Interaction of λ-cyhalothrin with chitosan and quartz sand: Attachment, transport, and cotransport in porous media

The insecticide λ-cyhalothrin a type II synthetic parathyroid. It is a hydrophobic and highly effective broad-spectrum insecticide commonly used in pest management. However, its presence in subsurface formations poses environmental toxicity risks and potentially may have adverse effects on humans. Chitosan, a polymer with unique physicochemical and absorption properties, is utilized in numerous various industrial applications. In this study, the interactions of λ-cyhalothrin with chitosan in the presence and absence of quartz sand were investigated under static, dynamic (batch), and column transport conditions at 25 °C. The experimental adsorption data were effectively modeled using a pseudo-second-order adsorption kinetic model, while the transport experiments were simulated with an advection dispersion model incorporating two-site linear or nonlinear particle attachment. The results indicate that the observed λ-cyhalothrin adsorption onto either Chitosan or quartz sand is governed by chemisorption. Cotransport experiments revealed bidirectional interactions, where chitosan forms aggregates with λ-cyhalothrin, enhancing chitosan attachment and significantly reducing λ-cyhalothrin retention. This, highlights chitosan's potential as a remediation agent for mitigating pesticide contamination in porous media.