The constant increase of CO 2 concentration in the atmosphere is recognized worldwide to severely impact the environment and human health. Zeolites possess a high adsorption capacity for CO 2 removal, but their powdery form prevents their use in many practical applications. When binding agents are used, a partial occlusion of the porosity can severely compromise the adsorption capacity. In this regard, a great challenge is producing compact composite adsorbents while maintaining a high specific surface area to preserve the pristine performance of zeolites. Here, this goal was achieved by preparing beads with a high content of zeolite 13X (up to 90 wt %) using a chitosan aerogel as the binding agent. A facile preparation procedure based on the freeze-drying of hydrogel beads obtained by phase inversion led to a peculiar microstructure in which a very fine polymeric framework firmly embeds the zeolite particles, providing mechanical coherence and strength (compressive strain >40% without bead fragmentation, deformation <20% under 1 kg f -load) and yet preserving the powder porosity. This allowed us to fully exploit the potential of the constituents, reaching a high specific surface area (561 m 2 g –1 ) and excellent CO 2 uptake capacity (4.23 mmol g –1 ) for the sample at 90% zeolite. The beads can also be reused after being fully regenerated by means of a pressure swing protocol at room temperature.

Organic dyes are extensively used in many industrial sectors, and their uncontrolled disposal into wastewaters raises serious concerns for environmental and human health. Due to the large variety of such pollutants, an effective remediation strategy should be characterized by a broad-spectrum efficacy. A promising strategy is represented by the combination of different adsorbent materials with complementary functionalities to develop composite materials that are expected to remove different contaminants. In the present work, a broad-spectrum adsorbent was developed by embedding zeolite 13X powder (ZX) in a chitosan (CS) aerogel (1:1 by weight). The CS–ZX composite adsorbent removes both anionic (indigo carmine, IC) and cationic (methylene blue, MB) dyes effectively, with a maximum uptake capacity of 221 mg/g and 108 mg/g, respectively. In addition, the adsorption kinetics are rather fast, with equilibrium conditions attained in less than 2 h. The composite exhibits good mechanical properties in both dry and wet state, which enables its handling for reusability purposes. In this regard, preliminary tests show that the full restoration of the IC removal ability over three adsorption–desorption cycles is achieved using a 0.1 M NaOH aqueous solution, while a 1 M NaCl aqueous solution allows one to preserve >60% of the MB removal ability.

Water pollution is one of the biggest environmental issues of our times. To address such a huge challenge, the full involvement of everyone is required. In this context, we report the results of outreach hands-on activities aimed at presenting to the general public two classes of materials with high potential in the removal of common water pollutants, such as heavy metals and dyes: zeolites and chitosan-based aerogels. Under the guidance of young students of materials science and engineering, participants have performed safe, fast, and easy to understand experiments for the removal of copper ions and dye molecules from water. The discussion of the results, which was adapted time by time to the knowledge and age of the audience, provided all participants with a general understanding of the two phenomena underlying water purification, namely, ion exchange for zeolites and molecular adsorption for chitosan aerogels. Besides raising awareness of young people about water pollution and, more in general, about environmental issues, the proposed activity highlights the key role of materials scientists in providing smart and feasible solutions to tackle everyday problems.