Use of Bentonite and Activated Carbon in Controlled Release Formulations of Carbofuran

Abstract

Controlled release systems (CRS), unlike the conventional formulations, facilitate a gradual and controlled discharge of the pesticides, reducing the losses by evaporation and leaching and minimizing pesticide pollution. In this study, carbofuran-an insecticide-nematicide identified as a groundwater pollutant-was incorporated in alginate-based granules to obtain controlled release properties. The effect on carbofuran release rate caused by the incorporation of bentonite, activated carbon, and different mixtures of both sorbents in alginate basic formulation was studied by immersion of the granules in water. The water uptake, sorption capacity of the sorbent, permeability, and time taken for 50% of the active ingredient to be released into water, T(50), were calculated by the comparison of the preparations. T(50) values were higher for those formulations containing bentonite and/or activated carbon (T(50) values range from 14.76 h for the alginate formulation containing only bentonite as the sorbent to 29.5 weeks for the alginate formulation containing only activated carbon as the sorbent) than for the preparation without these sorbents (11.72 h). On the basis of a parameter of an empirical equation used to fit the insecticide-nematicide release data, it appears that the release of carbofuran from the various formulations into water is controlled by a diffusion mechanism. The sorption capacity of the sorbents for carbofuran was the most important factor modulating carbofuran release. In addition, it was observed that there is a linear correlation of the T(50) values and the content of activated carbon in dry granules.

Interface interactions between insecticide carbofuran and tea waste biochars produced at different pyrolysis temperatures

“…[8,9] As carbofuran contains 166 μg kg −1 amount of arsenic, a group of academia had suggested the usage of carbofuran may be one of the possible contributions for chronic kidney disease of unknown etiology in north central and Uva province in Sri Lanka. [10] Several methods including ion exchange, [11] precipitation, [12] adsorption [13] and membrane separation process. [19] nevertheless, carbofuran adsorption mechanisms on to BCs have not been adequately described yet.…”

Prevention of Herbicides Pollution Using Sorbents in Controlled Release Formulations

“…As an example, the water uptake of the granules containing diuron and chloridazon vs. time is shown in Figure 3. The presence of a higher amount of microporosity in granules increases the amount of water uptake in formulations containing sorbents as modifying agents (Fernández Pérez et al, 2005). The extent of swelling of the anthracite, bentonites and activated carbon determines the volume occupied in the matrix and the area that can interact with the diffusing molecules of herbicide.…”

“…Alginate gel has been applied to produce an effective CR carrier of drugs (Liew et al, 2006) and pesticides 2004;2005) because it forms strong gels in aqueous media and is bioerodible. In this chapter, discussion is focused on the use of several sorbents as modifying agents in the preparation of alginate-based controlled release formulations of herbicides.…”

Structural effects of organobentonites on controlled release of pretilachlor

“…However, the intrinsic hydrophilicity of bentonite makes it an ineffective sorbent for hydrophobic organic molecules. In most cases, bentonite is taken as the additive of polymer-based CRF (Fernandez-Pérez et al, 2005;Garrido-Herrera et al, 2006;Flores-Cespedes et al, 2007;Li et al, 2009;Singh et al, 2009Singh et al, , 2010.…”