ADSORPTION OF GLYPHOSATE ON MODIFIED ZEOLITES

MARÍA ALCIRA TRINELLI; EVA CHMIELEWSKÁ; MARÍA DOS SANTOS AFONSO

Mar del Plata, Bs. As., Argentina

Congreso; V Congreso Iberoamericano de Fisica y Química Ambiental; 2008

Sociedad Iberoamericana de Física y Química ambiental, Universidad Nacional de San Martín, Facultad de Ciencias Exactas y naturales-UBA, Comisión Nacional de Energía Atómica

The glyphosate (N-phosphonometyl) glicine, PMG), is an organophosphorous compound, derived from the aminoacid glicine. It is a wide spectrum herbicide, not selective, very used in Argentina and in the rest of the world, mainly in cultivations of soya, corn, sunflower and wheat.                  The zeolites are groups of porous aluminosilicates (mineral tectosilicatos) found mainly in the nature in sedimentary rocks of volcanic origin. They possess cavities of molecular dimensions that allow them to work as ionic interchangers and as true molecular sieves. They have been used for the production of inclusion materials with diverse uses including different components inside their channels. They have also been used indeed in the treatment of columns of water for the removal of pollutants. The zeolites can be specifically modified to increase their detoxification capacity (1, 2).                  In this work batch adsorption experiments were carried out in 500 ppm PMG water solutions with carbonized clinoptilolite (2) (CMZ), clinoptilolite-rich tuff hydrofobized with an organic ammonium base, octadecylammonium acetate (1) (ODAZ) and with clinoptilolite without treatment (Slovak origin). The experiments were carried out preparing the zeolite suspensions in the pesticide solution; they were equilibrated for 24 hours, to constant ionic force, temperature and pH. They were centrifuged at 17000 rpm. The concentrations of remaining PMG were determined by ionic chromatography in the supernatant. They were also carried out studies of characterization of the surfaces by means of SEM, UV-Vis diffuse reflectance, IEPpH and powder XRD.                  It was found that the best PMG adsorption rate appears for ODAZ. The adsorption isotherms were determined.       References: 1)   Chmielewská, E. Adsorption of Arsenate and Chromate from Waters on Hydrophobized Zeolitic Media, Turk J Chem, 27, 639, 2003. 2) Chmielewská, E.; Pilchowski, K. Surface Modifications of Natural Clinoptilolite-Dominated Zeolite for           Phenolic Pollutant Mitigation, Chem Pap, 60, 98, 2006.