Biopolymers can be made from carboxymethyl cellulose
(CMC), which has a naturally occurring polysaccharide
cellulose base. CMC is made commercially by reacting
chloroacetic acid with sodium cellulose in slurry with
isopropanol and water. CMC based superabsorbent
products were produced during the 1970s and early
1980s (Buchholz and Graham, 1998). However, while
cost of the reactants required to produce CMC are
relatively cheap, there is a significant cost for the
purification needed for most applications. For this reason
CMC based SAPs were mostly discontinued in favor of
petroleum based SAPs. Studies have shown that the rate
of biodegradation of CMC polymers increase when starch
is introduced into the complex (Modelli et al., 2004). In
this study CMC polymer complexes were crosslinked with
aluminum ions to form non-permanent bonds when the
complex is swollen with water. Crosslinked CMC and
starch will create an environmentally friendly SAP that is
based on biopolymers and could be an alternative to
petroleum based SAPs as a water retaining aid in
irrigation.