Permanganate-mediated oxidation of Pachira aquatica shells as biosorbent for Chromium detoxification in Water

Résumé fourni par la source

In this study, shells of money tree chestnuts (Pachira aquatic, MT) were oxidatively modified using potassium permanganate to produce a MnOx-functionalized biosorbent (mMT) for efficient removal of hexavalent chromium (Cr(VI)) from aqueous media. Surface oxidation with KMnO4 significantly enhanced the adsorption performance by introducing oxygen-containing functional groups and Mn-based redox sites on the biomass surface. Adsorption experiments showed that Cr(VI) uptake increased with increasing concentration and was best described by the Langmuir model, yielding a maximum adsorption capacity of 179.31 mg/g. Sorption kinetics reached equilibrium within 60 min and were best fitted by the pseudo-second-order model, suggesting that chemisorption governs the rate-limiting step. The surface chemistry and structural changes of the materials were investigated using FTIR, SEM-EDX), XRD, and TGA analyses. The modified biomass exhibited strong pH-dependent behavior, achieving nearly complete Cr(VI) removal at pH 2.5 due to the combined effects of electrostatic attraction and surfacemediated redox interactions. Interference studies revealed moderate effects of coexisting ions, with phosphate showing the strongest competition for adsorption sites. Regeneration experiments using NaOH demonstrated that the sorbent retained approximately 75% of its initial adsorption capacity after five cycles.

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