3,4-Dichlorophenoxyacetate interleaved into anionic clay for controlled release formulation of a new environmentally friendly agrochemical

Abstract

A new layered organic-inorganic nanohybrid material, zinc-aluminum-3,4-dicholorophenoxyacetate (N3,4-D) in which an agrochemical, 3,4-dichlorophenoxyacetic acid (3,4-D), is intercalated into zinc-aluminum-layered double hydroxide (ZAL), was synthesized by coprecipitation method. A well-ordered nanomaterial was formed with a percentage loading of 53.5% (w/w). Due to the inclusion of 3,4-D, basal spacing expanded from 8.9 Å in ZAL to 18.7 Å in N3,4-D. The Fourier transform infrared study shows that the absorption bands of the resulting nanohybrid composed of both the 3,4-D and ZAL further confirmed the intercalation episode. Thermal analysis shows that ZAL host enhances the thermal stability of 3,4-D. Controlled-release experiment shows that the release of 3,4-D in the aqueous media is in the order of phosphate > carbonate > sulfate > chloride. These studies demonstrate the successful intercalation of the 3,4-D and its controlled release property in various aqueous media.

Figure 1

Molecular structure of 3,4-dichlorophenoxy acetic acid.

Figure 2

PXRD patterns of ZAL and its nanohybrids prepared at various concentrations of 3,4-D (0.035 to 0.5 M).

Figure 3

FTIR spectra of ZAL (a), pure 3,4-D (b), and N3,4-D nanocomposite (c).

Figure 4

Nitrogen adsorption-desorption isotherms of ZAL and their nanohybrids (N3,4-D) (a) and pore size distribution (b).

Figure 5

Surface morphology of (a) ZAL and N3,4-D (b).

Figure 6

TGA-DTA thermograms of ZAL (a), pure 3,4-D (b), and N3,4-D nanocomposite (c).

Figure 7

Release profiles of 3,4-D from N3,4-D into 0.005 M aqueous solutions containing PO₄³⁻, CO₃²⁻, SO₄²⁻, and Cl⁻.

Figure 8

Release profiles of 3,4-D. Fitting the release data of 3,4-D from the nanohybrid into various aqueous media (Na₃PO₄, Na₂CO₃, Na₂SO₄, and NaCl (0.005 M)) using first-order, parabolic diffusion, and pseudo-second-order kinetic models.