جستجوی مقالات مرتبط با کلیدواژه "آب" در نشریات گروه "شیمی"

Water is essential for human life and public health because up to 60% of the adult human body is made up of water. However, much of the world's population does not have access to sufficient and safe drinking water. The most common waterborne diseases are diarrheal diseases such as cholera, typhoid, paratyphoid, salmonella, giardiasis and cryptosporidiosis. Also, health risks may be caused by chemical and radioactive compounds of water. In fact, some chemicals dissolved in water may be essential substances for food consumption, and some may be harmful in higher than permissible concentrations. These compounds can include various metals, synthetic organic materials and essential elements such as fluoride, iodine and selenium. This is why drinking water quality is a global health concern, especially in developing countries. This review study was conducted with the aim of reviewing the current and past researches in the field of waterborne diseases and most importantly the effective factors in transmitted diseases as well as methods of prevention and finally identifying potential gaps in studies related to waterborne diseases. The review of the literature showed that unsafe water and lack of access to basic sanitation facilities are the main causes of the outbreak of water-borne diseases. Improving drinking water conditions, proper sanitary facilities, especially sanitary disposal of feces, leads to the reduction of water-borne diseases.

A manganese (II) catalyst loaded onto the SBA-15 support containing a bidentate N-O Schiff-base ligand was prepared and it was applied in the synthesis of quinoxaline, pyrazine and pyrido pyrazine heterocycles. The nanocatalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectroscopy and nitrogen adsorption/desorption isotherm. The results from X-ray diffraction and transmission electron microscopy show that the textile properties of SBA-15 are preserved after grafting of manganese (II) complex. A variety of aforementioned heterocycles were synthesized easily and with good yields under green conditions in aqueous medium via ring condensation of 1,2-diamines and 1,2-diketones in the presence of  catalytic amounts of catalyst.

The green and efficient three-component reaction between aromatic and heteroaromatic aldehydes, β-ketoesters (ethyl acetoacetate and ethyl benzoylacetate) and hydroxylamine hydrochloride in water and under natural sunlight leads to the formation of various derivatives of 4-arylidene-isoxazole-5(4H)-ones. In this reaction, natural sunlight was used outdoors as a green, cheap, clean, available, safe and non-toxic source of energy. The reactions were carried out in Damghan under sunlight. In this synthetic method using sunlight, the heterocyclization reaction was performed with simple tools and without the use of special equipment. In this three-component reaction, 4-arylidene-isoxazole-5(4H)-ones were synthesized in a range of 17-40 minutes and with yields ranging from 89-97%. The advantages of this suitable and green method can be mentioned abundant sunlight or low-energy visible light as an energy source, no environmental pollution, very mild reaction conditions, simplicity of the reaction method, easy separation, no use of organic solvents and catalysts. Some compounds were tested for antibacterial activity using Staphylococcus aureus and Escherichia coli by disk diffusion method. Some synthesized compounds have good antibacterial activity. The antibacterial activity of synthesized heterocycles is higher against Escherichia coli.

Thermal pollution is a rapid change in temperature in a natural body of water. This pollution is often caused by the discharge of heated water from an industrial facility or other human activities into the water. Thermal pollution is one of the most widespread and important pollutions and depends on various factors such as soil erosion, deforestation, flowing water and natural factors. Among the effects of warming waters and thermal pollution can be a decrease in the amount of dissolved oxygen in water, disruption of natural systems and stress in aquatic life, damage to larvae and fish eggs in rivers, increase in disease in aquatic life or even the death of damaged organisms that They have limited tolerance towards it, bleaching of corals, migration of living organisms from their environment and other environmental changes. The main causes of thermal pollution are thermal or nuclear power plants, industrial effluents such as oil refineries, pulp and paper factories, chemical factories, steel and smelting factories, sewage effluents and biochemical activities. Heat pollution is a global phenomenon that has become a major concern of people around the world because of its severe long-term consequences. However, heat pollution is a real and persistent problem in modern industrial society.

The purpose of this research is to investigate the relationship between the third chapter of 10th grade chemistry and science textbooks of the junior high school. This research is of a descriptive-content analysis type and its statistical population is science textbooks and the third chapter of 10th grade chemistry, which was published in 1401. In this research, the aims and educational content of the mentioned textbooks have been investigated and compared and analyzed. The results of the analysis will help 10th grade chemistry teachers to learn about the scientific background of students in connection with the third chapter of 10th grade chemistry titled "Water, the song of life" so that they can improve the learning process of the students accordingly. Also, methods are provided to improve the learning process of students. In this study, it was found that there is a correlation between the science textbooks of the first year of the junior high school and the third chapter of 10th grade chemistry, which is necessary to know for teaching the 10th grade chemistry. Also, if a student has not learned the concepts of the textbook of science well, he may have misunderstandings to analyzing chemistry topics and have incomplete learning.

In this study, aluminum and boron doped graphene has been used as adsorbent and catalyst to decompose water molecules in order to hydrogen production. The study has been done by density function theory and m062x/6-311G method using Gaussian 09 package. The interaction of two water molecules on mentioned nano sheets have been investigated, respectively. In order, the reaction pathway of the only spontaneous adsorbed water molecule decomposition has been studied. Also, the potential energy surfaces of water molecule and mentioned nano sheets have been surveyed. The water molecule adsorption was chemically and spontaneously for both nano sheets. The decomposition process of water molecule has been done in two steps by dissociation of two oxygen-hydrogen bond. The change of enthalpy, activation energy and change of Gibbs free energy for pathway of water decomposition has been calculated. The results shown that the number and position of boron atoms effect on the spontaneity of adsorption and decomposition process for water molecule, indirectly.

swimming pools As a recreational center and direct relevance of different human groups as a potential source of pollution, swimming pools (swimming pools)is a potential source of pollution, which in sound of lack of attention to health issues can be a source of transmission and outbreaks of bacterial, fungal and parasitic diseases. so the present study was carried out to study the pools of pool.

in this descriptive study of the active site of the saqqez city of 34 visitors and 34 sampling cases for کلرباقیمانده assay and pH of 15 and samples of microbial sampling were done randomly and with suitable culture medium to be tested on the samples. The amount of the remaining chlorine and the amount of water on the water were measured and recorded in a standard manner. the data were investigated using central inclination indices and person correlation coefficient.

all the items of کدورت were undesirable, and about 50 percent of the cases were favorable. On average, an average of 80 % of the safety points and swimmers average 60 % of their health points.

pay attention to disinfection, water control, turbidity and pH reduce contamination microbial is effective, but disinfection is the only way of prevention of the landfill is not. Health behaviors, including showers of soap before entering the pool, are likely to be effective from the pool of Bashawy and the basic sanitation of the pool environment in Decrease pollutions.

providing safe drinking water for human society is of vital importance. the purpose of this study was to determine the importance and performance of chlorination in the distribution network of drinking water in the level of utility of microbial quality and chlorination status in Tabriz and its surrounding villages.

this descriptive-analytical study, environmental and library study, and the necessary information were prepared using data collected from other articles and Tabriz water and Wastewater Company. after analysis, it was analysed.

the results of the study showed that the chlorination method used in the villages is a type of liquid chlorination or pottery method. chlorine is injected into the liquid by pressure. the chlorine type is used as a powder or crystalline perflorester. 95.5% of the rural population of the East Azarbaijan province benefited from water utilization. every day, various stages, such as chlorination, chlorination, sampling and testing, are carried out at the 7th level laboratory of the province, so that people will enjoy a healthy blue dream. The health center also monitors the company's performance and controls the supply of water and water entering and extinguishing, so that the water supplied is free from any pollution. of the 127 villages of over 20 households without plumbing, plumbing 95 villages are being run in rural or rural communities. about 400 villages, 20 percent of the province's population, have water facilities but are not covered by this company.

due to the fact that in recent years, the important chlorination of rural water reservoirs has been delegated to rural water and Sewage company, and perhaps the juicy juices of this company have not understood the necessity of the problem, in many villages of the country that covered this companies should be given more attention to chlorination, as well as villages that are not covered by this company, are virtually uncertain and do not assume the responsibility of chlorination, which requires that decisions be taken as soon as possible.

Providing safe drinking water for human society is of vital importance. The purpose of this study was to determine the importance and performance of chlorination in the distribution network of drinking water in the level of utility of microbial quality and chlorination status in Tabriz and its surrounding villages.
This descriptive-analytical study, environmental and library study, and the necessary information were prepared using data collected from other articles and Tabriz Water and Wastewater Company. After analysis, it was analysed. The results of the study showed that the chlorination method used in the villages is a type of liquid chlorination or pottery method. Chlorine is injected into the liquid by pressure. The chlorine type is used as a powder or crystalline perflorester. 95.5% of the rural population of the East Azarbaijan province benefited from water utilization. Every day, various stages, such as chlorination, chlorination, sampling and testing, are carried out at the 7th level laboratory of the province, so that people will enjoy a healthy blue dream. The health center also monitors the company's performance and controls the supply of water and water entering and extinguishing, so that the water supplied is free from any pollution. Of the 127 villages of over 20 households without plumbing, plumbing 95 villages are being run in rural or rural communities. About 400 villages, 20 percent of the province's population, have water facilities but are not covered by this company. Due to the fact that in recent years, the important chlorination of rural water reservoirs has been delegated to Rural Water and Sewage Company, and perhaps the juicy juices of this company have not understood the necessity of the problem, in many villages of the country that covered this Companies should be given more attention to chlorination, as well as villages that are not covered by this company, are virtually uncertain and do not assume the responsibility of chlorination, which requires that decisions be taken as soon as possible.

For long last time water has been considered as an inimical contaminant to pure Ionic Liquids (ILs) because the presence of a low amount of water drastically changes the properties of ILs. But, water is now a very important partner for ILs because mixing the IL-water is an easy strategy to control and access to unique properties of both of them. Applying this type of binary mixtures also provides a broad application in different fields. In this work, molecular dynamics simulations were used to study the details of the dynamical behavior of the binary mixture of 1-butyl-3-methylimidazolium nitrate ([bmim][NO3]) and water in different molar fractions in order to discover the influence of water addition on the properties of the ionic liquid. The dynamics of systems studied by the computing of mean-square displacement and self-diffusion coefficients of species. The presence of water causes significant enhancement of ionic self-diffusion coefficients. In neat IL and the concentrated IL solution, self-diffusion of the cation is higher than that of the anion; however, in the binary mixtures with the water molar fraction greater than or equal to 0.25, the anions diffuse faster than the cations.

Continuous wavelet transform together with zero-crossing technique was applied to the overlapping spectra of Fe(III) and Al(III) complexes. It was found that, at 5. 0 × 10-5 mol L-1 of DPBDO, pH 8.0 and 10 minute after mixing the complexation reactions were completed. The results showed that Fe(III and Al(III) could be determined simultaneously in the range of 0.5–7.0 mg L_1 and 0.5-6.5 mg L-1. Mexican and Symlet-4 from the family of continuous wavelet transforms were selected and applied under the optimal conditions for multi-component determinations. The method was tested by analyzing various synthetic birnary mixtures of analytes in different water and foodstuff samples. The obtained results of samples with proposed method have been compared with those predicted by flame atomic absorption spectrophotometry (FAAS).

Water shortages in many countries in arid and semiarid a major concern and a growing need for numerous. However, most organic material in the sewage treatment plant, but the number of materials using common processes currently available treatment are not or little plants are growing out of this country must, with proper management, use and sourcing water rather than replace conventional sources, to overcome this crisis. In this regard, recent research into complicated molecules resistant to simpler molecules led to the introduction of new technologies as advanced oxidation processes (AOPs), respectively. The process for industrial effluents such as wastewater chemical factories, refineries, rubber, paper making industry and many other industries have been successfully employed. The main objective of wastewater treatment, wastewater is suitable for discharge into the receiving environment. So that the waste water treatment standards have been met and losses to the environment are not receptive to enter.

There are chemical compounds¡ even in small amounts if it is more than the amount prescribed in international standards¡ it will be poisoning people and all creatures. Nitrate compounds are pollutant of groundwater resources in recent years due to agricultural expansion and human activities are increasing their average. This cross-sectional study is to evaluate and compare with the standard¡ the concentration of some chemical parameters of water resources in a number of villages Nazloo Urmia city. Concentration of ions of nitrite and nitrate in any of the samples higher than standard values but also the concentration of ammonium nitrate in summer¡ the intensity of agricultural operations is increasing and is likely to be due to excessive use of chemical fertilizers and nitrate leaching of soil caused by irrigation is repeated.

Reuse of treated wastewater instead of fresh water for agricultural irrigation is far cheaper than the desalination of sea water is salty. The problem in Iran is that in many places where people are facing a shortage of fresh water can be used in the consumption of fresh water for agricultural drought stress save. Most of the organic matter in the wastewater can be treated, but the number of materials using common processes, we are not treated or treated are small, is growing. Pollutants such as azo dyes, the largest group of coloring matter in the form of textile industry, in addition to the material in various processes such as hydrolysis, oxidation and other chemical reactions to become one of the aromatic amines are carcinogenic agents. Five advanced oxidation method used for production of OH radicals, ultraviolet light use of energy and consisting of ozone/ radiation UV UV)/O3), hydrogen peroxide and radiation UV (H2O2/UV), photo-Fenton/systems like Fenton, ozone and hydrogen peroxide and radiation, UV (UV/H2O2/O3) and photocatalytic oxidation (TiO2/UV), respectively. Clear and effective methods of electrochemical techniques, which directly (Anodic oxidation), or indirectly through Fenton's reagent (electronfenton), hydroxyl radicals to produce the product. Each of these processes has advantages and disadvantages which are set according to the type and nature of the contamination, we can chose the best mechanism to eliminate. The results have shown that applying a combination of two or more methods of advanced oxidation processes for contaminant removal efficiency than by using any of them (alone).

The present study was based on an economical، eco-friendly، and efficient method for the green synthesis of silver nanoparticles in plant extract. This synthesis shows attractive characteristics such as; the use of inexpensive and available plant extracts، non-toxicity، eco-friendly biological materials، and operational simplicity. The extracts incubated with AgNO3 solution showed gradual change in color of the extracts to yellowish brown، with intensity increasing during the period of incubation. Characterization of synthesized silver nanoparticles was made by UV–Visible absorption spectroscopy، Transmission Electron Microscope (TEM)، and X-Ray Diffraction (XRD) spectroscopy. The silver nanoparticles synthesized were generally found to be spherical in shape with variable size ranging from 5 to 30 nm، as evident by Transmission Electron Microscopy (TEM). The biosynthesized silver nanoparticles (AgNPs) showed good antibacterial activity against clinical strains of two bacteria (E. coli، and S. aureus).

Solar energy is a renewable and crucial form of energy for many natural processes on the Earth. The application of solar energy to provide hot water، heating and cooling of residential area has been considered in Iran in recent decades. In this paper، simulation and techno-economic investigation of a single-effect water-lithium bromide solar absorption chiller in Isfahan climate is presented. A single effect absorption chiller with a capacity of 19 kW (5 tons of refrigeration)، providing cooling for a 200 m2 residential area is proposed. Maximum energy required for cooling such a building is 17 kW، which occurs in July. The daily occupancy schedule is considered between 7a. m. and 7p. m. and the cooling schedule is considered between May 1st to September 30th. At low solar radiation، the system operates with the energy stored in the storage tank and with an auxiliary heater. Economic results show that the evacuated tube collector with total absorber area of 30m2 is the best option in this plant. This system in comparison to a similar capacity direct-fired absorption chiller will save 895 m3 of natural gas per year.

In recent study، physical properties of binary solution of soft water-sodium chloride and hard water-sodium chloride are investigated. Among the physical properties، dencity، viscosity، refractive index and electrical conductivity of sodium chloride solutions (10-20% w/w) have been studied. The results showed that there is a direct linear relation in the range of 10%-20% w/w solution. Also the results showed that these differences are bigger in hard water.