Multi-walled carbon nanotubes modified with iron oxide and manganese dioxide (MWCNTs-Fe3O4−MnO2) as a novel adsorbent for the determination of BPA

Abstract

Multi-walled carbon nanotubes modified with iron oxide and manganese dioxide (MWCNTs-Fe3O4−MnO2) was synthesized by using iron oxide (magnetic agent) and manganese dioxide (surface enhancer agent) to further approach in a magnetic solid-phase extraction (MSPE) coupled with high performance liquid chromatography (HPLC) method for the determination of bisphenol A (BPA) in plastic bottled drink samples. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and BET surface area measurement (BET) were used to characterized the materials. MWCNTs-Fe3O4MnO2 are more effective for BPA adsorption than other materials which compared in this study. The binding performances of sorbent were evaluated by static and kinetic adsorption experiments. The data were well fitted to the Langmuir isotherm model and pseudo-second-order model, which the maximum adsorption capacity (qmax) and the contact time of initial concentrations to achieve equilibrium were found to be 132.9 mg g−1 and 150 min, respectively. After adsorption, MWCNTs-Fe3O4−MnO2 can be conveniently and quickly separated from the media by an external magnetic field, and adsorption-desorption capacity can remain at least 6 times of usage. Several parameters affecting the extraction efficiency were investigated. Under optimal conditions, the sorbent was successfully applied to MSPE followed by HPLC determination of BPA in real sample. The limit of detection (LOD) and limit of quantification (LOQ) values of MSPE-HPLC was 0.092 ng mL−1 and 0.167 ng mL−1, respectively. Spiked recoveries ranged from 94.9 to 103.4% for four real samples, with relative standard deviations of less than 6.7%. It was concluded that the synthesized MWCNTs-Fe3O4−MnO2 could be used as an efficient adsorbent for the determination of BPA in different plastic bottled drink samples.