Non-conventional, burnt Shorea robusta leaf extract mediated green synthesis of zinc oxide nanoparticles and facile removal of eriochrome black T dye from water

Abstract

The present study evaluates the synthesis of zinc oxide nanoparticles (ZnO NPs) using water extract of Sal leaves (Shorea Robusta) for efficient removal of Eriochrome black-T from the water and wastewater. The material is characterized using FESEM, FTIR, EDX, pHzpc, XRD, BET, and TGA analysis. XRD confirmed the synthesis of ZnO with an average crystallite size of 35.24 nm a surface area of 95.939 m²/g and a pore volume of 0.280 cm³/g. The pH_zpc of the material is 7.45. The study evaluates the effects of contact time (0–100 min), pH (3–10), concentration (10–50 mg/L), and temperature (298–328K). The Langmuir isotherm model (R² = 0.993) and pseudo-second-order kinetic model (R² = 0.998) were found to be the best-fit models. The maximum uptake capacity is 265.554 mg/g. The interaction is spontaneous (ΔG° −12.889 to–14.898 kJ/mol), endothermic ΔH° (4.290–14.216 kJ/mol) with an increase in spontaneity at the solid-liquid junction. The dye-loaded ZnO NPs were successfully regenerated in dilute NaOH solution and 1:1 methanol water, achieving regeneration efficiencies of 78% and 60%, respectively. The reusability of the ZnO NPs was ascertained for up to three consecutive cycles.

NOVELTY STATEMENT

A promising method for synthesizing zinc oxide nanoparticles using water extract from burnt Shorea robusta leaves as a precipitating and capping agent has been demonstrated with a high yield. The method is economical and convenient without the use of any chemical precipitating agents. The prepared material efficiently removes Eriochrome black T dye, commonly used in various industries for dyeing silk and nylon, from the solution.

We report the first-ever synthesis of ZnO NP using the water extract of burnt leaves, and its application is tested for dye removal. A high surface area of 95.939 m²/g was determined, which is also higher in comparison to many works published. The maximum adsorption capacity recorded for EBT removal is 265.55 mg/g, which is relatively higher than other commercially synthesized zinc oxide.

Graphical Abstract

Keywords:

• Shorea robusta
• EBT
• leaf extract
• zinc oxide
• nanoparticle
• wastewater

Disclosure statement

No potential conflict of interest was reported by the author(s).