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Herein, we described the use of exfoliated graphene- (EG-) decorated magnetic MnFe2O4 nanocomposite (EG@MnFe2O4) for the removal and adsorption of Congo red (CR) dye from wastewater. Firstly, the precursors (EG, MnFe2O4) and EG@MnFe2O4 were fabricated, characterized using several physical analytical techniques such as X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and N2adsorption/desorption isotherm measurement. For the adsorption experiments, the effect of contact time (0–240 min), concentration (10–60 mg/L), solution pH (2–10), adsorbent dosage (0.03–0.07 g), and temperature (283–313 K) was rigorously studied. To elucidate the adsorption mechanism and behaviour of CR over EG@MnFe2O4 and MnFe2O4 adsorbents, the kinetic models (pseudo-first-order, pseudo-second-order, Elovich, and Bangham) and isotherm models (Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich) have been adopted. The kinetic results indicated that models adhered to the pseudo-second-order equation, exhibiting the chemisorption mechanism in heterogeneous phrase. Meanwhile, the isotherm results revealed the adsorption of CR over EG@MnFe2O4 obeyed the monolayer behaviour (Langmuir model) rather than multilayer behaviour (Freundlich equation) over MnFe2O4. The thermodynamic study also suggested that such adsorption was an endothermic and spontaneous process. With high maximum adsorption capacity (71.79 mg/g) and good recyclability (at least 4 times), EG@MnFe2O4 can be a potential alternative for the adsorptive removal of CR dye from water.

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The present study focused on the synthesis of novel NH 2 -PC700 adsorbent through the pyrolysis of NH 2 -MIL-88B (Fe) material under different pyrolysis temperatures (500, 700, and 900 C) and investigated its application for ciprofloxacin adsorption. The obtained adsorbents were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherm measurements. The parameters of the adsorption experiments that affect the removal efficiency, including solution pH (3e10), contact time (0e240 min), and initial concentration (10e40 mg/L), were also studied in detail. For the adsorption kinetic and isotherm studies, nonlinear models combined with error functions such as adjusted coefficient of determination (R 2 adj ), mean relative error (MRE), and squares of the errors (SSE) were used to evaluate the compatibility between kinetic models (pseudo-first-order, pseudo-second-order, Elovich, and Bangham) and isotherm (Langmuir, Freundlich, Temkin, and DubinineRadushkevitch) adsorption equations. Besides, the role of amino functionalization for the ciprofloxacin (CFX) adsorption of NH 2 -PC700 adsorbent was also explained. Through the Langmuir model, the maximum CFX adsorption capacity of NH 2 -PC700 was calculated to be 102.5 mg/g, considerably higher than that of NH 2 -MIL-88B (Fe). This outcome suggested that NH 2 -PC700 could be a promising adsorbent for the CFX remediation.

Natural graphite, a locally available, eco-friendly, and low-cost carbonaceous source, can be easily transformed into exfoliated graphite (EG) with many surface functional groups via a chemical oxidation route. Combination between EG and magnetic MnFe2O4 is a promising strategy to create a hybrid kind of nanocomposite (EG@MnFe2O4) for the efficient adsorptive removal of Congo red (CR) dye from water. Here, we reported the facile synthesis and characterization of chemical bonds of EG@MnFe2O4 using several techniques such as Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). In particular, the quantity method by Boehm titration was employed to identify the content of functional groups: Carboxylic acid (0.044 mmol/g), phenol (0.032 mmol/g), lactone (0.020 mmol/g), and total base (0.0156 mmol/g) on the surface of EG@MnFe2O4. Through the response surface methodology-optimized models, we found a clear difference in the adsorption capacity between EG-decorated MnFe2O4 (62.0 mg/g) and MnFe2O4 without EG decoration (11.1 mg/g). This result was also interpreted via a proposed mechanism to elucidate the contribution of surface functional groups of EG@MnFe2O4 to adsorption efficiency towards CR dye.