Prilling and characterization of hydrogels and derived porous spheres from chitosan solutions with various organic acids (original) (raw)

2019, International Journal of Biological Macromolecules

This work emphazises the importance of the solubilizing conditions for the elaboration of chitosan hydrogel beads, which were produced using electromagnetic laminar jet breakup technology, resulting in dried porous beads by further freeze-drying. Paramaters such as the acid nature and concentration (acetic, formic, citric, lactic, maleic and malic, 0.1 to 0.5 mol.L-1), the chitosan concentration (2 to 5 wt %) and composition of the gelation bath (NaOH, with or without EtOH) were studied. Viscosity versus strain rate measurements were carried out on chitosan acidic solutions and the viscoelastic behaviour was studied on hydrogels. The solutions exhibiting the highest viscosities led to the stiffest macrohydrogels, as a result of chitosan carboxylate interactions. Specific surface areas of the freeze-dried beads were determined in the range from 12 to 107 m².g-1. Their internal texture was observed by Scanning Electron Microscopy. Water uptake was also measured for further use in the field of water purification. 1. Introduction Chitosan (CS) is an aminated linear copolysaccharide of N-acetyl D-glucosamine and Dglucosamine, mainly produced dy deacetylation of chitin. Chitin is itself a by-product of see food industry, composing crustaceans' cuticles and can also be found in insects' cuticles and in fungi cell walls as a non animal source [1,2]. Solid-state heterogeneous N-deacetylation of chitin leads to chitosan of different acetylation degrees (DA), deacetylation pattern (DP) and molecular mass, depending on chitin source and N-deacetylation process [3-5]. Reacetylation of chitosan of low DA can also yield series of polymers of various DAs [6]. During the last decades, the use of CS has been envisioned in many applications, due to its interesting intrinsic physico-chemical and biological