title: Macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid.
abstract: Magnesia flue gas desulfurization is a promising process for small to medium scale industrial coal-fired boilers in order to reduce sulfur dioxide emissions, in which oxidation control of magnesium sulfite is of great importance for the recycling of products. Effects of four inhibitors were compared by kinetic experiments indicating that ascorbic acid is the best additive, which retards the oxidation process of magnesium sulfite in trace presence. The macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid were studied. Effects of the factors, including ascorbic acid concentration, magnesium sulfite concentration, oxygen partial pressure, pH, and temperature, were investigated in a stirred reactor with bubbling. The results show that the reaction rate is -0.55 order in ascorbic acid, 0.77 in oxygen partial pressure, and zero in magnesium sulfite concentration, respectively. The apparent activation energy is 88.0 kJ mol(-1). Integrated with the kinetic model, it is concluded that the oxidation rate of magnesium sulfite inhibited by ascorbic acid is controlled by the intrinsic chemical reaction. The result provides a useful reference for sulfite recovery in magnesia desulfurization.
authors.affiliation: School of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, China. wld@tsinghua.edu.cn
authors.forename: Wang
authors.initials: W
authors.lastname: Lidong
authors.forename: Ma
authors.initials: M
authors.lastname: Yongliang
authors.forename: Zhang
authors.initials: Z
authors.lastname: Wendi
authors.forename: Li
authors.initials: L
authors.lastname: Qiangwei
authors.forename: Zhao
authors.initials: Z
authors.lastname: Yi
authors.forename: Zhang
authors.initials: Z
authors.lastname: Zhanchao
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry*; D007700:Kinetics; D017616:Magnesium Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013447:Sulfites / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D013447:Sulfites; D001205:Ascorbic Acid