Multifunctional Magnetic Biochar Nanocomposite for Sustainable Water Treatment, Antimicrobial, Antioxidant, and Biocompatibility Investigations

The increasing level of aqueous discharge from industrial sectors has significantly deteriorated water resources. The development of sustainable materials for the effective mitigation of water contaminants is highly desirable. This study reports the fabrication of a multifunctional magnetic ZnCl₂-activated <i>Glycyrrhiza glabra</i> root biochar-based composite, AGGB/Fe₃O₄, and its effectiveness for the adsorptive removal of model Congo red (CR) and Nile blue (NB) dyes from aqueous solution. The nanocomposite (NC) was characterized by FT-IR, XRD, VSM, BET, FE-SEM-EDS, HR-TEM, SAED, and XPS techniques. For checking viability of the material, the effects of AGGB/Fe₃O₄ dose, dye concentration, pH, temperature, and contact time on the removal efficiency were examined. 2.0 g L^-1 of the NC exhibited a <i>Q_o</i> of 53.89 mg g^-1 for CR and 81.64 mg g^-1 for NB at 40 °C. The Freundlich isotherm and pseudo-second order kinetic models provided the best fit to the experimental data set. The NC demonstrated significant inhibition of both Gram-negative and Gram-positive pathogenic bacteria and fungal strains with durable antioxidant activity. Moreover, AGGB/Fe₃O₄ demonstrated no detectable hemolytic effect, establishing its nontoxicity and biocompatibility. Also, the AGGB/Fe₃O₄'s robustness and stability were evident, with stable capacity across five consecutive adsorption-desorption cycles, as confirmed by FT-IR, XRD, and HR-TEM of the spent AGGB/Fe₃O₄. Thus, AGGB/Fe₃O₄ can be a potential adsorbent to treat dye-laden wastewater and reduce bacterial/fungal contamination.