MII = Mg or Zn and MIII = Al and/or Fe) and carbonate or chloride between them have been synthesized. Chloride-LDHs and the solids obtained upon carbonate-LDHs calcination have been evaluated in the adsorptive removal of Cr(VI) from aqueous solutions. All the adsorption tests were carried out at 30 °C following two different stirring conditions: a) using a thermostatic bath with mechanical stirring at a speed of 52 rpm or b) in a sonicator bath under ultrasound waves. It was observed that no significant difference in the amount of adsorbed chromate is produced in both cases but the time spent to reach the equilibrium is much lower when the adsorbent/adsorbate mixture is submitted to ultrasounds. In all experiments L-type adsorption isotherms were obtained. The results show that chloride hydrotalcites are better adsorbents than calcined CO3-hydrotalcites and in these last ones their adsorption capacity increases with increasing the surface area: MgAlFe > MgAl > MgFe > ZnAl.
Keywords :
layered double hydroxides , chromate , Adsorption , Wastewater , Kinetics
Journal title :
Applied Clay Science:an International Journal on the Application...
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