Preparation of amino-functionalized magnetic biochar with excellent adsorption performance for Cr(VI) by a mild one-step hydrothermal method from peanut hull

Amino-functionalized magnetic biochar from wasted peanut hull (MPHC-HDA) with excellent adsorption properties for Cr(VI) was successfully prepared by a mild one-step hydrothermal method in the presence of iron chloride and hexamethylenediamine (HDA). The physicochemical properties of the peanut hull based biochar (PHC), HDA-modified PHC (PHC-HDA) and MPHC-HDA were comparatively characterized by XRD, SEM, FT-IR, VSM, N2 adsorption/desorption and XPS. Static adsorption experiments show that MPHC-HDA presents the maximum adsorption capacity of 142.86 mg g−1 among them; this adsorption follows pseudo-second-order kinetics model and Langmuir isotherm. Furthermore, MPHC-HDA with easily separated characteristic after adsorption can also be recycled for three times. Importantly, this method can be extended to other renewable wasted bioresource including sunflower seed shell, pumpkin seed shell, corncob, etc., indicating it has great potentiality in the field of wastewater treatment.