| Recently, electrochemical technology has been widely applied to treat organic wastewater, because of many advantages, such as wide application fields, simple operation, easy automatic control, good effect. Especially for bipolar three-dimensional electrode cell (BTDEC), it has a wide prospect in application of organic pollutants treatment because of large specific surface area and high efficiency on mass transfer in comparison with conventional two-dimensional electrodes. However, in practical projects, there are still some problems that limit BTDEC' s the application scope. First problem, with the action of stream and airflow, insulated filler separate.s from electric filler because of different density, accordingly the current efficiency becomes lower and lower. Second problem, owing to the suspend and colloid materials aggrading on the surface of particle electrcde, effective electrode area becomes smaller and smaller, so current efficiency falls. Third problem, there are different effects on degradating different kinds of organic pollutants and different substitutional groups. And trie rules and mechanisms of electrolysis are unclear, so there is some blindness in the application. Aim to the above problems, filler change and structure amelioration of BTDEC have been studied, and at the same time, several kinds of organic pollutants wastewater are studied. The rules of degradation for some specie,! organic pollutants by BTDEC are raised.(1) Fillers change of bipolar three-dimensional electrode cellA new insulated filler is found and used by comparison of several insulated filler' physical & chemistry characters. It is proved that the new filler can mix completely with active carbon through backwashing experiment. Therefore, first problem can be well solved when new filler is used. It is found that new filler will dissolve into solution in the presence of salt in electrolysis, the dissolved COD is about 60mg/L, and dissolving phenomenon continues long after electrolysis. In order to reduce side effects on electrolysis by dissolve phenomenon, high concentrated organic pollutants (COD is about 1200mg/L) are used.(2)The degradation behaviors of several refractory organic pollutants by electrolysis have been studied by using new and old mix fillers in this article. These organic pollutants include aniline, nitrobenzene, 2, 4-bichlorophenol, 2, 4-binitrophenol, phenol, benzoic acid and so on. The experimental results indicate that electrolysis can more or less remove all of pollutants using oldmix filler, however, the rates of removal are not high, about 20%. For some of the pollutants, such as aniline; phenol, there is little effect on pollutants removal using new mix filler, even with some side effect, and solution COD removal rate is less than 10%. Whereas, good removal effect can be reached for some pollutants, such as nitrobenzene, 2, 4-binitrophenol, and solution COD removal rate is 50% while organic pollutants removal rate is above 75%. These results are better than those of old mix filler, 30% and 55% respectively. These results provide some reference for choosing filler for BTDEC' practical application.(3)The influence of structures of aromatic pollutants on the efficiency of BTDEC has also been studied in this article. The influence rule of properties of substitutive radicals on the degradation reactivity has been also studied. The experimental results make clear that: when treating organic aromatic pollutans by BTDEC, the existence of electron-withdrawing group on benzene ring, such as nitryl or chlorine ion, can make the electrolysis efficiency higher. While, when treating organic aromatic pollutans by BTDEC, the existence of electron-donating group on benzene ring, such as hydroxide radicel or amidocyanogen, can make the electrolysis efficiency lower. These results provide some theory to guide the practical application of BTDEC.(2) Structure amelioration of bipolar three-dimensional electrode cell Treatment of aniline using a novel electrochemical reactor, three-dimensional three-ph... |
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