Superabsorbent materials from shellfish waste--a review.

Increasing global demand for improved absorbent materials for body fluids in disposable medical and personal-care articles creates an incentive for new basic research and development of efficient absorbent materials and systems with additional benefits such as biodegradability or certain biomedical functions. Highly absorbing materials based on polyelectrolyte polymers can absorb up to 50 grams of body fluid per gram of dry mass. Currently available synthetic superabsorbents are not biodegradable in landfills and do not offer any value-added functions to personal and medical-care products. Various academic and industrial research groups have put considerable amounts of effort and resources toward development of new absorbent materials from natural polymers, which would decompose in landfills. The basic substrates in these studies have been mainly polysaccharides, particularly cellulose and starch. The most common approach has involved converting these polymers into carboxymethyl derivatives followed by structural cross-linking. Commercial synthetic superabsorbent polymers as well as those derived from cellulose and starch are essentially polyanionic. On the other hand, polycationic absorbers seem to have potential functional advantages over the polyanionic counterparts. Chitin is the second abundant natural polymer, whose main derivative, chitosan, becomes polycationic in acid media. Currently, the main source of this polysaccharide is shellfish waste. This review provides basic information about new superabsorbent materials based on chitosan salts, their properties and preparation. Copyright 2002 Wiley Periodicals, Inc.