Ammonium removal from aqueous solutions by fixed-bed column using corncob-based modified biochar

This study investigated the potential of removing ammonium ([Formula: see text]) from aqueous solutions using corncob based on modified biochar (MBCC) in the fixed-bed column. Corncob biochar was soaked in a mixture of HNO₃ 6.0 M and NaOH 0.3 M to prepare active binding sites for ammonium removal. The effect of initial ammonium concentrations (10-40 mg/L), flow rates (1-9 mL/min) and MBCC fixed-bed heights (8-24 cm) on the breakthrough characteristics of the adsorption system were studied. The results showed that the highest adsorption capacity of fix-bed column, the breakthrough time and value of C_t/C_o were 12.83 mg/g, 480 min and 0.862 ± 0.025 at 10 mg/L of initial ammonium concentration, 8 cm of MBCC fixed-bed height and 3 mL/min of flow rate, respectively. The breakthrough curve model in this study also indicated that all Yoon-Nelson, Thomas and Adam-Bohart models well fit with the experimental data with a high R². The results also proved that MBCC can be used as a potential adsorbent for eliminating [Formula: see text] in the fixed-bed column. The saturated MBCC was also regenerated and reused consecutively for four cycles. The usage of mixture of NaOH and NaCl in recovering MBCC was better than NaCl only.