Fruit peel incorporated alginate based magnetic hydrogel bio-composite beads for removal of hexavalent chromium

High adsorption capacity, reusability and sustainability are the most important features sought in the adsorbent preferences to be used in wastewater treatment. In this research work, magnetic composite beads prepared from fruit peels (nectarine and orange) and alginate (ALG) as biopolymers (NAF and OAF) were synthesized by dropping and pH-precipitation method as alternative adsorbents. By encapsulating the adsorbent using alginate and imparting magnetic properties, the separation of the adsorbent from water after the adsorption process has been simplified. Fourier transform infrared spectroscopy analysis (FTIR), scanning electron microscopy (SEM) analysis, energy-dispersive X-ray (EDX)-mapping and X-ray diffraction (XRD) analyses were performed to examine the surface chemical structure and surface morphological structure of these new synthesized biosorbents. The calculated maximum adsorption capacities were 224.3 mg/g for OAF and 256.5 mg/g for NAF at 298 K and pH =2.0. It was observed that the adsorption process for both adsorbents was endothermic and spontaneous. Moreover, the adsorptions of Cr (VI) onto both adsorbents followed the pseudo-second order model and fit the Langmuir isotherm model better. OAF and NAF were found to be reusable with stable adsorption capacity for at least five cycles. Overall, this study demonstrates the performance of OAF and NAF in the removal of Cr (VI) ions from aqueous solutions, thus highlighting the promising potential of these magnetic bio-based adsorbents for sustainable water treatment.