Environmental Engineering Reference
In-Depth Information
low cost, biodegradability, numerous properties, and the relative ease with
which they can be modified chemically [258,9]. Numerous studies propose
the use of starch-based materials as useful adsorbent for removal of pollut-
ants [259-261]. Starch, one of the most abundant polysaccharides on earth,
represents an interesting alternative as a complexing material because of its
intrinsic characteristics (renewable and biodegradable raw resource) and
chemical properties (high reactivity, flocculation and adsorption proper-
ties) resulting from the presence of reactive hydroxyl groups in the mac-
romolecular chains. However, for non-food uses, it is necessary to modify
starch in order to obtain derivatives with properties suitable for environ-
mental applications. In the literature, there have been numerous studies
on the preparation, characterization, properties and applications of starch-
based derivatives. Among them, crosslinking materials have attracted great
attention due to their facile synthesis, high adsorption properties, and par-
ticular selectivity. Among all the reactions proposed, chemical crosslink-
ing using epichlorohydrin as crosslinker agent is the most straightforward
method to produce derivatives for environmental applications. The chemi-
cal modification of these crosslinked materials is also an interesting step
to introduce specific properties in order to enlarge the field of their poten-
tial applications. Starch-based materials have demonstrated interesting
removal abilities for certain dyes, as summarized in Table 10.10. The state-
of-the-art in the field of biosorption of dyes by starch-based derivatives
was reviewed by Crini and Badot [262]. Their literature survey showed that
starch was a promising tool for the purification of dye-containing wastewa-
ter because of its interesting adsorption capacity.
Crini [9] reported that crosslinked starch-based material showed a
higher capacity for adsorption of dyes than commercial activated carbons.
Cationic crosslinked starch was a rather better adsorbent than crosslinked
starch for acidic dyestuffs and its production is not costly [260]. The inter-
action between cationic starches and anionic dyes has also been intensively
investigated by Riauka [263]. He prepared both raw starches (CS) and
crosslinked starches (CCS) containing quaternary ammonium groups. His
investigations clearly indicated that CCS materials were more suitable than
CS, and they had a high selectivity for dye molecules. He concluded that
crosslinked cationic starches were very useful for the treatment of waste-
water from the textile industry. Wang's group [264-266] also reported that
crosslinked amphoteric starch may be useful adsorbents for dye removal
because of their high adsorption capacities. These adsorbents were efficient
for the removal of both acid and basic dyestuffs from aqueous solution
without changing the pH of the solution due to the particular electrical
character of the materials. They found that the maximum adsorption
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