Adenine adsorption in different pH acetate buffer

Abstract

The research results facilitate the description of adenine adsorption on the mercury electrode with reference to the pH of the supporting electrolyte which was the acetate buffer with pH of 3, 4, 5 and 6. The thermodynamic analysis indicates that the curves of the differential capacity of the studied systems with adenine do not overlap with the curves for the supporting electrolyte -the acetate buffer. This indicates the occurrence of adsorption of the studied compound on the mercury electrode within the whole range of applied concentrations in the case of every tested pH value of the acetate buffer. Adsorption energy and interaction constants were determined using the Frumkin isotherm and the viral isotherm. It was demonstrated that a adenine molecule is adsorbed on the mercury electrode in a buffer with pH 4, 5 and 6 through the negative pole, whereas in a buffer with pH 3 through the positive pole. Physical adsorption was observed in the studied systems. This is indicated by the occurrence of a typical maximum on the curve of the relation the relative surface excess amounts and the potential of the electrode; crossed curves of the following relation surface charge of the electrode from its potential (surface charge of the electrode from its potential σ = f(E)) at one point and, thus, the possibility of determining electrical parameters characterizing maximum adsorption as well as the absence of linearity of the function free energy of adsorption as a function of electrode potential ∆G 0 = f(E).

Comparison of adsorptive properties of adenine, cytosine, guanine and thymine in acetate buffer with pH 4.

“…Figure 3 indicates the occurrence of frequency dispersion for 6•10 − 3 M thymine. A similar effect was observed in all the tested concentrations of nitrogen bases found in DNA [7,[11][12][13][14][15]. It indicates absence of adsorption equilibrium in the applied experimental conditions.…”

“…The process of adsorption of organic substances on the mercury electrode is the key subject of studies of physical chemistry of interfaces [1][2][3][4]. The measurement results are used to interpret the nature of the double electric layer and its in uence on the kinetics of electrode processes [5][6][7][8][9][10].…”

“Cap‐Pair” Effect as the Reason of the Catalytic Properties of Nicotinic Acid: Experimental and Theoretical Studies

“…The introduction of NC into the acetate buffer causes a shift of E z values to negative potentials. These changes indicate that the organic molecule is adsorbed on the electrode with its negative pole, i. e., with the aromatic ring [27,28] . It is worth seeing that the dependence E z =f (log c ) is linear but d E z /d(log c ) coefficient (which is about −0.020 V) is lower that for alkalimetal salts with specifically adsorbed anions (approximately 2.3 RT/F [20] ).…”

Equilibrium and Kinetic Studies on Adsorption of Neutral and Ionic Species of Organic Adsorbates from Aqueous Solutions on Activated Carbon

“…Adsorption is a multi-phase process consisting of stages going on at different time ranges, and the rate of the process is determined by the slowest step. The effectiveness of the adsorption technique is determined by a number of factors, including the following: the properties of the adsorbent [11][12][13] and adsorbate [14][15][16], temperature [17][18][19], mixing speed [20][21][22], the presence of an accompanying substance [23][24][25], and the pH of the solution [26][27][28]. Even a seemingly small increase in the efficiency of adsorption processes used in water and sewage treatment, due to the scale and widespread use of these technologies, may mean achieving a competitive advantage over other solutions.…”