Leached compounds from the extracts of pomegranate peel, green coconut shell, and karuvelam wood for the removal of hexavalent chromium

Abstract

During biosorption, the biosorbent releases many organic compounds to the medium. In the present study, extracts of pomegranate peel (PP), green coconut shell (GCS), and karuvelam wood (KW) were prepared at three different conditions, namely 12 h, 3 h, and 3 h at pH 2, for the removal of hexavalent chromium [Cr(VI)]. The amount of organic compounds, mainly the leached organic compounds in the extract before and after treatment with Cr(VI) solution, was determined by chemical oxygen demand analysis. The total phenolic content, antioxidant activity, and total flavonoid content were used to estimate the chromium reduction potential of the extracts. The PP extract is the richest in all the three factors, followed by GCS and KW. The disappearance rate of Cr(VI) in the presence of PP extract reached 99.63% for the 50 mg/l concentration within 3 min, while it was 12% and 10% for GCS and KW, respectively, for the same concentration and time. Reaction mechanisms were formulated with the help of Fourier transform infrared spectroscopy to confirm the role of leached compounds from natural materials for the removal of heavy metal.