Cellulose with metal ions, interactions

Interactions of Cellulose with Metal Ions. Interactions of metal ions with cellulose and the influence of metals on the carboxyls on stability was discussed in the introduction. Some metals are held much more tenaciously than others, but research workers do not always agree concerning the relative order. Our concern in this chapter is with inter-... 

Non-covalent interactions between carbohydrate chains can be very powerful, as in the hydrogen-bonded structures of cellulose and chitin, and this is especially true if the bonds have a polar character and are in a hydro-phobic environment. Likewise, saccharide chains may interact through coordination of metal ions for example, the hydroxyl group—calcium ion interaction can be strong if steric factors favour it. Carbohydrates may also interfere dramatically with the structure of water, but all of these fascinating possibilities do not carry clear biosynthetic implications and so must lie largely outside the scope of this chapter. 

In order to utilize essential metallic ions as nutrients for growth, microorganisms must have the ability to adsorb and concentrate metal cations fi om solution. In many microorganisms, this may be accomplished, in part, through electrostatic interactions with reactive acidic groups (carboxyl and phosphoryl) contained within the constituent polymers of microbial cell walls (36,37), A number of experimental studies have clearly demonstrated that substantial quantities of various metals can be bound and accumulated by a variety of bacterial cells (38-40), whereas Kuyucak and Volesky (41) have shown that the cellulosic materials in filamentous algae played an important role in the biosorption of gold. 

Because protein and cellulosic fibers are buried in contact with copper metal objects, a chemical microsystem is established whereby the degradation of the fiber and the corrosion of the metal interact physically and chemically. As the corrosion solution impregnates and swells the fibers, polymer molecules in amorphous areas are spread apart but are prevented from complete dissolution by the resistant crystalline segments. Copper ion from the corrosion solution is bound to the polymers (Figure 5). As the fiber degrades and more end groups are formed, more copper is bound. Polymers expand further apart as interchain forces are reduced. 

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