Green and efficient adsorption of crystal violet onto Viscum album L. biomass using taguchi optimization and process evaluation

For the first time, raw Viscum album L. biomass was systematically evaluated as a novel biosorbent for crystal violet (CV) removal, optimized using a Taguchi L25 orthogonal array. The highest experimental removal efficiency of 82.37% was obtained in the Taguchi experimental matrix at pH 10, 20 mg/L, 90 min, 0.075 g, and 318 K, whereas the Taguchi optimization based on the S/N ratio predicted the optimum operating conditions as pH 10, 20 mg/L, 30 min, 0.05 g, and 318 K, yielding a validated removal efficiency of 91.45% in the independent confirmation experiment. Statistical analysis revealed pH (41.24%) and dosage (34.57%) as the most influential operational factors. Equilibrium data were best described mathematically by the Redlich-Peterson model, suggesting heterogeneous characteristics, while a maximum theoretical monolayer capacity ( \(\:{q}_{m}\) ) of 92.79 mg/g was calculated from the Langmuir isotherm at 298 K. Kinetic data fit the pseudo-second order kinetic model (R 2 ≥ 0.9998), although this kinetic model’s fit does not confirm a specific adsorption mechanism. Low enthalpy values (ΔH° = − 18.50 kJ/mol) are suggestive of predominantly physisorption. Evaluating adsorption performance in real water matrices (tap and drinking water) highlighted its high practical relevance. Reusability studies indicated a moderate initial stability, which decreased to 38.77% removal efficiency after five consecutive cycles. Overall, combining raw V. album L. biomass with Taguchi optimization offers a low-cost, eco-friendly, and sustainable strategy with potential applicability to industrial wastewater treatment.