Sorptive removal of neonicotinoid pesticides by nanobiochars: Efficiency, kinetics, and reusability

Abstract

The widespread use of neonicotinoid (NEO) pesticides has raised significant environmental concerns due to their toxicity. We investigated the performance of 16 nanobiochars (NBCs), including NBC produced by Douglas fir at 900 °C (Doug 900 NBC), as sustainable sorbents for removing three common NEOs from aqueous solutions: imidacloprid, clothianidin, and thiamethoxam. The NBCs showed high sorption efficiency (∼ 100 %) and fast sorption kinetics (< 0.5 h) for three NEOs at environmentally relevant concentrations (100 ng/L). The sorption efficiency of NEOs was determined by the physicochemical properties of NBCs, including specific surface area (SSA), pore volume (PV), pore diameter (PD), and elemental composition (carbon, nitrogen, and hydrogen contents). The NBCs with higher SSA and larger PV offered more abundant sorption sites, facilitating fast NEO sorption. Particularly, the Doug 900 NBC achieved ∼ 100 % removal efficiency of NEOs within 0.5 h under simulated groundwater conditions (67.5 mg/L of total dissolved solids and 10 mg/L of humic acid). The Doug 900 NBC also maintained high removal efficiency over four continuous reuse cycles. The structural equation modeling revealed that pyrolysis temperature indirectly affects NEO sorption by modifying NBC’s properties of SSA, PV, and PD. Our findings highlight the high potential of NBCs for sustainable removal of NEO pesticides in aquatic environments at environmentally relevant concentrations.