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1 – 3 of 3Zhijie Huangfu, Wei Zhang, Shang Hao, Mengdi Zhang and Jiming Yao
This study aims to evaluate the efficiency of metal electrode and electrolytes on the electroflocculation of indigo wastewater, produced by printing and dyeing factory, and to…
Abstract
Purpose
This study aims to evaluate the efficiency of metal electrode and electrolytes on the electroflocculation of indigo wastewater, produced by printing and dyeing factory, and to optimize the treatment system.
Design/methodology/approach
For effective purging, various types of metal electrodes (graphite, pure aluminum and stainless steel) and supporting electrolytes (sodium chloride and sodium sulfate) were selected for electroflocculation experiments. The decolorization rate and chemical oxygen demand (COD) removal rate were characterized.
Findings
The treatment effects of stainless steel and aluminum were similar, but the dissolution loss of aluminum and the production of flocs greatly limit its application. Electrolytes gave obvious effects to these systems. Sodium sulfate was better than sodium chloride, the decolorization rate was increased by 3.31%, the removal rate of COD in the solution was increased by 28.65% and the weight of flocculation precipitation was reduced by 0.214 g.
Research limitations/implications
The electrochemical treatment system was constructed to compare and analyze the influence of experimental parameters and to provide a reference for the actual treatment of indigo wastewater.
Practical implications
Electrochemical flocculation can remove the insoluble indigo solids and it plays a key role in wastewater treatment.
Originality/value
It is novel to optimize the combination of electrode and electrolyte to improve the efficiency of electroflocculation, which can be widely used in the actual wastewater treatment process.
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Wei Zhang, Mengdi Zhang, Zhijie Huangfu, Jiming Yao and Yuan Xie
This study aims to explore suitable anode materials used in the electrochemical system for indigo dyeing wastewater, to achieve optimal treatment performances.
Abstract
Purpose
This study aims to explore suitable anode materials used in the electrochemical system for indigo dyeing wastewater, to achieve optimal treatment performances.
Design/methodology/approach
The single factor experiment was used to explore the optimum process parameters for electrochemical decolorization of indigo dyeing wastewater by changing the applied voltage, electrolysis time and electrolyte concentration. At the voltage of 9 V, the morphology of flocs with different electrolytic times was observed and the effect of electrolyte concentration on decolorization rate in two electrolyte systems was also investigated. Further analysis of chemical oxygen demand (COD) removal rate, anode weight loss and sediment quantity after electrochemical treatment of indigo dyeing wastewater were carried out.
Findings
Comprehensive considering the decolorization degree and COD removal rate of the wastewater, the aluminum electrode showed the best treatment effect among several common anode materials. With aluminum electrode as an anode, under conditions of applied voltage of 9 V, electrolysis time of 40 min and sodium sulfate concentration of 6 g/L, the decolorization percentage obtained was of 94.59% and the COD removal rate reached at 84.53%.
Research limitations/implications
In the electrochemical treatment of indigo dyeing wastewater, the aluminum electrode was found as an ideal anode material, which provided a reference for the choice of anodes. The electrodes used in this study were homogenous material and the composite material anode needed to be further researched.
Practical implications
It provided an effective and practical anode material choice for electrochemical degradation of indigo dyeing wastewater.
Originality/value
Combined with the influence of applied voltage, electrolysis time and electrolyte concentration and anode materials on decolorization degree and COD removal rate of indigo dyeing wastewater, providing a better electrochemical treatment system for dyehouse effluent.
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Weiwei Lv, Zhijie Huangfu, Kangkang Wang, Wei Zhang and Jiming Yao
Indirect electrochemical oxidation and electro-flocculation were combined to degrade indigo wastewater.
Abstract
Purpose
Indirect electrochemical oxidation and electro-flocculation were combined to degrade indigo wastewater.
Design/methodology/approach
The degradation efficiency of indigo wastewater in single-cell and double-cell were investigated. Based on the previous single factor experiments, the oxidative degradation conditions of indigo wastewater in single cell were optimized by response surface methodology (RSM). The decolorization rate, chemical oxygen demand (COD) removal rate, the contents of flocculation precipitation and indigo were measured and analyzed.
Findings
The degradation efficiency in single cell was higher than in double cell. The electrolysis conditions were optimized by RSM and the decolorization rate was 99.01% with COD removal rate of 60.34% and conductivity of 89.75 mS/cm. The amount of flocculated precipitation decreased by 53.33% and the indigo increased by 86.34%. The content of Na and S decreased by 12.13 and 6.49%, respectively. The ratio of Fe3+ to Fe2+ in the solution was 4.62:1, indicating that most of the iron dropped on the electrode sheet was converted to Fe3+.
Research limitations/implications
The one-step electrochemical oxidation and flocculation method with the advantages of simple operation and environmental protection, provided a reference for the actual treatment of dyeing wastewater.
Practical implications
Combining the electrochemical flocculation and oxidation provided an efficient and practical solution for degradation of indigo wastewater.
Originality/value
Combining the advantages of electrochemical oxidation and electroflocculation, the application of electrochemistry in printing and dyeing wastewater treatment technology has been expanded.
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