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

Abstract

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

Production of Agarose-Hydroxyapatite Composites via Supercritical Gel Drying, for Bone Tissue Engineering

“…Specifically, spectra were collected for the samples AG1HA1 (when agarose and hydroxyapatite contents were comparable) and AG4HA10 (when hydroxyapatite outweighs agarose). In previous works [ 41 ], it was proved that SC-CO 2 drying did not affect agarose chemistry; therefore, in the present research, only agarose aerogel was analyzed as a reference. Figure 1 reports the obtained spectra.…”

“…The chosen pressure and temperature were 200 bar and 40 °C (ρ CO2 = 0.84 g/cm 3 ); the CO 2 mass flow rate was set at 0.5 kg/h. Each drying lasted about 5 h, following the indication provided in previous works [ 41 ].…”

Synchronously enhanced storage stability and adsorption ability of MXene achieved by grafting polyethylenimine

“…Organic adsorbents can be classified into natural and artificial organic adsorbents. 15 Most natural organic adsorbents are macromolecular polymers of polysaccharides, such as agarose, 16 amylum, 17 and glucose. 18 The common features of natural organic adsorbents are broad source, reasonable price, renewability and biodegradability.…”