Production of a reusable multifunctional magnetic cellulose-based biocomposite from hemp biomass and its application...

The sustainable utilization of renewable biomass is critical for developing environmentally friendly and cost-effective material for wastewater treatment. In this study, hemp biomass (HB), a cellulose-rich natural resource, was successfully converted into a multifunctional magnetic biocomposite (MFMBC) through graft copolymerization, surface functionalization, and Fe₃O₄ co-precipitation. Compared with pristine HB, the MFMBC exhibited markedly enhanced physicochemical properties, including higher thermal stability, a large BET surface area (155.87 m²/g), total pore volume (0.245 cm³/g), and a strongly negative zeta potential (-53.5 m), confirming improved surface reactivity and colloidal stability. The adsorption performance was assessed using Safranin O as a model cationic dye. Under optimized conditions, MFMBC achieved nearly complete dye removal (≈100 %) at a dosage of 0.5 g/L, whereas HB required 2 g/L to reach 85 %. The maximum adsorption capacity of MFMBC (119.1 mg/g) was nearly three times higher than that of HB (44.8 mg/g). Adsorption kinetic followed a pseudo-second-order model, while thermodynamic analysis indicated a spontaneous process dominated by electrostatic interactions. Notably, MFMBC maintained >90 % of its adsorption efficiency after 20 successive adsorption-desorption cycles and showed excellent performance in real wastewater and mixed-dye systems. These results demonstrate that hemp-derived MFMBC is a sustainable, highly efficient, renewable, and reusable adsorbent with strong potential for practical dye removal applications.