Author: Pampana Anil Kumar, Alpitha Suhasini Juttuka, M. Sudheera, Pulipati King, D. Appala Naidu, and Meena Vangalapati

DOI: http://doi.org/10.31788/RJC.2026.1919585

Green-synthesised copper nanoparticles were made using an extract from Litchi chinensis seeds and were studiedasan environmentally friendly material for eliminating methylene blue (MB) dye from an aqueous medium. Thestructural and morphological characteristics of the CuNPs were confirmed through FTIR, EDX, BET, and SEManalyses, demonstrating successful nanoparticle formation with functional groups capable of interacting withdyemolecules. Using a CCD–RSM framework, the key operational parameters - pH, adsorbent dosage, contact time, and temperature - were systematically optimised, yielding a maximum MB removal efficiency of 88.5%under theoptimal conditions (pH ≈ 8, 0.5 g/L, 30 min, and 318 K). The reliability of the predicted responses was confirmedbythe statistical model's excellent fit (R2 = 0.999). Kinetic results confirmed a pseudo-second-order mechanism, whileequilibrium data revealed monolayer chemisorption according to the Langmuir isotherm. The thermodynamicassessment further affirmed the spontaneous and endothermic nature of the adsorption. Concurrently, CuNPssynthesised from litchi seeds offer a resource-efficient, environmentally compliant, and effective platformfor treating dye-contaminated wastewater.

Keywords: Methylene Blue, Adsorption, CCD, RSM, CuNPs, Litchi Seed Extract, and Green Synthesis.