kinetic, isotherm, and thermodynamic modeling of methylene blue adsorption by hibiscus plant waste derived biosorbents

Dye pollution is a severe environmental issue for which there are no short-term fixes. adsorption has become the most popular method for removing dyes because of its remarkable effectiveness, ease of use, affordability, and environmental friendliness. this study intends to assess how well two biosorbents; dried powder (dhm) and charcoal (chm), made from hibiscus plant debris remove methylene blue (mb) from aqueous solutions. adsorption kinetics, isotherms, and thermodynamics were examined in order to better understand the adsorption mechanisms. the adsorption capacity and efficiency of methylene blue on both adsorbent materials were assessed using the batch adsorption experiment. several parameters, including ph, initial dye concentration, contact time, adsorbent dosage, and temperature, were examined in relation to the biosorption process. for both biosorbents, the biosorption equilibrium was reached in 20 min, and at ph 10.5, the maximum adsorption capacities were 11.60 and 11.80 mg g-1 for dhm and chm, respectively. despite not going through the extra activation step, chm was assessed in its non-activated condition and, surprisingly, showed equal or even slightly superior mb adsorption ability than dhm. the experimental data was well-fitted by the freundlich and pseudo-second-order models, indicating a physical adsorption mechanism. the thermodynamic study's conclusions demonstrated that mb's adsorption on chm was non-spontaneous and endothermic, with positive values for δho (15.900 kj mol-1), δgo (0.404 kj mol-1), and δso (0.052 kj mol-1 k-1). the mb adsorption on dhm, on the other hand, was exothermic and spontaneous, with negative values for δgo (-5.41 kj mol-1), δho (-42.36 kj mol-1), and δso (-0.124 kj mol-1 k-1). the study's findings demonstrate that hibiscus plant waste can be utilised as an inexpensive, environmentally beneficial biosorbent to remove mb from wastewater.