Novel Hybrid rGO-BC@ZrO2 Composite: A Material for Methylene Blue Adsorption

Abstract

This study reports the preparation of a novel hybrid composite and its application in adsorption. For this composite preparation, zirconia (ZrO2) was precipitated onto an integrated framework of reduced graphene oxide (rGO) and black cumin (BC) seeds. Characterization using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy confirmed the successful incorporation of ZrO2 nanoparticles (5–20 nm) into the integrated carbon framework of rGO and seed powder. The microscopic analysis further revealed that the ZrO2 NPs were dispersed throughout the integrated rGO-BC framework. Using the rGO-BC@ZrO2 composite, methylene blue dye was decontaminated from water through a batch adsorption process. The rGO-BC@ZrO2 composite achieved 96% MB adsorption at an adsorbent dose of 2.0 g/L, and nearly 100% when the adsorbent concentration was 3.0 g/L. Modeling of the experimental adsorption values was also established to verify the adsorption viability and mechanism. Thermodynamic modeling confirmed the feasibility and spontaneity of the present batch adsorption process. Isotherm modeling, which showed its compatibility with the Freundlich isotherm, suggested multilayer adsorption. rGO-BC@ZrO2 demonstrated good persistence and reusability for methylene blue for up to five consecutive adsorption cycles. Thus, this study presents optimistic results regarding water purification.