Adsorptive removal of methylene blue by raw and acid-treated bamboo leaves: A study using DFT, MPR, and GA modeling

Bamboo leaves (BL) and their acid-treated forms, H2SO4-treated bamboo leaves (SBL) and H3PO4-treated bamboo leaves (PBL), were investigated as low-cost biosorbents for the removal of methylene blue (MB) from aqueous solution. Batch adsorption experiments were conducted to evaluate the effects of pH, contact time, adsorbent dosage, initial dye concentration, and temperature. Maximum MB removal efficiencies of 89%, 94%, and 98% were achieved using BL, SBL, and PBL, respectively, under optimum conditions (pH 7, contact time of 180 min for BL and 120 min for SBL/PBL, and adsorbent dosages of 3, 2, and 2 gL–1, respectively). The pseudo-second-order model best described the adsorption kinetics, while the Langmuir isotherm provided the best fit, with a maximum adsorption capacity of 181.172 mgg–1 for PBL at 298 K. The Dubinin–Radushkevich isotherm indicated that the adsorption process was predominantly physisorption. SEM, BET, FTIR, and solid-state 13C NMR analyses confirmed that the enhanced adsorption performance was associated with increased surface characteristics and the presence of functional groups from cellulose, hemicellulose, and lignin. DFT calculations revealed the electronic properties governing the adsorbent–adsorbate interactions. Furthermore, multiple polynomial regression (MPR) and genetic algorithm (GA) models successfully predicted MB removal, demonstrating their potential for optimizing the adsorption process.