A case study of methomyl removal from aqueous solutions by four natural Albanian clays

This study evaluated the adsorption properties of four Albanian natural clays from the regions of Brari, Currila, Dardha, and Prrenjasi for commercial methomyl from aqueous solutions. Three methomyl concentrations, 0.200, 0.400, and 0.600 mg/ml, were tested at 25°C to study the influence of the insecticide concentration on the adsorption process for each natural clay type. Within 48 hr of contact time, the adsorption pathways of methomyl on the selected clays are well described by a Langmuir‐like adsorption kinetic model and an intraparticle diffusion model. Hydrolysis and desorption inhibit the overall removal process. The increase of methomyl concentration in solution within the first 48 hr leads to linear adsorption increases well described by Langmuir and Freundlich adsorption isotherms and disfavors the desorption step for the Brari, Currila, and Dardha clays. For the methomyl concentration of 0.600 mg/ml, within 24 hr of contact time, the Dardha and Prrenjasi clays reveal 1.471 and 1.956 mg/g methomyl uptake, respectively. The Brari and Currila clays show longer saturation times followed by better methomyl retention. The Dardha and Prrenjasi clays exhibit fast and high adsorption combined with low retention times.     

A review on the adsorption of diuron,carbaryl, and alachlor using natural and activated clays

Pesticides are considered predominant organic pollutants because they are widespread in many ecosystems. Pesticide residues can degrade chemically, physically, and biochemically in nature, but, because of their high stability and, in some cases, water solubility, they continue to persist in the environment. Pesticides have been eliminated from contaminated waters using a variety of methods that fall under the categories of biological, chemical, physical, and physicochemical remediation processes from various types of matrices, including water and soil. Due to their excellent qualities as adsorbents and pesticide transporters, the use of natural soil components such as clays, iron oxides, or humic acid has recently attracted growing interest. Clays have several advantages over other adsorbents, including large specific surface areas due to their small particle size, low cost, and widespread availability. Clay minerals have a great capacity for adsorption due to Coulombic forces and, attributable to their large surface area, van der Waals forces. This review describes historical, current, and emerging techniques and materials to remove the pesticides diuron, carbaryl, and alachlor using clays as adsorbents.