Agriculture Reference
In-Depth Information
According to Paradelo et al. (
2012
), the release process of actives from porous
granules can be described by the Higuchi model. In this model, the diffusion of the
solute occurs basically by three mechanisms: (1) diffusion within the granule;
(2) solubilization of the active ingredient; and (3) movement of the solubility
front inside the granule. Additionally, the authors correlated the release of a
pesticide from a one-dimensional porous solid matrix with a mechanism of solute
transport following the Ritger and Peppas model (
1987
), as depicted in Fig.
5.4
.
5.3 Some Nanomaterials or Nanostructured Materials
Used in CR Systems in Agriculture
5.3.1 Polymeric Matrices
Over the past few decades, several classes of nanostructured polymeric matrices
were used to combat environmental pollution by acting more specifically as carrier
vehicle in the CR systems of various agrochemicals. Beyond needing to be low
cost, it is essential that these matrices be constituted from biodegradable and
renewable sources. The controlled release formulations (or CRF) of agrochemicals
have become an important mechanism of the reduction of pesticides in the envi-
ronment. In the CRF, the formation of a chemical bond between a pesticide and the
polymeric matrix can maximize the release process and consequently improve the
safety, efficiency, and the economic cost for use in crop protection (Li-min
et al.
2005
).
Several authors have shown their contributions in this area. Corradini
et al. (
2010
) studied the sorption capability of the NPK fertilizer into polymeric
nanoparticles. The authors showed a full study of a chitosan nanoparticle stability
that related the efficiency of incorporation of the fertilizers into the nanoparticles
with the zeta potential and the average diameter of the particle. According to
Subbarao et al. (
2013
), slow release fertilizer technology may contribute in the
minimization of fertilizer loss because their indiscriminate use contributes to the
degradation of the environment and soil. In this study, they observed that the
coating of potash fertilizer by the deposition of polyacrylamide polymer decreased
its releasing rate. A novel CR pesticide system based upon self-assembled
nanocapsules with an aqueous core was developed by Sun et al. (
2014
). These
core-shell polymeric nanocapsules were obtained by a photo-cross-linking reaction
using azidobenzaldehyde (Az) and carboxymethyl chitosan (CMCS), as depicted in
Fig.
5.5
.
The authors observed that the encapsulation efficiency of methomyl pesticide-
loaded cross-linked nanocapsules reached approximately 90 %, where the aqueous
core was responsible in the accumulate of a fraction of the methomyl pesticide in its
free state, and other fractions of the absorbed pesticide were located in the surface
and the interior of the shell architectures. In relation to the release profiles of
