Enhancement of nitrate adsorption from aqueous solutions by glucose-derived nitrogen-doped carbonaceous adsorbent

Abstract

Developing effective nitrate removal methods is crucial for addressing water pollution. A nitrogen-doped glucose-derived carbonaceous adsorbent (UrGlu-4.5Z0.6–2nd) was prepared to enhance nitrate adsorption from wastewater. The optimization process of the adsorbent revealed the interaction principles among the raw materials, wherein the special brown porous foam-like intermediate formed after pre-treatment plays a decisive role in enhancing the adsorption performance of the adsorbent. UrGlu-4.5Z0.6–2nd exhibited a point of zero charge (pH_pzc) at the pH of 3.0 and a specific surface area (S_BET) of 6.13 m²/g. It was shown that the nitrogen-doped modified adsorbent exhibited a considerable capacity for adsorbing nitrate over a wide pH range of 2.0–10.0. The Langmuir isotherm model and the pseudo-second-order kinetic model can accurately describe the nitrate adsorption process of UrGlu-4.5Z0.6–2nd, and the maximum adsorption capacity (X_m) predicted by the Langmuir isotherm model was 1.18 mmol/g. Additionally, UrGlu-4.5Z0.6–2nd demonstrated an excellent adsorption capacity in practical applications using a fixed-bed column adsorption mode, with a breakthrough time of 136 min. It still exhibited preferential adsorption of nitrate in the coexisting ions solution. The results of nitrate adsorption studies and surface characterization indicate that the introduction of active quaternary nitrogen (N-Q) adsorption sites after nitrogen-doped is the primary mechanism for enhancing the adsorption capacity of nitrate.