Mesoporous silica nanoparticles, with and without the inclusion of a magnetic core, were hydrothermally synthesized and employed as carrier of the antibiotic norfloxacin (NFX). The antibiotic-loaded materials were prepared by wet impregnation. Differences in drug content (and in further release profile) were directly related to changes in surface area, particle aggregation and hydrophobicity of the solids.
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
March 2018
Interactions between pesticides (paraquat, glyphosate, 2,4-D, atrazine, and metsulfuron methyl) and soil organic and inorganic components have been studied in batch experiments by performing adsorption, dissolution, and chemical and photochemical degradation under different conditions. The obtained results confirm that the affinity of a pesticide to the solid surface depends on the nature of both and shows that each reactant strongly affects the mobility of the other one, e.g.
View Article and Find Full Text PDFMesoporous silica materials were synthesized in alkaline and acidic media, using cetyltrimethylammonium tosylate (CTAT), Pluronic triblock copolymers F127 and F68, and mixtures of CTAT with each copolymer in order to investigate the effects of pH, surfactant concentration, and CTAT/triblock copolymer molar ratios on the morphology and texture of the synthesized materials. The results show that the kind of mesoporous materials and their pore size can be tuned by changing not only the pH but also the proportion of components and the nature of the copolymer. In alkaline synthesis, microscopic bicontinuous materials are obtained, which are composed by nanoscopic plate-like particles having slit-shaped pores.
View Article and Find Full Text PDFJ Colloid Interface Sci
November 2011
The adsorption of the herbicide paraquat (PQ(2+)) on the binary system titania-silica has been studied in batch experiments by performing adsorption isotherms under different conditions of pH, supporting electrolyte concentration, and temperature. Adsorption kinetic on the studied material has also been carried out and discussed. PQ(2+) adsorption is very low on the bare silica surface but important on the composed TiO(2)-SiO(2) adsorbent.
View Article and Find Full Text PDFJ Hazard Mater
September 2011
Removal of the antibiotic tetracycline (TC) by TiO(2) and the mesoporous binary system TiO(2)-SiO(2) have been studied in batch experiments by performing adsorption isotherms/kinetics and photodegradation kinetics under different conditions of pH, supporting electrolyte concentration, temperature, adsorbent amount, and TiO(2)-loading. On the one hand, the adsorption of TC on the studied materials is strongly dependent on pH, increasing as pH decreases. The adsorption mechanism, controlled by diffusion processes, is strongly related to electrostatic attractions and H-bond formations mainly between amide, carbonylic and phenolic groups of the antibiotic and the functional groups of TiO(2).
View Article and Find Full Text PDFThe adsorption of the herbicide paraquat (PQ(2+)) on goethite and on the binary system humic acid-goethite has been studied in batch experiments by performing adsorption isotherms under different conditions of pH, supporting electrolyte concentration and temperature. The results were completed with capillary electrophoresis (CE) in order to measure the binding isotherm between PQ(2+) and humic acid (HA) molecules in solution. PQ(2+) adsorption is negligible on the bare goethite surface but important on the HA-goethite adsorbent.
View Article and Find Full Text PDFThe dissolution kinetics of humic acid particles has been studied in batch experiments, and the effects of monocarboxylic (formic, acetic, and propionic) acids are reported. The dissolution rate of the particles is significantly affected by the presence of monocarboxylic acids in the pH range 4-10. At pH 7, for example, propionic acid increases 30 times this dissolution rate.
View Article and Find Full Text PDFJ Colloid Interface Sci
July 2007
The adsorption kinetics of phosphate and arsenate on goethite is studied and compared. Batch adsorption experiments were performed at different adsorbate concentrations, pH, temperatures and stirring rates. For both oxoanions the adsorption rate increases by increasing adsorbate concentration, decreasing pH and increasing temperature.
View Article and Find Full Text PDFJ Colloid Interface Sci
August 2006
The adsorption kinetics of phosphate on goethite has been studied by batch adsorption experiments and by in situ ATR-IR spectroscopy at different pH, initial phosphate concentrations and stirring rates. Batch adsorption results are very similar to those reported by several authors, and show a rather fast initial adsorption taking place in a few minutes followed by a slower process taking place in days or weeks. The adsorption kinetics could be also monitored by integrating the phosphate signals obtained in ATR-IR experiments, and a very good agreement between both techniques was found.
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