| Rectorite(REC)is a kind of natural mineral material,it has special layered structure,good property of adsorption and cation exchangeable.The better modified rectorite can be prepared by exchanging with cation Na+?Mg2+?Li+ etc.Due to the good electrochemical properties,lithium was widely used in fields of batteries.Thus Li-REC not only has good adsorption property but also has good electrochemical property.Dyeing industry emits large amount of pollutants,most of dye wastewater is high concentration,high alkalinity,deep chromaticity and difficult to degrade,methylene blue(MB)is a kind of typical dye wastewater.The operation of treatment of MB using Li-REC is simple and effective.However it is easy to form slurry and difficult to separate,then the particles were fabricated by Li-REC with microwave activation in order to solve the problem of plugging of particles layered structure.This study presents the behavior and mechanism of treatment of MB by three-dimensional Li-REC particleelectrodes.TheRectorite which were modified by lithium before and after are characterized with some characterization analysis.It revealed that the inter-layer spacing,specific surface area and doubleelectrode layer of Li-rectorite were better than Rectorite,and theelectrochemical property of Li-rectorite was better than raw Rectorite.Further more the Rectorite particles were fabricated under the optimum microwave activation operating conditions(microwave power and irradiation time was 500 w and 10 mins,respectively).Then these fabricated particles were characterized with SEM.The results showed that Li-REC particles had more coarser and bigger specific surface than raw REC particles,and the particles with microwave activation had more coarser surface and more amount of pores than those without microwave activation.The three-dimensional electrode reactor of the system were builded,the anode and cathode electrodeswere Ti/RuO2 andsteel,respectively.The optimum electrochemical operating conditions of cell voltage,concentration of electrolyte solution,plate distance and concentration of MB is 9V,0.06mol/L,2cm,400mg/L,respectively.The removal rate of MB was 27.1%under the optimum electrochemical conditions.To study the effect of electrochemical degradation of MB by REC power and particles,some contrast experiments were made.The results of Rectorite power and particles simple electrochemical,simple adsorbent and electrochemical adsorbent treatment of methylene blue showed that:(1)In the powder group(Rectorite 0.1g),the Li-Rectorite electrochemical adsorbent of theMB(400mg/L,200ml)was 57.5%,which was better than the same treatment of raw Rectorite(47.9%).And the relationship of WElectrochemical-adsorbent> Welectrochemical+Wadsorbent was existed.The rectorite power were polarized by electric field,then the system of three-dimensional electrode was formed.Due to the big specific surface of power,the electrode contact area with methylene blue was increased,so the treatment of MB were better than two-dimensional electrode.(2)In the particle group(particles 1g),the electrochemical adsorbent of MB(400mg/L,200ml)treated by Li-Rectorite particleswas better than the same treatment by raw Rectorite particles.The order of electrochemical adsorbent of the fabricated particles is: Li-Rectorite particles with microwave activation(73.7%)> Li-Rectorite particles(70.0%)> raw Rectorite particles with microwave activation(67.68%)> raw Rectorite particles(63.32%).And the relationship of WElectrochemical-adsorbent>Welectrochemical+Wadsorbent was existed.The rectorite particles were polarized by electric field,then the system of three-dimensional electrode was formed.Due to the big specific surface of particles,the electrode contact area with MB was increased,so the treatment of MB were better than two-dimensional electrode.To study the behavior and mechanism of treatment of methylene blue by three-dimensional electrodes made of fabricated Li-REC particles and evaluated the performance of three-dimensional electrode,the ultraviolet absorption spectrum,Raman spectrum and the content of chemical oxygen demand(COD)of the reaction solution were tested.The results showed that the content of the COD were decreased gradually during the reaction time,and three-dimensional electrode reactor was more effective than two-dimensional electrode reactor.The peaks of the ultraviolet absorption spectrumwere attenuated and there was new peak existed at Raman shift 1000(cm-1)in Raman spectrumduring the electrochemistryreaction.It can be learned form that the concentration of the MB were decreased gradually during the reaction time and there are some new intermediate production produced such as benzene ring and hydroxyl.In the three-dimensional electrode system,the concentration of MB and COD decreased through the oxidizing reactionand free radical chain reaction with active substances of H2O2 and ·OH existed.In conclusion,the Li-Rectorite powder and particles could both form the three-dimensional electrode system and promote the degradation of methylene blue.The removal of MB of power per unit mass was better than particles,however the power easy to form slurry and difficult to separated,so the particles were fabricated with microwave activation in order to solve the problem of difficulty separating and plugging of particles layered structure.The study makes full use of natural resources to produce effective three-dimensional electrode materials,then laid certain theory and technical foundation for the treatment of difficultly biodegraded wastewaterby REC and three-dimensional electrode. |
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