Characterization and Optimization of Tamarindus indica Copper Nanoparticles (TA-CuNPs) for the Adsorptive Removal of Malachite Green

Copper nanoparticles doped with Tamarindus indica seed extract (TA-CuNPs) were greensynthesized to combine sustainability with an enhanced adsorption potential for wastewater treatment. Comprehensive characterization (SEM, FTIR, XRD, and BET) confirmed the porous structure and active surface functionalities of the materials. Batch adsorption studies of Malachite Green (MG) demonstrated a strong dependence on solution pH, adsorbent dosage, dye concentration, contact time, and temperature, with optimal performance at pH 6 and 0.5 g.L-1. The Langmuir isotherm provided the best equilibrium fit (R² = 0.999), yielding a monolayer capacity of 243.90 mg.g-1. Kinetic evaluation confirmed pseudo-second-order dominance (R² = 0.999), indicating chemisorption, while thermodynamic analysis revealed spontaneous and endothermic uptake (ΔG° < 0, ΔH° > 0). RSM-CCD optimization identified the ideal operational conditions: 19.85 mg.L-1 MG, 0.498 g.L-1 adsorbent, pH 6.18, and 318 K, achieving maximum removal efficiency with excellent model accuracy (R² > 0.98, low error statistics). These results collectively establish TA-CuNPs as a high-capacity, greensynthesized, and scalable adsorbent suitable for practical wastewater treatment.