Graphite oxide/AlZr polycation composites: Surface characterization and performance as adsorbents of ammonia

Graphite oxide/aluminium–zirconium polycation composites were prepared using graphite oxide and commercial solution of Rezal®. To improve the dispersion of graphene-like layers two different surfactant concentrations were used. The resulting materials were used as adsorbents of ammonia either in as received form or prehumidified for 2 h before the breakthrough test. The challenge gas was either dry or with 70% humidity. Although the highest amount adsorbed was measured on adsorbents after prehumidification, the strongest adsorption takes place at dry conditions. Water on the surface increases the amount adsorbed via acid–base reactions, whereas water in the challenge gas decreases the removal of ammonia owing to the competition with NH3 for adsorption centers. The amount of surfactant used for dispersion affects the final performance. More surfactant likely leads to a higher degree of dispersion of graphene-like layers and thus relatively less undisturbed inlerlayer space where intercalation of ammonia can occur. Higher dispersion of graphene layers leads also to higher dispersion of polycations and thus greater adsorption on their Brønsted acidic centers.