Dry residue is one of the main criteria for determining the quality of water, which reveals the degree of its mineralization. To determine the type of water, an ion-salt residue is used.
Features of the remainder
The main ions, due to which it is possible to determine the dry residue, are: sulfates, chlorides, carbonates, nitrates, bicarbonates. There is a division into organic and mineral residues that differ in boiling points. A dry residue implies the presence of dissolved non-volatile solids in water. There is a special technique for calculating it.
Gravimetric calculation method
With its help, the determination of the dry residue in the test sample is carried out. To conduct such a study, it is necessary to filter the sample, to separate it from organic impurities.
Water is used in almost all branches of modern production. For example, in the cosmetic industry it is used as drinking water, as a raw material for the creation of semi-finished products, as a substance for washing industrial containers.
Organoleptic indicators of products manufactured at the enterprise are associated with water: stability, smell, taste, color. For example, the appearance and taste of syrups are directly related to the minerals contained in the water. If the dry residue contains sodium chloride, then the water acquires some salty taste.
Sanitary standards
There are certain standards that water must comply with. If the solids content does not satisfy them, then it cannot be used. There are special physicochemical laboratories that are equipped with special measuring instruments.
In them, the mass fraction of solids is determined according to GOST "Drinking water" 18164-72. They use water in production only after it has been fully monitored for compliance with all quality indicators.
If in the course of research non-conformities are revealed for any indicators, it is necessary to draw up a protocol on non-compliance, the necessary corrective measures are taken.
Methods for determination of solids
There are several methods to determine the dry residue. GOST allows the procedure with the addition of soda or using salt. Let's consider both options in more detail.
In the first case, the sample is evaporated using a water bath. First, the container that will be used for evaporation is dried until a constant weight is obtained. Next, filtered water is poured into the porcelain container. After the evaporation of the last sample is completed, the cup is dried in a thermostat to constant mass at temperature.
To determine the dry residue, a special formula is used. It binds together the mass of an empty container, with a dry residue, as well as the amount of water that was taken for research.
The use of this method leads to overestimated results. This situation is explained by increased hygroscopicity, as well as the hydrolysis of calcium and magnesium chloride, and the difficulty of transferring water by calcium and magnesium sulfates .
To eliminate this drawback, pure sodium carbonate is added to the test sample. In the process of adding calcium and magnesium chlorides, they transfer to anhydrous carbonates. To completely remove crystallization water, the resulting dry residue is dried at an elevated temperature until a constant mass is obtained in a thermostat.
Soda solution technique
This option involves pre-filtering water using a paper filter. After drying the sample until a constant weight is obtained, the cup must be placed in a water bath. Here, evaporation of water samples taken for analysis is carried out. As soon as the last portion of water has been added, a solution of carbon dioxide is pipetted. Given that the weight of the soda taken refers to the mass of the dry residue as 2 to 1, mathematical calculations are performed.
To carry out further evaporation, it is necessary to mix the sample, while destroying the resulting crust. A glass rod is used for mixing. Then they wash the stick with distilled water. Then the resulting dry residue with soda in a cup is placed in a thermostat, dried at a temperature of about 150 degrees Celsius until a constant mass is obtained.
The average duration of evaporation is from two to five hours. The difference in weight between the capacity of the precipitate formed and the initial weight of the cup and soda is determined. This difference determines the amount of solids in the determined amount of water. The dry residue is determined by the formula linking the mass of the empty tank, the added soda, as well as the volume of water selected for analysis.
This analysis from a hygienic point of view consists in the fact that it is possible to carry out a technical adjustment of the analyzed water using filtration systems, while reducing the degree of mineralization.
Conclusion
The taste is considered balanced if the total salt content in water is 600 mg per liter. If it contains more than 1 g / l, it is considered unsuitable for drinking, as it has a bitter-salty taste.
If you constantly consume such water, serious physiological problems can occur in the body. First of all, there is an increase in the motor and secret function of the intestines and stomach, at an elevated temperature, the body overheats.