Activated magnetic porous carbon microspheres: Preparation based on electrostatic spraying and adsorption on methylene blue

Activated magnetic porous carbon microspheres (A-Fe3O4/C) based on chitosan (CS) were prepared using a two-step synthesis method. The prepared A-Fe3O4/C was employed as an adsorbent to remove the methylene blue (MB) from water. First, magnetic microspheres Fe3O4/CS were prepared through electrostatic spraying with CS and FeCl2/FeCl3 as the precursor. Subsequently, Fe3O4/CS was converted into A-Fe3O4/C using a combination method of high-temperature carbonization and alkali activation. The obtained magnetic microspheres were systematically characterized by scanning electron microscopy, Fourier transform infrared, and specific surface area analyzer, and several major factors of the adsorption-based removal were studied ( e.g., pH of the solution, adsorbent dosage, temperature, contact time, as well as alkali activator). The removal efficiency was significantly dependent on the pH of the solution, and high pH values facilitated the removal of MB from water. The adsorption to MB was consistent with the pseudo-second-order kinetic equation, and the adsorption process was expressed using the Langmuir isotherm model. The maximum adsorption capacity of MB was examined as 300.6 mg center dot g(-1). Notably, the synthesized adsorbent could be effectively regenerated and repeatedly used without significant capacity loss after six cycles.