The enzyme, carbonic anhydrase, is the biological catalyst responsible for the interconversion of CO 2 and bicarbonate in living organisms. The present research is aimed at the development of a CO 2 scrubber that can be used to reduce CO 2 emissions from, for example, fossil-fuel-burning power plants. In this system, the enzyme works as a catalyst to accelerate the rate of CO 2 hydration for subsequent fixation into stable mineral carbonates, the counterions for which may be supplied from such sources as brines from saline aquifers, waste brines from desalination operations, or seawater. Proof of principle has already been demonstrated. One of the requirements for the enzyme will be that it must be able to function in the presence of other chemical species likely to be present in the industrial application. The present results show excellent enzyme activity in the presence of low levels of SO x and NO x (that might be expected from flue gases) and also in solution representative of seawater. The effects of SO x and NO x are of interest because, although emissions of these species are strictly controlled, some very low level will still be present. The reason for examining enzyme performance in seawater-like solutions is to give a better approximation of the compositions likely in actual process streams based on either seawater or other brines.

Chitosan and alginate are two polyelectrolytes that can be used as thickening agents in the food industry, in drug-release systems in pharmaceutical applications as biomaterials in wound healing, and cell culture applications, or as ion exchange material for the removal of heavy metal ions from industrial wastewaters. These two polysaccharides can also be used together to form a polyelectrolyte complex, especially to encapsulate proteins, cells, and enzymes. Although there are many applications of these polyions, few publications explain the interaction between their functional groups. This is mostly because of the difficulty of following ionic interaction in an interface of macromolecules, especially since they alter much with the reaction conditions such as pH. The present study reveals the interaction between chitosan and alginate at different pH values by means of a particular method for Fourier transform infrared (FTIR) studies. A previously reported disagreement between the yield of the complexes in weight and density of the interacting functional groups is explained through this method. The obtained results are supported with the morphological studies of the polyelectrolyte beads prepared at different pH values. Freeze-dried beads of both alginate and chitosan-coated alginate beads could be viewed after hexamethyl disilazane (HMDS) treatment.

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