Multifaceted optimization of biochar for removing atenolol and sulfamethoxazole from aqueous solutions through response surface methodology

In this study, biochars derived from date palm fronds and leaves were investigated for their capacity to remove atenolol (ATE) and sulfamethoxazole (SMX) in single- and multi-solute solutions. Among the various biochars produced, date palm frond pyrolyzed at 600 °C (BF-600) achieved the highest removal efficiencies for both contaminants. Response surface methodology via Box–Behnken conducted to find the optimal operating conditions revealed that acidic conditions, higher dosages of BF-600 and longer contact times greatly improved the removal of ATE and SMX with removal efficiencies of 79.28% and 94.73%, respectively. Adsorption mechanisms were elucidated through fitting experimental data to Freundlich and pseudo-second-order models, suggesting chemisorption in heterogeneous multiple layers. Thermodynamic analysis indicated an endothermic and chemisorptive nature of adsorption. The effect of the concentration of NaCl ionic strength on SMX and ATE removal for BF-600 showed a drop from 79.28 to 43.47% and 94.7–362.57%, respectively, when concentrations increased from 0 to 0.1 M. In multi-solute systems, competition between ATE and SMX for adsorption sites was observed, notably influenced by pH levels. Regeneration studies indicated suitability to use BF-600 for at least 2 cycles. Characterization of the collected samples displayed successful adsorption of the contaminants onto BF-600. Further modifications of BF-600 can prove effective in further contaminant removals.