Background and Objective: Textile wastewaters are known as an important environmental pollutant. The main characteristic of textile wastewater is its colorness, which contains various organic and inorganic pollutants. Therefore it is necessary to treat such effluent effectively before discharging into the environment.Methods: In a fundamental-applicable study, removal efficiency of Acid red 18 and Acid red 14 using zero valent iron powder has been investigated. Parameters studied include pH (3-11), contact time (15-120 min), and initial concentration of iron powder (0.5-2 g/L).Results: Batch experiments show that dye removal was increased with increasing mass of iron powder and contact time, while decreased with increasing of pH. The high removal efficiency was observed in pH=3, contact time=120 min and iron powder concentration of 2 g/L. The result of kinetic studies shows that removal of Acid red 18 and Acid red 14 was best described by pseudo-second order kinetic model.Conclusion: the overall results of present work shows efficient removal of Acid red 18 and acid 14 by zero valent iron powder.

Wastewater from the textile industry, especially that containing azo compounds, often contains toxic materials that persist in the environment. Therefore, it is necessary to evaluate the performance of various methods for their removal. Acid red 37 combinations represent a single structure in the azo dyes which have already been widely used in the textile industry. The purpose this study is the optimization of effective factors and investigation performance of the electrofenton and electrocoagulation methods in synthetic wastewater for Acid Red 37 dye removal from aqueous solutions. In this study, synthetic wastewater was formed from Acid Red 37 dye and pilot Scale and the concentration, pH, electrical density and temperature parameters were investigated. Ultimately the optimum conditions were determined as well as the amount of energy consumption at 90 percent efficiency. To investigate the pollutant degradation GC-Mass was used and the results show that both methods had the ability to remove Acid Red 37. Electrocoagulation was found to be more efficient than the electrofenton method; respectively, the optimum conditions for removal by the electrofenton and electrocoagulation methods were pH=3, time=120 min, density- 30 mA.cm2, concentration=50 mg/L, consumption energy 142.8 KWh/Kg Dye and pH=7 time=120 min, density- 30 mA.cm2, concentration=150 mg/L, consumption energy 130.2 KWh/Kg Dye. These results show that the electrocoagulation method was better than electrofenton with its high ability for removal Acid Red 37.

The present study investigates the degradation of Acid Red 14 (AR14), commonly used as a textile dye in aqueous medium through the oxidation process by UV /S2O82- under a set of variables concentration of S2O82-, Ag+, AR14 and temperature. Commonly Ag+, heat and UV light can excite S2O82- to sulfate radical form (SO4-), a stronger oxidant (E0=2.60 V) than S2O82-, to enhance significantly the oxidation of contaminants. Also the changes in the absorption spectra of AR14 solutions during the photoxidation process showed that decrease of absorption peak of the dye at lmax=514 nm indicates a rapid degradation of the azo dye. The results of this study suggest that the oxidative treatment of AR14 by peroxydisulfate with UV is a viable option for removal of the textile dyes from effluents.

Background & Aims of the Study: Azo dyes are employed in industrial processes such as textile industry to create large quantities of colored sewages that have organic and nonorganic materials. So, remediation of them is essential. In this project, degradation and mineralization of Acid red 14 (AR14) that is a mono Azo dye and widely used in the textile industries was investigated by Sonocatalysis and Sono photo catalyst in the presence of homogeneous (Fe3+) photo catalyst.Materials & Methods: This study is an experimental investigation on a laboratory scale. The study performed on synthetic wastewater that hold Acid red 14.The influence of operational parameters such as initial dye concentration and ultrasonic power on the sonochemical degradation was also studied. The optimization of variables was done by one factor at a time method.Results: The efficiency of the Sonophotocatalytic process with Fe3+ was higher than Sonocatalysis and photo catalyst processes alone. The combination of sonolysis, Fe3+ and photo catalyst caused a highly synergistic effect and the synergy index obtained for Fe3+ Sono photo catalysis was 2.05. Chemical oxygen demand (COD) analysis was used to study the degree of mineralization. After 180 min of reaction, the removal of COD was 15, 25.4 and 55.5% for UV/Fe3+, US/Fe3+ and UV/US/Fe3+ process, respectively. The degradation by photocatalysis and sonolysis followed pseudo first-order with respect to the concentration of AR14.Conclusions: The results showed that the Sono photo catalytic degradation and mineralization of AR14 in the presence of Fe3+ was synergistic, most likely because of the participation of Sono-Fenton and photo-Fenton reactions.

In this article, the degradation efficiencies of UV/TiO2, UV/H2O2, and UV/O3 processes are compared in the removal of Acid Red 14 which is the most commonly used dye in the textile industry. Results show UV/TiO2 recorded a degradation efficiency of above 90% in 30 minutes (pH=3, [Dye]=40mg/L, [TiO2]=400mg/L), UV/H2O2 degraded 75mg/L of dye (a degradation efficiency of more than 90%) in 160 minutes, and the efficiency of UV/O3 was above 95% in only 15 minutes using an ozone concentration of 0.9gr/h ([Dye]=250mg/L, pH=9). Judging on their high efficiencies, the use of these processes is recommended for the treatment of textile effluents. It may be noted, however, that the two processes of UV/H2O2 and UV/O3 are effective in both dye degradation and COD removal, but UV/O3 is costly and needs especial equipment. UV/TiO2 is not effective in COD removal and requires the post-treatment separation of nano-particles (using a centrifuge or sedimentation process). Thus, the UV/H2O2 process seems to be the easiest and most effective process in the treatment of textile effluent due to its simplicity and effective COD removal in a short time.

Background & Aims of the Study: Azo Dyes are the most hazardous materials in different industries. Dyes and pigments used in industries for applications such as textiles, leathers, papers, foodstuffs, additives, etc. Application amounts of azo dyes in industries which can cause severe health problems in human and environmental pollutant problems. So, color wastewaters decomposition plan are necessary. The purpose of this study is the application statistical experimental design in photocatalytic decomposition of azo dye Acid Red 14 (AR14) from aqueous solutions using multi walled carbon nanotubes (MWCNTs) particles which was used UV/H2O2 process in photoreactor. Materials & Methods: MWCNTs particles as a catalyst used for the degradation of dye in aqueous solution. MWCNTs particles have been characterized by scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and Fourier transform infrared (FT-IR). Design of experimental (DOE) based design matrix was exerted for measure the effect of these three factors such as: A) pH, B) catalyst amount and C) H2O2 concentration at two levels. The full factorial experimental design was utilized in this process. The significant effects of each factor and interactions determined using analysis of variance (ANOVA) method. The decomposition kinetic of dye was studied. Results: The maximum photocatalytic degradation efficiency of dye obtained in this study was found 90. 65%, corresponding to the optimal conditions of 3, 30 mg L-1 and 20 ppm respectively, for the pH, catalyst amount and H2O2 concentration. The most effective factor in the photocatalytic degradation efficiency was H2O2 concentration. The interaction between pH×H2O2 concentrations was the most effective interaction. A pseudo first order reaction with a rate constant (k=0. 0696 min− 1) was observed for the photocatalytic degradation of dye. Conclusions: The results showed that photodegradation process can be suitable alternative to degradation dyes in aqueous solutions.

Introduction: In order to improve caries detection, invasive methods should not be used and caries detector is useful, and antibacterial solutions can be used as well as a biological method for caries detection. Aim of the present study was to differentiate sound dentin from infectious dentin by two coloring solutions: acid red and povidone iodine.Methods: In this experimental investigation, 140 carious molar teeth were collected. Teeth were kept in normal saline solution in room temperature and were divided into two groups, A and B (70 samples in each group). Teeth in group A were painted by acid red 1% solution and in group B by povidone iodine 10% and the painted points were recorded. After omission of the painted points, all samples of group A were painted by povidone iodine (group C) and all samples of group B by acid red (group D) and the painted points were recorded again. Data was analyzed using chi-square and Mc-Nemar tests.Results: Diagnostic accuracy of acid red for detection of dental caries was more than povidone iodine and the difference was statistically significant (P<0.05).Conclusion: It was concluded that the coloring power and accuracy of acid red is more than povidone iodine.