Estudo da typha angustifolia l. como material vegetal adsorvente para a remoção dos agrotóxicos trifluralina, clorpirifós e α-endossulfam de meio aquoso
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Data
2016-02-26
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Universidade Federal de Goiás
Resumo
Because of the toxicological relevance of pesticides introduced into the environment through
agricultural practices, it is necessary to develop simple methodologies with low cost, enabling
remove these pollutants from the environment, in particular of water intended for human
consumption. The adsorption process is an efficient and low cost technique that have wide
application. The adsorbent capacity of the leaves of Typha angustifolia L. herbaceous perennial
plant belonging to the family Typhaceae, in Brazil it is also popularly known as taboa, was
investigated for the removal of pesticides trifluralin, chlorpyrifos and α-endosulfan from
aqueous medium. The the analytical method using solid phase extraction (SPE) and
chromatography with electron capture detector (GC/ECD) was optimizates and validate. The
validation criterions were reached and the analytical methos was considered efficient for
trifluralin, chlorpyrifos and α-endosulfan quantification in an aqueous medium, providing
credibility to the results obtained in the adsorption experiments. The adsorption capacity of T.
angustifolia was evaluated under different parameters: treatment of the material, amount of
material, contact time between the plant material and the pesticides solution and
concentration of the pesticides solution. The results showed that treatment of the material
with distilled water and was satisfactory and, for all doses evaluated the pesticide removal
was efficient, with best results obtained at a dose of 3.0 g L-1
, equivalent to 60 mg of adsorbent
in 20.0 mL of solution, in which the pesticide removal were between 73 and 80%. The
adsorption kinetics of the pesticide by T. angustifolia showed that the adsorption equilibrium
was reached in 40 minutes for all pesticides, removing up to 90% and using a very small
amount of plant material (3 g L-1
). The experimental data were evaluated using the kinetic
models of pseudo-first order, pseudo-second order and Avrami. One of the limitations
encountered in the concentration influence study is the limited solubility of the agrochemical
in aqueous medium (between 0.33 and 1.00 mg L-1
), resulting in the study of a small
concentration range in the adsorption experiments. To study the pesticides adsorption
mechanism by T. angustifolia material, the experimental data were applied to Langmuir,
Freundlich and Sips non-linear isotherms models. Additional tests showed that the adsorption
capacity is unaffected when using natural water in the adsorption experiments. The results
indicate that the material obtained from of T. angustifolia leaves, has a great potential to be
used as an alternative adsorbent material in pesticide contaminated aqueous solution
treatment.
Descrição
Palavras-chave
Typha angustifolia L., Trifluralina, Clorpirifós, α- endossulfam, Adsorvente alternativo, SPE,, GC/ECD, Typha angustifolia L., Trifluralin, Chlorpyrifos and α- endosulfan, Alternative adsorbent, SPE, GC/ECD
Citação
MENDES, M. F. Estudo da typha angustifolia l. como material vegetal adsorvente para a remoção dos agrotóxicos trifluralina, clorpirifós e α-endossulfam de meio aquoso. 2016. 103 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2016.