Fixed-bed column studies for the removal of hazardous malachite green dye from aqueous solution using novel nano zerovalent iron algal biocomposite

Abstract

Sargassum swartzii, a marine alga was used as precursor for the synthesis of novel nano zerovalent iron S. swartzii (nZVI-SS) biocomposite for the removal of malachite green (MG) from simulated wastewater in a fixed-bed column. The performance of the biocomposite was evaluated in the fixed-bed column at various operating conditions such as bed height (3–9 cm), flow rate (5–15 mL/min) and initial MG concentration (5–15 mg/L). The lowest bed height (3 cm), lowest flow rate (5 mL/min) and highest inlet MG concentration (15 mg/L) resulted in highest MG uptake of 0.56 mg/g, compared to other experimental conditions. The column experimental data obtained at different conditions were analyzed using three different models, viz., Adam–Bohart model, Thomas model and Yoon–Nelson model. All three models provided a good breakthrough curve prediction; however, the results obtained from Thomas model and Yoon–Nelson model were more satisfactory. The well-recognized BDST model was also used for describing the effect of bed height on the breakthrough curve. The various characteristics of the biocomposite were studied using SEM, DLS, XRD, XRF and XANES. The nZVI-SS biocomposite fixed-bed column proved to be the potential biosorbent for the removal of MG from aqueous phase.