Efficient Adsorption of Toxic Heavy Metal Ions on the Surface Engineered Violuric Acid-Reduced Graphene Oxide Nanomaterial

Abstract

Herein, a surface-engineered violuric acid-functionalized reduced graphene oxide (rGO-VA) has been synthesized and characterized using XRD, FESEM, HRTEM-EDX, FTIR, XPS, Raman, and UV–vis spectroscopy. The surface morphology describes highly exfoliated graphene sheets and uniformly distributed VA showing a topography of average size ∼1.663 nm. The Raman and EDX spectra describe greater defects due to the presence of C, N, and O atoms on the surface of the rGO-VA. Hence, O and N-containing functional groups that are present on the surface and edge of rGO-VA facilitate the efficient adsorption of toxic metal ions. The synthesized rGO-VA efficiently removes metal ions up to 99.9% of Hg2+, Pb2+, and As3+, from their aqueous solutions (40 mg/L) within a short retention time (5–10 min). The removal efficiency results are unaffected even at various interferences like pH, temperature, organic pollutants, cations, and anions. The adsorption process is chemisorption, multilayer, spontaneous, endothermic, and random. During the adsorption process, the residual concentrations were initially analyzed using UV–vis spectroscopy, and the results were verified by AAS. Overall, the present surface-engineered rGO-VA may be crucial for developing an efficient adsorbent to remove toxic metal ions from wastewater.