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

Nguyen, Lan Huong, Vu, Thi Mai, Le, Thi Trinh, Trinh, Van Tuyen, Tran, Thi Pha, Van, Huu Tap
Environmental technology 2019 v.40 no.6 pp. 683-692
adsorbents, adsorption, ammonium, aqueous solutions, binding sites, biochar, corn cobs, environmental technology, models, nitric acid, sodium chloride, sodium hydroxide
This study investigated the potential of removing ammonium () 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 Cₜ/Cₒ 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 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.