Iranian Journal of

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Backgrounds and Objectives: Carcinogenic and mutagenic potential of some azo dyes as a category of common dyes in different types of industries has been reported. The degradation of one commercially available dyestuff [C.I. Reactive Red 198 (RR 198)] by means of ultraviolet radiation (UV), ultrasonic irradiation (US), UV/H2O2 and US/H2O2 processes was investigated.
Materials and Methods: Photolysis process was accomplished in a laboratory-scale batch photoreactor equipped with an 55W immersed-type low-pressure mercury vapour lamp (UVC) and sonication in a sonoreactor with low frequency (42 kHz) plate type transducer at 170W of acoustic power with emphasis on the effect of various parameters on decolouration and degradation efficiency.
Results: Initial results showed that, color removal efficiencies by US and US/H2O2 processes were negligible. Almost complete disappearance of RR 198 (20 mg/L) in UV/H2O2 process was possible to achieve after 10 min of irradiation. It is found that lower pH and lower concentration of dye favor the dye degradation. Hence any increase in initial dye concentration results in decreased decolouration rates. Also, the experimental results indicated that the kinetics of sono-oxidation and photo-oxidation processes fit well by pseudo-first order kinetics and first order reaction kinetics, respectively.
Conclusion: It is concluded that UV/H2O2 reaction was more effective than other reactions in bleaching and the reaction rate was sensitive to the operational parameters and increased with increasing H2O2 concentration up to 15 mM.

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MicrosoftInternetExplorer4 Background and Objectives: Environmental pollution and health risks of dyestuffs extensively are caused by many industries. Nonbiodegradability of dyes is important so that different methods are studied for removing them. The use of white rot fungi is promising technique in this regard. Therefore, objective of this work is to investigate Rimazol Brilliant Blue Royal decolorization by immobilized Ganoderma sp. in sodium alginate from aqueous solution.
Material and Methods: This is an experimental study. First, the nutritional, environmental, and operational conditions of decolorization process were optimized. Then, efficiency of immobilized fungal cells was investigated. Experimental designs were provided using fractional factorial methods and quadratic model was fitted on decolorization data by MiniTab software.
Results: Our findings showed that type and concentration of carbon source, temperature, and pH were the most important factors affecting decolorization and statistically significant. Optimal conditions to 95.3 percent color removal were: glycerol as carbon source at 19.14 g/L temperature, 27 oC and initial pH, 6.26. Moreover, decolorization efficiency increased from 75 percent up to 95 percent by improving process and fungal immobilization.
Conclusion: Ganoderma fungus has suitable potential to decolorization. Besides, optimization and cell immobilization can improve its capability. Application of experimental design to research methodology is important because of decreasing in experiments and saving resources. It is suggested to use these potentials in environmental pollution control.

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Background and Objective: Malachite green dye is used in many industries including textile industries. Disposal of wastewaters containing the dye to the environment, can lead to many environmental problems. Currently, many physico-chemical approaches are used for wastewater treatment. Because of limitations and difficulties of these methods, biological treatment is considered as an economic and effective treatment method. The aim of the present study was to study the feasibility of phytoremediation of malachite green dye using watercress and investigate the effect of some environmental factors in removal efficiency.

Materials and Methods: After collection, the plants were kept in the laboratory, and they were treated with different concentrations of malachite green. During the experiments, decolorization extent was determined by UV-Vis spectrophotometry. Intermediate compounds generated during the biodegradation of the pollutant were identified using GC-MS method.

Results: After 7 days, the ability of watercress in removal and biodegradation of 10 mg/L of malachite green solution was more than 90%. Five intermediate compounds were identified in the biodegradation pathway of the pollutant. It was also found that increasing dye concentration up to 20 mg/L led to the increase of the plant photosynthetic pigment contents and activities of antioxidant enzymes.

Conclusion: Our results showed that watercress has high ability in the dye removal of malachite green. The reusability of the plant for decolorization confirmed the biological degradation process. Moreover, an increase in the plant biomass, temperature and pH led to the increased decolorization efficiency.