Na-alginate, polyaniline and polypyrrole composites with cellulosic biomass for the adsorptive removal of herbicide: Kinetics, equilibrium and thermodynamic studies

This study was designed to prepare the sugarcane bagasse (SB) composite with polyaniline (PAn), polypyrrole (Ppy) and sodium alginate (NaA) and employed as an adsorbent for the adsorptive removal of herbicide (2,4-dicholorophenoxyacetic acid, 2,4-D). Fabricated composites were characterized by SEM and FTIR techniques. The affecting variables, i.e., temperature, contact time, initial herbicide concentration, medium pH and adsorbent dose were studied in batch mode. Different isotherms were employed on the adsorption data and the maximum adsorption capacity of SB was recorded to be 77.75 mg/g at pH 3.0, 150 mg/L 2,4-D initial concentration at 30 °C. The models (pseudo-second-order and Freundlich) best explained the adsorption experimental data with R2 values ≥ 0.90 and ≥ 0.96, respectively. The thermodynamics parameters (ΔG, ΔH, and ΔS) were computed and the herbicide adsorption onto the composites was an exothermic and spontaneous process. Results revealed that sugarcane bagasse composites with PAn, Ppy, and NaA are efficient adsorbents, which could be used for the remediation of 2,4-D in the effluents.