Adsorption transfer

Fig. 2.5. Test for the survival of methanol adsorbate in the UHV the potential scan was applied a) after adsorption in 5 x 10 J M C H3OH5 x 10 2 M H2S04 followed by electrolyte exchange with base solution (b) after adsorption, transfer in the UHV chamber and reimmersion in base electrolyte dotted line base voltammogram sweep rate 62.5 mV/s.

In 1976 he was appointed to Associate Professor for Technical Chemistry at the University Hannover. His research group experimentally investigated the interrelation of adsorption, transfer processes and chemical reaction in bubble columns by means of various model reactions a) the formation of tertiary-butanol from isobutene in the presence of sulphuric acid as a catalyst b) the absorption and interphase mass transfer of CO2 in the presence and absence of the enzyme carboanhydrase c) chlorination of toluene d) Fischer-Tropsch synthesis. Based on these data, the processes were mathematically modelled Fluid dynamic properties in Fischer-Tropsch Slurry Reactors were evaluated and mass transfer limitation of the process was proved. In addition, the solubiHties of oxygen and CO2 in various aqueous solutions and those of chlorine in benzene and toluene were determined. Within the framework of development of a process for reconditioning of nuclear fuel wastes the kinetics of the denitration of efQuents with formic acid was investigated. 

In order to obtain high conversion efficiencies, optimization of the short-circuit photocurrent (z sc) and open-circuit potential (Voc) of the solar cell is essential. The conduction band of the TiO is known to have a Nernstian dependence on pH [13,18], The fully protonated sensitizer (22), upon adsorption, transfers most of its protons to the TiO surface, charging it positively. The electric field associated with the surface dipole generated in this fashion enhances the adsorption of the anionic ruthenium complex and assists electron injection from the excited state of the sensitizer in the titania conduction band, favoring high photocurrents (18-19 inA/cm ). However, the open-circuit potential (0.65 V) is lower due to the positive shift of the conduction-band edge induced by the surface protonation. 

Adsorption transfer of a substance from a solution to the surface of a solid resulting in relatively high concentration of the substance at the place of contact see also Chromatographic adsorption. 

Masarik M, Kizek R, Kramer K), et al. Application of avidin-biotin technology and adsorptive transfer stripping square-wave voltammetry for detection of DNA hybridization and avidin in transgenic avidin maize. Anal. Chem., 2003 75(11) 2663-2669. 

Schmidt number see equation (9-125) number of adsorption transfer units = kadsL/v) number of equilibrium stages reaction order Laplace transform parameter... 

Eojta, M., Havran, L., Fulneckova, J., Kubicarova. T. (2000). Adsorptive transfer stripping ac voltammetry of DNA complexes with intercalators. Electroanalysis 12, 926-934. 

Electrochemical Transducer for Oligonucleotide Biosensor Based on the Elimination and Adsorptive Transfer Techniques... 

Adsorptive transfer stripping voltammetry (AdTSV) was introduced in 1986 as a new anal5 ical procedure based on the adsorptive pre-concentration of biomacromolecules on an electrode, the transfer of the adsorbed layer into a background electrolj e and subsequent voltammetric analysis [35]. The advantages of AdTSV were summarized as follows (i) the method utilizes differences in adsorbability of substances to their separation, (ii) due to their strong adsorption, analytes (oligonucleotides) can be separated from complex media, which are not suitable for voltammetric analysis of the conventional type, (iii) the interaction of biomacromolecules immobilized on the surface of the electrode with substances contained in the solution is possible, and (iv) all mentioned points can be affected by electrode potential [35]. 

Our results showed that EVLS in connection with the adsorption procedure [adsorptive or adsorptive transfer stripping, i.e., AdS or AdTS) is a useful tool for qualitative and quantitative studies of short oligonucleotides and can be used as a proposed transducer for the electrochemical sensor. EVLS sensitively reflects not only the sequence of nucleobases in the ODN chain, but also the structure of ODN, which can be changed on electrode surfaces. 

Fig. 67. Adsorptive transfer stripping voltammetry on HMDE. The timing sequence accumulation time, tacc, washing time, t sh deaeration time, t, rest (equilibrating) period, t p, stripping time, tg. (During the washing period interfering substances can be removed.) Electrodes RE the reference electrode, AE the auxiliary electrode. Adapted according to [157].

The drop shape method is possibly the most useful one for the investigation of the adsorptive transfer, i.e. the adsorption kinetics at the interface between two liquid phases containing the surfactant from the partition equilibrium. This phenomenon is particularly significant when situations far from the partition equilibrium are considered, in systems characterised by a high solubility of the surfactant in the recipient phase or by a large solubility of the surfactant in both phases. The latter case represents a typical situation for many types of ionic surfactants in water-oil and water-alkane systems, as demonstrated by the partition coefficients measured for various solvents [52, 53, 54, 55, 56]. 

An example of such behaviour, studied by the drop shape method described here, is shown in Fig. 1 lb, where the dynamic surface tension during the adsorptive transfer of CioEOg at a fresh water/hexane interface is shown. The diffusion controlled approach can be applied to model the... 

Moreover, adsorptive transfer occurs often in limited size systems, for example at the interface of droplets in an emulsion or at the interface of bubbling droplets. The main characteristics in the study of such finite phase systems is the significant depletion of the bulk due to adsorption and transfer processes, which in some cases are the main factors controlling the adsorption dynamics. In fact, the depletion of the finite volume coupled to the transfer across the interface, can produce a non-monotonic behaviour of the dynamic adsorption T(t), with minima in the dynamic interfacial tension y(t) [58, 59]. 

The problem of the adsorptive transfer in finite systems can be successfully studied with the drop shape method by arranging large volume ratios between the droplet and the surrounding liquid. Moreover, in these studies the contact between the two liquids must be avoided until the interface has formed. This can be conveniently arranged by leaving an air bridge between the two liquids into the capillary, that is blown out and eliminated by the buoyancy, when forming the drop. 

Examples of such non-monotonic behaviour of y(t) are given in Fig 15b, corresponding to the adsorptive transfer of C13DMPO at a freshly formed water/hexane interface [60]. In this case, drops of the aqueous surfactant solution were formed in a cell filled with pure hexane, arranging a ratio Q= Vh xA wat " 10 between the volumes of the two phases. The minimum... 

Fig. 15 Dynamic interfacial tension during the adsorptive transfer of CnDMPO at a fresh water/hexane interface a) a drop of pure hexane formed in the aqueous surfactant solution, Q = 10, initial concentrations in water are Coi = 1.5, 2.3, 5.3 10 mol/cm (top to bottom) b) a drop of the aqueous surfactant solution is formed in pure hexane at a volume ratio of Q = I0 initial concentrations in water are Coi=l, 2, 3 10 mol/cm (top to bottom) solid lines are obtained from model calculations...

In 2001, Nagatani et al. reported a method to analyze ion adsorption-transfer kinetics using PMF [140]. The results just discussed were confirmed, and it was further shown that the PMF response for kinetically controlled adsorption is expressed as a semicircle in the complex plane in which the characteristic frequency of maximum imaginary component is proportional to the adsorption and desorption rate constants. Considering that the potential dependence of adsorption exhibits the opposite sign whether the process takes place from the aqueous or organic phase, the corresponding PMF responses appear in different quadrants of the complex plane. This work therefore confirms that the adsorption at an ITIES can take place on either side of the interface. 

Electrochemical activity of biopolymers inspired the development of adsorption transfer voltammetric stripping [420] and of derivative constant current chronopo-tentiometric stripping analysis [421, 422] the latter method turned out to be particularly sensitive for determining catalytic evolution of hydrogen at mercury electrode by the peak H [423, 424]. 

Automatized Determination OF Metallothioneev by Adsorptive Transfer Stripping Technique Coupled WITH Brdicka Reaction... 

Adsorptive Transfer Stripping (AdTS) Techniqne Connected with Brdicka Reaction... 

Adsorptive Transfer Stripping (AdTS) technique was firstly used for detection of MT by Palecek [88]. Principle of the AdTS is based on the strong adsorption of the studied analyte on the surface of electrode at an open electrode circuit. The excess of analyte is rinsed from the surface of the working electrode in the buffer. The adsorbed analyte is finally detected in the presence of indifferent electrolyte. It is possible to describe the individual steps of this technique as follows (Figure 6A) (1) renewed surface of HMDE is placed into a drop containing MT, (2) MT binds on the surface of HMDE only, (3) low molecular compoimds. 

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