Adsorption-desorption controlled by electrical fields

Electric fields at field emitter tips, as discussed before, are typically on the order of 10 V ran-1. This is in the same range as the electrostatic fields that are present in zeolite cages (see below) and at the interface of electrode and electrolyte interface. Since these fields are all of the same order as the fields inside atoms and molecules, they are strong enough to induce the rearrangement of electronic orbitals of atoms and molecules. It is therefore expected that it should be feasible to stimulate chemistry with such electric fields. 

In this section we are particularly interested infield-induced adsorption/ desorption (Kreuzer, 2004). In the review by Kreuzer, electric field effects are classified either as physical, for fields below 10 Vnm 1 which mainly 

A question that arises is whether one can modify the electrostatic fields (or their gradients) around active sites in zeolite cages or around the pores in an MOF, by applying an external field. As far as we know experiments of this kind have not been reported, but a possible experimental configuration to do so is a capacitor in which the zeolite is sandwiched between two 

For reasons of fouling or deactivation, it may be desirable to be able to replace immobilized enzymes in time, and for this a programmable way of adsorption and release of enzymes would be very welcome. An example of this is the use of a 4nm thin polymer film that can be thermally switched between a hydrophilic (swollen) state at 20 °C and a more hydrophobic protein-adsorbing (collapsed) state at 48 °C, integrated into a micro hotplate with fast heating options so that a protein monolayer can be adsorbed and released within 1 s (Huber et al., 2003). 

The application of heat to enzymes is not always desired furthermore, it may turn out to be difficult to localize the heat. Electric fields have an advantage in this respect, since they can be locally applied by design of 

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