Evaluation of orange peel (Citrus sinensis) as a source of bioactive components and its use as a bioadsorbent

The juices and nectars of orange produce large quantities of low-value commercial waste such as their peels. These residues have become a major environmental worry due to their high organic matter load, having a high fermentability rate, and causing serious economic and environmental problems for their disposal. However, these residues retain functional compounds such as vita-mins C, phenols, and flavonoids which are recognized for their antioxidant, anti-inflammatory and anticancer properties. The present study aims to evaluate the Cr(III) adsorption capacity in aqueous solutions using treated orange peel (OPT) as adsorbent at 15°C, 30°C and 45°C and different ratios (8 to 40 g L–1) of adsorbent-solution. The results show that the adsorption isotherms conform to the Sips model having the maximum adsorption capacity of 15.3 mg g–1 with 95% removal of Cr(III). It was observed that the process is endothermic and spontaneous. The adsorption kinetics of Cr(III) follows a pseudo-second-order model. Cr(III) removal using OPT was analyzed with the techniques of X-ray diffraction, Fourier-transform infrared spectroscopy, ultraviolet-visible and scanning electron microscopy images. The obtained results suggest that it is feasible to take advantage of OPT to obtain functional compounds and remove Cr(III) from aqueous solutions.