دوماهنامه مهندسی شیمی ایران
پیاپی 119 (بهمن و اسفند 1400)

Drinking water supply in the household consumption sector has always been emphasized due to its direct impact on human health. One of the common methods to reduce soluble solid pollutants that is used in many parts of the country, is the use of household water purifiers. Despite the usefulness of filters in these devices which need to be replaced at regular intervals, they waste 70-80% of piped water by transferring it to sewage due to their mechanism of action based on reverse osmosis. In contrast, there are solar distillation systems that produce distilled water using solar energy. The use of solar distillation systems has a high potential to provide quality drinking water for sparsely populated areas and hot weather due to its prevention of water loss, easy use and long life. The purpose of this research was to Techno-economic study the use of household water purifiers and solar distillation system to achieve quality and potable water in homes, as well as to analyze the sensitivity of water cost, operating cost and increase the initial fixed cost. The results show that despite the higher initial cost of the solar distillation system, the cost of using these systems in the long run is more economical, and the water loss for these systems can be ignored.

The use of pipelines is one of the most important methods of gas transmission. Leakage in gas transmission lines causes financial and life-threatening damages. For this reason, it is very valuable to obtain information such as maximum safe radius of fire, explosion and leakage of materials. This information can play an important role in dealing with accidents in emergencies. In this study, safe privacy for 42-inch gas pipeline was studied using PHAST software version 7.11. The highest amount of radiation is related to the horizontal state and the lowest amount of radiation is related to the vertical state. The vertical direction has the lowest radiation distance from the propagation source, while the horizontal direction at an angle of 45 degrees shows the highest radiation distance from the propagation source. Simulation results showed the lowest radiation outcome for pressurized environments and the most dangerous radiation for hazardous areas. For example, if the ratio of leakage diameter to hole diameter is 0.25 and leakage mode is horizontal. The safety privacy caused by fire for hazardous areas, enclosed environments and pressure environments is 850, 1070 and 1360 meters, respectively.

In this study, the physico-chemical and antimicrobial properties of alcoholic extract of propolis were evaluated. Physico-chemical properties of propolis samples including moisture content, color, turbidity and antioxidant activity and chemical composition were measured. The antimicrobial properties of the extract were also investigated. The antioxidant property of propolis was 92.75%. In chemical analysis of the extract, 61 bioactive compounds were identified. Chalcone is the most abundant substance in the extract. Antimicrobial tests showed that the minimum inhibitory concentrations of propolis extract against Salmonella enteritidis, Staphylococcus aureus and Escherichia coli and Candida albicans was 40, 10, 40 and 5 (μg/ml) and the minimum bactericidal concentration of the provided extract against mentioned microorganisms was 40, 10, 80 and 5 (μg/ml), respectively. Findings indicate that propolis is an antimicrobial compound with high antioxidant properties and can be used in food and pharmaceutical industries.

In this research, a hybrid water falling film plasma reactor dielectric barrier discharge with synthesized zeolite has been used to remove the tetracycline from aqueaus solution. Three types of zeolites have been synthesized by the hydrothermal method based on the ratio of sodium dioxide to silicate dioxide 1, 2 and 3. Infrared spectroscopy (FT-IR),X-ray diffraction (XRD), electron microscopy (SEM), specific surface area, X-ray energy diffraction (EDX), and dot-mapping have been performed on these synthesized zeolites. The tetracycline removal efficiency was about 81% at 60 min in a hybrid reactor designed for synthesized zeolite with a ratio of sodium oxide to silica 1. It was found that this removal percentage is 55% higher than the only plasma system. The percentage of COD removal in hybrid system was about 71% based on the tests performed. Based on experiments related to the effect of active species in the tetracycline removal as a radical trapping experiment, the hydroxyl radical was 12% effective than the superoxide radical. The proposed mechanism is discussed for performingan advanced oxidation reaction to remove tetracycline.

Pinch Technology is one of the effective and practical methods for energy consumption economization. In this research, Pinch Technology has been used for energy consumption optimization in the isomerization unit. As a result, heat pumps have been used for energy consumption optimization in this unit in which the amount of energy consumption in heating and cooling utilities has decreased from 128.61 GJ/h and 143.9 GJ/h to 127.8 GJ/h and 152.0 GJ/h, respectively. This energy-saving leads to a decrease in the amount of energy consumption and an increase in the efficiency of the unit. Heat pumps have been additionally applied to study the heat exchangers with the highest amount of cross-pinchheat transfer. This study resulted in a significant decrease in the cross-pinch heat transfer, from 22.47 GJ/h to 19.90 GJ/h (11.3% decline).

High concentrations of algae cause the sea surface to turn red and there is a possibility of discoloration to yellow, green and brown, which has eventually led to the death of many marine aquatic animals. The extent of the red tide has polluted the sea surface, making it impossible to accurately predict this phenomenon. These algae are phytoplankton with a concentration of about 2000 per liter. With the growth and multiplication of these phytoplankton in the Persian Gulf, the turbidity of seawater has increased sharply and desalination units in the region have problems such as rapid clogging of filters and reduced freshwater production. In this research, using GPS-X 8.0 simulator software, the effect of red tide phenomenon on the conventional reverse osmosis unit pre-treatment process and also the optimization of the reverse osmosis unit pre-treatment process with two methods DAF+DMF and UF+DMF are investigated. it placed. The results showed that the removal rate of TOC variable in the conventional method was 44% and in the two optimized methods mentioned was 95% and 76%, respectively, and the turbidity removal rate was 18% in the conventional method and in the two optimized methods mentioned was 94% and 78%, respectively. Also, with the economic evaluation, the cost of implementing the DAF+DMF method was estimated to be approximately 27% lower than the cost of implementing the UF+DMF method. The results show that the DAF+DMF method in the pretreatment process, technically and economically has the best performance when the red tide occurs, which is suggested to be considered in the design of seawater desalination units.