关键词: 脱硫废水, 电解, 镁离子, 离子交换, 膜, 电耗

Abstract: Limestone-gypsum wet desulfurization process is the most widely used flue-gas desulfurization technology, this process produces a certain amount of desulfurization wastewater. The enrichment of Cl^- included in desulfurization wastewater will increase the corrosivity of the slurry and they are difficult to be removed using conventional processing methods. The electrolysis-electrodialysis process is a promising recycling-treatment, but the Mg²⁺ included in desulfurization wastewater will influence reliable operation of the system. This paper adopted an electrolysis setup with three compartments and a pair of membranes and used a mixture of CaCl₂ and MgCl₂ at different concentrations of Mg²⁺ to simulate desulfurization wastewater, and proceeded to study the effect of Mg²⁺ during the electrolysis-electrodialysis process. Results show that the increase of the concentration of Mg²⁺ can make the electrolyte pH difficult to increase, increase the cell voltage and the energy consumption. When the concentration of Mg²⁺ is more than 0.179mol/L, the desulfurization wastewater should be pretreated by chemical precipitation or other suitable methods before electrolysis to ensure reliable operation of the electrolysis-electrodialysis system.

Key words: desulfurization waste water, electrolysis, magnesium ions, ion exchange, membranes, energy consumption