Comment on the article by Isaac Cohen Orantes and Gert Rosenthal "Reflections on the conceptual framework of Central American economic integration"

Includes bibliography

Study of adsorption and preconcentration by using a new silica organomodified with [3-(2,2′-dipyridylamine)propyl] groups

In this work, a silica surface chemically modified with [3-(2,2′-dipyridylamine)propyl] groups, named [3-(2,2′- dipyridylamine)propyl]silica (Si-Pr-DPA) was prepared, characterized, and evaluated for its heavy metal adsorption characteristics from aqueous solution. To our knowledge, we are the first authors who have reported the present modification. The material was characterized using infrared spectroscopy, SEM, and NMR 29Si and 13C solid state. Batch and column experiments were conducted to investigate for heavy metal removal from dilute aqueous solution by sorption onto Si-Pr-DPA. From a number of studies the affinity of various metal ions for the Si-Pr-DPA sorbent was determined to follow the order Fe(III) > Cr(III) >> Cu(II) > Cd(II) > Pb(II) > Ni(II). Two standard reference materials were used for checking the accuracy and precision of the method. The proposed method was successfully applied to the analysis of environmental samples. This ligand material has great advantage for adsorption of transition-metal ions from aqueous medium due to its high degree of organofunctionalization associated with the large adsorption capacity, reutilization possibility, and rapidity in reaching the equilibrium. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preconcentration and determination of metal ions from fuel ethanol with a new 2,2'-dipyridylamine bonded silica

A silica surface chemically modified with [3-(2,2'-dipyridylamine) propyl] groups was prepared, characterized, and evaluated for its metal ion preconcentration in fuel ethanol. To our knowledge, we are the first authors who have reported the present modification on silica gel surface. The material was characterized using infrared spectra, scanning electronic microscopy, and 13C and 29Si solid-state NMR spectra. Batch and column experiments were conducted to investigate for metal ion removal from fuel ethanol. The results showed that the Langmuir model describes the sorption equilibrium data of the metal ions in a satisfactory way. From the Langmuir isotherms, the following maximum adsorption capacities (in mmolg -1) were determined: 1.81 for Fe(III), 1.75 for Cr(III), 1.30 for Cu(II), 1.25 for Co(II), 1.15 for Pb(II), 0.95 for Ni(II), and 0.87 for Zn(II). Thermodynamic functions, the change of free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) showed that the adsorption of metal ions onto Si-Pr-DPA was feasible, spontaneous, and endothermic. The sorption-desorption of the metal ions made possible the development of a preconcentration and quantification method of metal ions in fuel ethanol. © 2012 Elsevier Inc.

Comentario sobre el artículo de Isaac Cohen Orantes y Gert Rosenthal "Reflexiones sobre el marco conceptual de la integración económica centroamericana"

Incluye Bibliografía

Avaliação histopatológica e imuno-histoquímica do miocárdio de cães com leishmaniose visceral: Fernando Azadinho Rosa. -

Pós-graduação em Ciência Animal - FMVA

Organização e espontaneidade: a autonomia das massas no pensamento dialético de Rosa Luxemburg

Pós-graduação em Ciências Sociais - FFC

A construção da imagem em O Espelho in Primeira estórias de João Guimarães Rosa e em Las meninas de Pablo Picasso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

As poesias de Guimarães Rosa em Ave, Palavra: um caminho de leitura

Pós-graduação em Estudos Literários - FCLAR

Construcción de vivienda de bajo costo en Perú: casos Los Precursores y Santa Rosa

Incluye Bibliografía

Análise intertextual do conto “A volta do marido pródigo”, de Guimarães Rosa, com a parábola O filho pródigo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Terapia fotodinâmica em esporos de bacillus atrophaeus e bacillus subtilis: estudos com LASER, LED, azul de metileno, rosa bengala e verde malaquita

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Guimarães Rosa à luz de uma transposição cinematográfica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Representações da velhice em alguns contos de Guimarães Rosa e Mia Couto

Pós-graduação em Letras - IBILCE

Entre beleza e tristeza: experiência e memória em Campo geral de Guimarães Rosa

Pós-graduação em Letras - IBILCE