Reduced Graphene Oxide/Attapulgite-Supported Nanoscale Zero-Valent Iron Removal of Acid Red 18 from Aqueous Solution

In this paper, reduced graphenoxide/attapulgite (rGO/APT)-supported nanoscale zero-valent iron (nZVI) composites (rGO/APT-nZVI) were synthesized to remove acid red 18 (AR18) and other organic dyes from aqueous solutions. The structure of synthetic rGO/APT-nZVI composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD), and the removal properties of rGO/APT-nZVI on AR18 were investigated. The factors of various experimental parameters (ratio, pH, initial concentration, temperature, and time) impacting on removal of AR18 were studied as well. Comparison experiment of different materials showed that 93.5% of AR18 was removed using rGO/APT-nZVI, while only 7.9% and 64.8% of AR18 were removed using rGO/APT-nZVI after reacting for 30 min with an initial AR18 concentration of 100 mg L−1, respectively. Moreover, kinetic and thermodynamic analyses were used to study the reduction process, and possible mechanism of AR18 removal was discussed. The results show that the rGO/APT-nZVI composites can effectively degrade AR18 over a wide range of pH and keep degradation activity in a long storage. In addition, the superior behaviors for other organic dyes removal highlight the great potential as an efficient adsorbent for water pollution.