The Innovation Comes from the Sea: Chitosan and Alginate Hybrid Gels and Films as Sustainable Materials for Wastewater Remediation

Abstract

The growing utilization of renewable and residual biomasses for environmental preservation and remediation are important goals to be pursued to minimize the environmental impact of human activities. In this paper, sodium alginate (derived from brown algae) was crosslinked using chitosan (mainly derived from the exoskeleton of crustaceans) in the presence of biowaste-derived substances isolated from green compost (BBS-GC), to produce hydrogels and dried films. The obtained materials were tested as adsorbents for wastewater remediation. To this purpose, gels were characterized using a multi-analytical approach and used as active substrates for the removal of three differently-charged molecules, chosen as model pollutants: crystal violet, rhodamine B, and orange II. The effectiveness of the gel formulations was demonstrated and attributed to the variety of active functionalities introduced by the different precursors, the structural factors and the peculiar physicochemical properties of the resulting materials.

A Way to Close the Loop: Physicochemical and Adsorbing Properties of Soybean Hulls Recovered After Soybean Peroxidase Extraction

“…(Chen et al, 2017 ; Shi et al, 2020 ) have been widely described in the literature. More recently, supported humic-like substances, natural polysaccharides (as chitosan, alginate, starch, cellulose), but especially various types of agricultural/domestic scraps have been exploited for adsorption purposes (Dai et al, 2018 ; Singh et al, 2018 ; Tummino et al, 2019 , 2020 ). In this context, soybean hulls, rich of hemicellulose and cellulose, containing oxygenated functional groups including carbonyl groups, hydroxyl groups, and ethers, can bind heavy metal ions and organic pollutants by different kinds of interaction (chelation, complexation, coordination, formation of hydrogen bonds).…”

Waste Cleaning Waste: Combining Alginate with Biowaste‐Derived Substances in Hydrogels and Films for Water Cleanup

“…Among these materials, Algs are particularly promising: isolated from the cell walls of various species of brown algae, [20] they are low cost, biocompatible, and biodegradable. Due to this, Algs have been tested in many fields, [21, 22] including biomedical applications, [23] food technology, [24] energy, [25] cultural heritage preservation, [26] and environmental remediation [27] …”

“…The adsorption saturation limit of Alg gels can be increased by increasing the space within the Alg chains to favor diffusion of adsorbate molecules within the network with a consequent increase in interactions [22] . Thus, additional substances with suitable structures and reactive functional groups can be inserted into the Alg framework during the gelification step to produce materials with enhanced adsorbing capacity [32] …”

“…We recently suggested chitosan‐Alg‐BBS‐GC gels for dye adsorption; [22] the results obtained were promising, but some issues related to the preparation step were observed. Na Alg and chitosan are soluble in water at different pH values; additionally, both biopolymers result from viscous solutions and this can be a disadvantage for homogenization of the mixture.…”

“…Na Alg and chitosan are soluble in water at different pH values; additionally, both biopolymers result from viscous solutions and this can be a disadvantage for homogenization of the mixture. If Alg and chitosan are mixed, their chains have to slide over each other to allow the interaction of chitosan amino groups with Alg carboxylic groups for the formation of the 3D polyelectrolyte complex (PEC) [22, 41] …”