Synthesis and Characterization of Hybrid Bio-Adsorbents for the Biosorption of Chromium Ions from Aqueous Solutions

Industrial effluents include toxic chemicals, particularly heavy metals, that remain in the environment and jeopardize human and ecological health. This research synthesized hybrid biosorbents (HBs) for the extraction of Cr (III) from wastewater by using sugarcane bagasse, banana peels, and orange peels in conjunction with magnetite at ratios of 1:2, 1:1, and 2:1. The synthesized biosorbents—MSC, MBP, and MOP—were characterized using FTIR, XRD, TEM, BET, and SEM/EDX, therefore validating their structural, functional, morphological attributes and elementary composition. Batch studies showed MBP (1:1) to be the most efficient sorbent, with over 80% removal of Cr (III). Optimization experiments indicated that the peak removal efficiency (92.10%) was achieved at an initial concentration of 100 mg/L, a pH of 3, a dose of 0.4 g/100 mL, and a contact duration of 60 min. Isotherm analysis revealed that adsorption adhered to a homogeneous monolayer mechanism, optimally characterized by the Langmuir Type 1 model (R2 = 0.9688), whereas kinetic analysis demonstrated that the pseudo-second-order model (R2 = 0.9419) yielded the most accurate fit. MBP (1:1) has significant promise as an economical and sustainable biosorbent for the efficient removal of Cr (III) from wastewater.