Composition optimization of activated carbon-iron oxide nanocomposite for effective removal of Cr(VI)ions

Abstract

In the present study, nanocomposites (NCs) of activated carbon and iron oxide nanoparticles (NPs) in different w:w ratio were synthesized via. co-precipitation technique and evaluated for the removal of Cr (VI) ions. Detailed characterization of NCs was performed by FT-IR, XRD, BET, SEM-EDX, TEM and VSM analyses. The loading of NPs on activated carbon was evidenced from TEM images. Fe57 Mössbauer spectroscopy was used to identify the phase of iron oxide NPs and indicated the presence of hematite and goethite. The saturation magnetization values decreased with increasing activated carbon content and ranged from 14.4 to 28.1 emug−1. The composition of the nanocomposite was optimized for efficient Cr (VI) removal. The nanocomposite with 2:1 w:w ratio of activated carbon and NPs had the highest Cr (VI) removal efficiency, among synthesized nanocomposites and pristine NPs. The Langmuir model fitted the adsorption isotherms commendably. The maximum adsorption capacity of iron oxide NPs was 83.3, and it increased to 500.0 mgg−1 in nanocomposite with 2:1 ratio of activated carbon and Iron oxide NPs. The kinetic data was well described by pseudo-second order kinetic model. The thermodynamic analysis depicted spontaneous and exothermic nature of the adsorption process. The reducing characteristics of activated charcoal and the magnetic nature are important features of NCs for the removal of Cr (VI) ions, magnetic separation and regeneration. The results showed that optimizing the composition of activated charcoal-NPs nanocomposites served as an effective strategy for the removal of Cr (VI) ions. The ecotoxicity assessment showed that the synthesized nanocomposite is environmentally friendly.