| Serious lack of water resources and the increase of water pollution have become theobstacles to economic and social development and the important factors improving people’sliving standard. The important measure to solve the shortage of water resources and waterpollution is sewage resource recycling. Conventional physical, chemical and biologicalmethods can degrade the harmful pollutants in the water, but it is not so effective to eliminatethe water salinity, so in the process of wastewater resource reuse, desalination is an importantcomponent of this technology. Conventional desalination method in practical application iseasy to produce secondary pollution, high energy consumption and material separationrecycling or renewable difficulties. Electric adsorption desalination technology is a newtechnology of desalination, controlled by voltage on the surface of the electrode, stripping ofpollutants in aqueous solution, through the reverse or sub regeneration adsorption saturationof the adsorbent, which has high desalination rate, no need for chemical regeneration, lowenergy consumption and the advantages of strong ability to resist pollution, displaying uniqueadvantages and larger development space.This experiment employed handmade electric adsorption desalination equipment, using304stainless steel plate composite activated carbon fiber (ACF) as electrode plate material.At the early stage of the experiment we prepare for NaCl aqueous solution simulation,conduct a detailed research on the factors affecting the electric adsorption to determine theoptimal control parameters, and then test the influence of pollutants such as turbidity,ammonia nitrogen, and phenol, on electric adsorption desalination in the simulation water; atthe middle stage, the focus is to work out the mechanism of electric adsorption desalinationand analyzing the adsorption characteristics, while at the late stage, it is to validate the effectsof desalination of the secondary water in refining enterprises in order to replace the reverseosmosis pretreatment process.In this thesis, the main work and conclusions are as following:(1) Electric adsorption experiment device after improving has the following advantages:water rate of the device doubled; stainless steel plate composite activated carbon fiber waschosen as electrode plate, which has large adsorption capacity and excellent adsorptionperformance, and enhances the effect of desalination; Electric adsorption device’s internalserial channel type structure is beneficial for the device’s miniaturization and improves waterquality, and the common electrode of stainless steel plate is beneficial for saving device cost;Using mesh partition can easily form the disturbed flow, and improve the effect of masstransfer and the rate of desalination. (2) In the single factor experiment, for certain electric adsorption device, electrodevoltage, flow velocity, the initial concentration have the best parameter combination. Whenthe power supply voltage is2.2V, the velocity is30ml/min, the electric adsorption averagedesalination rate is46.17%.(3) In the orthogonal experiment, the electric adsorption can be judged according to thesize of the poor R2, affecting electric adsorption device average desalination rate of primaryand secondary factors order: Initial concentration> Voltage> pH> Velocity. Orthogonalexperiment data uses SPSS Statistics17.0to carry out the Durbin-Watson model simulation,and from the standardized equations, we can find out that the main factors are voltage andinitial concentration, and that the simulation results are in conformity with orthogonalexperiment results of the analysis. The influence of desalination effect, the velocity and pHvalue are less than the initial concentration and the voltage.(4) When the voltage is1.4V,1.4V,2.2V,2.6V respectively, Langmuir and Freundlichadsorption isotherm have higher fitting degree. In the Langmuir adsorption isotherm model,when the voltage increases, the KLincreases too, which shows that when the voltage increases,adsorption speed becomes faster, but the qmaxis not correspondingly increase, which showsthat with the increase of salinity, its capability of adsorption doesn’t develop. In theFreundlich isothermal adsorption model, when the voltage increases, the1/n value decreases,which means that with the increase of salinity, the speed of electrode adsorption capacitydecreases, but the KFincreases accordingly, which shows that when the voltage increases,adsorption capacity is growing. Considering the characteristics of activated carbon fiberparameters,84%of the pore size distribution is under1nm, and therefore, electric adsorptioncan better conform to the Langmuir monolayer adsorption isotherm model.(5) When the power supply voltage is1.4V,1.8V,2.2V,2.6V respectively, three kindsof reaction kinetics model fitting degree are higher, but the Elovich equation fittingcorrelation coefficient R2are all higher than Lagergren’s first order reaction kinetics modeland the secondary reaction kinetics model, and the fitting effect is good. For Elovich’ssimulation equation, under the condition of the optimal voltage2.2V, the maximum of bvalue is10.204, which shows adsorption rate is slow to maintain the low water conductivityfor a long time. For Lagergren’s first order reaction kinetics model, with the increase ofvoltage, the adsorption rate K1value increases accordingly, and the saturated adsorption timeis shorter. For the secondary reaction kinetics, along with the increase of voltage, the initialadsorption rate increases, and the secondary adsorption rate constant K2will also increase.(6) Electric adsorption desalination plant is used in refinery sewage, wastewater treatment,and the pollutants in water (Turbidity, Salinity, Ammonia nitrogen, CODcr, UV254) have a better removal effect, so it’s feasible to substitute the electric adsorption desalination processwith alternative reverse osmosis pretreatment process. |
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