INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Adsorption of glyphosate on modfied zeolitas
Autor/es:
A. TRINELLI; E. CHMIELEWSKÁ; M. DOS SANTOS AFONSO
Lugar:
Mar del Plata, Argentina
Reunión:
Congreso; V Congreso Iberoamericano de Fisica y Quimica Ambiental; 2008
Institución organizadora:
UNSAM, UBA, SiFyQA
Resumen:
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Glyphosate (N-phosphonometyl)
glycine, PMG), is an organophosphorous compound, derived from the glycine
aminoacid. It is a wide spectrum herbicide, non selective, widely in Argentina and worldwide, mainly in soybean,
corn, sunflower and wheat crops.
Zeolites are groups of porous
aluminosilicates (mineral tectosilicates) found mainly in the nature in
sedimentary rocks of volcanic origin. They possess cavities of molecular
dimensions that allow them to work as ionic exchangers 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 contaminated waters for the removal
of various kinds 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 aqueous solutions with
carbonized clinoptilolite (CMZ) (2), clinoptilolite-rich tuff hydrofobized with
an organic ammonium base, octadecylammonium acetate (ODAZ) (1) and with clinoptilolite without treatment (CZ)
(Slovak origin). The experiments were carried out at constant ionic strength,
temperature and pH. Suspentions were .preparing
at fixed pH and ionic strengths of KCl. After that, the herbicide solution was
added and suspensions were kept with permanent agitation during 24 hours. The
pH was readjusted to a constant value by adding aliquots of NaOH or HCl and was
measured prior to all analyses The samples were centrifuged at 17000 rpm. The
concentrations of remaining PMG were determined by ionic chromatography in the
supernatant. Some complementary studies were carried out for characterization
of the surfaces by means of SEM, UV-VIS diffuse reflectance, IEPpH and powder
XRD.
The PMG adsorption isotherms
on CMZ, ODAS and CZ were determined. It was found that the best PMG adsorption
rate appears for ODAZ