Agriculture Reference
In-Depth Information
Fig. 11.6 Cumulative release of atrazine from granules into static water (error bars represent the
standard deviation of three replicates). Reprinted (adapted) with permission from Fern´ndez-P´rez
et al. (
2004
), copyright 2014 American Chemical Society
controlled-release formulation AALB-0.5 (containing 1.2 % of technical grade
atrazine (A), 1.4 % of sodium alginate (AL), and 5 % of acid-treated bentonite).
Singh et al. (
2009
) studied the incorporation of clays such as kaolin and
bentonite as reinforcement to alginate and starch, intended for the controlled release
of the fungicide Thiram
®
. The presence of both clays in the polymer delayed the
fungicide release. The authors found out that the use of such composites as
controlled-release systems can be very useful for safely handling of pesticides. In
the study conducted by Chevillard et al. (
2012
), a slow release of ethofumesate was
observed due to the use of hydrophobic montmorillonites as carrier matrixes. Such
a behavior was explained by the higher affinity of ethofumesate with the composite
in the presence of hydrophobic clay than of the hydrophilic montmorillonite. They
observed that the release mechanisms were particularly governed by interactions
between pesticides and montmorillonite. The clay acted at the component interface
decreasing or even nullifying the chemical incompatibility.
Grillo et al. (
2014
) studied the controlled-release behavior of the pesticide
Paraquat
®
, in hydrogels composed of poly(vinyl alcohol) cross-linked with glutar-
aldehyde. The authors observed that the pesticide release process was strongly
dependent on the concentration of glutaraldehyde. The hydrogels exhibited a poor
release capacity of pesticide when it was confined in highly cross-linked hydrogels.
More recently, some works (Zhang et al.
2006
; Kasgoz and Durmus
2008
)
described the influence of the addition of calcium montmorillonite on the controlled
release of herbicides from a hydrogel based on carboxymethyl cellulose. They
found out that the addition of montmorillonite significantly prolonged the herbicide
release.
