Anion capture with calcium, aluminium and iron containing layered double hydroxides

Abstract

The competitive adsorption of nitrate, chloride and carbonate in layered double hydroxides (LHD) with the general formula Ca

Innovative method for hydrocalumite-like compounds' preparation and their evaluation in the transesterification reaction

“…Additionally, HC and HLC materials have been employed in environmental remediation for chloride, nitrate and carbonate (Phillips and Vandeperre, 2011), borate, sulfate, and arsenate (Reardon and Valle, 1997), chromate and phosphate (Qian et al, 2012), Cd 2+ , B, Cr, Mo, and Se (Hang and Reardon, 2003), Zn 2+ (Liu et al, 2011), perchlorate (Kim et al, 2011), dye (Pereira de Sá et al, 2013); (Zhang et al, 2012a) and organic pollutant (Zhang et al, 2012b) removal.…”

Effect of formation pH, molar ratio and calcination temperature on the synthesis of an anionic clay based adsorbent targeting defluoridation

“…However, Chrysochoou and Dermatas (2006) suggested a higher pH of above 10.5 for calcium based HTlc. Generally, studies suggest a pH range of 11 to 13 for the preparation of calcium based LDH (Rousselot et al, 2002;Phillips and Vandeperre, 2011;Woo et al, 2011;Sipiczki et al, 2013;Rojas, 2014). As discussed in Section 1, the calcination should be conducted at an optimal range of temperature to enhance the adsorption capacity of LDH.…”

Effect of microwaves, ultrasounds and interlayer anion on the hydrocalumites synthesis

“…In the particular case of hydrocalumites, the layers are formed by [Ca 2 Al(OH) 6 ] + whereas the interlayers are composed of water molecules and anions (e.g. OH À , NO 3 À , SO 4 2À , CO 3 2À , or Cl À ) [1][2][3][4][5][6][7][8][9]. For hydrocalumite, Ca 2+ and Al 3+ , fixed in a molar ratio of two, are seven and sixfold coordinated, respectively, being the seventh ligand of the Ca-polyhedron a water molecule from the interlayer [5].…”

“…For hydrocalumite, Ca 2+ and Al 3+ , fixed in a molar ratio of two, are seven and sixfold coordinated, respectively, being the seventh ligand of the Ca-polyhedron a water molecule from the interlayer [5]. Hydrocalumites have been extensively used in the immobilization of toxic cations [4][5][6][7][8][9][10][11], the optimization of concrete properties [2,3,[12][13][14], and, in less extent, for catalysis due to their basic properties [15]. The structure of hydrocalumites collapses at temperatures between 400 and 600°C due to the dehydroxylation of their octahedral layers, giving rise to the formation of an amorphous, basic Ca-Al mixed oxide, Ca(Al)O x , which may be also used as catalyst for organic reactions such as the Meerwein-PonndorfVerley reaction [16], the isomerization of 1-butene [17] or the transesterification of castor bean oil and methanol [18].…”