A facile and eco-friendly hydrothermal synthesis of magnetic graphite nanocomposite and its application in water purification

In this research, a magnetic graphite nanocomposite (MGN) was synthesized by an easy and efficient hydrothermal process from magnetite nanoparticles (NP-SYN) and graphite nanoplatelets (GR). MGN was characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), N2 adsorption and desorption analysis, X-ray photoelectron spectroscopy (XPS), and point of zero charge (pHpzc) analysis. The thickness for GR was found to be 34 nm, and crystallite sizes for NP-SYN and MGN were around 37 and 48 nm, respectively. MGN shows the presence of GR and iron oxides from the NP-SYN. The surface areas for GR, NP-SYN, and MGN were around 191, 18, and 121 m2 g-1, respectively. The pHpzc results for GR, NP-SYN, and MGN ranged from 6 to 7. The NP-SYN, GR, and MGN were used as adsorbents to remove reactive black 5 (RB5) dye from aqueous solution. This method's batch removal process was designed based on a central composite rotational design (CCRD). The efficiency of RB5 uptake for all adsorbents was obtained from the quadratic model under optimum conditions of prominent parameters by desirability function (mass of adsorbent 6.6 mg, dye concentration 85.1 mg L-1, and agitation speed 902.7 rpm). Under these conditions, the adsorption capacity values were 10.16, 92.08, and 28.83 mg g-1 for NP-SYN, GR, and MGN, respectively, indicating that the adsorption power of the nanoparticle increased after incorporating GR, maintaining its magnetic properties. Therefore, the proposed adsorbents in this work have potential for removing RB5 dye from water solutions.