Mechanochemically Scaled-Up Alpha Cyclodextrin Nanosponges: Their Safety and Effectiveness as Ethylene Scavenger

Aiming at the development of a greener ethylene removal alternative, the goal of this study was to scale up and ensure the safety of α-cyclodextrin nanosponges (α-CD-NS) for further use as ethylene scavengers. The solvent-free synthesis of α-CD-NS was successfully scaled up using α-cyclodextrin and N,N'-carbonyldiimidazole as cross-linkers (1:4 molar ratio) by means of mechanical alloying using a PM 100 ball mill by focusing on varying the rotation frequency, as determined by FTIR-ATR, X-ray diffraction, and TGA. α-CD-NS washing optimization was performed in water by monitoring the imidazole concentration in the washing solution through the validation of a fast and sensitive HPLC-DAD method. After 6 h at 40 °C, all imidazole was extracted, allowing a faster and less energy-dependent extraction. α-CD-NS absorbent capacity and porosity were also evaluated through BET isotherms and ethylene absorption experiments using α-CD-NS and commercially available absorbents (zeolite and bentonite) were performed by means of gas chromatography (GC) coupled to a flame ionization detector (FID). With a 93 µL h^-1 kg_adsorbent^-1 ethylene removal capacity, α-CD-NS revealed the best ethylene scavenging activity when compared to the other absorbents, opening the doors for a safer, innovative, and eco-friendlier ethylene removal active packaging.