Efficient elimination of basic red 9 from wastewater using ceramic metal oxides containing carbon as novel...

Basic red 9 is a cationic triphenylmethane dye of considerable environmental concern because of its toxicity, persistence, and harmful impact on aquatic systems. In this study, two multiphase ceramic metal oxide/carbon nanohybrids, namely Sr₆Co₅O_14.3/SrCO₃/MgO/C (MSC600) and SrCoO_2.5/SrCO₃/MgO/Sr(OH)₂.H₂O/C (MSC800), were synthesized via the Pechini sol-gel method at 600 and 800 °C, respectively. The synthesized nanohybrids were evaluated for the adsorption of basic red 9 from wastewater. XRD confirmed the multiphase crystalline structures of both nanohybrids, with average crystallite sizes of 58.12 nm for MSC600 and 68.62 nm for MSC800. EDX verified the presence of Mg, O, C, Co, and Sr in both samples, while FE-SEM and HR-TEM revealed marked morphology evolution from a more open rod-like network in MSC600 to more compact spherical/polyhedral aggregates in MSC800. Adsorption experiments demonstrated superior maximum capacities of 436.68 mg/g for MSC600 and 313.48 mg/g for MSC800. The adsorption process was found to be physical, spontaneous, exothermic, and followed the Langmuir isotherm and pseudo-first-order kinetic model. Both nanohybrids also exhibited good regeneration/reuse behavior and maintained high removal efficiency in real laboratory wastewater. These findings highlight the strong potential of the developed multiphase nanohybrids for the efficient treatment of basic red 9-contaminated wastewater.