Attain Adsorption Equilibrium Research Articles

Study on adsorption of nonionic and cationic polymers on silica gel by using total organic carbon analysis

The adsorption behaviour of poly(ethylene oxide) and trimethylammonium glycol chitosan iodide from water onto silica gel is reported. A total organic carbon analytical method was employed to determine precisely the small quantity of polymer remaining after the attainment of adsorption equilibrium. The adsorption isotherms and the curves of equilibrium adsorption against pH were obtained and compared with the ionization properties of the silanol groups investigated by potentiometric titration. The results obtained are discussed in terms of the adsorption mechanism for nonionic and cationic polymers.

Electrochemical behaviour of mono- and oligonucleotides Part VII. Comparative studies on the adsorption of cytidine at the mercury—aqueous solution interface by pulse polarography and AC polarography

Cytidine has been investigated in order to explore the potentialities of normal pulse polarography and phase-sensitive ac polarography (out-of-phase mode) in connection with the DME for the study of the adsorption and interfacial behaviour of nucleotides. The results are compared with those of a previous study [8] by single-sweep and phase-sensitive ac voltammetry at the HMDE. While the joint application of these latter approaches yields more comprehensive and also more reliable information on the adsorption parameters, normal pulse polarography is also able to provide, with good approximation, the values of certain adsorption parameters for the dilute layer (adsorption coefficient b , free adsorption enthalpy − G 0 , interaction coefficient a ) provided the span of the drop life before the application of the pulse is adjusted to a period sufficiently long to attain adsorption equilibrium. Normal pulse polarography is particularly valuable for estimation of the kinetic parameters of the electrode process of non-adsorbed cytidine provided that the electrode surface is incompletely covered. Phase-sensitive ac polarography at the DME yields — for the adsorption parameters b , − G 0 and a — data of equivalent reliability to the more laborious approach by phase-sensitive ac voltammetry at the HMDE provided the drop time of the DME has been adjusted to a period sufficiently long to attain adsorption equilibrium.

Electrochemical behaviour of mono- and oligonucleotides: Part VII. Comparative studies on the adsorption of cytidine at the mercury-aqueous solution interface by pulse polarography and ac polarography

Cytidine has been investigated in order to explore the potentialities of normal pulse polarography and phase-sensitive ac polarography (out-of-phase mode) in connection with the DME for the study of the adsorption and interfacial behaviour of nucleotides. The results are compared with those of a previous study [8] by single-sweep and phase-sensitive ac voltammetry at the HMDE. While the joint application of these latter approaches yields more comprehensive and also more reliable information on the adsorption parameters, normal pulse polarography is also able to provide, with good approximation, the values of certain adsorption parameters for the dilute layer (adsorption coefficient b, free adsorption enthalpy − G 0, interaction coefficient a) provided the span of the drop life before the application of the pulse is adjusted to a period sufficiently long to attain adsorption equilibrium. Normal pulse polarography is particularly valuable for estimation of the kinetic parameters of the electrode process of non-adsorbed cytidine provided that the electrode surface is incompletely covered. Phase-sensitive ac polarography at the DME yields — for the adsorption parameters b, − G 0 and a — data of equivalent reliability to the more laborious approach by phase-sensitive ac voltammetry at the HMDE provided the drop time of the DME has been adjusted to a period sufficiently long to attain adsorption equilibrium.