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This article reports the obtention of a new gellan-based hydrogel linked with Fe3+ and loaded with a natural micro/nanostructured carbon designed as a contaminant’s removal from wastewater. Hydrogels are known for their water-retaining properties, high binding capacity, and eco-friendly features. The new material is expected to behave as one cost-effective and efficient sorbent, including natural carbon structures with various functional groups. The encapsulation efficiency ranges between 89% and 95%. The obtained hydrogel particles were characterized using FT-IR spectroscopy and scanning electron microscopy techniques. The hydrogel particles’ water stability was evaluated by measuring the transmittance for 10 days, and the capacity to retain water was assessed by determining the swelling degree (Q%). The results showed that hydrogel particles are stable (the transmittance value is higher than 97.8% after 10 days), and their properties are influenced by the cross-linking degree, the amount of the carbon particles encapsulated, and the concentration of gellan. For example, the Q% values and encapsulation efficiency increased when the cross-linking degree, the carbon microstructure quantity, and the gellan concentration decreased. The new hybrid material can retain Pb(II) ions and diclofenac molecules, and could be used in different adsorption–desorption cycles.

Amylase is an enzyme used to hydrolyze starch in order to obtain different products that are mainly used in the food industry. The results reported in this article refer to the immobilization of α-amylase in gellan hydrogel particles ionically cross-linked with Mg2+ ions. The obtained hydrogel particles were characterized physicochemically and morphologically. Their enzymatic activity was tested using starch as a substrate in several hydrolytic cycles. The results showed that the properties of the particles are influenced by the degree of cross-linking and the amount of immobilized α-amylase enzyme. The temperature and pH at which the immobilized enzyme activity is maximum were T = 60 °C and pH = 5.6. The enzymatic activity and affinity of the enzyme to the substrate depend on the particle type, and this decreases for particles with a higher cross-linking degree owing to the slow diffusion of the enzyme molecules inside the polymer’s network. By immobilization, α-amylase is protected from environmental factors, and the obtained particles can be quickly recovered from the hydrolysis medium, thus being able to be reused in repeated hydrolytic cycles (at least 11 cycles) without a substantial decrease in enzymatic activity. Moreover, α-amylase immobilized in gellan particles can be reactivated via treatment with a more acidic medium.