Adsorption of hexavalent chromium from aqueous solution using pomegranate peel as low-cost biosorbent

• DOI: 10.1007/s42398-021-00192-8
• Publication Date: 2021-06-03T04:02:41Z
• Authors: Rakhi Giri; Nisha Kumari; Monalisha Behera; Avimanu Sharma; Sanjeev Kumar; Narendra Kumar; Ritu Singh
• Keywords: Hexavalent Chromium; Langmuir adsorption model; Endothermic process

Hexavalent chromium (Cr VI) is a toxic heavy metal that causes severe environmental and human health hazards. This study explores the potential of using pomegranate peel as an economical and environment-friendly solution for the removal of Cr (VI) from aqueous solution and investigates its adsorption characteristics. The prepared material was characterized using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDX). The removal efficiency of pomegranate peel and the effect of experimental parameters on Cr (VI) sorption were evaluated through batch experiments. The removal efficiency of the pomegranate peel was found to be dependent on the pH of the Cr (VI) solution, with pH 2 being optimal. Further, it was observed that Cr (VI) removal enhances with the rise in the adsorbent dosages, temperature, contact time, and agitation speed while it reduces with increasing pH, initial concentrations, and ionic strength. Excellent removal capacities (96%) were observed at 2 pH, 300 mg adsorbent dosage, and 30 min contact time. The kinetics of Cr (VI) adsorption fitted well with the pseudo-second-order rate model, and the calculated adsorption capacity of the model showed good agreement with the experimental values. The Langmuir isotherm described the adsorption mechanism of Cr (VI) onto pomegranate peel, indicating monolayer adsorption of Cr (VI) with an adsorption capacity (qmax) value of 20.87 mg/g. Thermodynamic studies further revealed spontaneous and endothermic adsorption of Cr (VI) on the adsorbent’s surface. The findings of this study indicate that pomegranate peel could be utilized as an efficient, eco-friendly and low-cost biosorbent for the removal of Cr (VI) from the contaminated aqueous matrices.