Application Of Capacitive Deionization Technology In Desulfurization Wastewater Treatment And Analysis Of Adsorption Model

Desulfurization wastewater has the characteristics of high salt content,high hardness and heavy metal content,which make it cannot be discharged directly.With the application and popularization of "zero emission" technology in power plants,as the most difficult wastewater to be treated in coal-fired power plants,the desulfurization wastewater treatment has been upgraded from conventional compliance treatment to"zero emission" treatment,so the study of "zero emission" for desulfurization wastewater treatment technology has become the focus of power plant wastewater treatment.As a new low energy consumption and low cost wastewater treatment technology emerging in the 21st century,capacitive deionization technology(CDI)is favored by more and more researchers.From the analysis of the mechanism to the exploration of the treatment effect of the single component salt solution,it has been gradually developed and applied.However,in the treatment of desulfurization wastewater,no one has carried out related research experiments.This topic proposes the application of capacitive deionization technology in the treatment of desulfurization wastewater.First of all,the pretreatment scheme of the desulfurization wastewater water sample is selected,and the most cost-effective scheme is selected to pretreat the desulfurization wastewater.Subsequently,a self-made capacitor deionization treatment system was used to conduct a "reduction" test on the pretreated desulfurization wastewater,and a single variable method was used to change the operating parameters to optimize the desalination effect.Finally,model the adsorption process,select a kinetic model that is more suitable for simulating the treatment process,and compare the adsorption strength of each ion according to the thermodynamic model fitting effect.The main conclusions and results are as follows:(1)The lime-coagulation method can more effectively remove the dissolved silicon materials and turbidity in the desulfurization wastewater.The double alkali method Ca(OH)2 and Na2CO3 soften the desulfurization wastewater to be the most economical and effective.After pretreatment of the desulfurization wastewater,the removal rates of turbidity,dissolved silicon,total hardness,calcium hardness and magnesium hardness reached 70.84%,83.25%,91.15%,98.53%and 89.60%,respectively,and the electrical conductivity was higher than that of raw water.In order to avoid contamination of the electrode during CDI treatment,a pretreatment process is necessary.(2)Taking the conductivity and ion concentration of produced water as evaluation indexes,it is found that the adsorption process of CDI treatment of desulfurization wastewater shows a certain law,and it has good practical application value for the reduction treatment of desulfurization wastewater.Within the scope of this experiment,when the hydraulic residence time is 40 s,the power supply voltage is 1.1 V,and the electrode material coating thickness is 0.8 mm,the capacitive deionization adsorption system has the best effect on the pre-treated desulfurization wastewater treatment.The higher the water conductivity,the better the quality of the produced water.The CDI treatment effect of the pretreated desulfurization wastewater is better than that of the desulfurization wastewater that has not been pretreated.(3)The divalent ions of desulfurization wastewater treated by CDI are easier to be adsorbed than the monovalent ions,and this rule is not affected by the relevant parameters of the device.This conclusion was verified during the fitting process of the Freundlich isotherm adsorption model.The fitting correlation coefficient of the model is between 0.97 and 0.98,and the fitting effect is relatively good.The values of 1/n are all in the range of 0.5?2.All ions in CDI treatment desulfurization wastewater are relatively easy to be adsorbed.The adsorption intensity order of several ions is:Ca2+>Mg2+>SO42->Na+>Cl-?(4)The adsorption process of the self-made CDI treatment of desulfurization wastewater conforms to the class-one reaction kinetic model,and the correlation coefficient can reach 0.998 or more.It can well describe the change of the concentration of different ion effluent with the adsorption time during the CDI process;The kinetic model and the quasi-second-order kinetic model can well describe the change law of the adsorption amount of each ion with the adsorption time under different adsorption time in the process of CDI treatment of desulfurization wastewater.The fitting correlation coefficient is between 0.997 and 0.998.Taking the change of electrical conductivity and the removal effect of each ion as the evaluation index,it was found that the adsorption process of CDI treatment of desulfurization wastewater showed a certain law,and a better treatment effect can be achieved under the condition of lower operating cost,indicating that CDI is used in desulfurization wastewater The reduction process has very good practical application value.