title: Preparation, characterization, and CuX2 and CoX2 (X=Cl-, Br-, ClO-4) adsorption behavior of a polyhedral oligomer silsesquioxane functionalized with an organic base.
abstract: In this paper we report on the synthesis, characterization, and adsorption properties of the first 3-amino-1,2,4-triazole-modified porous silsesquioxane (ATPS). The isotherms of adsorption of MX(2) (M=Cu(II), Co(II); X=Cl(-), Br(-), ClO(-)(4)) by ATPS were studied in ethanol and aqueous solutions at 298 K. The results showed that there is a good fit between the experimental data and the Langmuir isotherm. The adsorption capacity in both solvents followed the sequence Cu(II)>>Co(II). The lowest adsorption for Co(II) should be related to the largest hydration volume, which obstructs the adsorption capacity of the surface, and consequently causes a decrease in the number of cations adsorbed. For the salts with different anions the sequence was MCl(2)>MBr(2)>M(ClO(4))(2) in both solvents. The low affinity for M(ClO(4))(2) toward the solid phase is a consequence of the poorer coordination ability of the ClO(-)(4). Adsorptions from ethanol solutions were higher than those from aqueous solutions due to the higher polarity of water, which can more strongly solvate the solute and the basic sites on the surface. The following adsorption capacities (in mmol g(-1)) were determined: 0.24 (aq) and 0.84 (eth) for CuCl(2), 0.09 (aq) and 0.16 (eth) for CuBr(2), and 0.08 (aq) and 0.11 (eth) for Cu(ClO(4))(2); 0.02 (aq) and 0.07 (eth) for CoCl(2), 0.02 (aq) and 0.06 (eth) for CoBr(2), and 0.01 (aq) and 0.05 (eth) for Co(ClO(4))(2).
authors.affiliation: Departamento de Física e Química, UNESP-Universidade Estadual Paulista, Ilha Solteira, SP, Brazil. nldias@dfq.feis.unesp.br
authors.forename: Newton Luiz
authors.initials: NL
authors.lastname: Dias Filho
authors.forename: Fabiane
authors.initials: F
authors.lastname: Marangoni
authors.forename: Reginaldo Mendonça
authors.initials: RM
authors.lastname: Costa