A chemometric strategy based on a Box–Behnken design to optimize the removal of hexavalent chromium from water using Pomegranate peels as an eco-friendly adsorbent

The current study aims to investigate the elimination behavior of hexavalent chromium from aquatic media by using dry Pomegranate peel powders (PGPs). The pomegranate peels powder used was well prepared and then characterized using various techniques including FTIR, pHpzc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\rm{pH}}_{\rm{pzc}}$$\end{document}, BET, XRD, and SEM–EDX microscopy. A Box–Behnken design was employed to study the influences of four operating factors including solution pH (1–7), PGPs quantity (20 mg–200 mg), Cr(VI) starting concentration (10 mg L−1–100 mg L−1) and media temperature (20 °C–50 °C) on the adsorption process, which allows satisfactory removal of Cr(VI) from water media. The highest elimination efficiency (100%) was achieved with an adsorbent amount of 152.08 mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rm{mg}$$\end{document} in medium highly acid (pH 1) at a temperature of 50 °C and a Cr(VI) initial dose of 100 mg L−1, with a maximum adsorbent loading of 25.74 mg g−1. The non-linear kinetic modelling study showed that the adsorption kinetics of Cr(VI) obey a pseudo-second order model. The thermodynamic investigation shows that the removal process is exothermic, spontaneous and of a stable configuration.