Thermodynamics and Kinetics of Pretilachlor Adsorption on Organobentonites for Controlled Release

Abstract

Thermodynamics and kinetics of pretilachlor adsorption on organobentonites modified with hexadecyltrimethyl ammonium chloride were investigated to reveal the structural effects of organobentonites on the interaction with pretilachlor and the diffusion of the herbicide and were related to the controlled release from organobentonites. The adsorption of pretilachlor was entropically driven by hydrophobic interaction. The entropy change dropped with increasing surfactant loading from 0.4 to 1.50 times the cation exchange capacity (CEC) of the bentonite used, corresponding to a decrease in the degree of freedom of pretilachlor molecules due to the enhanced order of surfactant in the interlayer. The kinetics of pretilachlor adsorption was well fitted to the pseudo-second-order model and related to the structural features of organobentonites. The enhanced packing density of the surfactant in the interlayer generally resulted in a reduction of the rate constant of the pretilachlor adsorption onto organobentonites. However, the stepwise increase in the basal spacing due to the surfactant arrangement transition, from lateral-monolayer to lateral-bilayer at a loading level of more than 0.8 × CEC, benefited the diffusion of pretilachlor and diminished the influence of the increase in surfactant packing density. The release of pretilachlor from organobentonites was predominated by Fickian diffusion, which could be understood from the adsorption thermodynamics and kinetics. The time taken for the release of 50% of active ingredient was 16–23 times that for the control formulation and exhibited a linear increase with the relative value of the equilibrium constant to the rate constant of pretilachlor adsorption.

Azo-functionalized superparamagnetic Fe3O4 nanoparticles: an efficient adsorbent for the removal of bromocresol green from contaminated water

“…The negative values of DG imply that BCG adsorption on ADFS is a spontaneous process and that the adsorbate prefers to remain in the stationary/adsorbed phase rather than in the solution phase. 67,68 These results coincide with those of the adsorption isotherms.…”

“…The adsorption of BCG on ADFS was found to be enthalpy-driven by hydrogen bonding and van der Waals interactions ( Table 2 ). 68 …”

Pretilachlor Releasable Polyurea Microcapsules Suspension Optimization and Its Paddy Field Weeding Investigation

“…Then, the precipitate was dispersed in 3 mL of solution (pH 4.0), continuously shaken at 25 o C at certain intervals, and centrifuged at a rate of 10,000 r/min to collect the precipitate and quantify the release of pretilachlor (M t ). The release kinetics of the microcapsules were measured with the Korsmeyer-Peppas model (Ritger and Peppas, 1987a,b;Wu et al, 2020), which is described according to Equation 3:…”

“…The overuse of pretilachlor may cause harm to the environment by damaging non-target plants, water, sediment, and food (Ismail and Handah, 1999;Vencill et al, 2012;Palma et al, 2014;Papadakis et al, 2015). For these reasons, numerous efforts have been devoted to minimizing the adverse effects and environmental toxicity of herbicides, such as using them along with safeners, packing them with carrier materials, or loading them into microcapsules (Hedaoo et al, 2013;de Oliveira et al, 2015;Cao et al, 2016;Liu et al, 2016;Wu et al, 2020). Microcapsules with controlled release abilities can prevent herbicides from leaking via evaporation or degradation during application so as to ultimately improve the herbicidal efficiency and minimize non-target toxicity (Hedaoo et al, 2013(Hedaoo et al, , 2014Zhang et al, 2016Zhang et al, , 2018, which has become a popular and feasible trend in recent years.…”

Capability of Organically Modified Montmorillonite Nanoclay as a Carrier for Imidacloprid Delivery

“…The preparation of organically modified clays, including nanoclay and clay-based nanocomposites, has attracted much attention because of their various commercial and industrial applications, − among others, as adsorbents for the removal of organic pollutants, − such as pesticides. , Organically modified clays have also been well investigated as potential carriers for the preparation of controlled-release formulations (CRFs) for pesticides. − Recently, the preparation of CRFs has become a promising approach to enhance the efficiency of pesticides and limit the release of large doses into the environment. − To prepare a successful CRF, it is important to ensure a high loading of active ingredients to the carriers as well as their controlled-release behavior from the carrier matrix. To this end, clays are modified with organic molecules which alter their surface properties from hydrophilic to hydrophobic. , Therefore, sorption of organic molecules (e.g., pesticides) is facilitated via hydrophobic interaction, while the release behavior is controlled via the partitioning mechanism …”