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Laboratory experiments were conducted to examine ability of clay minerals and organic matter to remove the cadmium(II) and chromium(III) ions from aqueous effluents. Sample materials for the experiments were taken in Poland and Spain. Their chemical composition, specific surface area, pH in water and potassium chloride, ion exchange capacity and absorption of Cr (III) and Cd (II) have been studied. The clay samples exhibited greater sorption capacity for Cr(III) than for Cd(II) while organic matter, especially brown coal, better sorbed Cd(II) than Cr(III). The Langmuir binding strength parameter (k) was always greater for Cr than for Cd. On the basis of the sequential extraction and microanalysis by SEM it was stated that iron oxides were not involved in the Cd ion binding while their role in Cr(III) binding was essential. Ion binding by Fe oxides and their missing at exchangeable positions yields weak both susceptibility to leaching and mobility of Cr(III) ions. Instead, Cd(II) ions are mainly bound at exchangeable positions, susceptible to leaching.La industria y las urbes descargan sobre los ríos aguas que representan un factor importante en la contaminación medioambiental. La agricultura se ve afectada, siendo uno de los problemas el alto contenido en metales pesados presentes en el suelo o las aguas utilizadas para el riego. En este trabajo se expone la posibilidad de utilizar materiales de bajo costo, minerales arcillosos y carboníferos, tomados en España y Polonia, para remediar esta contaminación. Se ha estudiado su composición química, superficie específica, pH en agua y cloruro potásico, capacidad de intercambio iónica y absorción de Cr (III) y Cd(II). Las muestras arcillosas mostraron mayor capacidad de absorción para el ion Cr(III) que para el Cd(II), mientras que las orgánicas, especialmente la denominada “ brown coal” (lignito), fueron mejores adsorbentes del ion Cd. El parámetro k obtenido en las isotermas de absorción según Langmuir, que define la fortaleza del enlace, fue siempre mayor para el Cr que para el Cd. Basándose en los análisis químicos de las extracciones secuenciales efectuadas y en los microanálisis puntuales por Microscopía electrónica de barrido (MEB+EDS) se puede concluir que la presencia de hierro en determinadas microáreas es determinante para la fijación del Cr y sin embargo los iones Cd quedan retenidos por enlaces a posiciones intercambiables y por eso son susceptibles de ser lixiviados.

Chitosan (CS) and purified sodium beidellite (Na-Bd) were used to obtain a nanocomposite able to carry anionic pharmaceutical ingredients. Diclofenac sodium (DS) was chosen as a model drug and was loaded by intercalation solution technique. Solid state characterization of the resultant hybrids was performed, including X-ray diffraction, Fourier transformed infrared spectroscopy, Thermal analysis and high resolution transmission electron microscopy coupled with energy dispersive X-Ray analysis. Drug loading capacity and encapsulation efficiency were quantified by measuring equilibrium concentration by UV-Vis spectroscopy at 276 nm. Solid-state characterization of the samples confirmed both chemical and physical interaction of DS with the nanocomposites. High drug loading along with a modified cumulative release of the drug in simulated intestinal fluid was obtained. The developed clay/polymer hybrids can act as potential candidates for the design of modified dosage forms of anionic drugs., (Copyright © 2018 Elsevier B.V. All rights reserved.)