Magnetically recyclable Fe3O4/Bi2S3 microspheres for effective removal of Congo red dye by simultaneous adsorption and photocatalytic regeneration

Abstract

Abstract Novel magnetic bayberry-like Fe 3 O 4 /Bi 2 S 3 microspheres (Fe 3 O 4 /Bi 2 S 3 MSs) combining highly effective adsorption and photocatalytic regeneration were prepared by a facile hydrothermal method. The resultant Fe 3 O 4 /Bi 2 S 3 MSs were characterized by XRD, SEM, EDS, VSM, BET and DRS. Fe 3 O 4 /Bi 2 S 3 MSs possessed a relative large surface area of 36.0 m 2 g −1 and narrow pore size distribution around 4.72 nm. The equilibrium and kinetics of adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetic model, respectively. Maximum adsorption capacity of CR as 92.24 mg g − 1 was achieved on Fe 3 O 4 /Bi 2 S 3 MSs, while only 66.28 mg g −1 was found on Bi 2 S 3 MSs. High saturation magnetization, low coercivity and remnant magnetization values of Fe 3 O 4 /Bi 2 S 3 MSs indicated that easy separation and fast re-dispersion in aqueous solution can be realized. What’s more important, Fe 3 O 4 /Bi 2 S 3 MSs with a stronger absorption in the visible light region can be regenerated by photocatalysis under simulated solar light irradiation. Fe 3 O 4 /Bi 2 S 3 MSs also showed excellent stability and reusability for continuous removal of Congo red dye by synergistic adsorption and photocatalytic regeneration. As a result, Fe 3 O 4 /Bi 2 S 3 MSs provided effective and conveniently recyclable materials for environmental remediation by means of providing the facile preparation, easy magnetic separation, high adsorption, and simple regeneration.