Magnetic biochar modified with crosslinked chitosan and EDTA for removing cobalt from aqueous solutions

To effectively remove cobalt, magnetic biochar was modified with chitosan and ethylenediaminetetraacetic acid (CMBC-EDTA), and its properties were examined through surface area and pore size analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, and vibration sample magnetometry. Moreover, according to the Langmuir isotherm model, the maximum capacity of CMBC-EDTA reached 0.7311 mol center dot kg(-1). Over 50% of 50 ppm Co2+ was removed within 20 min, and the adsorption equilibrium was reached after 2 h. At pH 3-7, the 20 ppm Co2+ removal efficiency was more than 90%, and it decreased rapidly below pH 2.