Enhanced adsorption of gentian violet dye from water using lignocellulosic agricultural waste modified with di- and tri-carboxylic acids: Artificial intelligence modeling, practical comprehension, mechanistic and regeneration analyses

This study investigated the preparation of reusable bioadsorbents derived from the overripe Abelmoschus esculentus seeds (OAES) by thermodynamically-regulated esterification in the presence of oxalic, citric and tartaric acids. The carboxylic acid-modified OAES materials were used for the removal of hazardous gentian violet (GV) dye from an aqueous solution and the effects of the key operating parameters such as carboxylic acid concentration (0.6-1.5 mol/L), solution pH (3.0-9.0), bioadsorbent dosage (0.4-3.2 g/L), initial GV concentration (50-900 mg/L), temperature (15-45 degrees C) and contact time (0-300 min) were analyzed. The optimum contact time to achieve equilibrium was found to be 210 min, while the optimum bioadsorbent dosage was 2.0 g/L. The maximum adsorption capacity of the three types of carboxylic acid-modified OAES was 354.08, 412.99 and 292.00 mg/g, respectively, at pH similar to 5.67 and 45 degrees C. The Redlich-Peterson isotherm model showed the best fit for the adsorption equilibrium data and the adsorption kinetics followed a fractal-like pseudo-first-order model. The normalized Gudermannian equation demonstrated that the exact equilibrium time was steadily increased with an increase in the initial concentration of GV. The thermodynamic parameters suggested that the adsorption process of GV was endothermic, spontaneous and favorable in nature. The apparent activation energy showed that the adsorption behavior was mainly attributed to both chemisorption and physisorption. Artificial neural networks (ANNs) were successfully applied to model and simulate non-linear relationships of process parameters in the adsorption process. The optimized networks exhibited high goodness-of-fit measures reflecting the significant applicability of ANN models that predict the adsorption capacity of bioadsorbents.

Automated summary

This study prepared reusable bioadsorbents derived from overripe Abelmoschus esculentus seeds using thermodynamically-regulated esterification with carboxylic acids. The carboxylic acid-modified materials showed high adsorption capacity for gentian violet dye, with optimal conditions found at pH 5.67 and 45 degrees C. The adsorption process was determined to be endothermic, spontaneous, and favorable, with chemisorption and physisorption playing key roles. Additionally, artificial neural networks were successfully utilized to model and predict the non-linear relationships of process parameters in the adsorption process, demonstrating their applicability in predicting adsorption capacity.