This paper is solely concerned with the mechanism of electron transfer in zeolite-modified electrodes (ZMEs) where the zeolite has been modified with electroactive transition metal ions or complexes. First, data were obtained from ZMEs prepared with zeolite Y-encapsulated Co(salen) or [Fe(bpy)3]2+ complexes (where salen = N,N‘-bis(salicylidene)ethylenediammine and bpy = 2,2‘-bipyridine). Changes in the cyclic voltammetry seen for such ZMEs in nonaqueous solutions are discussed in terms of the interpretive difficulties that can arise without proper controls and blanks. Specifically, the various methods of complex synthesis and purification and the effects of the electrode materials used in the fabrication of a ZME can give rise to voltammetric features which may be misattributed. Integration of the peak area, repeated voltammetric cycling, and scan-rate dependencies demonstrate that electron transfer occurs outside the zeolite pore system for these zeolite-encapsulated transition metal complexes, i.e., by an extrazeolite mechanism, rather than by an intrazeolite mechanism where electron transfer occurs to an encapsulated complex present within the zeolite framework. Second, data were obtained for transition metal (Ag(I)- and Cu(II)-) exchanged zeolites prepared as ZMEs and studied in aqueous and nonaqueous electrolytes. An extrazeolite mechanism for electron transfer was determined to be operative once effects were considered which arise from changes attributable to metal deposition on electrodes, the nature of the electrode material, and the presence of solution-phase charge- and/or size-excluded moieties.

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In this paper the electrochemical response of electrodes modified with silver ion exchanged Y type zeolites is examined. The cyclic voltammograms for the fully exchanged materials resemble closely those observed previously for silver mordenite zeolites. At low exchange levels (<10%, i.e., <5.6 silver ions per unit cell) cathodic linear sweep voltammetry indicates the presence of two electrochemically distinct silver ions. These arc shown to be slowly interconverting by measurements recorded as a function of both scan rate and temperature. Of these two species, the more difficult to reduce apparently migrates from its site following electrochemical reduction. The population of this site reaches a maximum at low exchange levels, whereupon further loading of the zeolite with silver occurs in other sites. The relative population of these two sites is also sensitive to eocation. The behavior of the cathodic waves as a function of concentration and cocations that are known to displace silver ions from the hexagonal prisms is discussed. These data show that the two cathodic waves observed at low silver concentrations are related to oecupancy of sites I and .

An artificial neural network (ANN) was developed to predict heat and mass transfer during deep-fat frying of infinite slab-shaped foods coated with edible films. Frying time, slab half-thickness, film thickness, food initial temperature, oil temperature, moisture diffusivity of food and film, fat diffusivity through food and film, thermal diffusivity of food, heat transfer coefficient, initial moisture content of food, and initial fat content of food (mf o ) were inputs. Temperature at the center (T 1 ), average temperature (T ave ), fat content (mf ave ), and moisture content (m ave ) of food were outputs. Four ANNs with 50 nodes each in 2 hidden layers with learning rate = 0.7 and momentum = 0.7 provided most accurate outputs, that is maximum absolute errors for T 1 and T ave were < 1.2°C, < 0.004 db for m ave , and < 0.003 db for mf ave . The predictions of mf varied linearly with mf.