Preparation of multi-walled carbon nanotubes coated with CoFe2O4 nanoparticles and their adsorption performance for Bisphenol A compound

Abstract

In this study, the adsorption performance and characterization properties of the multi-walled carbon nanotubes were improved by coating this material with CoFe2O4 nanoparticles. The resultant adsorbent (MWCNTs/CoFe2O4) was first synthesized using solvothermal co-precipitation and Electrophoretic precipitation methods, characterized, then used in the adsorption system of Bisphenol A (BPA) wastewater. The influence of pH (3–11), initial BPA concentration (25–100 mg/L), MWCNTs/CoFe2O4 dosage (0.1–1.5 g/L), contact time (0–240 min), and temperature (283–328 K) on BPA removal adsorption onto MWCNTs/CoFe2O4 was investigated. Better results for BPA removal ( 99%) were achieved in acidic conditions (pH = 3), and the equilibrium state was reached at 150 min of contact time. The Langmuir and pseudo-second order models were suitable to describe the adsorption isotherm and kinetics, as verified by goodness-of-fit analysis. The adsorption of BPA molecules onto MWCNTs/CoFe2O4 active groups was occurred via chemisorption interaction, based on the analyses of Dubinin-Radushkevitch and Freundlich isotherms. Moreover, the endothermic, favorable, and spontaneous nature of BPA adsorption onto MWCNTs/CoFe2O4 was proved by thermodynamic studies. Reusing MWCNTs/CoFe2O4 after 6 cycles showed a ten percent reduction in adsorption capacity, which indicates the good stability and reusability. The maximum adsorption capacity of MWCNTs/CoFe2O4 for BPA adsorption from Langmuir model was 416.6 mg/g, which is much higher than that of reported other adsorbents used for the same purpose. This study revealed that MWCNTs/CoFe2O4 is a promising adsorbent for BPA adsorption with high removal efficiency, easy separation, and good reusability properties.