The current work investigated the effect of ZnS and ZnS/ZnO assembly on the photocatalytic removal of Reactive Red 66 from an aqueous solution. The photocatalytic activities were carried out using both UV irradiation and visible light, and the effects of various operating parameters, such as pH, catalyst loading, dye concentration, and contact time, were studied. The results showed that the ZnS/ZnO heterostructure exhibited a higher dye removal percentage than ZnS alone and assisted in the photodegradation of Reactive Red 66. Maximum adsorption was found at pH 2 and 5, indicating that the dye removal was strongly pH-dependent. The highest dye removal efficiency under UV light was 77. 7 and 91. 7% using ZnS and ZnS/ZnO, respectively. Furthermore, the degradation percentage of Reactive Red 66 by ZnS and ZnS/ZnO decreased to 43. 3 and 75. 2% under visible light. The enhanced photocatalytic activity of the ZnS/ZnO heterostructure is attributed to its high absorption of light, efficient separation of electron-hole pairs, and quick surface reaction in the heterostructure.

This study provides information on the application of the Fenton process as an advanced oxidation method for the treatment of wastewater containing an azo reactive dye (C.I. Reactive Red 120). To establish cost-efficient operating conditions for potential application of Fenton oxidation process, the influence of the main operating parameters such as iron sulfate and hydrogen peroxide doses, solution pH, temperature, initial dye concentration and presence different concentrations of sodium chloride and sodium sulfate have been studied systematically in a laboratory scale. The obtained results showed that the best pH value for decolorization of dye solution was 3. The decolorization of RR120 enhanced with the increasing of reaction temperature but decreased as a presence of chloride and sulfate ions. The increase of Fe2+ and H2O2 doses accelerated the color and COD removals until a point where further addition of Fe2+ or H2O2 became inefficient and unnecessary. The result indicated that over 99% color removal and up to 74% COD removal can be obtained by Fenton’s oxidation.

In this study, chitosan-coated magnetically nanoparticles were used to remove the Reactive Red 120 dye from aqueous solution. Chitosan is one of the most famous biological polymers that can be used as adsorbent in the removal of color pollutants. Magnetic Fe3O4 nanoparticles synthesized by mixing FeCl3. 6H2O and FeCl2. 4H2O were coated on low molecular weight chitosan polymer. Magnetic nanoparticles coated with chitosan were then characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and vibrating sample magnetomer (VSM) analysis. The effect of three parameters of pH, dye concentration, and the adsorbent dosage on adsorption was investigated. Under these conditions, the optimal adsorption was obtained at pH = 4, initial dye concentrations = 150 mg/l, and the adsorbent dosage of 2 g/l. Adsorption data were adapted to Langmuir and Freundlich isothermic models. The results showed that the data obtained from the dye adsorption on the chitosan-coated magnetically nanoparticles fit better with Langmuir model.

Background: and purpose: Dye is one of the problems of industrial effluent such as textile industries. The dyes can be removed by various methods. Therefore, the aim of this study was the evaluation of adsorption rate of reactive red 198 from aqueous solution by activated red mud.Materials and methods: This research was a lab study. Activated red mud was used as an adsorbent to remove reactive red 198 dye. The effect of various parameters on performance of adsorbent was investigated and the isotherm of adsorption was determined. The dye concentration was measured in wavelength of 518 nm by spectrophotometer.Results: The results indicated that the adsorption efficiency reduced by increasing of initial dye concentration. Increasing of contact time and adsorbent dose can lead to increasing of the removal efficiency. The maximum removal efficiency was occurred pH between 2 to 3. The data was best fitted on Frandlich and Temkin isotherms.Conclusion: The red mud had a satisfactory quality in dye adsorption. It can be used as effective and inexpensive adsorbents for treatment of textile effluent.

Background and Objectives: Discharge of textile colored wastewater industries without providing enough treatment in water bodies, is harmful for human and aquatic organisms and poses serious damages to the environment.Most of conventional wastewater treatmentmethods don.t have enough efficiency to remove textile dyes from colored wastewater; thus in this research the efficiency of electrocoagulation treatment process with aluminum electrodes for treatment of a synthetic wastewater containing C.I. Reactive Red 198 in batch reactor was studied.Material andMethods: The experiment conducted in a Plexiglas reactor with a working volume of 2L that equipped with 4 aluminum electrodes. The effects of operating parameters such as voltage, time of reaction, initial dye concentration and interelectrode distance on the color removal efficiency, electrical energy consumption and electrode consumption were investigated.Results: in the optimum operational condition electrocoagulation, is able to remove color and COD as high as 99.1 and 84.3% in aluminum electrode in 75 minutes at 20 volt and 2 cm interelectrode distance, respectively. Under this condition, operating cost was 2986 rails per cubic meter of treated wastewater. Increase in the interelectrode distance and initial dye concentration, lead to the decrease in efficiency of dye and COD removal.While as the voltage and time of reaction increased, energy consumption, electrode consumption, final pH and color removal, increased too.Conclusion: electrocoagulation process by aluminum electrode is an efficient and suitable method for reactive dye removal from colored wastewater.