Eco-friendly biochar for chlorantraniliprole removal from sandy loam soil: LC-MS/MS-based method optimization and application

Chlorantraniliprole is a widely used insecticide in vegetables, fruits, and cotton. This research investigates the application of biomass-derived biochar as an eco-friendly adsorbent for removing chlorantraniliprole (CAP) from sandy loam soil. Adsorption performance was evaluated using kinetics, isotherm modeling, thermodynamics, and advanced characterization. The results indicated that the process adhered to a pseudo-second-order model, suggesting chemisorption as the primary mechanism. Adsorption experiments showed a clear improvement in pesticide retention when biochar was added to the soil. In untreated soils, the adsorption ranges from 23.77 % to 30.15 %. However, the addition of biochar in sandy loam soil significantly increased adsorption efficiency, with ranges from 74.61 % to 83.89 % and 94.34 % to 97.04 %, respectively. To support the analytical methods and to determine the actual concentrations of pesticides after adsorption from the soil amendment and control soil, preliminary optimization of LC-MS/MS parameters has been performed. Isotherm analysis followed the Langmuir model, indicating adsorption occurs as a uniform monolayer on a homogenous surface. Thermodynamic analysis revealed that the adsorption was spontaneous (negative Delta G degrees), exothermic (negative Delta H degrees), and reduced randomness at the soil-liquid interface (negative Delta S degrees). Furthermore, density functional theory (DFT) were used to investigate the interaction between pesticide and biochar. Comprehensive characterization techniques, including XRD, FT-IR, BET, TGA, SEM-EDAX and TEM were utilized to examine the biochar. XRD confirmed the crystalline properties, FT-IR analysis identified functional groups, BET analysis measured alterations in surface area and porosity, TGA highlighted the thermal stability, SEM-EDAX revealed changes in surface morphology and elemental composition, and TEM provided detailed images and structural information. The study highlights invasive weed-derived biochar as an effective and sustainable solution for removing chlorantraniliprole from sandy loam soil, offering a promising approach for pesticide remediation.