Abstract:
Dyes are serious environmental contaminants having negative effects on human health.
Due to the tenacity and resilience of dyes to natural degradation, the careless dumping
of wastewater containing azo dyes has turned into a significant environmental problem.
Researchers have focused their efforts and made substantial attempts to address this
problem since dyes cannot be removed from the environment by standard wastewater
treatment procedures. Manganese dioxide (MnO2) – reduced graphene oxide (rGO)
nanocomposite was synthesized by using KMnO4 and rGO. MnO2-rGO nanocomposite
was used as a model for the efficient removal of methylene blue (MB) from an aqueous
medium. The nanocomposite obtained was characterized by Fourier transforms infrared
spectroscopy, X-ray diffraction, and thermogravimetric analysis. The effect of pH, dosage
of the nanocomposite, MB initial concentration, and reusability of nanocomposite were
studied. MnO2–rGO nanocomposite showed high performance for oxidative decolorization
and removal of MB. Typically, 25 mL of MB (10 ppm) can be decolorized in 15 min
with 25 mg of the MnO2–rGO nanocomposite with 98% decolorization efficiency. The
optimum pH is 7 for MnO2-rGO nanocomposite. Moreover, the dye decolorization rate
was decreased with increasing MB concentration. The Pseudo-second-order model (R2
= 0.9958) was the applicable kinetic model. The nanocomposite material exhibited
recyclability and durability with the degradation value of 76% for MB after three
consecutive cycles. Results revealed that the MnO2-rGO nanocomposite is capable of
successfully degrading MB in aqueous solutions.
