up to the temperatures studied ($1200^\circ\mathrm{C}$) promote the formation of a crystalline carbon structure. Thus, if at a temperature of $1000^\circ\mathrm{C}$ peat crystallites without additions of iron oxides have an average size of 51.5 Å, then with additions it is 68 Å; and at $1200^\circ\mathrm{C}$, respectively, 67.5 and 104.5 Å.

Conclusions

1. The introduction of finely dispersed iron oxides into peat contributes to a change in the nature of the pore-size distribution.

2. An increase in the heating temperature of the peat-ore material promotes burnout of pores due to the oxygen of the oxides.

3. The introduction of iron oxides promotes the formation of a crystalline carbon structure.

Literature

1. G. G. Plachenov. Mercury Porometric Apparatus P-3M. L., 1961.

2. W. Radmacher, P. Mohrhauer, “Brennstoff-Chemie” 36, Nos. 15, 16, 1955.

3. Ya. S. Umanskii. X-ray Diffraction of Metals and Semiconductors. Moscow, Metallurgiya Publishing House, 1969.

STUDY OF THE ADSORPTION OF $\beta$-NAPHTHOL ON A MERCURY ELECTRODE FROM A SODIUM SULFATE SOLUTION

Yu. N. Oblivantsev, V. E. Gorodovykh

The influence of adsorption of surface-active substances (SAS) on the rate of the electrode process is determined by the nature and properties of the adsorption layer and of the electroactive particle. With changes in the adsorption region, the degree of filling, the pH of the solution, etc., various effects of the influence of SAS on the kinetics and mechanism of the electrochemical reaction can be observed.

In this connection, the study of the kinetics of electrode processes in the presence of aromatic SAS is of particular interest, since for them reorientation of adsorbed molecules is possible both when the electrode potential changes and when the concentration of SAS in the solution changes /1/. Solving this problem is impossible without a detailed investigation of the regularities of adsorp-

...of aromatic surfactants on the electrode.

Previously we /2/ studied the adsorption of $\beta$-naphthol on mercury against a background of 0.1 N $H_2SO_4$. It was shown that in this case there are two adsorption regions with different orientations of the $\beta$-naphthol molecules at the interface (flat and vertical), which correspond to two potentials of maximum adsorption, $\varphi_{m,1} = -0.25$ and $\varphi_{m,2} = -0.6$ V (sat. calomel electrode).

In the present work, the adsorption of $\beta$-naphthol on mercury from a neutral background (0.1 N sodium sulfate) was studied by the differential-capacitance method.

The differential capacitance of the mercury electrode was determined using an R-568 alternating-current bridge. The measurement procedure was analogous to that described in /3/. A dropping mercury electrode with a long drop time (16–40 s) was used in the work. Water and reagents were prepared by the procedures adopted in studies of this kind. Oxygen was removed from the solution by purging with argon.

The obtained $C,\varphi$ curves had the form characteristic of the adsorption of aromatic compounds. The potentials and heights of the cathodic desorption peaks changed regularly as the concentration of $\beta$-naphthol in the solution was varied. Anodic desorption peaks were not observed. At sufficiently negative potentials ($-1.3 \div -1.4$ V, sat. calomel electrode), $\beta$-naphthol was completely desorbed from the electrode surface. At a $\beta$-naphthol concentration exceeding $1.7 \cdot 10^{-4}$ M, a linear dependence of the height of the desorption peaks on the logarithm of concentration was observed. This indicates that the $C,\varphi$ curves obtained by us did not differ too greatly from equilibrium ones.

On the $C,\varphi$ curves corrected for the background capacitance, two regions of maximum adsorption were observed, whose potentials were, respectively, $-0.25$ and $-0.6$ (relative to the sat. calomel electrode). By extrapolating the dependence of the reciprocal capacitance on the reciprocal concentration to infinitely high concentration, the limiting capacitances corresponding to the two adsorption regions were found. They proved to be approximately equal in magnitude (12.2 and 11.5 $\mu$F/cm$^2$), which indicates a slight change in the flat orientation of the molecules upon going from positive to negative potentials.

On the basis of the model of two parallel capacitors /4/, adsorption isotherms of $\beta$-naphthol were constructed at various

potentials and the dependence of the degree of coverage on the potential for various concentrations of $\beta$-naphthol in the solution. Analysis of the isotherms obtained showed that adsorption of $\beta$-naphthol on mercury obeys the Frumkin isotherm.

From the experimental adsorption isotherms, attraction constants were then calculated and a linear dependence of these quantities on the potential was established.

From the $\varepsilon,\psi$ curves ($\varepsilon$ is the electrode charge, found by integrating the differential-capacitance curves) and the $c,\psi$ curves recorded in diluted background solutions, the dependence of the adsorption potential jump on the degree of coverage was found. The character of this dependence is similar to the regularity in the change of the $\psi_1$ potential with the degree of coverage during adsorption of $\beta$-naphthol from 0.1 N $H_2SO_4$.

References

1. M. A. Gerovich. DAN SSSR, 96, 543 (1954); 105, 1278 (1955).
2. Yu. N. Oblivantsev, T. V. Gomza, V. E. Gorodovykh. Advances in Polarography with Accumulation. TSU, Tomsk, 1973, p. 101.
3. B. B. Damaskin. Zh. fiz. khim., 32, 2199 (1968).
4. B. B. Damaskin, O. A. Petrii, V. V. Batrakov. Adsorption of Organic Compounds on Electrodes. Moscow, “Nauka,” 1968.

INVESTIGATION OF THE EFFECT OF $\beta$-NAPHTHOL ON THE KINETIC PARAMETERS OF THE CADMIUM DISCHARGE–IONIZATION REACTION BY THE FARADAIC IMPEDANCE METHOD

Yu. N. Oblivantsev, V. E. Gorodovykh

In this work, the effect of the structure of an adsorption film of $\beta$-naphthol on the kinetic parameters of the cadmium discharge–ionization reaction was studied by the Faradaic impedance method.

Measurements were carried out on a dropping amalgam electrode in two backgrounds—neutral (1 M $Na_2SO_4$) and acidic (0.1 N $H_2SO_4$). A platinum cylinder, arranged symmetrically with respect to the investigated electrode, was used as the auxiliary electrode. The cadmium amalgam was prepared by electrolysis of an acidified solution of 1 M cadmium sulfate with soluble cad-