Effects of Constant Electric Field on Biodegradation of Phenol by Free and Immobilized Cells of Bradyrhizobium japonicum 273

It is shown that bacteria Bradyrhizobium japonicum 273 were capable of degrading phenol at moderate concentrations either in a free cell culture or by immobilized cells on granulated activated carbon particles. The amount of degraded phenol was greater in an immobilized cell preparation than in a free culture. The application of a constant electric field during cultivation led to enhanced phenol biodegradation in a free culture and in immobilized cells on granulated activated carbon. The highest phenol removal efficiency was observed for an anode potential of 1.0 V/S.H.E. The effect was better pronounced in a free culture. The enzyme activities of free cells for phenol oxidation and benzene ring cleavage were very sensitive to the anode potential in the first two steps of the metabolic pathway of phenol biodegradation catalyzed by phenol hydroxylase—catechol-1,2-dioxygenase and catechol-2,3-dioxygenase. It was observed that at an anode potential of 0.8 V/S.H.E., the meta-pathway of cleavage of the benzene ring catalyzed by catechol-2,3-dioxygenase became competitive with the ortho-pathway, catalyzed by catechol-1,2-dioxygenase. The obtained results showed that the positive effect of constant electric field on phenol biodegradation was rather due to electric stimulation of enzyme activity than electrochemical anode oxidation.

Generation of plasma in low-pressure discharge

A hydrodynamic model of plasma has been developed, which takes into account both secondary and primary electrons. It has been shown that a solution with a plasma potential higher than the anode potential is possible if the ionization frequency is higher than some critical value. At lower ionization frequencies, it is possible to obtain a solution with a plasma potential below the anode potential

Demystifying the role of temperature in lithium plating: a tug-of-war between anode kinetics and impedance

The study demonstrates the interplay of temperature-induced interfacial heterogeneity and propagation of lithium plating which influences the rate of capacity degradation and cell failure. Inoperando anode potential measurements are used to quantify lithium plating and anode impedance during cycling at different temperatures

ON THE KINETICS OF ANODIC PROCESSES AT OXIDATION OF AQUEOUS SOLUTIONS OF DIMETHYL SULFOXIDE

Dimethyl sulfoxide is a feedstock for a large number of organic substances syntheses. Nowadays research is considerably focused on the production of general products of dimethyl sulfoxide oxidation – dimethyl sulfone and methane sulfonic acid. Dimethyl sulfone is well–known as a food supplement for the treating and strengthening of human joints and ligaments. dimethyl sulfone is basically synthesized by oxidation of dimethyl sulfoxide in hot 30 % hydrogen peroxide in glacial acetic acid. Synthesis is accompanied by significant losses of hydrogen peroxide, the target product has to be significantly purified. It becomes possible to control the synthesis of pure dimethyl sulfone and methane sulfonic acid when using the electrochemical method of oxidation of dimethyl sulfoxide in its aqueous solution with chemically resistant anode and high overvoltage of oxygen reaction Controlled synthesis is relevant because sulfur tends to change the oxidation rate. Study of kinetics of anodic processes at platinum electrode was performed in the dimethyl sulfoxide concentration range about 1.0…4.0 mol∙dm–3. Current raise was observed at potentials that are more positive than 1.3…1.4 V. This potential range corresponds to oxygen release. Dissolved sulfuric acid (0.2 mol∙dm–3) was added in order to inhibit the oxygen release and achieve the potential for the formation of peroxide radicals in aqueous solutions of dimethyl sulfoxide. It is known that sulfate ions are adsorbed on the surface of the platinum anode, displacing molecules of protonated water. This allows to shift the potentials and increase of the electrolysis current in 0.2 mol∙dm–3 H2SO4 to 1.7…1.9 V. It indicates the processes of formation of peroxide radicals on the surface of the platinum anode. Further shift of the anode potential into more positive area than 2.00…2.05 V leads to a rapid increase in current density. At such potentials, dimethyl sulfoxide and dimethyl sulfone are oxidized to methane sulfonic acid with a parallel oxygen and hydrogen peroxide release. Current–voltage study has shown that the oxidation of dimethyl sulfoxide in aqueous solutions runs through the formation of dimethyl sulfone. When conducting electrochemical synthesis with control of the anode potential, it is possible to produce dimethyl sulfone without further oxidation to methane sulfonic acid. The addition of 0.2 mol∙dm–3 H2SO4 to aqueous dimethyl sulfoxide solutions inhibits oxygen release and intensifies oxidation of dipole dimethyl sulfoxide molecules adsorbed on the platinum surface. The influence of adsorption processes on the kinetics of anode processes at the platinum anode in aqueous solutions of dimethyl sulfoxide at high anode potentials has been studied.