Health risks from drinking demineralized water. Possible increase in the intake of toxic metals into the body
Distilled (demineralized) water is used in chemical laboratories for many purposes: for preparing solutions, rinsing dishes after washing, etc.
Getting distilled water
Distilled water is water that contains almost no inorganic and organic substances, obtained by distillation of tap water, i.e. water is turned into steam and condensed.
To obtain distilled water, there are distillation cubes of various sizes and capacities.
The distilled water is collected in glass bottles, and the tube (the end of the refrigerator) is inserted into the neck of the bottle, sealed with cotton. This prevents dust from entering the water.
For laboratories that consume a relatively small amount of distilled water, the PK-2 automatic electric still is very convenient. The scheme of this device is shown in fig. 8. The alembic consists of an evaporation chamber 11, with an electric heater built into its bottom 15, steam condenser / and device for automatic filling of the chamber with water or equalizer, 10. Excess water is poured out through a rubber tube put on the nipple 17. This warm water can be used for washing dishes.
Through the nipple 3 through a rubber tube, water from the water supply continuously enters the condenser jacket /, where it is heated, and then enters through the equalizer
into the camera 11. Water vapor enters the condenser / through pipe 5, and the resulting condensate flows down through the nipple 4 through a rubber tube into a distilled water receiver. To prevent an increase in vapor pressure in the condenser, a hole is made in the latter's casing. 2 to release excess steam.
The device is connected to the electrical network using a wire coming out through the sleeve 14 casing 12. The latter has a ground terminal 13.
The electric heater must be periodically cleaned mechanically from scale. The higher the hardness of the tap water, the more frequently cleaning should be carried out. The performance of the distillation cube PK-2 reaches 4-5 l[h\ electric heater power 3.5-4 ket.
Currently, the industry produces more advanced distillation apparatuses D-1 (Fig. 9). Apparatus D-1 differs from that described above in the design of the heating element and equalizer. The performance of the device is about 5 l[h]
Distilled water always contains minor impurities of foreign substances that enter it either from the air in the form of dust, or due to leaching of the glass of the dish in which the water is stored, or in the form of traces of the metal of the refrigerator tube.
In addition, together with water vapor, gases dissolved in water (ammonia, carbon dioxide), as well as some volatile organic compounds, which may be present in water, and, finally, salts, which enter the distillate along with the smallest droplets of water carried away by steam.
For some analytical work, the presence of traces of metals in distilled water is unacceptable. To remove them, a method is proposed * for treating distilled water with activated carbon. For 1 l distilled water add 1 drop of 2.5% purified ammonia solution and 0.4-0.5 G activated carbon BAU, crushed to grains with a diameter of 0.15-0.20 mm. The water is shaken with coal, then allowed to settle and shaken again several times, allowed to stand no more than 5 min,
* Mednkoiskaya E. II., Dalmatov and T. V., Suvorova E. R., Bull, scientific and technical. Information of the MG and ON of the USSR, No. 5 (1957) .. .
Then filtered through an ashless filter. First 200-250 ml the filtrate is discarded. The resulting filtrate is tested for the ion to be determined.
Rice. 8. Schematic diagram
distillation cube PK-2 for
getting distilled
/ - capacitor; 2 - a hole for the exit of excess steam; 3 - nipple for connection to the water supply line; 4 - nipple for draining distilled water; 5 - branch pipe through which steam enters the condenser; 6 - screw; G - flange; 8 - drain pipe; 9 - equalizer funnel; 10 - equalizer; 11 - evaporation chamber; 12 - metal casing; 13 - Ground terminal; 14 - bushing for wire entry; 15 - electric heater; 16 - tap for water release from the evaporation chamber; 17 - nipple for draining water from the equalizer; 18 - equalizer cross.
However, it is also useful to further purify such water by treating it with a dithizone solution. To do this, distillate is poured into a large separating funnel up to half of it.
water, add an average of about 10% of the volume of water taken in a 0.001% solution of dithizone in carbon tetrachloride and, tightly closing the funnel, shake it well for several minutes. The liquid is allowed to settle, the colored dithizone solution is drained off, the same amount of fresh dithizone solution is added, shaken again and the extraction is repeated until the dithizone solution ceases to change its color, i.e. remains green. When this is achieved
Rice. 10. Apparatus AA-1 for receiving
pyrogen-free water: 1 - capacitor; 2 - chamber for water; 3 - condensation chamber; 4 - valve; 5 - nipple; 6 - safety slot; 7 - steam pipe; S - trap; 9 - casing; 10 - evaporation chamber; // - electric heater; 12 - bottom; 13 - drain cock; 14 - ground bolt; 15 - drain tube; 16 - wiit dispenser; 17 - locknut; 18 - dispenser; 19 -bracket; 20 - rubber ring; 21 - filter; 22 - a glass vessel; 23 - clamp; 24 - dropper; 25 - collection equalizer; 26 - union; 27 - water-indicating glass.
then, pure carbon tetrachloride is added to the water and shaken thoroughly to remove the dithizone dissolved in it from the water.
To purify distilled water from organic substances, it is subjected to secondary distillation, adding a little (~ 0.1 g/l) potassium permanganate and a few drops of sulfuric acid. Such water, which does not contain traces of organic substances, is called pyrogen-free. To obtain it, the apparatus AA-1 (model 795) is used. This device has a capacity of 8 ket designed for voltage 220 in and has a performance of 10 l/h(Fig. 10). Another same distiller *, but with a capacity of 18 ket has a performance of 20 l/h
* Both devices are produced by the Leningrad Production Association "Krasnogvardeets" (Leningrad, P-22, Instrumentalnaya st., 3).
The water obtained with the help of these devices meets the requirements of the State Pharmacopoeia. As chemical reagents for water purification are used: permanganate and potassium x. hours, potassium alum x. hours and Na 2 HP0 4 pharmacopoeial or h. Solutions of these reagents automatically enter the distilled water strictly according to the calculation given in the description attached to the apparatus.
To retain salts, the distillation apparatus should be equipped with a Kjeldahl nozzle or the so-called "Czech" nozzle, which is more reliable than the Kjeldahl nozzle.
When very pure water is needed, special measures are taken to prevent any impurities from entering the water, for example, a silver or quartz refrigerator is used. The receiver (also quartz or silver-plated, or from special types of glass that are not subject to leaching) is covered with a calcium chloride tube filled with an appropriate absorber to prevent ammonia, carbon dioxide, hydrogen sulfide and other impurities from entering the distilled water. The receiver can also be closed with a Bunsen valve (see page 65), which is a sufficient precaution against the ingress of impurities from the air during distillation. It goes without saying that impurities that are volatile with water vapor must first be removed from the water (gases - by boiling, organic substances - by oxidation, etc.).
A self-acting apparatus with a swinging holder (according to Stadler) is also very convenient for obtaining distilled water (Fig. 11). It consists of a 1.5 liter flask with a built-in distributor and a condenser. The apparatus is mounted on a tripod equipped with a swinging holder. Water is supplied to the refrigerator, heated in it and enters the distributor. When the flask becomes lighter as a result of the evaporation of water, the apparatus automatically turns it in such a way that the heated water from the distributor enters the flask and restores its previous level there. Excess water goes down the drain. The open tube at the top of the distributor only serves to equalize the pressure inside the flask with atmospheric pressure. At the lower end of the refrigerator there is a protective funnel that prevents contamination from entering the receiver for distilled water.
bidistillate: 1 - flask for distilled tap water; 2 - fridge; 3 - funnel; 4 - flask for distillate evaporation; 5 - protective funnels.
To obtain bidistillate, special installations are used that provide high quality received water. One of these setups is shown in Fig. 12. Flask 1 capacity 1.5 l heated either by electricity or by a gas burner. Water enters the flask continuously
but from the shirt of the refrigerator 2. The water supply should be adjusted to compensate for the evaporated water. The flask should be approximately two-thirds full. Condensed water from the refrigerator flows through the funnel 3 into the flask 4. To prevent contamination from entering above the funnel 3 reinforce the protective funnel 5, which has a slightly larger diameter than the funnel 3.
When in a flask 4 about 1 liter of distilled water will accumulate, heating of this flask begins and bidistillate is collected in a special receiver. You need to take care that dust does not get into it, for which a small funnel is inserted into the receiver for bidistillate through a cotton or other plug, and above it is a protective funnel 5.
To prevent the absorption of carbon dioxide, ammonia and other water-soluble volatile impurities from the air by the bidistillate, the bidistillate receiver can be equipped with special absorption devices (such as calcium chloride tubes). The inner surface of the receiver must be covered with a thin layer of paraffin or other inert coating.
The entire device is mounted on an iron tripod suitably equipped. Fastening of the flask and refrigerator. shown in fig. 12 right.
It must be remembered that doubly distilled distilled water (the so-called bidistillate) is not always needed, but only for particularly precise work. In the vast majority of cases, ordinary distilled water is used in the laboratory, which fully meets the requirements for purity.
The quality of each new batch of distilled water entering the laboratory (as well as standing in the laboratory for a long time) should be controlled by determining the pH and salt composition.
To determine the pH of water around 25 ml it is poured into a clean glass and a few drops of methyl orange are added. Pure water is neutral, and therefore the color of the indicator in it should be yellow; the addition of one drop of 0.04 N. a solution of sulfuric or hydrochloric acid should cause a pink tint to appear.
To test for impurities, a small amount of water (5-10 drops is enough) is evaporated on a platinum plate, in extreme cases - on a clean watch glass.
Pure water after evaporation should not leave a residue, otherwise a small coating remains on the plate.
The quality of distilled or demineralized water is also judged by electrical conductivity. The specific resistance of good distilled water should be at least 5-10 5 ohm ~ 1 -cm ~ 1 .
It should be a rule not to close bottles of distilled water with untreated barks.
Rice. 13. Bottle, equipped - Fig. 14. Bottle with a tube
naya for storage of distillate - for storage of distillate
bathroom water. bathroom water.
or rubber stoppers (see page 179); it is best to close such bottles with ground glass stoppers.
It is also very convenient to use a bottle with a tube! near the bottom (Fig. 14). The tube is firmly closed with a rubber stopper, in the middle of which a hole for the elbow tube is drilled. When filling the bottle with water, the elbow must be in a vertical position. To take water, the elbow tube is tilted towards its open end, and then brought back to its original
position. This device allows you to work neatly and protects the water from contamination.
Prolonged storage of distilled water in glassware, even good chemically resistant glassware, always results in contamination with glass leaching products. Therefore, distilled water cannot be stored for a long time and it is better to keep it in old bottles that have been used for this purpose more than once and have been sufficiently leached. For particularly important work (for example, the preparation of color standards, titrated solutions, carrying out some colorimetric determinations, etc.), only freshly distilled water or even bidistillate should be taken. For example, to prepare a solution of sodium sulphate, water obtained from a distillation apparatus with an untinned copper condenser cannot be used. Such water must be distilled again, avoiding even traces of copper, since copper can catalytically accelerate the decomposition of salt.
In the preparation of alkali solutions, they strive to free water from CO 2. To do this, either air freed from CO 2 is passed through the water for several hours, or the water is boiled. In the latter case, still hot water is poured into the vessel in which the solution will be prepared, and closed with a cork equipped with a calcium chloride tube to prevent CO 2 from entering from the air. To store distilled water so that it does not absorb CO2 from the air, a flask equipped as shown in Fig. 15. A calcium chloride tube filled with ascarite is inserted into a rubber plug with two holes in one hole, and a drain tube bent in a U-shape into the second hole. A rubber tube with a spring clip is placed on the outer end of the drain tube. Distilled or demineralized water must first be boiled in the same flask for at least 30 min. After boiling is over, close the flask with a regular stopper, allow the water to cool slightly, and then tightly close the flask with still warm water with a rubber stopper fitted as described above. After opening the clamp, air is blown into the flask through the calcium chloride tube until water begins to flow out of the drain tube. Then the air blowing is stopped and the Mohr clamp is lowered. The drain tube will work
act like a siphon. To take water, just open the clamp.
If water needs to be freed from oxygen dissolved in it, proceed as follows. Water is heated to 75-85 ° C and pieces of Wu-da alloy are lowered into it. When the latter has melted, the water is agitated and distilled under conditions to prevent the ingress of air. The receiver can be equipped with a V-shaped safety tube filled with either an alkaline solution of pyrogallol or another oxygen scavenger, such as very thin sticks of yellow phosphorus. In the latter case, the protective tube should be wrapped in black paper to protect the phosphor from the action of light. Absorption of oxygen by phosphorus occurs only at a temperature not lower than 16-18 ° C.
Similar information.
In the first part of the article on water, I will talk about what kind of water is best to drink in order to be healthy, and why “filtered”, melted, “structured” and boiled water is dangerous.
- Demineralized, from reverse osmosis filters
Water-loving gurus now feed their followers with baseless fantasies that drinking demineralized water from home reverse osmosis filters is the main thing for "detoxification", "dissolution of toxins", etc. Some, especially zealous, madmen even recommend fasting on distilled (that is, completely devoid of any mineral salts) water.
At the same time, scientific studies show that the use of water without a sufficient amount of mineral salts is very dangerous! You will learn more about what the mineralization level should be for the greatest health in the second part of the water-bearing article.
Demineralized (desalinated water) is water devoid of minerals. It is called such if the content of soluble salts (total mineralization) is less than 50 mg/l.
In nature, consumers at a watering place do not get such water so often: it is rainwater or “melt”, that is, water that has fallen from heaven or obtained by melting ice, if they have not yet had sufficient contact with the ground (from where they quickly get a significant amount of mineral salts).
Such natural water without salts in its qualities and effect on the body is almost similar to distilled water, and water from the so-called "household reverse osmosis filters", which remove all mineral salts from the water. The same properties have distilled water and "thawed" - that is, the one that we get if we freeze it, and then melt the ice.
Better than holes can only be mountains
Observation by the World Health Organization (WHO) of mountaineers, who for a long time consumed mainly glacier melt water, which is very poor in minerals, showed the occurrence of "acute health problems", which are often associated with the so-called "altitude sickness".
In the early stages of Altitude Sickness, symptoms can include fatigue, headaches, weakness, as well as muscle spasms and even heart rhythm disturbances. In the later ones - even worse, I won’t scare.
The consumption of significant amounts of demineralized water by athletes after intense and prolonged physical activity also sometimes caused acute symptoms of a neurological disorder - such as delirium or stroke. This shows that when using demineralized, there is a violation of the passage of nerve impulses and the normal functioning of the brain.
Inside me - water, well, what to do with this?
Voditsa gurgles not only inside the mermen, but also in each of us.
Water in the human body always contains well-defined concentrations of various mineral salts (they are also called electrolytes), the content of which is very clearly controlled by the body.
This certain concentration of mineral salts is necessary for the flow of electrical signals in the brain and nerves and to ensure normal internal pressure in tissue cells.
If we drink water devoid of mineral salts, then in order to assimilate it, our intestines must first add electrolytes to it, and it can get them only by drawing them out of the body's reserve reserves. This leads to the depletion of these reserve reserves, swelling, improper redistribution of water in the body, which can disrupt the functioning of vital organs.
"Dissolution of toxins" and "removal of toxins" occurs according to completely different laws.
The use of demineralized water of any kind, as you already understood, disrupts the normal salt balance of the body and spoils health. What about slag?
To reverse the accumulation of KIDNEY STONES, or GOUT, for example, it is necessary not to pump with distilled water, but to stabilize the acid-base balance of the body and reduce the formation of uric acid and the binding of oxalic acid.
This is done by increasing the amount of vegetables and greens, bringing the consumption of fruits (as high-fructose foods) and sweets to a healthy minimum. You need to bring your protein intake to a healthy optimum (not so important - plant or animal), and make some other important changes in the diet.
It is these detox wisdoms that I teach in my Weight Loss and Health Course.
Hard water for a soft heart
In November 2003, WHO even held a special conference in Rome on the relationship between the incidence of cardiovascular disease and the presence of minerals in water.
Summarizing the results of more than 80 studies on this topic show that in countries with a higher mineralization of drinking water, the risks of getting diseases of the cardiovascular system are lower.
The same is shown by the generalized results of studies over 50 years: the higher (up to reasonable limits) hardness of water, the lower the mortality rate from cardiovascular diseases.
More arguments and facts:
When boiling vegetables in demineralized water, they lost up to 60% more calcium and magnesium than in regular water. Copper in such water is lost by 68%, manganese - by 80%, cobalt - by 86% more, and so on through the list of usefulness!
But the amount of heavy metals in "demineralized" water is often higher than normal. In the USA in 1993-94 there were even cases of severe poisoning of children who consumed demineralized water. The fact is that due to the absence of salts, such water dissolves and absorbs heavy metals much more actively, passing through pipes or when stored in metal containers.
So all purified and so bottled all ...
Demineralized reverse osmosis or distilled water does not taste very good. In order to somehow reduce this drawback, some manufacturers of reverse osmosis filters install special devices that add some kind of salt to this water. What is the question. It is clear that they will not add the whole wide range of natural micro- and macrominerals. Yes, and narrow - too!
The addition of 3-5 basic minerals, however, can at least somehow secure the resulting “product” in terms of demineralization and slightly improve its taste. If you read “purified tap” on the label, or simply “purified”, then you have 100% ordinary water passed through the filter (that is, demineralized), to which some salts were then added.
It is best to buy artesian water from deep wells. About what level of mineralization is the healthiest, you will learn from the second part of the article.
Such water is filtered, sometimes treated with ozone or ultraviolet light to kill bacteria, and bottled.
- ember
Water from filters that use activated carbon is slightly different than demineralized water - a little more mineral salts remain in it. To obtain it, all kinds of jugs with filters and nozzles put on the faucet are used. The principle of operation is the same as that of a gas mask. At first, while the filter is new, chlorine, part of the dissolved poisonous organochlorine, bacteria and part of mineral salts are removed from the water. However, after a few days, coal is saturated with all sorts of dirty tricks. Because of this, it begins to absorb chlorine and mineral salts much worse, and pathogenic bacteria begin to develop in the filter itself.
So if it’s completely impossible to buy or bring artesian water, drink water from a carbon filter while the filter is new. Change the filters more often, and when the filter is used for a long time, it is better to boil the water - there will be less bacteria.
- "Structured" water
It's hard for me to say something about her ... good. Now, in the scientific community, this topic is bypassed in silence, which cannot be called anything other than contemptuous. A few decades ago, official science and medicine actively explored "structured" water and did not find anything worthy of attention in the topic of "structuredness".
In fact, there is no scientific evidence that the use of “structured, that is, frozen-thawed-magnetized water brings at least some health benefit, alas, is not.
From scientific laboratories, the idea of "structuring water" migrated to various areas of alternative medicine and dietology. And they still give this topic a very great importance and write about the "energy component", naturally structured water, etc.
Alas, the whole process of “structuring” leads to the removal of hardness salts necessary for health: after all, it involves freezing, in which calcium and magnesium salts precipitate. Accordingly, structured water has all the disadvantages of demineralized water, but science somehow did not find the advantages of “structuring”, although it was looking for it.
- boiled
Although everything is not good with boiled water either ... I still shudder, remembering this vile taste of boiled water from Soviet-era decanters ... In fact, this is almost the same demineralized water: boiling transfers “hardness salts” (calcium and magnesium) from a soluble form into sediment (scale). The rest of the salts mostly remain. But in general, boiled water is also fairly demineralized (I almost wrote - demoralized).
In the second part of the article on water, I will talk about what kind of water is best to drink in order to be healthy, what diseases are caused by drinking low- and high-mineralized and carbonated water, and how much water you should drink.
- “Filtered” and remineralized water destroys your health: this is water from reverse osmosis filters, distilled, melted water, rainwater. Promotion of its use in order to detoxify the body and remove salt deposits - pure water is an irresponsible or deliberate deception.
- "Structured" and simple - boiled water is not much better than "filtered".
- The most useful is mineral artesian water from deep wells or spring water that has not been purified.
Sources of inspiration:
- Ingegerd Rosborg "Drinking Water Minerals and Mineral Balance: Importance, Health Significance, Safety Precautions"
- Ctrl+Enter .
Getting purified water
Distillation is water collected in drops. The distillation or distillation method is the most common in pharmacies or industrial production.
To obtain purified water in cities, tap or demineralized water is used. Water used in rural areas needs preliminary purification from organic substances, ammonia, salts that give it hardness, and various suspended particles.
general characteristics water distillers
To obtain water by distillation, apparatuses are used - water distillers. Drinking water or water that has undergone water treatment is placed in a water distiller, which consists of three main units: an evaporator, a condenser and a collector.
The evaporator, which contains water, is heated to a boil. Water vapor enters the condenser, where it liquefies and enters the collector in the form of condensate. All non-volatile impurities in the source water remain in the water distiller.
When water boils in the evaporator, bubble and surface vaporization occurs.
In the first case, during boiling, vapor bubbles are formed, which escape from the liquid, entraining a thin layer of initial water on their surface. This results in contamination of the distillate.
Surface vaporization does not give rise to droplets of undistilled water.
In order to prevent bubble vaporization, it is necessary:
· Strive to reduce the thickness of the fluidized bed.
· Adjust the heating temperature to ensure an even (not violent) boil.
Maintain optimum steam generation rate.
Water demineralized
AT recent times pay attention to the use of demineralized water instead of purified water. This is due to the fact that distillers, especially electric ones, often fail. The salts contained in the source water form scale on the evaporator glasses, which worsens the distillation conditions and reduces the quality of the water.
For desalination (demineralization) of water, various installations are used. The principle of their operation is based on the fact that water is freed from salts when it is passed through ion-exchange resins - network polymers of a gel or microporous structure, covalently bonded to ionogenic groups. The dissociation of these groups in water gives an ion pair: - an ion fixed on a polymer carrier;
Mobile - a counterion that is exchanged for ions of the same charge.
The main part of water demineralization plants are columns filled with cation exchangers and anion exchangers.
The activity of cation exchangers is determined by the presence of a carboxyl or sulfonic group, which has the ability to exchange hydrogen ions for alkali and alkaline earth metal ions.
Anion exchangers are network polymers capable of exchanging their hydroxyl groups for anions.
The plants also have tanks for solutions of acid, alkali and distilled water, necessary for the regeneration of resins. Regeneration of cation exchangers is carried out with hydrochloric or sulfuric acid.
Anion exchangers are restored with an alkali solution (2-5%).
Typically, an ion exchange plant contains 3-5 cation and anion columns. The continuity of work is ensured by the fact that one part of the columns is in operation, the other is being regenerated. Tap water passes through ion-exchange columns, then it is fed to a filter that traps particles of destruction of ion-exchange resins.
For a warning microbial contamination the resulting water is heated to 80-90 0 C.
It is advisable to use the demineralizer in inter-hospital, large hospital and other pharmacies for supplying demineralized water to distillers and washing rooms for washing dishes.
Productivity of a demineralizer is 200 l/hour.
To obtain pure demineralized water, the so-called ion-exchange filters are used (Fig. 16). Their action is based on the ability of certain substances to selectively bind cations or anions of salts. Tap water is first passed through a cation exchanger that binds only cations. The result is water that is acidic. This water is then passed through an anion resin that binds only the anions. Water passed through both ion exchangers is called demineralized(i.e. does not contain mineral salts).
Figure 15. Flask for storing distilled water with protection against carbon absorption.
The quality of demineralized water is not inferior to distilled water and often corresponds to bidistillate
Ionites gradually saturate and stop working, but they are easy to regenerate, after which they can be used again. In practice, regeneration can be carried out many times and a large amount of water can be purified with the same ion exchanger. Ionite installations are widely used not only for water purification and demineralization in industry, but also in analytical laboratories instead of water distillation devices.
Rice. 16. Laboratory installation for obtaining demineralized water.
Rice. 17. Scheme of a laboratory installation for obtaining demineralized water: 1 - plug; 2 - glass wool; 3 - cation exchanger; 4 - three-way edge; 5 - plug; 6-anion exchanger; 7 - drain pipe.
To obtain demineralized water, you can install a plant that will allow you to get 20-25 l / h of water. The installation (Fig. 17) consists of two tubes (columns) 70 cm high and about 5 cm in diameter. The columns can be glass, quartz, and even better - from transparent plastics, such as plexiglass. 550 g of ion-exchange resins are placed in the columns: a cation exchange resin (in the H + form) is placed in one, and an anion exchange resin (in the OrT form) is placed in the other. In the test tube / column with cation exchanger 3 there is a drain tube, which is connected with a rubber tube to a water tap.
The water that has passed through the cation exchanger is sent to the second column with the anion exchanger. The water flow rate through both columns should be no more than 450 cm3/min. In the first portions of water passed through the cation exchanger, it is necessary to establish the acidity. A water sample is taken through a three-way valve 4 connecting the columns. Preliminary determination of water acidity is necessary for the subsequent quality control of demineralized water.
Since the ion exchangers are gradually saturated, it is necessary to control the operation of the installation. After about 100 liters of water have passed through it or it has worked continuously for 3.5 hours, a sample of the water that has passed through the cation exchanger column should be taken. Then 25 cm3 of this water is titrated with 0.1 N. NaOH solution on methyl orange. If the acidity of the water has sharply decreased in comparison with the result of the first test, the passage of water should be stopped and the ion exchangers should be regenerated. For -reeneration of the cation exchanger, it is poured out of the column into a large jar, filled with a 5% HCl solution and left overnight dissolved in this. After that, the acid is compared and the cation exchanger is washed with distilled or demineralized water until the test for Cl- ions in the washing water becomes negative. The test is done as follows: 2-3 drops of washing water are placed on a watch glass and a drop of 0.01 N is added to it. AgNO3 solution. With a negative reaction, turbidity is not formed.
The washed cation exchange resin is reintroduced into the column. Anion exchange resin for regeneration is poured into a large jar, filled with 2% (0.5 N) NaOH solution and left overnight. The alkali is then drained off, and the anion exchange resin is thoroughly washed with distilled or demineralized water until the washings are neutral when tested with phenolphthalein. . " "
In the laboratory, it is useful to have two such installations: one is in operation and the other is in reserve. While one installation is being regenerated, the other is in operation.
From ion-exchange resins * manufactured in the USSR, ion exchangers of the KU-2, SBS, SBSR, MSF or SDV-3 brands can be used as cation exchangers.
It is recommended to use KU-2 and EDE-10P** ion exchangers to obtain highly pure water, which is superior in quality to bidistillate. First, ion exchangers with a grain size of about 0.5 mm are converted into H- and OH-forms, respectively, by treating KU-2 with a 1% hydrochloric acid solution, and EDE-10P with a 3% sodium hydroxide solution, then the sweat is barely washed well. Then they are mixed in a volume ratio of KU-2: EDE-10P = 1.25: 1 and the mixture is placed in a plexiglass column with a diameter of about 50 mm and a height of 60-70 cm.
The bottom and top plug of the column should also be made of plexiglass, the water supply and waste pipes should be made of polyethylene or aluminum.
To obtain highly pure water, ordinary distilled water is used, which is passed through a column with a mixture of ion exchangers. One kilogram of such a mixture can purify up to 1000 liters of distilled water. Purified water should have a resistivity of 1.5-2.4 * 10 -7 1 / (ohm * cm). This mixture of ion exchangers is not recommended for demineralization of tap water, since ion exchangers are quickly saturated in this case. When the specific resistance of the purified water begins to decrease, the water purification is stopped, and the ion exchangers are regenerated. To do this, a mixture of ion exchangers is poured from the column onto a sheet of filter paper, leveled, covered with another sheet of the same paper, and left to dry. Or, the ion exchangers from the column are poured into a Buchner porcelain funnel and sucked off on it until an air-dry mass is obtained.
The air-dry mass is placed in a separating funnel of an appropriate capacity so that the mixture of ion exchangers occupies about "D. After that, a 3% NaOH solution is added to the separating funnel, filling the funnel by approximately 3D, and quickly mixed. In this case, an instant separation of the ion exchangers occurs. The lower layer containing the KU-2 cation exchanger is lowered through the faucet of a separating funnel into a vessel with water and washed many times using decantation until the wash water sample gives a neutral reaction when adding I-2 drops of phenolphthalein.
The top layer containing EDE-10P anion exchanger is drained through the neck of a separating funnel into a vessel with water. The ion exchangers are regenerated as described above, each ion exchanger separately, and after that they are again used for water purification.
Chapter 5
5.6. Water treatment
Information about tap water
Drinking water should be epidemically safe, harmless in chemical composition and have favorable organoleptic properties. Epidemiologically, water safety is determined by total number microorganisms and the number of bacteria of the Escherichia coli group.
Another source of water is natural water, which contains a large amount of chemical impurities, so it is subjected to special purification.
The main requirement of water treatment is the use of source water that does not contain or contains a minimum amount of impurities capable of distillation.- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of forming vapors "> distillation in apparatuses to form a solid layer - scale. Various substances are involved in the formation of scale - the main calcium and magnesium bicarbonates, which, when heated break down into free carbonic acid and insoluble calcium and magnesium carbonates.
Ca (HCO 3) 2 → CO 2 + H 2 O + CaCO 3
Mg (HCO 3) 2 → CO 2 + H 2 O + MgCO 3
Water containing a lot of calcium and magnesium salts is called Water hardness - the total concentration of calcium and magnesium salts. Water that contains a lot of calcium and magnesium salts is hard; water with a low content of them is soft. Classification of water according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-eq. "> hard, and water with a small amount of them - soft. Full water hardness is the total concentration of calcium and magnesium salts. Water that contains a lot of calcium and magnesium salts is hard; water with a low content of them is soft. Classification of water according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-Eq. soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-eq. "\u003e hardness of natural water that has not been heated or any other type of softening. Under total water hardness is the total concentration of calcium and magnesium salts. Water that contains a lot of calcium and magnesium salts is hard; water with a low content of them is soft. Classification of water according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-eq. "\u003e water hardness is understood as the total concentration of calcium and magnesium salts.
When heated, calcium and magnesium bicarbonates decompose in water, and precipitate- an extraneous admixture to the liquid in the form of tiny solid particles, sinking to the bottom or on the walls of the vessel, or an insoluble substance released from the solution as a result of a chemical reaction "> calcium and magnesium carbonates precipitate. As a result, water hardness is the total concentration of calcium and magnesium salts Water that contains a lot of calcium and magnesium salts is hard, water with a low content of them is soft Water classification according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-eq. Water that contains a lot of calcium and magnesium salts is hard; water with a low content of them is soft. Classification of water according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-eq. "\u003e water hardness.
- very soft - 0-1.5;
- soft - 1.5-3;
- medium - 2-6;
- very hard - more than 10 mg-eq / l.
So, mineral salts, mechanical impurities, dissolved organic substances, silica, silicates, iron bicarbonate, alumina and other substances are involved in the formation of scale, which before distillation- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of the forming vapors "> by distillation must be removed.
Thus, water treatment refers to the improvement of the quality of water coming from a water source for industrial use.
Depending on the nature of impurities and the purpose of water, its purification is carried out in various ways.
Removal of mechanical impurities. Mechanical impurities usually separate Settling - slow separation of a liquid dispersed system (suspension, emulsion, foam) into its constituent phases: a dispersion medium and a dispersed substance (dispersed phase), which occurs under the action of gravity. In the process of O., the particles of the dispersed phase settle or float, accumulating, respectively, at the bottom of the vessel or at the surface of the liquid "> settling followed by decantation or Filtration- separation of substances using semi-permeable membranes (reverse osmosis and ultrafiltration methods), for example, purification of IUDs from mineral salts "> filtration. Sand filters are used for this purpose.
Water with high temporary and permanent Hardness of water - the total concentration of calcium and magnesium salts. Water that contains a lot of calcium and magnesium salts is hard; water with a low content of them is soft. Classification of water according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2-6 mg-eq; very hard - more than 10 mg-eq. "> hardness is subjected to preliminary softening, which can be carried out in two ways.
Deposition method. This method consists in converting calcium and magnesium ions into poorly soluble compounds by adding solutions of calculated amounts of calcium hydroxide, sodium hydroxide, crystalline sodium carbonate, etc. to water.
Ca (HCO 3) 2 + Ca (OH) 2 → 2CaCO 3 ↓ + 2H 2 O
MgSO 4 + Ca (OH) 2 → Mg (OH) 2 ↓ + CaSO 4 ↓
Ca (HCO 3) 2 + Na 2 CO 3 → CaCO 3 ↓ + NaHCO 3
Mg (HCO 3) 2 + 2NaOH → MgCO 3 ↓ + Na 2 CO 3 + 2H 2 O
MgCO 3 + NaOH → Mg (OH) 2 ↓ + Na 2 CO 3
After several hours of interaction of scale formers with the indicated reagents, a precipitate is formed.- an extraneous admixture to the liquid in the form of tiny solid particles, sinking to the bottom or walls of the vessel, or an insoluble substance released from the solution as a result of a chemical reaction "\u003e precipitation, which are then removed Settling - slow separation of a liquid dispersed system (suspension, emulsion, foam ) into its constituent phases: the dispersion medium and the dispersed substance (dispersed phase), which occurs under the action of gravity. In the process of O., the particles of the dispersed phase settle or float, accumulating, respectively, at the bottom of the vessel or at the surface of the liquid- separation of substances using semi-permeable membranes (reverse osmosis and ultrafiltration methods), for example, purification of IUDs from mineral salts "> filtration.
Ion exchange method. The method is based on the exchange of calcium and magnesium cations for sodium or hydrogen cations contained in a material that is practically insoluble in water - a cation exchanger.
Water that has passed through cationic filters will contain only sodium salts or mineral acids, which are highly soluble and are not capable of forming scale in distillation apparatuses.- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of the forming vapors "\u003e distillation. This method has several advantages over precipitation: better elimination Water hardness - the total concentration of calcium and magnesium salts. Water, which contains a lot of calcium and magnesium salts - hard; water with a low content of them - soft Classification of water according to Zh.: very soft - 0-1.5 mg-eq; soft - 1.5-3 mg-eq; medium - 2 -6 mg-eq; very hard - more than 10 mg-eq. "\u003e water hardness; simple device and equipment maintenance; low cost of water treatment; possibility of simultaneous removal of organic substances. The disadvantage of the method is an increase in alkalinity and the amount of some salts in softened water.
Coagulation of colloidal impurities. Colloidal turbidity can be removed only after preliminary coarsening of suspended particles. To destroy the colloidal system, it is necessary to neutralize electric charge particles. Chargeless particles under the influence of forces of mutual attraction combine - coalesce. Aluminum sulfate or potassium alum are used as such electrolytes. In the presence of ammonia in the water, the main source of which is natural waters are protein compounds, before starting distillation- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of the forming vapors "> distillation, alum is also added to the source water (5 hours per 10 l of water). As a result of the interaction of alum and ammonia, non-volatile ammonium is formed sulfate and excreted hydrochloric acid. For binding the latter before starting distillation- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of the forming vapors "\u003e distillation, crystalline disubstituted sodium phosphate (3.5 h per 10 l of water) is added.
Toxicological indicators of water quality characterize its harmlessness. chemical composition. Concentration chemical substances found in natural waters or added to water during its processing should not exceed existing standards.
Obtaining purified water (distilled). The requirements for her
Purified water FS 42-2619-89 (Aqua purificata) used in production injection sites are divided into: intradermal, subcutaneous, intramuscular, intravascular, spinal, intraperitoneal, intrapleural, intraarticular, etc.- the state attached to the drug or medicinal plant raw materials, which is convenient for use, in which the necessary therapeutic effect is achieved"\u003e dosage forms, should be chemically purified as much as possible and meet the relevant NTD. In each series of the resulting water, the pH value must be checked (5.0-6, 8), the presence of reducing substances, carbonic anhydride, nitrates, nitrites, chlorides, sulfates, calcium and heavy metals- a group of chemical elements with the properties of metals (including semi-metals) and a significant atomic weight or density"\u003e heavy metals. The presence of ammonia is allowed - no more than 0.00002%, Dry residue- substances dissolved in water and remaining after evaporation of water at a temperature of 105–110 ° C per liter "\u003e dry residue - not more than 0.001%. To continuously assess the quality of the resulting water, the measurement of electrical conductivity is used. However, the method is not objective enough, since the result depends on the degree of ionization of water molecules and impurities.
Purified water is obtained mainly by the method of distillation- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of the forming vapors "> distillation (distillation) tap water or demineralized water- water freed from salts by passing it through ion-exchange resins "\u003e demineralized water in distillation apparatuses of various designs (photo). The main components of any distillation apparatus are the evaporator, Condenser(lat. condenso- I condense, thicken) - a heat exchanger for the condensation (transformation into liquid) of the vapors of a substance by cooling "> condenser and Collector- a container for collecting, moving and storing raw materials, semi-products (intermediate products) and finished products "\u003e collection. The essence of the Distillation method- the process of cleaning a liquid from non-volatile impurities dissolved in it or separating mixtures of liquids into fractions by evaporation and subsequent condensation of the forming vapors"\u003e distillation consists in the fact that the source water is poured into the evaporator and heated to boiling. A phase transformation of the liquid into vapor occurs, while water vapor is sent to the condenser(lat. condenso- condense, thicken) - a heat exchanger for condensing (turning into a liquid) the vapors of a substance by cooling"\u003e condenser, where they condense and enter the receiver in the form of a distillate. This method requires a large amount of energy, therefore, at present, some plants receive water purified by membrane separation methods.
Purified water is obtained at pharmaceutical enterprises using distillation apparatuses, high-performance column units and various designs of thermocompression distillers.