Description of environmental parameters of the mos

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Description of environmental parameters of toxic chemicals

I. solubility of compounds in water (s)

natural realization of advanced battery materials. The supporting environment contains rich water resources and good water circulation. With good solubility, water can almost dissolve all solid, liquid and gaseous substances. There are few substances that are completely insoluble in water in nature, but the amount of dissolution is different. Therefore, in the process of environmental monitoring and environmental effect research of chemicals, especially toxic chemicals, their solubility in water may be one of the most important properties that affect the migration and transformation of chemicals in various environmental elements, such as atmosphere, water body, aquatic organisms and sediments (sediment). Most inorganic compounds are ionic in water, so their solubility is relatively large. Many organic compounds are non-ionic, but their solubility in water is relatively small. The solubility of non-ionic compounds mainly depends on their polarity. Non polar or weak polar compounds are easy to dissolve in non-polar or weak polar solvents. On the contrary, strong polar compounds are easy to dissolve in polar solvents, and water is one of the strong polar solvents. Therefore, nonpolar compounds such as methyl chloride and carbon tetrachloride are rarely dissolved in water. Aromatic compounds are weakly polar and have little solubility in water. With the increase of substituents on aromatic rings (such as PAH), their solubility in water is getting smaller and smaller. On the contrary, strongly polar alcohols, organic acids and compounds with Oh, SH, NH and groups have considerable solvability in water

II. Octanol water partition coefficient (kow)

kow is the ratio of the equilibrium concentration of organic compounds in water and n-octanol. According to the research, the distribution of octanol to organic matter is very similar to that of organic matter in soil, so when the distribution ratio of compound in octanol and water is kow, Beijing opera can calculate Koc smoothly. Generally, the solubility of organic compounds in water can often be reflected by their affinity for non-polar organic phases. Lipophilic organic compounds have a high partition coefficient in octanol water system, and the concentration in organic phase can reach 101~106 times that in aqueous phase. For example, common environmental pollutants such as PAH, PCBs and phthalates. The partition coefficient in octanol water system is a dimensionless value. Kow value is a very useful index to describe the distribution of an organic compound between water and sediment, organic matter or aquatic organism fat. The greater the value of partition coefficient, the greater the solubility of organic matter in organic phase, that is, the smaller the solubility in water

III. sediment water partition coefficient (Koc)

koc is the equilibrium concentration relationship of compounds in water and sediment soil phases. It is also the ratio of the amount of compounds adsorbed on sediment per unit weight divided by the amount of the same compound dissolved in environmental water per unit volume. Koc is a quantitative parameter indicating the concentration distribution of a compound in solid-liquid two phases. Through this parameter, the concentration distribution of a compound in sediment or soil can be predicted according to its concentration in water. Therefore, this parameter plays a very important role in the research of environmental science


kow value can be used to predict the behavior of a compound in the water environment, and the distribution coefficient can be used to predict the distribution of a compound in the environment. In fact, it is based on various molecular reaction forces distributed among water, sediment and organisms, because this reaction force is very similar to octanol water system

IV. vapor pressure (PV)

the vapor pressure of a compound expresses the degree of migration of the compound from the environmental water phase to the atmosphere. Generally speaking, compounds with high vapor pressure, low solubility and high activity coefficient are the most likely to volatilize, and the speed of volatilization sometimes depends on wind, water flow and temperature. Generally, low molecular weight compounds such as alkanes, monocyclic aromatic hydrocarbons and some organic nitrides have high vapor pressure and low water solubility. Some data also use the Henry constant HC to express the volatility of compounds (calculation unit: torr/mol). The closed-loop control is really realized. At the bottom of the system, HC represents the relative equilibrium concentration of the compound in air and water under standard temperature and pressure, and the ratio of vapor pressure to the solubility of the compound in water, indicating the volatility of the compound

v. biotransformation and degradation coefficient (KB)

biotransformation refers to the catalytic conversion process of compounds by biological enzymes. The possibility of biotransformation depends on the stability and toxicity of compounds, the existence of domesticated microorganisms and environmental factors (including pH value, temperature, amount of dissolved oxygen and available nitrogen). The degree of difficulty of biodegradation is usually called biodegradability. Biochemical proportion is often used to express the important index of treating toxic organic wastewater by biochemical method, and the biochemical process is a long process. The second-order reaction rate constant of biotransformation rate depends on the concentration of compounds and the amount of microorganisms

VI. bioconcentration factor (BCF)

bcf is the ratio of the concentration of compounds in biological tissue (dry weight) to the concentration dissolved in water. It can also be considered as the ratio of the absorption rate of compounds by organisms to the purification rate of compounds in organisms. The bioconcentration coefficient is an important indicator to describe the accumulation trend of chemicals in organisms. For example, according to IRPTC data, the enrichment coefficient of fish living in water with a PCB content of 1 g/l after 28 days is 37000 times the content of water, and the structural capacity 1 promotes the healthy development of e-commerce, industrial interconnection and interconnected finance, which is generally 1000 lb. if it is put back into clean water without PCB, the purification rate after 84 days is 61%. The absorption and accumulation of chemicals by aquatic organisms in water bodies are often accomplished through the distribution between water and fat

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