Effect of annealing on the spectral and optical characteristics of nano ZnO: Evaluation of adsorption of toxic metal ions from industrial waste water

• Nano Zinc Oxide was synthesized using biogenic method.
• The effect of annealing temperatures on the spectral and optical properties has been studied.
• Bio-sorption studies were carried out using industrial waste water.
• Kinetics and Equilibrium Profiles were drawn to know the adsorption efficiency.
• In-vitro cyto toxicity studies were carried out to understand the environmental impacts.

The present work accentuates an unexploited and environmentally benign method of synthesizing ZnO nanomaterials using Sugar cane juice. The synthesized nanomaterials were characterized by XRD, SEM, TEM, BET, EDS and FTIR. UV–visible and photoluminescence studies were also carried out to understand the absorption properties of synthesized nanomaterial. From the adsorption studies, it would be clear that synthesized ZnO should be used as an effective adsorbent for Pb(ll) and Cd(ll) removal. The kinetic data followed the pseudo-second-order model. The equilibrium attained at 120 min and isotherm follows the order Sips>Langmuir>Freundlich. The adsorption–desorption studies conducted over 6 cycles illustrate the viability and repeated use of the adsorbent for the removal of Pb(ll)and Cd(ll) from aqueous solutions. The practical efficiency and usefulness of the adsorbent was tested using real industrial wastewater also. Cytotoxicity result shows that, ZnO was biocompatible at lower concentrations, and it was used as an ecofriendly nanoadsorbent for industrial and environmental applications.

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