Synthesis, Characterization, and Environmental Applications of Hybrid Materials Based on Humic Acid Obtained by the Sol Gel Route

Autor(es)

de Oliveira, Lilian Karla ^[1] ; Molina, Eduardo Ferreira ^[1] ; Moura, Andre L. A. ^[1] ; de Faria, Emerson Henrique ^[1] ; Ciuffi, Katia Jorge ^[1]

Afiliação do(s) autor(es)

^[1] Univ Franca, Ave Armando Salles Oliveira 201, BR-14404600 Franca, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ACS APPLIED MATERIALS & INTERFACES; v. 8, n. 2, p. 1478-1485, JAN 20 2016.
• Citações Web of Science: 4

Resumo

Humic acids (HAs) are ubiquitous macromolecules in the environment. Due to their high contents of oxygenated functional groups, they can interact with contaminants present in the natural environment and therefore influence the behavior of pollutants. However, a pH of 2 or lower is required to maintain HAs in the solid form. To increase the stability of HAs and their capacity to bind to contaminants, this work proposes the development of new hybrid materials based on alkoxysilanes and HAs for environmental applications such as dye adsorption. Three different materials with new functional groups were prepared by employing the following alkoxysilanes: tetraethyl orthosilicate, (3-aminopropyl)triethoxysilane, and N-{[}3-(trimethoxylsilyl)propyl]ethylenediamine. The final materials were denoted HWA, HOA, and HTA, respectively, and they were characterized by elemental analysis, diffuse reflectance Fourier-transform infrared spectroscopy (DRIFT), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and N-2 gas-volumetric adsorption. The point of zero charge (pzc) and stability of these materials were also determined. Their selectivity was evaluated in adsorption experiments performed with two different charged dyes in aqueous medium, namely anionic rose bengal (RB) and cationic methylene blue (MB). The elemental, DRIFT, SAXS, SEM, and textural analyses confirmed the presence of a combination of the features of HAs and alkoxysilanes. The pzc results showed that the new materials displayed different characteristics and affinities. All the materials were stable in aqueous solution up to pH 10. For MB, the percentage removal values obtained by using HWA, HOA, and HTA were 98, 85, and 67%, respectively. As for RB, the percentage removal values were 19, 18, and 44% for HWA, HOA, and HTA, respectively. These hybrid materials have potential use as adsorbents for the removal of cationic or anionic species and could be viable alternatives to remove various substances present as contaminants in natural environments. (AU)

• Processo FAPESP: 13/27039-4 - Materiais híbridos baseados em substâncias húmicas e alcóxidos silanos: avaliação da eficiência e seletividade na adsorção de contaminantes orgânicos e inorgânicos
• Beneficiário: Lílian Karla de Oliveira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado