| The principle of Electric Flocculation Wastewater Treatment: under the applied voltage,the anode is dissolved metal ions generated in the appropriate pH water solution and then generate a large amount of multi form hydroxyl polymer in water,will target pollutants by flocculation and sedimentation or flotation and removal,Electrocoagulation combined with electrochemical redox adsorption,coagulation and flotation separation technology,has high removal efficiency,without additional reagents,two small pollution,wide application range,simple equipment easy operation and maintenance and the like,in heavy metal wastewater treatment field has become a hot research topic.But the high cost of processing,and the removal mechanism of complex electrode passivation problems limit the electric flocculation is applied in wastewater treatment,so to discuss the removal mechanism and improve the processing efficiency and reduce the cost is to promote its application in heavy metal wastewater treatment problems.In this study,Fe-Al electrode was used to treat Ni-EDTA wastewater.Study on the electrode material,current density,initial pH,aeration rate,temperature and water of common ions on the removal rate of Ni and TOC,and through the analysis of floc properties and structure of security,discusses the factors that influence the results,at the same time through the research on the reaction characteristics of in-depth analysis of the removal mechanism of Ni-EDTA.The experimental results show that iron anode aluminum flocculant Fe produced the oligomeric state cathode case(b)up to TOC and the highest removal rate of Ni;the more current density,TOC and Ni removal efficiency is high,but the current efficiency reaches a certain level began to decrease,energy consumption began to increase;the initial removal of pH=3 the best,with the removal rate of pH increased gradually began to decline;the air aeration is better than that without aeration,the removal rate of aeration too large or too small is not conducive to Ni and TOC: Fe at different temperatures(b)yield due to different treatment effect of different water;common cation Ca2+,Mg2+ to some extent inhibited the reaction of in SO42-,anion in favor of floc growth,while NO3-,H2PO4-has certain inhibitory effect on the formation of flocs,The results of orthogonal test showed that the optimum conditions of current density is 4.5 mA/cm2,the initial pH value is 3,the aeration rate is 0.3 L/min,the temperature is 313 K,the removal of TOC and Ni were 98.5%,99.9%.The concentration of Ni was reduced to below 0.1 mg/L.This paper analyzes the mechanism under the above conditions,the floc SEM/EDS and FT-IR analysis results show that Fe contains α Fe2O3,various forms of floc in X(OH)and carboxyl nitrogenous organic compounds(EDTA),the removal of Ni-EDTA flocculation mainly through the hydrolysis of iron ions produced by precipitation,in addition to the analysis of UV the experiment showed that the Fe spectra of solution(III)can replace Ni-EDTA in Ni so that the Ni(II)from EDTA(displaced)removal by precipitation or adsorption etc..In summary,the removal mechanism of Ni-EDTA is: electrolytic ferrous ion is oxidized to ferric ions and hydroxyl ions combine to produce three kinds of different forms of iron oxide strong flocculation body,these flocs by charge neutralization and adsorption bridging and sweep and a series of the role of Ni-EDTA in water removal,Fe(III)also you can turn complexation replace the Ni-EDTA of the Ni,the OH-Ni2+ in the wastewater and hydroxide precipitation,thereby reducing the content of Ni in wastewater,the removal of EDTA also include active chlorine produced during electrolysis and pre oxidation reaction with Fenton reagent decomposition comprehensive effect. |
