Kinetics, Isotherm, Thermodynamics, and Recyclability of Exfoliated Graphene-Decorated MnFe 2 O 4 Nanocomposite Towards Congo Red Dye

• Published in: Journal of chemistry Vol. 2019; pp. 1 - 16
• Main Authors: Pham, Van Thinh, Nguyen, Hong-Tham T., Tran, Thuan Van, Nguyen, Duyen Thi Cam, Le, Hanh T. N., Nguyen, Thuong Thi, Vo, Dai-Viet N., Le, Thi Hong Nhan, Nguyen, Duy Chinh
• Format: Journal Article
• Language: English
• Published: 17-06-2019
• ISSN: 2090-9063; 2090-9071
• DOI: 10.1155/2019/5234585

Herein, we described the use of exfoliated graphene- (EG-) decorated magnetic MnFe
2
O
4
nanocomposite (EG@MnFe
2
O
4
) for the removal and adsorption of Congo red (CR) dye from wastewater. Firstly, the precursors (EG, MnFe
2
O
4
) and EG@MnFe
2
O
4
were fabricated, characterized using several physical analytical techniques such as X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and
N
2
adsorption/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@MnFe
2
O
4
and MnFe
2
O
4
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@MnFe
2
O
4
obeyed the monolayer behaviour (Langmuir model) rather than multilayer behaviour (Freundlich equation) over MnFe
2
O
4
. 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@MnFe
2
O
4
can be a potential alternative for the adsorptive removal of CR dye from water.