Ordered mesoporous graphitic carbon nitride/cobalt ferrite composite for highly effective magnetic solid-phase extraction of bisphenols in lake and tap water samples

Abstract

Development of sensitive monitoring method for environmental contaminants is of great interest in both environmental science and analytical chemistry. Here we report the facile hydrothermal fabrication of ordered mesoporous graphitic carbon nitride/cobalt ferrite composite (MCN/CoFe2O4) with large surface area and adequate magnetic property. The prepared MCN/CoFe2O4 was developed as an adsorbent for magnetic solid-phase extraction for bisphenols (bisphenol F, bisphenol A and bisphenol AF) prior to HPLC coupled with variable wavelength detector. The factors influencing the extraction procedure, adsorption kinetics, isotherms and thermodynamics were investigated in detail. The extraction performed with 20 mg of MCN/CoFe2O4 sorbent in 15 mL of sample solution was accomplished within only 15 min and gave the enrichment factors of 123.6–154.6. Meanwhile, the adsorption process followed the pseudo-second-order kinetic and Freundlich models. Under the optimized conditions, the method provided the limits of detection (S/N = 3) and limits of quantification (S/N = 10) of 0.15–0.25 μg/L and 0.50–0.90 μg/L, and the recoveries of 80.5%−104.0%. Moreover, the adsorbent was stable enough after 16 adsorption-desorption cycles. The developed approach not only presented an alternative strategy for sensitive and rapid determination of bisphenols in environmental water samples, but also promoted the synthesis and application of MCN in the field of sample pretreatment.