Microwave Plasma Assisted Internal Electrolysis Used For Treatment Of Reactive Dye Wastewater

Microwave plasma assited inner electrolysis was studied in this paper. This process was applied in the treatment of simulation dye wastewater. Textile dye wastewater contains high concentrations of organic compounds, non-biodegradable matters, toxic substances and other compounds such as detergents, oils and suspended partocles. The quantity of dye wastewater is large and the quality of the dye wastewater is always different from each other.In this research, water-soluble dyes, reactive bright red X-3B and reactive blue KN-R, that commonly used in the textile industry were choosen as model dye wastewater. The mechanism of the process includes three parts: 1) adsorption of dye from the wastewater by active carbon; 2) The inner electrolysis of dye in wastewater and 3) The strengthen effect of microwave plasma . Some parameters, such as exposure time, the number of exposures, particle size of the iron filings, pH, concentration of wastewater, the microwave output, were investigated to optimize the operation conditions. The results showes that two dye solutions give the same results, i.e: the property of active carbon / iron mixture can be recovered by microwave exposure of 2min. The removal rate of dye from the wastewater decreases slightly with the number of microwave exposures, (in this research the active carbon was exposed to the microwave up to 5 times). The particle size of the iron filings in the range 0.9 - 2mm is suitable, the active carbon /iron ratio is 1:1. Excess carbon or iron show no significant effect on removal rate of dye. The optimum conditions were found that pH=7 and the initial concentration of the wastewater was less than 1g/L when the largest output of microwave was used. The reaction process can be persumed to be: (a) A portion of the dye is absorbed by active carbon, and another portion is degraded by the carbon / iron mixture, thus the colority and COD of the wastewater is largely reduced (b) In microwave field, the mixture of activated carbon and iron absorbs the microwave energy, which causes the carbon and iron filings to spark, i.e,. the microwave plasma forms under atmospheric pressure, which results the degradation of adsorbed and adhered dye from the active carbon/iron mixture.Microwave plasma promotes the regeneration of the activate carbon / iron mixture. Therefore, the carbon / iron mixture which has been exposed to the microwave field has a higher rate of degradation than that of no exposured.In summary, this technology can raised the availibility of carbon / iron. The removal of colority and COD for two different dyes were 95% and 60% respectively.