engleski

Fractality of the Adsorbed Layer of Triton-X-100 on the Mercury Electrode and its Influence on the Oxido-Reduction Processes of o- and p-Nitrophenols

Fractal morphology of the adsorbed layer of Triton-X-100 has been studied. The study has been conducted using ac voltammetry in combination with recently developed method, size scaling of the hanging mercury drop electrode, for determination of the adsorbed layer fractal dimension.1 Simultaneously, the adsorption process of Triton-X-100 has been studied by means of phase-sensitive ac voltammetry (out of phase mode) in 0.5 M NaCl, 3x10-2 M NaHCO3, pH 8.3. The investigation has been performed in the concentration range from 0.06 to 10 mg/l Triton-X-100, for 1 min accumulation time. Results were elaborated for –0.35 V vs. Ag/AgCl/3 M KCl reference electrode. It was found that the adsorbed layer of Triton-X-100 has a fractal structure. The fractal dimension varies depending on fractional electrode coverage and reflects the structural changes of the layer during the adsorption process. At fractional electrode coverage of   0.8, corresponding to the bulk concentration of  0.4 mg/l, Triton-X-100 the fractal dimension shows pronounced peak with D 2.6. This jump of D indicates complete reorganization of Triton-X-100 adsorbed layer. The electroreduction of o- and p-nitrophenols in the presence of adsorbed layer of Triton-X-100 have been studied by phase sensitive ac (in phase mode) and SW voltammetry. The reduction mechanism of nitrophenols is completely changed from non-reversible 4 e&macr ; step to reversible one-electron reduction leading to radical anions, exactly at the T-X-100 concentration for which the peak of fractal dimension was observed. For the o-nitrophenol the stabilization of radical-anion was observed for the fractional electrode coverages  > 0.8. For p-nitrophenol for  > 0.8 the irreversibilization of one-electron reduction was observed. These results reflect differences in electrode reaction kinetics of two nitrophenols and their incorporation into Triton-X-100 adsorbed layer.

adsorption; fractal; T-X-100; nitrophenol; oxido-reduction process

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