This study examined the photolytic degradation of C.I. Acid Red 73(AR73), in aqueous solution by KMnO4/UV/H2O2 process. A continuous circulated photoreactor equipped with a UV lamp was used. (I) Potassium permanganate was used for decolourisation of AR73 dye solution. The stoichiometric amount of potassium permanganate required for 1 mol of AR73 complete color removal was determined (2.79 mol). In the acidic solution, 100% of AR73 color removal and near 10% dye mineralization have been observed in no more than 5 minutes. (II) After decolourisation period, UV/H2O2 system was applied for mineralization of the dye solution. Under the best operational conditions, after 180 minutes of UV irradiation, 90% of dye mineralization was observed. III) The results of this method were compared with those of obtained by using UV/H2O2 system (without KMnO4). It was found that within the same irradiation time, KMnO4/UV/H2O2 process is about 10% more effective for mineralization of AR73 dye solution.

Background: polychlorinated biphenyls (PCBs) are occupational and environmental pollutants and hazardous organic compounds that have created major environmental and occupational challenges. PCB compounds have different health effects in humans depending on sex, age, route of entry, intensity, and frequency of exposure. This study was conducted to determine the effect of microwave rays, hydrogen peroxide, Tio2, catalyst and ethanol on the composition of PCBs in order to reduce occupational exposure.Methods: This was an experimental study carried out in the laboratory of Tarbiat Modares University between May and September 2011. This experiment used a MW oven, Pyrex vessel reactor (250 ml volume), Pyrex tube connector and condensing system. A 900 W domestic MW oven with a fixed frequency of 2450 MHZ was used to provide MW irradiation. Ray powers of 540, 720 and 900 W were used. A hole was pierced in the top portion of the oven and the Pyrex vessel reactor was connected with the Pyrex tube connector. PH and temperature was continuously monitored. The experiments were performed in triplicates and the results are presented as mean concentrations. The PCBs were analyzed by GC-ECD. Then, data were analyzed by SPSS software version16, ANOVA with repeated measurements, and t-test, and P<0.05 was significant.Findings: The mean degradation of total PCBs in terms of microwave ray power of 540, 720 and 900 W was 84.25%, 88.81%, and 95.84% respectively. The mean degradation of total PCBs in terms of ratio of solvent to askarel oil of 1: 1, 2: 1 and 3: 1 was 53.82%, 79.06%, and 94.95% respectively. The mean degradation of total PCBs in terms of lack of usage of H2O2 and usage of 10% and 20% of H2O2was 70.9%, 84.65% and 88.91% respectively. The mean degradation of total PCBs in terms of lack of usage of Tio2 and usage of 0.05, 0.1, 0.15 and 0.2 g of Tio2 was 70.9%, 76.53%, 77.32%, 79.10%, and 80.19% respectively. The mean degradation of total PCBs in terms of lack of usage of H2O2/ Tio2 and the simultaneous usage of 10% of H2O2 and 0.05, 0.1, 0.15, and 0.2 g of Tio2 was 70.9%, 89.3%, 91.18%, 92.17%, and 93.16% respectively. The mean degradation of total PCBs in terms of lack of usage of H2O2/Tio2 and simultaneous usage of 20% of H2O2 and 0.05, 0.1, 0.15, and 0.2 g of Tio2 was 70.9, 93.95%, 94.95%, 95.84%, and 97.22% respectively.Conclusion: The results of these experiments showed that using microwave rays, H2O2 oxidant and Tio2 catalyst lead to an efficient degradation of PCBS only in the presence of ethanol. Increasing the concentration of ethanol should increase the generation rate of hydroxyl radical, and thus the oxidation and dechlorination of the PCBs. The degradation rate of PCBs increased with increasing of the concentration of H202 and amount of Tio2.

Background: Poly chlorinated biphenyls (PBCs) are the group of organic chemical materials that have a great chemical stability. These compounds are hazardous pollutants which pose various occupational and environmental problems. This study was conducted to determine the effect of microwave rays, hydrogen peroxide, Tio2 catalyst, and ethanol on the decomposition of PBCs.Materials and Methods: In this experimental study, a vessel reactor (250ml volume)that was connected with a tube connector to the condensor system was used. A microwave oven with a fixed frequency of 2450 MHZ was used to provide microwave irradiation and ray powers used at 540, 720 and 900w. pH and temperature of the samples were continuously monitored and the experiments were repeated three times. Askarel oils were analyzed by GC-ECD.Results: The mean of total PCBS degradation at 540, 720, and 900w was 83.88±1.63, 89.27±2.44, and 95.98±0.81%, respectively. The mean of total PCBS degradation in terms of ratio to solvent with oil transformer in 1:1, 2:1, and 3:1 was 53.8±3.26, 79.04±1.24, and 95.08±1.69%, respectively. The mean of total PCBS degradation in terms of not using H2o2/Tio2 and using H2O2 (20%) and 0.05, 0.1, 0.15, and 0.2 g of Tio2 concurrently was 71.47±0.81, 87.9±2.16, 89.48±1.69, 91.7±1.24, and 93.07±3.09 %, respectively.Conclusion: Using microwave irradiation in the presence of H2O2 oxidant and Tio2 catalyst leads to the reduction of PCBS.

UV/H2O2, UV/H2O2/Fe (II) and UV/H2O2/Fe (III) processes are very effective in removing pollutants from wastewater and can be used for treatment of dyestuff units wastewaters. In this study, Rhodamine B was used as a typical organic dye. Rhodamine B has found wide applications in wax, leather, and paper industries. The results from this study showed that this dye was degradable in the presence of hydrogen peroxide under UV-C irradiation (30W mercury light) and Photo-Fenton process. The dye was resistant to UV irradiation. In the absence of UV irradiation, the decolorization efficiency was very negligible in the presence of hydrogen. The effects of different system variables such as initial dye concentration, duration of UV irradiation, and initial hydrogen peroxide concentration were investigated in the UV/H2O2 process. Investigation of the kinetics of the UV/H2O2 process showed that the semi-log plot of the dye concentration versus time was linear, suggesting a first order reaction. It was found that Rhodamine B decolorization efficiencies in the UV/H2O2/Fe (II) and UV/H2O2/Fe (III) processes were higher than that in the UV/H2O2 process. Furthermore, a solution containing 20 ppm of Rhodamine B was decolorized in the presence 18mM of H2O2 under UV irradiation for 15 minutes. It was also found that addition of 0.1 mM Fe(II) or Fe(III) to the solution containing 20 ppm of the dye and 5mM H2O2under UV light illumination decreased removal time to 10 min.

One of the main carcinogenic pollutants occurring in in the wastewater of some chemical industries is ortho toluidine (OT). In this project the removal of OT was investigated by UV/H2O2 and UV/US/H2O2 processes in batch recirculated reactors. The effect of three main factors including initial concentration of OT, H2O2, and pH was investigated as an influencing variables on UV/H2O2 process at 25°C and the optimum conditions were obtained as 40 mM of hydrogen peroxide, 50 mg/l of OT, and pH at 9. The rate constant of the reaction was increased by addition of ultrasonic waves to UV/H2O2 process. The UV/US/H2O2 process was investigated at 25, 30, and 35 °C and the maximum efficiency was found at 35 °C. Through kinetic studies, the psudo first order rate constants were obtained as 0.0442 min-1 (at optimum conditions) and 0.0593 min-1 in UV/H2O2 and UV/US/H2O2 processes, respectively. The removal of total organic carbon (TOC) was obtained as 38 and 52.5% in UV/H2O2 and UV/US/H2O2 processes. Also, the effect of volume and volumetric flowrate of the circulated wastewater and kinetic reactions were explored so that the efficiency of the processes was reduced by increasing in the volume of the wastewater and it was decreased by increasing in the volumetric flowrate of circulated waste water.

Background & Aims of the Study: Organic dyes with a complex structure are often toxic, carcinogenic, mutagenic, non-biodegradation and stable in the environment and if released to the environment without treatment can endanger the environment and human health. The aim of this study was to evaluate the performance of H2O2 and H2O2/Fe0 Iron in removal of dye Acid Red 18 from aqueous solutions.Materials & Methods: This study was conducted at the laboratory scale. In this study, the removal efficiency of Acid Red 18 from a synthetic solution by H2O2 and H2O2/Fe0 was investigated. As well as Effect of solution pH, dye concentration, Concentration of Nanoscale Zero-Valent Iron, H2O2 and contact time in decolorization efficiency was investigated.Results: Results show that in pH=3, Contact time of 80 minutes, dye concentration of 50 mg/l and Concentration of Nanoscale Zero-Valent Iron of 2 g/l and H2O2 concentration equal to 200 mmol/l, the removal efficiency was about 98%.Conclusions: According to the results of experiments, H2O2/Fe0 has high efficiency in removal of Acid Red 18 from aqueous solution.