349
has generated much negative debate and criticism, although Professor József Szejtli,
one of the prestigious researchers who contributed to the development of cyclodextrins, accepted it and congratulated our work. At the time, we abandoned it and then
used the terms cyclodextrin polymer, cyclodextrin material, or simply gel/hydrogel.
A few years later, the term “microsponges” was adopted over by other researchers.
In 1996, my interest also extended to starch, cellulose, and chitosan biopolymers,
after two fruitful meetings in Milano, the first with Dr. Torri, Dr. Carmen Vecchi,
and Professor Piero Sozzani organized at the Stazione Sperimentale per i
Combustibili and the second with Professor Casu, Professor Bonaventura Focher,
and Professor Kjell Vårum at the Stazione Sperimentale per la Cellulosa, Carta e
Fibre Tessili. A year later, I joined the University of Franche-Comté where, with
Professor Joël Vebrel, I created a research group working on adsorption processes
based on oligosaccharides and polysaccharides for pollutant removal. At that time,
our work focused mainly on the use of cyclodextrin-epichlorohydrin polymers and
chitosan-based materials used as adsorbents for the removal of dyes from industrial
effluents. Our current research focuses on the design of new functionalized macromolecular networks based on oligosaccharides (linear or cyclic dextrins), polysaccharides (starch, chitosan, cellulose), or agricultural fibers (hemp) for applied
research for environmental purposes.
The purpose of this chapter is to present a review of some 30 years of research
within my team as part of a scientific and industrial strategy. Our main area of
research focused on the design and use of cyclodextrin-based materials for the
removal of trace contaminants from polycontaminated industrial effluents from the
textile, pulp and paper, wood, and surface treatment industries. The work involved
the production of a series of water-insoluble cyclodextrin-epichlorohydrin polymers
with different physical and textural properties, their chemical modification and
solid-state NMR characterization, and their use as complexing agents in wastewater
treatment. An important part of the work has also focused on explaining the contaminant removal mechanisms according to the type of cross-linked material used.
8.2 Synthesis of Water-Insoluble
Cyclodextrin-Epichlorohydrin Polymers
8.2.1 Cross-Linking Reaction
Chemical cross-linking using epichlorohydrin as cross-linking agent is the most
straightforward method to produce water-insoluble cyclodextrin-based polymers.
These cyclodextrin-epichlorohydrin polymers known as ECP materials were first
proposed in 1964 by the Swiss chemist Jürg Solms (Research Laboratory of the
Nestlé Group, Vevey), who patented their chemical synthesis by block polymerization and their analytical applications as “inclusion resins” in chromatography and
separation science (Solms and Egli 1964, 1965; Solms 1966, 1967, 1969).
8 Water-Insoluble Cyclodextrin-Epichlorohydrin Polymers
has generated much negative debate and criticism, although Professor József Szejtli,
one of the prestigious researchers who contributed to the development of cyclodextrins, accepted it and congratulated our work. At the time, we abandoned it and then
used the terms cyclodextrin polymer, cyclodextrin material, or simply gel/hydrogel.
A few years later, the term “microsponges” was adopted over by other researchers.
In 1996, my interest also extended to starch, cellulose, and chitosan biopolymers,
after two fruitful meetings in Milano, the first with Dr. Torri, Dr. Carmen Vecchi,
and Professor Piero Sozzani organized at the Stazione Sperimentale per i
Combustibili and the second with Professor Casu, Professor Bonaventura Focher,
and Professor Kjell Vårum at the Stazione Sperimentale per la Cellulosa, Carta e
Fibre Tessili. A year later, I joined the University of Franche-Comté where, with
Professor Joël Vebrel, I created a research group working on adsorption processes
based on oligosaccharides and polysaccharides for pollutant removal. At that time,
our work focused mainly on the use of cyclodextrin-epichlorohydrin polymers and
chitosan-based materials used as adsorbents for the removal of dyes from industrial
effluents. Our current research focuses on the design of new functionalized macromolecular networks based on oligosaccharides (linear or cyclic dextrins), polysaccharides (starch, chitosan, cellulose), or agricultural fibers (hemp) for applied
research for environmental purposes.
The purpose of this chapter is to present a review of some 30 years of research
within my team as part of a scientific and industrial strategy. Our main area of
research focused on the design and use of cyclodextrin-based materials for the
removal of trace contaminants from polycontaminated industrial effluents from the
textile, pulp and paper, wood, and surface treatment industries. The work involved
the production of a series of water-insoluble cyclodextrin-epichlorohydrin polymers
with different physical and textural properties, their chemical modification and
solid-state NMR characterization, and their use as complexing agents in wastewater
treatment. An important part of the work has also focused on explaining the contaminant removal mechanisms according to the type of cross-linked material used.
8.2 Synthesis of Water-Insoluble
Cyclodextrin-Epichlorohydrin Polymers
8.2.1 Cross-Linking Reaction
Chemical cross-linking using epichlorohydrin as cross-linking agent is the most
straightforward method to produce water-insoluble cyclodextrin-based polymers.
These cyclodextrin-epichlorohydrin polymers known as ECP materials were first
proposed in 1964 by the Swiss chemist Jürg Solms (Research Laboratory of the
Nestlé Group, Vevey), who patented their chemical synthesis by block polymerization and their analytical applications as “inclusion resins” in chromatography and
separation science (Solms and Egli 1964, 1965; Solms 1966, 1967, 1969).
8 Water-Insoluble Cyclodextrin-Epichlorohydrin Polymers