Different Drying Techniques Can Affect the Adsorption Properties of Agarose-Based Gels for Crystal Violet Removal

Agarose-based gels were produced either by freeze-drying or supercritical drying for crystal violet (CV) removal from aqueous solutions. The microporosity features of these structures highly affected the final adsorption properties. In particular, agarose cryogels characterized a macroporous and irregular morphology, with low value specific surface area (11 ± 6 m2/g) respect to nanoporous aerogels (154 12 m2/g). To test efficacy CV removal, two different types performed, i.e., batch-mode multi-step mode. Operating in mode, performance was larger both aerogels, since this method allowed more effective contact between adsorbent. using 300 mg cryogels, efficiency 74% achieved; same quantity 96% reached after eight steps adsorption. Desorption realized ascorbic acid and, regeneration, 93% preserved, even three cycles filtration