Environmental risk mitigation of lambda-cyhalothrin using tryptophan-modified magnetic nanoparticles: A sustainable emergency response strategy

[Display omitted] •Fabrication of tryptophan-modified magnetic nanoparticles (Trp-MNPs) in one step.•Trp-MNPs enhanced the adsorption capability and dispersion of MNPs.•Trp-MNPs could quickly and massively adsorb pyrethroids leaked in the environment.•Trp-MNPs exhibited excellent magnetism and regenerative properties. Lambda-cyhalothrin, a synthetic pyrethroid pesticide extensively used in agriculture, poses significant environmental challenges due to its extensive and long-term application. To remediate pollution caused by such organic contaminants, our study introduces a rapid and convenient one-pot synthesis method for creating amino acid-modified magnetic nano-adsorbents (AA-MNPs). Research found that after modification with tryptophan (Trp), the adsorption effectiveness of MNPs on Lambda-cyhalothrin significantly increases. This modification enhances the carbon content of the magnetic nanoparticles, while minimally affecting the magnetic saturation of the MNPs. Trp-MNP exhibited an approximate particle size of 450 nm and a specific surface area of 52.36 m2 g-1. The isotherm and kinetic experiments were well-fitted to the Liu isotherm model and the pseudo-second-order model, respectively. Thermodynamic assessments suggested that the adsorption process is spontaneous and exothermic. Results indicated that the maximum adsorption capacity 144.34 mg g-1 for Trp-MNPs at 298 K, outperforming adsorbents reported in the literature. The half-adsorption time was reduced to 8 min at 298 K with an initial concentration of 60 mg L-1. This enhancement was likely influenced by the aromatic ring modification and hydrophobicity of Trp-MNPs. The study explored potential removal mechanisms from a tri-phase perspective, investigating the interactions between the adsorbent, adsorbate, and solvent.