Carbon enriched mixed metal oxides as novel nanocomposites for efficient brilliant green decontamination

Brilliant green dye is a cationic pollutant that poses serious ecological and public-health implications due to its mutagenic as well as cytotoxic effects and its resistance to biodegradation, leading to contamination of aquatic ecosystems and potential organ toxicity in humans. In this study, novel SrPbO₃/MgO/SrCO₃/PbO/C and SrPbO₃/MgO/Sr₂PbO₄/C nanocomposites, designated as MSP600 and MSP800, were successfully synthesized via a facile Pechini sol-gel route at 600 and 800 °C, respectively, for the efficient removal of brilliant green dye from aqueous media. XRD revealed that the average crystallite sizes of MSP600 and MSP800 nanocomposites is 65.29 nm and 76.94 nm, respectively. EDX confirmed the presence of O, C, Sr, Pb, and Mg, with atomic percentages consistent with temperature-induced phase transformation. FE-SEM images showed spherical, homogeneously distributed nanoparticles in MSP600 and irregular, rod-like aggregates in MSP800. HR-TEM analysis confirmed these morphologies, revealing average particle diameters of 23.48 nm for MSP600 and 59.09 nm for MSP800. The maximum uptake capacities were 375.94 mg/g for MSP600 and 304.88 mg/g for MSP800, demonstrating superior performance compared with some adsorbents described previously. Thermodynamic analysis indicated that the uptake method was physical, spontaneous, and exothermic. Kinetic and isotherm studies confirmed that adsorption obeyed the pseudo-first-order model as well as the Langmuir isotherm. Both nanocomposites exhibited excellent regeneration efficiency, maintaining high removal performance over five adsorption-desorption cycles, establishing them as promising, reusable adsorbents for dye-contaminated wastewater treatment.