Simple bio-sorbents derived from Mimusops elengi plant for the effective removal of molybdate from industrial wastewater

Elevated molybdate concentrations in industrial wastewater discharges are an important environmental concern because it effects aquatic life, ecosystems, and human life, and hence, treatment before discharge into the aqueous environment is essential. Simple and effective adsorbents are required for the removal of molybdate ions from industrial wastewater. In this aspect, bio-adsorbents derived from plant materials are proving to be effective, simple, eco-friendly, and economical. In the present investigation, stem powders of Mimusops elengi (MESP), their active carbon (MESAC), iron oxide-coated active carbon (MESAC.Fe), and ‘MESAC.Fe’ doped in zirconium alginate beads (MESAC.Fe-Zr.alg) are investigated as adsorbents. The adsorbents are characterized with respect to various physicochemical parameters and also by adopting XRD and FTIR analysis methods. The suitable conditions for the maximum extraction of molybdate are optimized at pH: 4.0. The maximum adsorption capacity for molybdate at the optimum condition is: 2.92, 9.3, 9.5, and 15.7 mg/g for MESAC, MESAC.Fe, & MESAC.Fe-Zr.alg, respectively. The extraction is marginally effected by common co-ions. The adsorbents can be regenerated and reused for three cycles. The mechanism of the adsorption process is described by thermodynamic parameters, isotherms, and kinetic models. Further, the magnitude of ∆H values confirms that the nature of adsorption is ‘ion exchange and/or a sort of surface complex formation’. The methodology developed is used to treat real wastewater samples collected from industrial and mining effluents. The novelty of the present investigation is that simple and effective adsorbents are developed for the removal of the toxic molybdate ions from industrial wastewater.