Environmentally sustainable production of cellulose-based superabsorbent hydrogels

Abstract

The development of new products and materials, especially those which are non-petrolchemical reserves and based on renewable organic resources, using innovative sustainable processes is nowadays of increasing interest and deserves the attention of both academic and industrial research. Cellulose and its derivatives, as renewable organic resources, have been used to synthesize novel superabsorbent hydrogels. Although the production of cellulose is one of the causes connected to deforestation, the production of suitably engineered cellulose superabsorbent hydrogel materials has been proposed to preserve water in typically arid areas in the world. Paradoxically, divinylsulfone (DVS), a small di-functional highly toxic molecule, was used as a crosslinker for the preparation of the hydrogel. An environmentally sustainable heterogeneous TiO₂ photo-catalysed process has been performed in order to achieve the detoxification (and a possible re-use) of washing waters deriving from the purification process carried out after the synthesis of a bio-degradable cellulose based superabsorbent hydrogel. The main species present in the washing water was DVS. DVS is a well known toxic agent and it was efficiently removed along with the unreacted polymers and oligomers by irradiating the washing waters in the presence of suspended polycrystalline TiO₂. The photoprocess was studied not only by monitoring the total organic carbon (TOC) present in the solution but also by following the evolution of sulfate anions.