| At present,industrial wastewater was widely distributed and caused serious pollution.This wastewater would threatened human living environment if it was discharged casually.However,this wastewater contained a wide variety of metal ions,it is difficult to remove individually.Thus,treatment this wastewater has become a hot research.In this thesis,the source,harm and processing techniques currently used of metal wastewater were reviewed,including chemical precipitation,electrochemistry,adsorption,membrane separation and flotation,but these methods have limitations,For example.capacitive deionization(CDI)technology caused the attention by people.CDI was economical and environmentally friendly.But in the process of wastewater treatment exposed many problems.For it's shortcoming,it was improved.Ion-exchange membrane Was put into CDI.This method made up for lack of capacitive deionization.Membrane capacitive deionization(MCDI)technology can absorb a variety of metal ions,and metal ions can be effectively removed.In this study,electrode and ion exchange membrane were bound.built a:nembrane capacitive deionization.Using this device,influence of voltage?flow rate and initial concentration on zinc ions removal rate were discussed?to determine the optimum process parameters.Under the optinal process parameters,wastewater of Hunan mining was treated by membrane capacitive deionization technology,measuring various ions re,noval rate,water production rate,the maximum amount of adsorption TDS.Finally,electrical adsorption isotherln model and dynamic model were used to fit the experimental datas to investigated the adsorption mechanism.The research showed that the optimum preparation conditions of the ion exchange membrane is sulfonation degree of 55%.The four cation exchange membranes that were prepared,the membrane of?2,?3.#4 had low water content,small price and poor deionized.Performance of#1 cation exchange membrane was preferable.Using a membrane capacitive deionization unit,optimum processing parameters were:voltage of 1.2 V,flow rate of 17 1L/min,the initial concentration of the solution of zinc ion for 45mg/L,the removal rate of zinc ion was 97.64%,Under optimun parameters,#1 membrane had the shorter time of adsorption equilibrium and minirnum solution conductivity of adsorption equilibrium than the other three kinds of ion-exchange membranes,the removal rate of total hardness?zinc ion.calcium ion,magnesium ion,water production rate and TDS adsorption amount respectively were 67.39%,90.2%,47.92%,40.49%,27.30%,26.61 mg/g.The four ion-exchange membrane performed cycle test,when the membrane electrode reached saturation,lowest conductivity of four kinds of cationic membranes solution were 55?S/cm?485 ?S/cm,233?S/em,66 ?S/cm.After three cycles of desorption solution could reached initial conductivity values,indicating that it has good performance of recycling deionized performance.Minimum conductivity of MCDI and CDI were 55 ?S/cm and 495 ?S/cm,and conductivity of MCDI after desorption could achieve the value of the raw water,and conductivity of CDI was 1310 ?S/cm only,whereby the ion-exchange membrane can improve the reproduction performance of the membrane electrode.Electrical adsorption kinetics and adsorption thermodynamics were studied to investigate zinc ion adsorption mechanism using membrane capacitive deionization.First-order kinetic model had a better fitting result than the second-order kinetic model,and the adsorption capacity and ions removal rate increases as the voltage increases under the voltage was less than 1.2 V,which illustrated the voltage was an important factor for electric adsorption capacity. |
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