Oxidation reduction potential(ORP) analysis method has been gradually used in the field of limestonegypsum wet desulfurization slurry oxidation control

but there is a lack of corresponding theoretical research. In this paper

firstly

the standard electrode potentials of each pair in the slurry oxidation process

E~θ(O_2(αq))/H_2O and E~θ(S(Ⅵ)/S(Ⅳ))

were obtained based on density functional theory and acid dissociation equilibrium calculation;and the standard electromotive force of each reaction was calculated. Then

based on the main reaction of slurry oxidation

2HSO_3~–+O_2→2H~++2SO_4~(2–)

the theoretical calculation model of the electromotive force of the reaction system was established by the Nernst equation. It was found that the measured ORP of the electromotive force of the reaction system was quite different from that by theoretical calculation

which meant the Nernst equation was not suitable for the slurry oxidation system. Finally

a good multivariate linear fitting relationship between the measured ORP

pH

ln(c(Ca~(2+)))

ln(c(HSO_3~–)) and ln(c(O_2)) was established by the stepwise regression. The results indicated that the process of slurry oxidation was not only related to the single indicator of ORP

but also controlled by pH

calcium ion and dissolved oxygen concentration. When ORP is used as the oxidation control indicator of wet desulfurization slurry

the influence of pH

calcium ion and dissolved oxygen concentration should be taken into account at the same time.