Zeolitas naturales en la protección del medio ambiente

BOTTO, I L., AGOSTO, M F. ZUCCHI, B. MILLÁN, G, VAZQUEZ, M., CABELLO, C., SCHALAMUK, I.

Ciencia

Lugar: Argentina ; Año: 2007 p. 1 - 9

Rich -ammonium liquid industrial waste represents a serious environmental problem affecting human health, water life and production development. Most methods used for ammonium removal are very expensive. However there are simple and lower cost alternatives associated to the structural role of some mineral species such as clays and zeolites.  From an interdisciplinary point of view, the present work assesses the potentiality of zeolite minerals from Argentinian deposits to process rich -ammonium liquid industrial waste, analyzing  also the eventual agricultural application of the residual solid material. The highest selectivity of clinoptilolite zeolite  (theoretical composition Na6Si30Al6O72.nH2O) towards higher cations (NH4>Na>Ca>Mg),  enables the cationic exchange capacity and  constitutes the basic treatment of an industrial  contaminated liquid  with a mean ammonium content of  1.7%. The procedure leads to the formation of exchanged ammonium-zeolite, where the ammonium interacts with a Na-free zeolite  matrix. The reduction of ammonium toxicity is around 80%. This value is reached after two kinds of treatments in batch at room temperature for 96 h and slight stirring. Simultaneously, it is observed a considerable clearness of the treated liquid, advantage associated  to the additional role of mineral species as filter of colloidal organic matter. Composition and structure features of the solid material have been studied through several techniques such as: X Ray Diffraction (XRD); Fourier Transformed Infrared Spectroscopy (FTIR); Chemical analysis by Inductively coupled Plasma (ICP), Analysis of specific surface by Brunauer, Emmett and Tellet method (BET), Scanning Electronic Microscopy complemented with semi-quantitative analysis by Dispersive Energy by X Ray Absorption (SEM, EDAX) and Chemical Analysis of nitrogen by Kjeldhal method.  The assessed parameters are relevant for soil behavior (slow N-release, high structural stability of the mineral to use as support material, excellent hydrous retention and acidity close to neutrality), ensuring the presence of an indispensable macronutrient for the vegetable growth.  The preliminary results are promising as regards the use of a natural resource in the contaminant removal, profiting the potentiality of the remaining solid for soil conditioner with very low risk of environmental impact.