Adsorption of copper(II) and cobalt(II) complexes on a silica gel surface chemically modified with 3-amino-1,2,4-triazole

RETRACTED: Designed pendant chain covalently bonded to analogue of heulandite for removal of divalent toxic metals from aqueous solution: Thermodynamic and equilibrium study

“…The Gibbs free energy can be calculated by the equation DG = ÀRTln K S , the entropy is finally calculated from DG = DH À TDS [19,20].…”

Preparation, characterization, and CuX2 and CoX2 (X=Cl−, Br−, ClO−4) adsorption behavior of a polyhedral oligomer silsesquioxane functionalized with an organic base

“…The adsorption capacity of ATPS for CuX 2 from ethanol solution is higher than that obtained with silsesquioxane 3-npropylpyridiniumchloride polymer (SiPyCl) [10], or silica gel surface chemically modified with benzimidazole [18,27], imidazole [20,21], or 3-amino-1,2,4-triazole [28]. For instance, the adsorption capacity for the determination of CuCl 2 from ethanol solution on SiPyCl [10] and benzimidazole-modified silica [18,27] is 0.34 and 0.22 mmol g −1 , respectively.…”

Kinetics and equilibrium parameters of Hg(II) adsorption on silica–dithizone

“…This value represent, in average, the occupation of about 45% of the total silanol groups on the surface [1,28]. Assuming that the molecules cover the surface uniformly, and knowing that the specific area of the Sil-dtz (S BET ) was 350 ± 20 m 2 g −1 , the average density, d, of the attached molecules and the average intermolecular distance, l, can be calculated by applying the equations [29] (2)…”

“…The second mass loss step, about 140-350 • C, is due to the release of the immobilized dithizone molecule. For this mass loss region, the presence of an asymmetric DTG peak suggests the release of different forms of silica-immobilized dithizone molecule, using both the thiol and the secondary amine groups [1,5], since other silica-immobilized bifunctional organic molecules also presented relatively similar reaction behavior [4,7,23,29]. The third mass loss region, from 300 to 700 • C, present several DTG peaks, suggesting the progressive release of the different forms of the silica-attached alkoxysilane molecule (cpts), as well observed earlier, using both solid-state 13 C and 29 Si RMN [1].…”