Adsorptive Removal of Recalcitrant Auramine-O Dye by Sodium Dodecyl Sulfate Functionalized Magnetite Nanoparticles: Isotherm, Kinetics, and Fixed-Bed Column Studies

Presently, the treatment of dye-polluted water is a challenging task worldwide. In this study, the adsorptive removal of Auramine-O (AO) dye by magnetite nanoparticles (MNs) and sodium dodecyl sulfate (SDS) functionalized MNs (SFMNs) were investigated. FESEM, HRTEM, EDX, and XRD were employed to characterize the MNs. In batch optimization, dye removal efficiency of 74% was obtained at contact time (40[Formula: see text]min), pH 6.5, sorbent dosage (20[Formula: see text]mg), and initial dye concentration (20[Formula: see text]mg/L). The maximum adsorption capacity of 55.56[Formula: see text]mg/g was estimated from Langmuir model and the isotherm data were fitted with Freundlich model ([Formula: see text]) for SFMNs. Pseudo-second-order kinetics was followed by both MNs and SFMNs for the adsorption of AO dye. The continuous AO dye adsorption was studied in fixed-bed column and the effects of bed height, influent flow rate, and initial dye concentration were investigated. The column performance was evaluated by breakthrough kinetic modeling and Yoon–Nelson model was fitted with the data. The results of this study showed that the surface modification of MNs using SDS enhanced the AO dye removal efficiency and SFMNs can be employed as an efficient nanoadsorbent for AO dye removal in batch and continuous mode of operation.