Eco-Friendly adsorption performance of Spartium junceum L. for the efficient removal of Crystal Violet: a low-cost biosorbent approach

This research provides a comprehensive evaluation of the adsorption-based elimination of Crystal Violet dye from aqueous environments utilizing Spartium junceum L. as a sustainable, bio-based and economically viable adsorbent. The study systematically investigated the influence of key operational parameters, namely initial dye concentration, pH of the solution, adsorbent dosage, temperature and contact duration, on the overall adsorption performance. A removal efficiency of 91.57% was achieved after 240 min at pH 6.2, with an adsorbent dosage of 10 g/L and an initial dye concentration of 100 mg/L. Adsorption equilibrium was assessed using both Langmuir and Freundlich isotherm models, with both providing strong conformity to the experimental data. The Langmuir model predicted a maximum monolayer adsorption capacity of 31.25 mg/g. Kinetic analysis demonstrated that the adsorption behavior aligns more closely with the pseudo second order model, indicating a chemisorption controlled mechanism. Thermodynamic assessments revealed that the adsorption process is spontaneous and endothermic, as indicated by negative Gibbs free energy (ΔG°) values alongside positive enthalpy (ΔH°) and entropy (ΔS°) changes. In addition, the adsorbent was thoroughly characterized through surface and structural analyses including FTIR, SEM-EDX, BET and XRD. The collective findings confirm that Spartium junceum L. possesses substantial potential as a green and effective biosorbent for the treatment of dye laden wastewater.