Fabrication and evaluation of Lambda-Cyhalothrin nanosuspoemulsion with pH- and temperature-responsive based on polyethylene wax as carrier

Using polyethylene wax (PW) as the coating matrix, the lambda-cyhalothrin-PW nanosuspoemulsion (LC-PW) with a particle size of 80-150nm was prepared through high-speed stirring, hot melt emulsification and ultrasonic dispersion. The formulation and composition of the LC-PW were optimized, the morphology of the LC-PW was analyzed by dynamic light scattering (DLS) and TEM, and the structure of the LC-PW was characterized by UV and IR. The anti-photolysis test showed that LC-PW had a good anti-photolysis performance. Furthermore, LC-PW could sustainably release Lambda-cyhalothrin, which was pH- and temperature dependent. The insecticidal activity analysis in the greenhouse indicated that the toxic strength between LC-PW and LC-SC (lambda-cyhalothrin-suspension concentrate) to Mythimna separata was similar within the same concentration ranges tested, but the insecticidal duration of LC-PW was significantly longer than LC-SC. Thus, the new type of LC-PW with the properties of anti-photolysis and controlled release is suitable for application in the field as a better insecticide.

Surfactant modified ZnO-Bi2O3 nanocomposite for degradation of lambda- cyhalothrin pesticide in visible light: A study of reaction kinetics and intermediates

Coupling of semiconductor photocatalyst attracted more attention in the area of heterogeneous photocatalytic process. Herein we developed a low-cost visible light responsive coupled ZnO-Bi₂O₃ semiconductor with a molar ratio of 1:4, 1:2, and 3:4 by facile one-step hydrothermal method using a surfactant. The influences of Bi₂O₃ content on coupled catalyst were investigated. The synthesized catalysts were characterized by X-Ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectrum (FT-IR), UV-Vis diffuse reflectance (UV-DRS). Photocatalytic performance of ZnO-Bi₂O₃ was investigated using Lambda-Cyhalothrin (L-CHT), a pyrethroid pesticide that is harmful to human beings and animals under visible light irradiation. Kinetic study of the degradation of L-CHT reveals that there is a shift in the reaction order from first-order to second-order. The photocatalytic degradation of L-CHT using ZnO-Bi₂O₃ is found to be more efficient since the separation of photogenerated holes and electrons are improved by coupling of ZnO with Bi₂O₃. When compared to bare ZnO the degradation percentage of 85.7% was achieved within 120 min of the photocatalytic process using the catalyst dosage of 1.2 gm/L in 50 mg/L of L-CHT solution with formation of Phthalic acid, butyl 2-ethyl butyl ester and Diethyl phthalate as intermediates. No other hazardous intermediates are formed and a scheme for photodegradation pathway was proposed.