Decontamination of Cr(VI) and Mn(II) from aqueous media by untreated and chemically treated banana peel: a comparative study

Untreated banana peels (UTBPs), alkali-hydrolyzed banana peels (AlBPs), acid-hydrolyzed banana peels (AcBPs), and bleached banana peels (BBPs) were used as adsorbents separately for the removal of Cr(VI) and Mn(II) from aqueous solution during batch experiments. Different parameters like pH, temperature, contact time, adsorbent dose, and initial concentration were studied. The maximum removal capacities for Cr(VI) were UTBP (45%), AlBP (87%), AcBP, (67%) and BBP (40%). While for Mn(II), the maximum removal capacities of theses adsorbents were UTBP (51%), AlBP (90%), AcBP (74%) and BBP (67%) at optimum conditions. The maximum removal of Cr(VI) and Mn(II) was obtained at initial concentration 3 mg/L, adsorbent dose of 4 g/L, pH 6, and contact time 60 min. It was noted that the metal ions removal capacity of these adsorbents was AlBP > AcBP > UTBP > BBP, which indicated that chemical treatment of banana peels enhances the biosorption of metal ions. This study showed that chemically treated banana peel can be used as suitable and cost-effective adsorbent for the removal of Cr(VI) and Mn(II) ions from aqueous solutions.