Efficient removal of Victoria Blue B dye from water using novel nanocomposites based on carbon, metal borates, and metal oxides

Victoria Blue B is a persistent cationic dye that threatens water quality and reuse. Two Pechini-derived multiphase nanohybrids, MgSrB2O5/PbB2O4/SrB2O4/C (MSPB500) and MgSrB2O5/PbB2O4/SrPbO3/Pb3O4/Mg2B2O5/C (MSPB700), were fabricated and evaluated for efficient Victoria Blue B removal. The novelty lies in constructing a carbon–metal borate/oxide nanohybrid in which several borate/oxide phases coexist within a carbon-containing matrix, providing oxygen-rich binding sites and synergistically enhancing dye–surface interactions. The maximum adsorption capacities were 369.00 and 282.49 mg/g for MSPB500 and MSPB700, respectively. XRD confirmed the targeted phase assemblages and yielded crystallite sizes of 57.89 nm (MSPB500) and 74.47 nm (MSPB700), while HR-TEM showed sheet-like/flake-like features for MSPB500 and denser spherical/oval aggregates for MSPB700 with mean particle sizes of 59.34 nm and 160.72 nm, respectively. Under optimal conditions (pH 10, 298 K), MSPB500 and MSPB700 achieved removal efficiencies of 96.22 and 72.21%, reached equilibrium within 60 and 80 min, and retained 86.64 and 59.79% removal after five adsorption–desorption cycles, demonstrating practical reusability. The nanohybrids were well described by Langmuir equilibrium isotherm and pseudo-first-order kinetic model, indicating predominantly physical adsorption with strong electrostatic affinity.