Abstract
Abstract
Hierarchically porous Na-P zeotype composites with excellent ammonium adsorption performance were prepared via a two-step method. A porous ceramic support was first prepared using coal fly ash, red mud, and coffee grounds, and then zeolite in situ crystallized on the support surface. Characterization of obtained materials indicated that hierarchical porosity was generated from microporous NaP1 zeolite and macroporous ceramic support, and the former accounted for about 23.1 wt% of the total material. Batch experiments were carried out to investigate the ammonium ion adsorption performance on the as-prepared adsorbent. Results indicated that the adsorption capacity could be affected by contact time, initial ion concentration, and solution temperature. Adsorption kinetics followed a pseudo-second-order model with a small thickness of boundary film revealing a chemical reaction related to valence forces and weak ion diffusion resistance to adsorption sites due to the hierarchically porous structure of the adsorbent. Adsorption isotherms coincided well with the Langmuir model. The thermodynamic study suggested that the adsorption was an endothermic and spontaneous process. Moreover, all targeted toxic metals analyzed in the leachate were far below the regulatory levels of toxicity characteristic leaching procedure, demonstrating the feasibility and environmental friendliness of the as-prepared adsorbent for wastewater treatment.
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