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.

This study evaluates and compares the adsorptive properties of four natural clays from Albania regions: Brari, Currila, Dardha and Prrenjasi, in regards to the adsorption of two insecticides, dimethoate and methomyl, from their aqueous solutions. Special studies on the adsorption of these two insecticides have been previously published by authors, [45], [58], [59], and [60] while this research is focused on the comparison of the adsorbent properties of the four above mentioned clays based on the obtained experimental results. Dimethoate adsorption was performed at T=25

Desorption of some insecticides used in agriculture from natural Albanian clays impregnated with these insecticides is evaluated in this study. There are well-known compounds in this field such as: Dimethoate, Methomyl, Metribuzin and 2-4-D which have been studied as insecticides. The study was performed using natural clays selected from the regions of Brari, Currila, Dardha and Prrenjasi, which have been used in parallel for other studies in the field of adsorption of insecticides through natural clays. In the course study the clays were impregnated with insecticides with a concentration of 1mg/g of clay -calculated as pure insecticide, while the desorption process was investigated from 2 hours to 24 hours and in special cases up to 48 hours. It has been noticed that the insecticides desorption from clays occurred fast, within the first few hours. Most of the insecticides are transferred into the water, with the exception of 2,4-D which desorbs slowly and for 48 hours reaches a desorption rate of 27%. Based on the studied desorption process of the selected insecticides from the natural clays, it is possible to impregnate clays with different insecticides with well-calculated concentrations and use these clays in agriculture to combat crop damage. In this way the quantities of released insecticides are completely controlled and do not create environmental pollution. The use of natural clays as adsorbants/desorbants presents an effective formulation in combating crop damage. Since the insecticides desorption from clays requires a certain time, their aimed activity is prolonged whilst causing less damage on the agricultural crops.