Adsorption of Poly-phenolic Compounds of Optimized Extract of the Bark of Pittosporaceae by Pillared Clay in View of the Formulation of Powdered Insecticides

The aim of this work is to formulate a powdery insecticide by adsorption of optimized poly-phenol extracts by aluminum pillared clay of Boboyo; in order to reduce the loss of post agricultural crops by preserving the environment. Different parameters (pH, initial concentration of adsorbate, temperature, and mass of adsorbent) those influence the formulation of the insecticide were optimized by adsorption of the gallic acid on the pillared clay. The study revealed that the maximum quantity of adsorption is reached after 10 minutes, it is believed that the quantities adsorbed with the increase in the concentration of the adsorbate and quantities adsorbed decreases with the increase of the mass of the clay, the pH and temperature. The kinetic model best suited for the adsorption of gallic acid is that of pseudo-second order. The adsorbed quantity from the monolayer coverage deduced from the Langmuir model is 11.82 mg/g. Thus, the formulation powdery snow of the insecticide is obtained by adsorption of an extract of poly- phenols on the clay materials while respecting the optimal condition provided by the gallic acid. The test insecticides of this formulation powder on the weevils of maize have shown that the lethal dose is 4%. This quantity induces a mortality rate of Sitophilus zeamais of 49±12.6% and an LD50 = 0.20% (R2= 0.63) on 7 days compared to Malathion which is considered as the standard insecticide with a mortality rate of 100% on 7 days.