Optimizing the removal of methylene blue from aqueous solutions using persulfate activated with nanoscale zero valent iron (nZVI) supported by reduced expanded graphene oxide (rEGO)

Abstract

Background: To remove methylene blue (MB) from aqueous solutions, nanoscale zero-valent iron (nZVI) predicated on reduced expanded graphene oxide (rEGO) was used as the activator of persulfate. Methods: Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analyses were used to investigate the surface morphology and to examine the surface elemental composition. X-ray diffraction (XRD) was used to determine the chemical compositions of the synthesized compound. In this study, the effects of pH (3-9), activator dose (0.4-1.6 g L-1), persulfate concentration (0.192-0.768 g L-1), and reaction time (0-60 minutes) on the removal of 10 mg L-1 MB were studied by nZVI -reduced expanded graphene oxide/persulfate (nZVI@rEGO/PS) process. Results: The maximum removal efficiencies of MB at optimum operational conditions (pH 3, activator dose = 1.2 g L-1, persulfate concentration = 0.576 g L-1, and reaction time = 20 minutes) by nZVI@rEGO/PS process was 96%. The chemical method was used to prepare expanded graphene. The volume of natural flake graphite increased about 25 times after the process. SEM image of the nZVI@rEGO showed the presence of nZVI placed on the EGO surface in chain structure with a diameter about 100 nm. The EDS analysis of the activator indicated the existence of Fe element to an amount greater than 50%. Conclusion: According to the results, nZVI@rEGO is considered as a promising activator of persulfate.

Use of Zero-Valent Iron Nanoparticles (nZVIs) from Environmentally Friendly Synthesis for the Removal of Dyes from Water—A Review

“…Nonetheless, the presence of active oxygen species in solution also plays a key role in the degradation process. For instance, persulfate activation, facilitated by nZVIs, yields sulfate radicals with potent oxidizing power, offering high selectivity in pollutant degradation [194][195][196]. Additionally, aerobic degradation pathways, enabled by nZVIs, involve the reductive activation of molecular oxygen, generating reactive oxygen species for the oxidation or mineralization of organic pollutants [197].…”

Comparison of sono-direct and sono-alternate current electro-coagulation processes for removal of color and turbidity from domestic wastewater

“…In this study, the testing room result shows that one hour of backlash time is somewhat enough to remove the contaminant. Increasing the reaction time increases the removal efficiency of contaminants from wastewater (21,(47)(48)(49).…”

“…RSM is a concerning manipulation of numbersmathematical procedure useful for optimizing concerned with atom and molecule change response and related to manufacturing processes and is used frequently as a second-hand fashionable method in the design of experiments (49,50). One of the main advantages of RSM by central composite design is to obtain the optimum conditions for removal of pollutants based on the laboratory experiments.…”