Adsorption of Aqueous Organic Dyes onto α-Fe2O3/Graphene Oxide: Insights into the Interaction Mechanism

Abstract

Removing organic dyes from wastewater is an important task of environmental remediation. In this work, a nano composite α-Fe2O3/graphene oxide (α-Fe2O3/GO) was fabricated with a facile hydrothermal process. The as fabricated α-Fe2O3/GO was characterized and tested as adsorbent for removing two typical ionic dyes Congo red (CR) and methyl violet (MV) from aqueous solutions. The interaction mechanisms of α-Fe2O3/GO with CR and MV were analyzed. Findings presents, synergistic effect between α-Fe2O3 and GO made α-Fe2O3/GO outperform either α-Fe2O3 or GO. α-Fe2O3/GO exhibited high adsorption capacity and cycling performance, most importantly, ultrafast adsorption kinetics especially on MV. Adsorptions of CR and MV equilibrated in 8 min and 5 min, the corresponding adsorption percent/quantity were 95.78%/239.45 mg·g−1 and 99.907%/1998.14 mg·g−1, respectively. The good adsorption performance of α-Fe2O3/GO originated from its thin morphology, abundant oxygen containing groups, as well as strong chemical interaction with CR and MV. The adsorptions were thermodynamically spontaneous and endothermic, while kinetically controlled by surface reaction. Hydrogen bond and π–π interaction was the primary interaction mechanism between adsorbate and adsorbent. The merits including simple fabrication and superior adsorption performance may endow α-Fe2O3/GO promising application in removing organic dyes.