Preparation of biochar-based surface molecularly imprinted polymers and evaluation of their selective adsorption and removal of carbaryl from rice and corn.

• Soybean hulls as raw materials can improve resource utilization and reduce costs. • Molecular imprinting techniques confer selectivity to common adsorbents. • Biochar is used as a carrier to improve the adsorption and mass transfer rate. • Solid-phase extraction improves the convenience of solid-liquid separation. The residue of carbaryl in food is a threat to human health. In this study, activated soybean shell biochar (A-SBC) was used as a carrier, methacrylic acid (MAA) was used as a functional monomer, and carbaryl was used as a template molecule to synthesize the activated biochar surface molecularly imprinted polymer (A-SBC@MIP). The synthesized A-SBC@MIP was characterized by SEM, FT-IR, XRD and XPS techniques, and then applied as adsorbent for carbaryl removal. The adsorption capacity of A-SBC@MIP for carbaryl was 8.6 mg‧g−1 and the imprinting factor was 1.49 at the optimum ionic strength and pH. The kinetic and isothermal data indicated that it had fast mass transfer rate and high binding capacity(Qmax=47.9 mg‧g−1). A-SBC@MIP showed good regenerative properties and the adsorption of carbaryl was excellent in its structural analogues. A solid-phase extraction (SPE) column composed of A-SBC@MIP was developed for the detection of rice and corn under optimized conditions, with recoveries of 93–101% for the spiked carbaryl. The limit of detection (LOD) of the method was 3.6 μg‧kg−1 with good linearity (R2=0.994) in the range of 0.01–5.00 mg‧L−1. The results show that the developed MIPs-SPE can enrich carbaryl from food samples as a specific and cost-effective method. [ABSTRACT FROM AUTHOR]