Enhanced methylene blue dye sequestration by carbon-embedded mesoporous zinc oxide nanoparticles fabricated utilizing Aloe barbadensis miller biowaste: Batch optimization, simulation modeling, and textile effluent feasibility

The present study reports novel carbon-embedded mesoporous zinc oxide nanoparticles (ZnO/C NPs) utilizing Aloe barbadensis miller (Aloe vera) biowaste extract as size-reducing agent and bio-stabilizer via a one-pot green fabrication approach. The fabricated nanoparticles were carbonized at 250 °C and characterized using FTIR, UV-Vis, ZPA, TEM, SEM/EDX, XRD, BET, and TGA techniques. Using Brunauer, Emmett, and Teller's theory, the ZnO/C NPs specific surface area was determined to be 63.25 m2/g, and the average pore diameter (3.46 nm) was in the mesoporous range. Fabricated ZnO/C NPs have an un-uniform size distribution, with an average crystallite size of 17.37 nm. The methylene blue (MB) dye adsorption of mesoporous ZnO/C NPs was studied in batch mode experiments at 37 °C using an aqueous solution. Detailed isotherms and kinetics modeling were performed, and it established that the Langmuir isotherm and Pseudo second order kinetic correctly fit the optimized MB dye adsorption data due to their higher correlation coefficients than other analyzed models. The Langmuir isotherm-based monolayer adsorption was found to be 105.26 mg/g. The pseudo second order kinetic best explains the adsorption reaction, indicating that the chemisorption mechanism is more likely to regulate the MB dye adsorption. Further, thermodynamics parameters showed that the MB dye adsorption onto ZnO/C NPs was spontaneous, endothermic, and accompanied by increased entropy. The ZnO/C NPs demonstrated remarkable MB dye sequestration from aqueous solution upto four reusability cycles, with regenerability of ≥84.52 %. Furthermore, feasibility study revealed an outstanding decolorization efficacy of MB dye upto 58.18 % from textile effluent, establishing mesoporous ZnO/C NPs as viable, environment-friendly, and cost-effective remedies for textile wastewater treatment. [Display omitted] •Aloe barbadensis miller biowaste was employed to fabricate green mesoporous ZnO/C NPs.•Methylene blue was efficiently adsorbed, and pseudo second order kinetic explained chemisorption.•The Langmuir isotherm predicts the monolayer coverage of 105.26 mg/g for MB dye.•Ad-desorption cycles ensure ≥84.52 % ZnO/C NPs regenerability with superior MB dye adsorption.•MB dye decolorization of 58.18 % from textile effluent suggests practical effectiveness.