Background: Synthetic dyes have several harmful effects on human health as well as aquatic life. In this study, activated carbon (AV-AC), based on Aloe vera leaf shells, was used as a novel agricultural adsorbent, one that is low-cost and available for the removal of Congo red (CR) as a carcinogenic dye from aqueous solutions. Methods: In the batch system, the influence of different parameters like contact time, pH, adsorbent dosage, and initial CR concentration were examined on the dye removal from liquid medium. The experimental data were fitted by pseudo-first-order and pseudo-second-order kinetics, and also Langmuir and Freundlich isotherms models. Results: The optimum contact time and pH for the uptake of CR were obtained at 20 minutes and acidic pH of 2. The maximum uptake capacity of CR dye by AV-AC was 1850 mg/g. The results showed that the experimental data were well-fitted by the pseudo-second-order kinetic model (R 2 > 0.99) and Freundlich isotherm model (R 2 > 0.99). Conclusion: According to the results of our study, the AV-AC is a low-cost, non-toxic, and effective adsorbent for the uptake of CR dye from aqueous media.

Background: Modeling the dispersion of pollutants from factory stacks addresses the problem of matching emissions of a cement plant with the capacity of the environment to avoid affecting the environment and society. The main objective of this study was to simulate the dispersion of carbon monoxide (CO) from the main stack of a cement plant in Doroud, Iran using SCREEN3 software developed by the US Environmental Protection Agency (US EPA). Methods: Four samplings were conducted to measure the concentration of CO in the three-stack flow of a cement factory. The input parameters were those affecting gas dispersion and included CO rate, meteorological parameters, factors associated with the stack, and various factors related to the receptor. All factors were incorporated in the model, and dispersion was modeled by SCREEN3. Results: Southwesterly winds have been dominant in the past 5 years. According to the results of this study, the highest and the lowest CO levels were estimated by the model in spring and autumn as having maximum amounts of 842.06 and 88.31 µg/m 3 , respectively, within distances of 526 and 960 m from the cement plant, respectively, at a downwind southwesterly direction from the plant. Conclusion: Although the maximum predicted CO levels in each of the four seasons were lower than the NAAQS criteria, the simulation results can be used as a base for reducing CO emissions to prevent the potentially significant health and environmental impacts imposed by long-term contact to such emissions.

Introduction: Desirable lighting is of the main factors in educational spaces. It is clear that schools with inadequate lighting cause great musculoskeletal injuries, vision problems, neurological and learning problems in students. Therefore, this study aimed to measure the lighting intensity of elementary schools in Ahvaz city and to compare it with the standard values in 2017. Methods: This descriptive cross-sectional study was carried out among the elementary schools in the eastern area of Ahvaz. A number of classes and halls were selected from each school by cluster sampling method. Then, the intensity of general lighting was measured using a network method. The 1339 Tes brightness measuring instrument was used to measure the general and local illumination. Finally, data were analyzed by Excel software. Results: The results showed that the average brightness intensity was lower than the recommended standard in 75 percent of classes and 62.5 percent of  halls. In terms of lighting conditions, girls' schools were more undesirable compared with boys' schools. Moreover, measurement of localized lighting on boards and tables showed that only 12.5 percent of classrooms had a good condition. Conclusion: The inappropriate and faulty sources of lighting systems have led to a non-uniform distribution of lighting in schools. Therefore, in order to improve the level of students' health and learning, lighting systems should be corrected to achieve appropriate illumination in accordance with the standard values in schools.