Brinjal (Solanum melongena) stalk waste as an effective scavenger for Eriochrome Black-T from water and wastewater: an approach towards waste to best

Abstract

Stalks of brinjal (Solanum melongena), hereinafter SM, have been exercised as an efficient and sustainable adsorbent material for the elimination of Eriochrome Black-T (EBT) from an aqueous solution. The material was characterized by FTIR, FESEM, BET surface area, pH_pzc, and proximate analysis. FTIR spectrum suggests the presence of polyphenolic moieties, responsible for successful dye binding. FESEM images show an unprecedented octopus-like texture containing micropores. The central head transforms the architecture of a flower. The evaluated BET surface area of 10.042 m²/g and pore volume 1.055 × 10⁻²cm³/g suggest a porous material. The pH_pzc of the material was evaluated to be 7.05, and under optimized conditions, the maximum adsorption capacity was found 52.631 mg/g at pH 7. The operational parameters were studied concerning contact time (0–90 min), pH (5–11), initial concentration (10–40 mg/L), and interfering ions (PO₄⁻³, AsO₄⁻³, Hg⁺², Pb⁺²). Adsorption follows Langmuir isotherm best (R² = 0.996), and pseudo-second-order kinetics (R² = 0.991) indicate a monolayer and homogeneous adsorption. 83% regeneration was successful with 0.1(M) sodium hydroxide solution. The material can be reused for up to three cycles with 90% efficiency retention. Analysis of EBT containing industrial effluent indicates that 52.62% of EBT can be removed.

Novelty statement

Brinjal (Solanum melongena), being one of the most cultivated vegetables around the globe, generates voluminous waste as stalks which warrant proper management. With this aim, such stalks were converted to a phytosorbent and selected for removal of Eriochrome black-T (EBT), a dye that is used by industry persons and science students in their laboratory experiments. The prepared material is highly porous, water-stable, regenerable, and reusable. The protocol is economically viable, easy, and efficient for industrial effluent treatment as well. With a notable maximum adsorption capacity of 52.631 mg/g, the material could offer an ideal choice for dye decontamination.

Keywords:

• Brinjal stalk
• EBT dye
• industrial effluent
• phytosorbent
• Solanum melongena

Acknowledgment

MAQ, PPS, and SD thank the Central University of Jharkhand for providing a fellowship

Disclosure statement

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