Antimicrobial magnetic <i>Glycyrrhiza glabra</i> nanocomposite for decolouration of water through adsorption and photodegradation

A sustainable hybrid magnetic nanocomposite based on <i>Glycyrrhiza glabra</i> (GG), GG/γ-Fe₂O₃, was synthesized <i>via</i> one-pot co-precipitation method, and efficiently utilized for adsorption and photocatalytic degradation of two toxic model dyes, Congo red (CR) and Nile blue (NB) dyes from water. The characterization of the GG/γ-Fe₂O₃ was performed by using FT-IR, P-XRD, BET-BJH, FE-SEM-EDX, TEM, SAED, XPS, TGA, UV-visible, and PL techniques. The GG/γ-Fe₂O₃ showed significant inhibition of bacterial and fungal growth. The inhibition statistics towards gram-(+) and gram-(-) bacteria, and fungal strains were found superior as compared to the naive plant material. The influence of adsorption parameters, on dye removal efficiency, was appraised <i>via</i> batch methodology. The fitting of isothermal and kinetic datasets into their respective models indicated that the adsorptive removal process was governed by the Freundlich isotherm and pseudo-second order kinetics. The Langmuir saturation capacity for CR and NB was found to be 47.50 and 15.36 mg g^-1, respectively. The spontaneous and physical sorption of CR and NB was delineated to be exothermic and endothermic, respectively, from 30 to 50 °C. The band gap of the GG/γ-Fe₂O₃ were found 1.69 eV (indirect), and 2.30 eV (direct) which established its semiconducting design, with CR solar-degradation efficiency of 92.7%, following pseudo-first-order kinetics. The degradation intermediates and mechanism have been investigated from radical quenching experiments and high-resolution LC-MS. The GG/γ-Fe₂O₃ exhibited structural integrity and excellent regeneration, supported by post-treatment FT-IR analysis. The reproducibility of the optimum experimental dataset under realistic conditions, including real wastewater, co-existing ions, and dye mixtures, revealed potent application of multifunctional and cost-effective GG/γ-Fe₂O₃ for the efficient removal of both cationic and anionic water contaminants, as well as for reducing microbial loads.