Manisha Chadha, Shiwani Berry
The current work represents the effectiveness of an untreated, cost-efficient and sustainable biosorbent derived from papaya peels (PP) for the crystal violet dye removal from wastewater. Batch adsorption experiments were conducted to assess the effects of pH, adsorbent dose, dye concentration, and contact time on adsorption efficiency. The PP adsorbent was characterised using techniques including “X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) Spectroscopy, Zeta Potential Analysis, Energy Dispersive Spectroscopy (EDS), and Field Emission Scanning Electron Microscopy (FE-SEM)”. To analyse the adsorption behaviour, various isotherm and kinetic models were applied. The maximum adsorption capacity (q e ) was determined to be 99.01 mg g − 1 . Among the kinetic models tested, the “Pseudo second order model” provided the most accurate fit, while the “Langmuir isotherm model” accurately described the equilibrium data, with R 2 values exceeding 0.9. Furthermore, the “Dubinin-Radushkevich (D–R) isotherm model” was employed to determine the nature of adsorption. The calculated “mean free energy of adsorption” (0.71 kJ mol − 1 ), being below “8 kJ mol − 1 ”, suggested that the process predominantly involved “physical adsorption”. Overall, the results affirm that PP adsorbent serves as an effective and eco-friendly biosorbent for the elimination of dyes from aqueous solutions, operating primarily through physisorption.