The Study Of Recovering Sodium Alkali From Desulfurization Products By Membrane Electrolysis

The membrane electrolysis technology is studied in this research, in which process SO? is efficiently absorbed by sodium alkali absorbent which would be regenerated via membrane electrolysis. This subject adopts the anionic and cationic membranes in three-compartment membrane electrolysis where the sodium sulfate and sodium sulfite are treated. Initially, the process and mechanism of sodium alkali recycling via ion-exchange membrane is analyzed. Thereafter, the influences of parameters have been examined systematically.And then from the point of cost analysis, it can manifests that the proposed design is promising and economic feasible.Firstly, the process and mechanism of sodium alkali recycling were discussed and the theory about the establishment of the laboratory reactor was analysed which confirmed the feasibility of the method.Secondly, the effect of the relevant parameters on the electrolyzing process were studyed under the circular flow condition.The optimal operating voltage and current density were3.6-3.9V and74.0A/m2respectively. The experimental result showed that the suitable residence time was the moderate residence time160s. As the difference between the salt concentration and the acid-base concentration in the middle chamber and two side chambers increased, the mass transfer driving force and the current efficiency increased. The optimum concentration in the middle chamber and two side chambers were1.40mol/L and0.40mol/L respectively.The electrode reaction with the SO32-was confirmed when Na2SO3added in to the middle chamber, but the current effciency has no significantly change.At the same time, the effect of the relevant parameters on the electrolyzing process were studyed under the unidirectional flow condition.The result showed that the effect of concentration was different from that under circular flow condition.The appropriate way was that the concentration in the middle chamber was slight high than two side chambers.Lastly, the economic estimate demonstrated that the electricity requirement per ton NaOH is2540kWh for the lab reactor which was lower than the chlor-alkali industry and market price. Besides, it could obtain about1.55L hydrogen energy, which indicated that the method was highly efficient, environmentally friendly and worth popularizing.