m. kermani

2,4 dinitrophenol is observed in sewage produced from chemical and petrochemical industries. Contamination of drinking water with these pollutants causes toxicity, health problems and change in taste and odor. The present study was developed to evaluate the efficiency of removal 2,4-DNP through dried sludge adsorbent and modified calcium chloride sludge adsorbent.

At first, sludge was dried at temperature of 60 °C. Next, CaCl2 was used to improve adsorption capacity. The removal efficiency of 2,4 dinitrophenol were determined by HPLC at wavelength of 360 nm. The effects of influencing factors including pH, initial pollutant concentration, contact time, and adsorbent dose were examined.                            

The optimum pH of adsorption for both adsorbents was found to be 7. The optimum concentration of 2,4-DNP was 10 ppm. The results obtained from the present research showed that the removal of the contaminant using dried and modified sludge sorbent was increased from 72.6% to 86% at a dosage of 1.5 g. The adsorption kinetics were fitted with the pseudo second order kinetics model for both adsorbents. The isotherm data also showed that the adsorption of this pollutant on both adsorbents is fitted with the Freundlich model.

Results obtained from the present study indicated that the efficiency of the modified sludge ash is more than the non-modified sludge in 2,4 dinitrophenol removal. This can reduce adsorbent consumption in industrial treatment plants.

The activities of various industries produce a wide range of pollutants and toxic compounds. One of these compounds is the catechol, a cyclic organic compound with high toxicity and resistant to degradation. Therefore, the purpose of this study was to investigate efficiency of powder activated carbon magnetized with Fe3O4 nanoparticles in the removal of catechol from aqueous solutions by response surface methodology. The co-precipitation method was used to synthesize magnetic powder activated carbon and its properties were analyzed by SEM and XRD analysis. Then, the effect of the parameters such as pH, contact time, absorbent dose, initial concentration of catechol and temperature on the efficiency of adsorption process were investigated using a response surface methodology (Box–Behnken). The residual concentration of catechol was measured by HPLC at 275 nm. The results showed that the maximum efficiency of the adsorption process was obtained at concentration of 20 mg/L, pH=3, contact time 90 minutes, at 25 °C and absorbent dose of 1.5 g/L. The study of isotherm and kinetics showed that the experimental data of the catechol adsorption process correlated with the Langmuir and pseudo-second order models, respectively. Thermodynamic study of the reaction also expresses the Exothermic and Spontaneous process. The results showed that the adsorption process using powder activated carbon magnetized with Fe3O4 nanoparticles at acidic pH had better efficiency. As a result, the studied process as an effective, rapid and inexpensive method for removal of catechol from aqueous solutions is proposed. Due to its short reaction time, it is economically affordable process.

Catechol is one of the most common compounds in the industrial wastewater including oil and petrochemical, pesticides industries. The drainage of these industries leads to aquatic organisms poisoning and adverse effects on the environment. Therefore, this study aimed to evaluate the effects of catechol toxicity changes before and after the catalytic ozonation process by Daphnia Magna bioassay. This study is an applied research in which the toxicity of catechol and its products from degradation was evaluated by bioassay method during the Catalytic ozonation process. First stock solution was prepared at concentration of 250 mg/l followed by preparation of 10 samples that each contained 0 (control), 0.5, 1, 3, 6, 12, 25, 50, 75 and 100% of volume of primary solution. Initial samples were prepared from reactor effluent in the same volume. Based on the standard method, 10 Daphnia infants were added to prepared samples. Samples were evaluated after 24, 48, 72 and 96 hours. Finally, lethal concentration (LC50) and toxic units (TU) were calculated using probit analysis. According to the results, LC50 (24 hours) of raw effluent with an initial concentration of 250 mg / L of catechol increased from 13.30 ml/100 ml to 33.9 ml/100 ml after 60 minutes treatment. Consequently, the toxicity unit decreased from 7.51 TU to 0.9 TU which means that the toxicity dropped by 88%. Finally, the toxicity of treated effluent decreased during catalytic ozonation process to degradation of catechol. Bioassay is a simple and effective way to evaluate the toxicity potential of Catechol to discharge it to surface water. Based on the bioassay by Daphnia Magna, Catalytic ozonation process is able to reduce the toxicity of catechol by degradation this compound and breaking into other products.

Basic and reactive dyes such as basic violet16 and Reactive Red 120 have most common in different industries such as textile, leather and food industry. The degradation of basic violet and Reactive Red 120 by means of UV/H2O2 processes was investigated in the current study.

photolysis process was accomplished in a laboratory-scale batch photoreactor equipped with an 55 W immersed-type low-pressure mercury vapor lamp(UVC) with emphasis on the effect of various parameters on decolouration and degradation efficiency.

The results showed that radiation of UV alone cannot remove dyes completely and needs to accompany with UV/H2O2 process for getting best results. According to the obtained results, the removal efficiency increased with increasing H2O2concentration until especial concentration of H2O2and decreasing the initial dye concentration. Mean while, the electrical energy (EE/O) for decolorization of solution was calculated.Concclusion: It is concluded that the application of UV/H2O2 process for degradation of basic violet 16 and reactive red 120 was suitable and have a high removal efficiency.

In recent years, because of excessive population growth, increasing of vehicles and developing of the industries, Tehran has been encountered with serious environmental crisis, such as air pollution. So, for setting the control programs, air pollution monitoring and determination of Tehran air quality are necessary

In the present study, Tehran air quality index (AQI) was calculated based on the five criteria pollutants levels (O levels in 1387 and with regarding to the national air quality standards for each pollutant categorized as good, moderate, unhealthy for sensitive groups, unhealthy and very unhealthy.

The results of this research showed that in 2008-2009, with attention to United State environmental protection agency standards, in 43 days, air quality index was calculated lower than 100 and in the other 323 days, air quality index was higher than 100, that unhealthy for sensitive groups, very unhealthy and unhealthy was 40%, 27% and 21%, respectively. Also, in the summer, ozone and in the winter, carbon monoxide was determined as the pollutant responsible for the highest index value that is called the ''critical'' pollutant. The most polluted months with the average index of 204 and 214 were occurred in Tir (22 June to22 July) and Mordad (23 July to 22 August), respectively.

comparison of the results of this study with others can be found that Tehran air quality did not improved and is in the very serious situation with regarding to public health, especially for sensitive groups. 3, PM10, SO2, NO2 and CO) through linear interpolation based on these