Adsorption of atrazine from aqueous systems on chemically activated biochar produced from corn straw. Issue 1 (February 2022) - do Nascimento, Cleuciane Tillvitz
Abstract: In this research, the atrazine adsorption onto activated biochar produced from corn straw was evaluated based on kinetic and equilibrium studies and physical, chemical and morphological analyses. Batch adsorption experiments were performed to obtain kinetic and equilibrium parameters which were used to simulate the process' performance on fixed-bed column. The activated biochar showed specific surface area, total pore volume and average pore radius of 573 m 2 g −1, 0.3054 cm 3 g −1 and 10.7 Å, respectively, while the non-activated biochar exhibited lower specific surface area (504 m² g −1 ) in comparison with the activated biochar. The atrazine adsorption mechanism was predominantly driven by hydrogen bonds and π-π stacking. The experimental equilibrium data was adequately described by Langmuir isotherm, showing high adsorbate-adsorbent affinity (KL = 4.287 L mg −1 ). The adsorbent also showed favorable kinetics which was well described by the intraparticle diffusion model. The atrazine adsorption dynamics on fixed-bed column packed with the produced biochar was investigated by using an experimental design associated to phenomenological mathematical modeling. The approach was able to predict the column behavior from the batch parameters and was experimentally validated, showing an efficiency of 72% and breakthrough time of 520 min. The results evidenced the effectiveness of the produced biochar to remove atrazine from water as well as the model to adequately predict the batch and column's performance. Graphical Abstract: ga1 Highlights: Biochar produced from an abundant waste material (corn straw) in Brazil. A major contribution of micropores was observed in porous structure. Robustness identification of kinetic and equilibrium parameters from batch studies. Phenomenological-statistical modeling was successfully used in fixed-bed study. Biochar was efficient in atrazine removal on fixed-bed column.