Biosorption of heavy metals from actual electroplating wastewater using encapsulated Moringa oleifera beads in fixed bed column

Abstract

In this study, encapsulated Moringa oleifera bead (EMB) was synthesized using M. oleifera seed powder with Ca-alginate for the biosorption of heavy metals (Zn²⁺, Cu²⁺, Mn²⁺, Co²⁺, and Ni²⁺) from electroplating industrial wastewater. In batch mode, the effects of various experimental parameters (contact time, biosorbent mass, and pH) were investigated. Equilibrium modeling studies (Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich) were established and the maximum sorption capacity (q_max) of about 5.8, 4.78, 4.6, 1.3, and 1.02 mg/g was reported for Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Mn²⁺, respectively. Further, biosorption of heavy metals was carried out by fixed bed column studies by varying the parameters such as effect of influent flow rate (1–10 mL/min) and bed height (5–25 cm). Based on the experimental results, the breakthrough capacity (Q_0.5 mg/g) was acquired at 55.5, 63.1, 74.5, 64.9, and 104.5 for Zn²⁺, Cu²⁺, Mn²⁺, Co²⁺, and Ni²⁺ with influent flow rate of 1 mL/min. In addition, Thomas and Yoon–Nelson models were applied to the experimental data to predict the breakthrough curves using linear equation and to establish the distinctive parameters of the column. Finally, EMB was examined before and after biosorption using SEM/FTIR analytical techniques. In conclusion, based on our results, EMB is expected to be a competent biosorbent for the removal of heavy metals from the wastewater.

Keywords:

• Electroplating wastewater
• Column study
• Breakthrough curve
• Heavy metals
• Moringa oleifera
• Biosorption

Acknowledgment

The authors would like to thank Nanotechnology Research Centre, SRM University, Chennai, for helping them with instrumentation facilities for this work.