Kinetic features of chromium(VI) reduction and phenol degradation in aqueous solution by treatment in atmospheric-pressure air direct-current discharge

The kinetics of the processes of simultaneous reduction of Cr(VI) and degradation of phenol during the treatment of their aqueous solutions with different initial concentrations using an atmosphericpressure air direct-current discharge have been studied. The solution served as the discharge cathode. It has been shown that the discharge treatment leads to a decrease in the concentration of both Cr(VI) and phenol. Phenol additives accelerate the Cr(VI) reduction process and make it irreversible. The phenol degradation and Cr(VI) reduction kinetics are described well (R² > 0.99) by the pseudo-first-order rate equation in phenol and Cr(VI) concentrations, respectively. The apparent rate constants of the processes have been determined, the energy efficiency of the processes has been evaluated, and possible mechanisms of the proceeding reactions have been discussed.