Ecological strategy and optimization of the RSM process to remove organic pollutants (Violet Crystal) in aqueous solution from pine bark through adsorption modeling and experimental research

This study investigates the effectiveness of raw pine bark (SB) as a bio-adsorbent for removing crystal violet (CV) dye from aqueous solutions. Batch adsorption experiments were conducted to optimize the adsorption parameters, including pH, adsorbent dosage, contact time, initial dye concentration, and temperature. The physical and chemical properties of pine bark were characterized using various analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS). The results showed that under optimal conditions, a removal efficiency of 82.47% was achieved, with a maximum adsorption capacity of 33.51 mg/g. Thermodynamic analysis revealed a spontaneous adsorption process, with a negative Gibbs free energy value (ΔG° = -33.35 kJ/mol at 298 K). Additionally, pine bark exhibited good thermal stability, with a moisture-related mass loss of 11.10%. The adsorbent demonstrated excellent reusability, maintaining an adsorption efficiency above 84% after multiple cycles. Furthermore, the adsorption isotherms indicated that the process followed the Langmuir model, with a theoretical maximum adsorption capacity of 153.84 mg/g. These findings suggest that pine bark is a promising adsorbent for industrial wastewater treatment applications.