After a course of radiation therapy, patients develop radiation sickness, which has a depressing effect on many vital functions of the body.

The development of radiation sickness is due to the fact that healthy tissue cells are affected by ionizing radiation along with tumor cells.

Ionizing radiation has the ability to accumulate in the body.

Early and later signs of radiation sickness - pain, nausea and vomiting, swelling, fever, intoxication, cystitis, etc. - are caused by negative impact on active cells of the body ionizing radiation. The epithelial cells of the gastrointestinal tract are most susceptible to damage. nerve tissue, immune system, bone marrow, genitals.

The intensity of manifestations of radiation sickness varies depending on the radiation exposure and the characteristics of the patient’s body. What should cancer patients do to prevent complications after radiation therapy and to improve their well-being?

Radiation sickness has several stages, with each subsequent stage of the disease characterized by an increase in symptoms and a deterioration in the patient’s condition. So, if at first a person is worried only about general weakness, loss of appetite and dyspeptic symptoms, then over time, with the development of the disease, he feels a pronounced asthenia (weakening) of the body, suppression of the immune system and neuroendocrine regulation.

After radiation therapy, serious damage to the skin can develop - the so-called. radiation burns requiring rehabilitation. Radiation burns often go away on their own, but in some cases they are so severe that they may require special medical care to treat them.

Radiation therapy can also provoke inflammatory processes, which easily develop into complications such as exudative epidermitis, esophagitis, pulmonitis, and perichondritis. Sometimes complications affect the mucous membranes of organs located close to the site of exposure to rays.

In addition, radiation therapy can have a serious effect on the hematopoietic process in the body. Thus, the composition of the blood may change, in particular, anemia may develop when the amount of hemoglobin in the blood drops below the permissible limit.

It should be noted that high-tech modern equipment minimizes possible complications.

During the recovery period, it is necessary to periodically check the results of therapy, take the necessary tests on time, and regularly undergo follow-up examinations with an oncologist.

The specialist will promptly determine the cause of the violations, give the necessary recommendations, and prescribe the necessary medications for treatment.

For example, drugs based on erythropoietin, as well as iron supplements, vitamin B12 and folic acid, will help increase the amount of hemoglobin in the blood.

A serious reaction of the body to radiation therapy procedures can be a depressive state, manifested incl. and increased irritability. During this period, it is necessary to find positive emotions in life and tune in to an optimistic mood. The support of loved ones is very important in this difficult and responsible period of life.

Currently everything large quantity Patients who have undergone radiation therapy successfully cope with the disease and return to a normal, fulfilling life. However, it must be remembered that even if a person has recovered after a period of 2-3 years, one should not refuse regular examinations by a doctor in order to detect possible relapses, as well as courses of supportive and restorative therapy and sanatorium-resort treatment.

The use of herbal medicine to restore the body

Some patients recover fairly quickly after radiation therapy with rest and a balanced diet. In another part of patients, after treatment, serious complications may arise, caused by general intoxication of the body and requiring medication.

To speed up the body's recovery processes, traditional medicine can also be of great help. An experienced herbalist will select herbs and their mixtures that will help cleanse the body of radionuclides, improve the blood formula, strengthen the immune system and have a positive effect on the patient’s well-being.

Using lungwort

Experts recommend using lungwort preparations after radiation therapy.

The plant contains a rich complex of microelements that help restore and improve the blood formula.

In addition, taking plant preparations helps stimulate and strengthen the immune system, increase the adaptogenic functions of the body, improve the psycho-emotional state, and get rid of emotional exhaustion.

For patients who have undergone radiation therapy, herbalists recommend using a water infusion and an alcohol tincture of the plant. There are no contraindications to lungwort preparations, but they should be used with caution in cases of intestinal atony and increased blood clotting. You should not take the plant preparations on an empty stomach - this may cause nausea.

To prepare the infusion 2 tbsp. spoons of chopped herbs are poured into a glass of boiling water, left for 3-4 hours, filtered. Drink 1/4 cup 3-4 times a day, with a small amount of honey. Externally, the infusion can be used for douching of the rectum or vagina.

The alcohol tincture is prepared as follows: put raw crushed grass into a 1-liter jar, filling 0.5 volume (if the raw material is dry, fill 0.3 volume of the jar), fill it to the top with vodka, close it and put it in a dark place for 14 days. Filtered. Use the drug 1 teaspoon 3-4 times a day, with a small amount of water.

Use of Rhodiola rosea and Eleutherococcus

The use of adaptogen plants such as Rhodiola rosea and Eleutherococcus are very effective for the recovery of patients undergoing radiation therapy. The drugs weaken the toxic effects of radiation on the body and improve blood counts. Experts also point to the antitumor properties of these plants.

Alcohol tinctures of Rhodiola and Eleutherococcus are used as medicinal preparations. It is important to note that the stimulating effect of these drugs on hematopoiesis begins on the 5-6th day from the start of drug use, and a pronounced therapeutic effect is observed by the 10-12th day. Therefore, it is better to start taking plant preparations 5-6 days before the start of irradiation.

An alcoholic tincture of Rhodiola rosea is prepared as follows: 50 g of rhizomes, previously crushed, are poured with 0.5 liters of vodka and placed in a dark place for 2 weeks, after which it is filtered. Take 20-30 drops 2-3 times a day half an hour before meals (the last dose should be no later than 4 hours before bedtime). For people prone to high blood pressure, start taking the drug with 5 drops three times a day. In the absence of negative effects, the dosage is increased to 10 drops.

Alcohol tincture of Eleutherococcus is drunk 20-40 drops twice a day before meals. The course of drug treatment is 30 days. After a short break, the course of treatment can be repeated if necessary.

Using herbal teas

For the rehabilitation of patients who are severely weakened after a course of radiation therapy, herbalists recommend the use of special healing herbs.

Healing infusions prepared from such preparations supply the depleted body with vitamins, increase immunity, effectively remove toxins, and ensure the stable functioning of all organs and systems of the body.

A very effective collection with such components as: birch (buds), immortelle (flowers), oregano (herb), angelica officinalis (root), St. John's wort (herb), stinging nettle (leaves), cordate linden (flowers), mother common stepmother (leaves), peppermint (leaves), dandelion (root), great plantain (leaves), motherwort (leaves), chamomile (flowers), common pine (buds), common yarrow (herb), thyme (herb), greater celandine (herb), sage (herb).

All components of the collection are taken in equal weight quantities, crushed and mixed. 14th century spoons of the collection, pour 3 liters of boiling water, cover with a lid, wrap tightly and let it brew for at least 8 hours. Next, the infusion is filtered through several layers of gauze, poured into a jar and stored in the refrigerator. The shelf life of the product is 5 days. Drink the infusion 2 times a day: on an empty stomach (an hour before the first meal) and during the day (but not before bedtime). Single dose – 1 glass of infusion. Infusion does not have side effects, it can be used for a long time.

Using bergenia and nettle

To improve the blood count, especially when platelets are low, herbalists recommend using preparations of bergenia root and nettle leaves.

To prepare a decoction of bergenia root, pour 10 g of raw material into a glass of boiling water, keep it in a water bath for 30 minutes, leave for an hour, and filter. Take 1-2 tbsp. spoons three times a day before meals.

To prepare nettle decoction: 1 tbsp. pour a spoonful of fresh crushed leaves of the plant into a glass of hot water, bring to a boil, and boil for 8-10 minutes. Remove from heat, let it brew for an hour, strain. Take 2-3 tbsp. spoons 3-4 times a day before meals.

In the cold season, you can use an infusion prepared from dry nettle leaves. 10 g of dry raw material is poured with a glass of boiling water, left in a thermos for 20-30 minutes, filtered. Drink the healing infusion in small portions throughout the day, before meals.

Let us remind you that any independent treatment measures must be agreed upon with the attending physician.

When a person is faced with a disease associated with neoplasms in the body, he asks the question “Radiation therapy - what is it and what are the consequences.”

Radiation therapy is a generally accepted and relatively effective method of combating one of the most insidious diseases of mankind - cancer. For many years, this type of fight against malignant tumors of various locations and degrees has been actively used in oncology. According to statistics, in more than half of cancer cases, radiation therapy, in combination with other treatment methods, gives a positive result and the patient is cured. This fact gives an undeniable advantage to the use of radiation therapy over other treatment methods.

History of the creation of radiation therapy

Opening x-rays gave many opportunities in medicine. It has become possible to accurately diagnose various types of diseases by examining internal organs with X-rays. Having studied X-ray radiation, scientists came to the conclusion that a certain dose of it has a detrimental effect on harmful cells. This was a real breakthrough in medicine; there was a chance to cure all cancer patients. A lot of side effects were also identified after the radiation reaction, since healthy cells were also affected.

Many scientists were skeptical about radiation therapy. It got to the point where research was banned, and researchers working on the possibilities of X-rays were sharply criticized both by some eminent colleagues and by the public. But the steady increase in the number of cancer patients forced physicists, oncologists, and radiologists to return to research. Today, modern equipment makes it possible to carry out radiation therapy without harm to healthy cells, which gives many patients hope for healing. And in many cases this is the only chance to overcome the disease.

Leading clinics in Israel

So, let’s figure out what “radiation therapy” is.

Radiation or radiotherapy (radiology) is one of the methods of treating cancer tumors using high-energy radiation. The purpose of this therapy is to eliminate cancer cells by directly destroying their DNA, thereby preventing them from reproducing.

The side effects of this type of radiation have decreased significantly compared to the first applications, which gives a good prognosis for healing. It became possible to change the direction and dose of radiation, thanks to which the effectiveness of therapy increased. If cancer is detected early, using radiation therapy alone offers a chance for a complete recovery.

Types and methods of radiation therapy

Cancer cells respond well to treatment with radiation therapy because they differ from healthy cells in that they multiply very quickly, which makes them sensitive to external influences. Their elimination is carried out by destroying the DNA of malignant cells. Radiation therapy is often combined with other cancer treatments such as chemotherapy, chemoradiotherapy, laser therapy, and surgery. The type of therapy, their combination, is selected depending on the size of the formation, location, stage, and concomitant diseases. For example, radiation therapy is often carried out before surgery.

The reason for this is the reduction in tumor size, as well as the failure of malignant cells to enter healthy areas of the body during surgery. In severe cases of disease, when a malignant tumor is actively metastasizing, radiation therapy is the only possible method of combating the disease, since other methods are no longer effective. This therapy is used after surgery if doctors assume that there are still malignant cells in the areas adjacent to the tumor site.

1. Alpha particles– affect the body with alpha radiation through isotopes, in particular radon and thoron products. The patient takes radon baths, drinks radon water, and bandages soaked in radon and thoron products are applied to the necessary areas of the skin. Ointments containing these substances are also used. Their use is advisable only for certain diseases of the nervous, circulatory, endocrine system. In case of cancer, this method is contraindicated;
2. Beta particles- beta particles and some radioactive isotopes are used, such as phosphorus, thallium, etc. There are interstitial, intracavitary and application beta therapy. For example, application therapy is used for inflammatory processes of the eyes that have become chronic. Interstitial therapy is used to treat radioresistant tumors. Radioactive solutions such as solutions of gold, yttrium, and silver are used. The fabric is impregnated with them and applied to the affected area. During intracavitary therapy, colloidal solutions of a certain type are administered. This type of beta therapy is mainly used for tumors of the peritoneum or pleura;
3. . An achievement of science is that it has become possible to regulate X-ray radiation, thereby influencing lesions of various types. The higher the radiation energy, the higher the penetrating power. Thus, for relatively shallow lesions or mucous membranes, short-focus radiotherapy is used. For deeper damage, the radiation energy increases;
4. . Another important achievement of modern medicine. Also called gamma knife. The essence of the technology is that ionizing radiation occurs in very high doses, mostly applied once. Radiosurgery or stereotactic surgery is also used to eliminate non-malignant tumors in hard-to-reach places. Its most important advantage is that there is no need for craniotomy and other surgical interventions, which significantly reduces the patient’s recovery time and possible complications;
5. External beam radiotherapy. The name itself gives an idea of ​​this method of therapy. The device is located outside the body. The beam is directed at the tumor, passing through the skin and tissue;
6. Contact therapy, when the radiation carrier is directly injected into the tumor tissue. The carriers can be intracavitary, intravascular, or interstitial. When fighting the disease, a contact type of therapy such as brachytherapy is often used. She has proven herself excellent in wrestling;
7. Radionuclide radiotherapy – radioactive particles in certain doses they are contained in drugs, when taken, they can accumulate in the problem area of ​​​​a person. An example of this therapy is iodine in the thyroid gland.
8. Proton beams. A real breakthrough in medicine was the use of proton beams, which have proven to be a very effective method of treating cancer. Protons are accelerated in special accelerators. Having reached their destination, protons emit radioactive radiation, whose purpose is to destroy malignant cells. The effectiveness of the method lies in the fact that, thanks to targeted radiation, healthy cells are not affected, and harmful cells are destroyed to the maximum. The only drawback is the high cost of both the treatment itself and the equipment. Only 1% of patients in Russia have the opportunity to use this treatment method.

Each type of therapy is used for certain types of diseases and has its own individual characteristics. External beam radiotherapy, for example, is often used in the postoperative period for breast cancer to remove cancer cells remaining after surgery. This will prevent the recurrence of malignant cells. But if metastases already exist, then to reduce their size, a remote method is also used. Remote therapy is widely used for malignant tumors in the female genital organs, both in combination with surgery and as independent therapy.

Widely used for treatment. Capsules and needles, which contain a certain dose of isotopes, are placed into the tumor formation. Thus, the tumor tissue itself is destroyed, while nearby healthy tissue is not affected.

Stages of radiation therapy.

When treating any disease using radiation therapy, every stage of treatment is important. This is due to the complexity of the therapy itself and the patient’s condition before and after it. It is very important not to miss or underfulfill any of the specialists’ instructions. Let's look at these steps:

The first stage is the so-called pre-radiation period. Preparing the patient for the therapy itself plays a very important role in the fight against the disease. The patient is carefully examined for the presence of concomitant diseases, in the presence of which the patient is given therapeutic therapy. The skin is carefully studied, since its integrity and healthy condition are important for radiation therapy. After all this, a number of specialists, such as an oncologist, a radiotherapist, a physicist, and a dosimetrist, decide what dose of radiation will be used and exactly through which areas of tissue the therapy will be carried out.

The distance of the beam to the tumor is calculated with millimeter accuracy. For this, cutting-edge technology is used, which is capable of recreating a three-dimensional image of the affected organ. After all the preparatory procedures have been completed, specialists mark the areas on the body from where the effect on the tumor cells will be carried out. This is reproduced by marking these areas. The patient is advised how to behave and what to do to maintain these markers until the upcoming therapy.

Second phase and the most responsible – this is the direct ray period. The number of radiation therapy sessions depends on several factors. It can last from one month to two. And if radiation therapy is carried out to prepare the patient for surgery, then the period is reduced to 2-3 weeks. Usually the session is carried out for five days, after which the patient regains his strength for two days. The patient is placed in a specially equipped room where he lies or sits. A radiation source is placed on the marked area of ​​the body. To avoid damaging healthy tissue, the remaining areas are covered with protective blocks. After which the medical personnel, having instructed the patient, leave the room. Communication with them occurs through special equipment. The procedure is absolutely painless.

Third And The final stage – post-radiation period, rehabilitation period. The patient went through a difficult time fighting the disease, and when the main period, namely the radiation therapy process itself, has passed, the person feels severe physical and emotional fatigue and apathy. The patient's relatives and friends must create an emotionally comfortable environment for him. A person must fully rest and eat, attend cultural events, theaters, museums, in a word, lead a full, healthy life. This will help restore your strength. If radiation therapy was carried out using the remote method, it is necessary to care for the skin that was exposed to radiation, following the doctor's instructions.

After all stages of treatment, it is necessary to periodically visit specialists. The doctor must monitor the patient's condition to avoid complications. But if the condition worsens, it is necessary to visit your doctor unscheduled.

During radiation therapy, the doctor gives recommendations on what can and cannot be done during this very important period of treatment. Basically these rules are:

Nutrition plays a big role important role to restore the patient's strength. A person's food must contain proteins, fats, and carbohydrates in the required quantities. High-calorie foods are not prohibited, as a person loses a lot of energy and strength. Doctors recommend consuming more fluids. The reason for this is the presence in the body of toxins in large quantities, which arise during the breakdown of harmful cells.

It is undeniable to give up bad habits such as smoking and drinking alcohol.

Since the skin is mainly exposed to irradiation, it is necessary to carefully care for it, do not wear synthetics, do not expose it to direct sun rays. If the patient detects any changes in the form of itching, dryness, redness, you should immediately consult your doctor and not self-medicate.

Don't waste your time searching for inaccurate cancer treatment prices

*Only upon receipt of information about the patient’s disease, a representative of the clinic will be able to calculate the exact price for treatment.

Adequate rest and walks in the fresh air are a must. This will not only strengthen physical health the patient, but also the psychological state.

Side effects of radiation therapy

Despite the undeniable advantages of radiotherapy, there are a number of side effects that affect your well-being:

Each patient's tolerance is individual. It all depends on the radiation dose, skin condition, age and other indicators. Despite the presence of side effects, radiation therapy is effective method treatment of many diseases. Side effects will disappear some time after the end of therapy, and the person will quickly recover. You just need to follow the doctors' recommendations.

Contraindications to radiation therapy

In some cases, radiation therapy should not be used. These are:

1. Intoxication of the body for one reason or another;
2. High temperature, the cause of which must be identified and, if possible, eliminated;
3. Cachexia – when cancer cells are so widespread that radiation therapy is no longer effective;
4. Diseases associated with radiation damage;
5. A number of serious diseases;
6. Severe form of anemia.

Various rumors about the harmfulness of radiation treatment for cancer, side effects, force some people to turn to traditional healers. But many diseases, especially cancer, where radiation therapy is the only cure, cannot be cured folk remedies, but time can only be wasted. Therefore, you should not believe rumors and speculation, but get treatment only in specialized centers under the supervision of doctors.

Most cancer patients undergo radiation therapy. Its main goal is to destroy cancer cells and suppress their ability to reproduce. Despite the fact that irradiation techniques have improved significantly over the past decade, healthy tissue located near the tumor still suffers. This method cannot be called completely safe for health. However, its effect in terms of reducing and destroying the tumor in most cases overlaps Negative consequences.

What can be the consequences of radiation therapy?

The consequences of exposure to radiation depend on its type, depth of penetration into tissue, and individual human reactions. The stronger and longer the exposure, the more noticeable the body’s reaction will be. Most often, complications occur in patients who undergo long-term treatment. The side effects of radiation therapy are not always severe; some patients tolerate such treatment quite easily. In some cases, the consequences develop immediately after the session, in others only after discharge from the hospital, because the therapeutic effect is realized even after the end of the course of radiation therapy.

Complications after radiation therapy:

• Skin reactions
• Pain, tissue swelling at the site of exposure,
• Shortness of breath and cough
• Reactions from the mucous membranes,
• Fatigue,
• Mood and sleep disorders
• Nausea, vomiting, disturbances in the gastrointestinal tract,
• Hair loss.

Most common skin reactions

After irradiation, the skin loses its resistance to mechanical influences, becomes more tender and sensitive, and requires more careful treatment and careful care.

The skin in the irradiated area changes color, discomfort, burning, and soreness are felt in this area. The skin's reaction to radiation is similar to a sunburn, but it develops gradually. The skin becomes drier and sensitive to touch. Blisters may form and break, revealing a weeping, painful area of ​​skin. Without treatment and proper care, such areas of the skin become entry points for infection. Abscesses may form in these places. Non-healing ulcers after radiation therapy develop in severe cases when patients have particularly sensitive skin, weakened immunity, or suffer from diabetes.

As a rule, skin reactions appear 10-15 days after the start of treatment and disappear 4-5 weeks after the end of the radiation procedures.

Degrees of skin damage resulting from radiation therapy:

• 1st degree - slight redness,
• 2nd degree - redness accompanied by peeling or swelling,
• Grade 3 - extensive redness with moist peeling and severe swelling.

Treatment of burns after radiation therapy depends on the extent of skin damage. In the first stage, it is enough to maintain daily skin hygiene and apply moisturizer after the irradiation procedure. In the second and third stages, if itching occurs, a cream containing corticosteroids can be prescribed, which will significantly improve the condition of the skin. However, its use should be limited in time (no more than 7 days). To prevent infection from entering the wound, bandages are applied to it. If signs of infection appear, antibacterial dressings with active silver ions or iodine should be applied.

Signs of radiation wound infection:

• Increased pain
• Sharp swelling,
• Increased redness
• An increase in the amount of fluid in the wound,
• The appearance of an unpleasant odor.

High temperature after radiation therapy may be due to infection entering the wound. In this case, it is necessary to conduct additional examinations to determine the nature of the infection.

Reactions from the respiratory system

Shortness of breath, difficulty breathing, and cough after radiation therapy develop when the effect is on the chest area, for example, with breast cancer. Radiation damage to the lungs appears within three months after irradiation. Typically, the cough is nonproductive (that is, it does not bring relief). If an infection occurs, the temperature may rise and the general condition may deteriorate. Treatment of radiation injuries to the lungs is limited to several methods:

• Electro- and phonophoresis,
• Magnetotherapy,
• Inhalation therapy,
• Massage,
• Breathing exercises.

In each specific case, methods are selected individually, taking into account the nature of changes in the respiratory organs and the nature of the tumor for which irradiation is performed.

With extensive irradiation of the abdominal and pelvic organs, the mucous membranes of the intestines, stomach, and bladder may suffer. In this regard, the functioning of these organs deteriorates. Irradiation of the ENT organs can lead to stomatitis, dryness and sore throat, and pain in this area.

Many cancer patients report fatigue as a side effect of radiation therapy. This is a rather unpleasant condition. The fact is that it does not go away after sleep or rest. The patient has a feeling that he lacks energy. All this happens not only due to the effect of radiation on the body, but also due to emotional experiences, changes in lifestyle and nutrition.

In order to alleviate the condition, at least slightly reduce the feeling of fatigue, you need to try to follow a routine, sleep enough time, and engage in feasible physical exercise. There is no need to do hard work. You may need to ask friends or loved ones for help and support.

How to recover after radiation therapy? This question is asked by almost all patients. After completing the course of treatment, the body regains its strength after some time and improves the functioning of the organs that were damaged. If you help him, the recovery period will go faster.

Usually, after a course of radiation therapy, special medications are prescribed. Strictly follow all doctor’s recommendations, take medications according to the doctor’s suggested regimen.

Even if you always want to lie down, find the strength to move, do not let your body stagnate. Movement will give you energy. Light simple exercises and walks are suitable. You need to spend as much time as possible in the fresh air.

The liquid will help the body get rid of toxins and harmful substances formed as a result of treatment. You should drink about 3 liters of liquid. It can be regular or mineral water, juices. Carbonated drinks should be excluded.

To reduce the amount of toxins entering your body, stop smoking and drinking alcohol. Drinking alcohol in small doses (usually red wine) may only be indicated in certain cases. Then it is recommended by the attending physician.

Proper nutrition will help the body “come to its senses” faster. Food should be natural, without preservatives or artificial additives. There should be no smoked meats or pickles in the diet. More vegetables and greens.
Avoid being in the sun.

Wear loose clothing made of soft fabrics to prevent chafing of the radiation site.

See your doctor regularly. Be sure to tell him about cases when something has changed in your health, pain has begun to bother you, or your temperature has risen.

Treatment of cancer for many patients becomes a real challenge due to serious side effects. However, the day comes when a person feels relief. He understands that the disease is receding and life is getting better.

Diffusion potential

In electrochemical circuits, potential jumps occur at the interfaces between unequal electrolyte solutions. For two solutions with the same solvent, such a potential jump is called diffusion potential. At the point of contact between two solutions of the spacecraft electrolyte, which differ from each other in concentration, diffusion of ions occurs from solution 1, which is more concentrated, into solution 2, which is more dilute. Typically, the diffusion rates of cations and anions are different. Let us assume that the rate of diffusion of cations is greater than the rate of diffusion of anions. Over a certain period of time, more cations than anions will pass from the first solution to the second. As a result, solution 2 will receive an excess of positive charges, and solution 1 will receive an excess of negative charges. Since solutions acquire electrical charges, the rate of diffusion of cations decreases, that of anions increases, and over time these rates become the same. In a steady state, the electrolyte diffuses as a single unit. In this case, each solution has a charge, and the potential difference established between the solutions corresponds to the diffusion potential. Calculation of the diffusion potential is generally difficult. Taking into account some assumptions, Planck and Henderson derived formulas for calculating the central value. So, for example, when two solutions of the same electrolyte with different activities come into contact (b1b2)

where and are the limiting molar electrical conductivity ions. The value of the CD is small and in most cases does not exceed several tens of millivolts.

EMF of an electrochemical circuit taking into account the diffusion potential

……………………………….(29)

Equation (29) is used to calculate (or) from the measurement results of E if (or) and are known. Since determining the diffusion potential is associated with significant experimental difficulties, it is convenient to eliminate the EMF when measuring it using a salt bridge. The latter contains a concentrated electrolyte solution, the molar electrical conductivities of the ions are approximately the same (KCl, KNO3). A salt bridge, which contains, for example, KS1, is placed between electrochemical solutions, and instead of one liquid boundary, two appear in the system. Since the concentration of ions in the KC1 solution is significantly higher than in the solutions it connects, almost only K+ and C1- ions diffuse through the liquid boundaries, at which very small and opposite-sign diffusion potentials arise. Their sum can be neglected.

Structure of the electrical double layer

The transition of charged particles across the solution-metal boundary is accompanied by the appearance of an electric double layer (DEL) and a potential jump at this boundary. The electric double layer is created by electric charges located on the metal and ions of opposite charge (counterions) oriented in solution near the surface of the electrode.

In the formation of the ion plate d.e.s. Both electrostatic forces take part, under the influence of which the counterions approach the electrode surface, and the forces of thermal (molecular) motion, as a result of which the d.e.f. acquires a blurry, diffuse structure. In addition, in the creation of a double electrical layer at the metal-solution boundary significant role plays the effect of specific adsorption of surface-active ions and molecules that may be contained in the electrolyte.

The structure of the electric double layer in the absence of specific adsorption. Under the building of the D.E.S. understand the charge distribution in its ionic plate. To put it simply, the ion plate can be divided into two parts: 1) dense, or Helmholtz, formed by ions that come almost close to the metal; 2) diffuse, created by ions located at distances from the metal exceeding the radius of the solvated ion (Fig. 1). The thickness of the dense part is about 10-8 cm, the diffuse part is 10-7-10-3 cm. According to the law of electrical neutrality

……………………………..(30)

where, is the charge density on the metal side, on the solution side, in the dense diffusion part of the emp. respectively.

Fig.1. The structure of the electrical double layer at the solution-metal interface: ab - dense part; bv - diffuse part

The potential distribution in the ionic plate of the electric double layer, reflecting its structure, is presented in Fig. 2. The magnitude of the potential jump μ at the solution-metal interface corresponds to the sum of the magnitudes of the potential drop in the dense part of the emp and in the diffuse part. Structure of the D.E.S. is determined by the total concentration of the solution. As it increases, the diffusion of counteractive substances from the surface of the metal into the mass of the solution is weakened, as a result of which the size of the diffuse part is reduced. This leads to a change in -potential. In concentrated solutions, the diffuse part is practically absent, and the double electric layer is similar to a flat capacitor, which corresponds to the model of Helmholtz, who first proposed the theory of the structure of electrical power.

Fig.1. Potential distribution in the ion plate at different solution concentrations: ab - dense part; bv - diffuse part; ts is the potential difference between the solution and the metal; w, w1 - potential drop in the dense and diffuse parts of the emp.

The structure of the electric double layer under conditions of specific adsorption. Adsorption - the concentration of a substance from the volume of phases at the interface between them - can be caused by both electrostatic forces and forces of intermolecular interaction and chemical ones. Adsorption caused by forces of non-electrostatic origin is usually called specific. Substances that can be adsorbed at the interface are called surface-active agents (surfactants). These include most anions, some cations, and many molecular compounds. The specific adsorption of the surfactant contained in the electrolyte affects the structure of the double layer and the value of the -potential (Fig. 3). Curve 1 corresponds to the potential distribution in the electric double layer in the absence of a surfactant in solution. If the solution contains substances that produce surface-active cations upon dissociation, then due to specific adsorption by the metal surface, the cations will enter the dense part of the double layer, increasing its positive charge (curve 2). Under conditions that enhance adsorption (for example, an increase in adsorbate concentration), the dense part may contain an excess amount of positive charges compared to the negative charge of the metal (curve 3). According to the potential distribution curves in double layer it can be seen that the -potential changes during the adsorption of cations and may have a sign opposite to that of the electrode potential.

Fig.3.

The effect of specific adsorption is also observed on an uncharged metal surface, i.e. under conditions where there is no exchange of ions between the metal and the solution. The adsorbed ions and corresponding counterions form an electrical double layer located in close proximity to the metal on the solution side. Adsorbed polar molecules (surfactant, solvent) oriented near the metal surface also create an electrical double layer. The potential jump corresponding to the electric double layer with an uncharged metal surface is called the zero charge potential (ZPC).

The potential of zero charge is determined by the nature of the metal and the composition of the electrolyte. When adsorption of cations p.n.s. becomes more positive, anions - more negative. Zero charge potential is an important electrochemical characteristic of electrodes. At potentials close to p.s.e., some properties of metals reach limiting values: surfactant adsorption is high, hardness is maximum, wettability by electrolyte solutions is minimal, etc.

The results of research in the field of the theory of the electric double layer made it possible to more broadly consider the issue of the nature of the potential jump at the solution-metal interface. This jump is due to the following reasons: the transition of charged particles across the interface (), specific adsorption of ions () and polar molecules (). The galvanic potential at the solution-metal interface can be considered as the sum of three potentials:

……………………………..(31)

Under conditions under which the exchange of charged particles between the solution and the metal, as well as the adsorption of ions, does not occur, there still remains a potential jump caused by the adsorption of solvent molecules - . Galvani potential can be equal to zero only when and compensate each other.

At present, there are no direct experimental and computational methods for determining the magnitude of individual potential jumps at the solution-metal interface. Therefore, the question of the conditions under which the potential jump becomes zero (the so-called absolute zero potential) remains open. However, to solve most electrochemical problems, knowledge of individual potential jumps is not necessary. It is enough to use the values ​​of electrode potentials expressed in a conventional scale, for example, a hydrogen scale.

The structure of the electrical double layer does not affect the thermodynamic properties of equilibrium electrode systems. But when electrochemical reactions occur under nonequilibrium conditions, the ions are influenced electric field double layer, which leads to a change in the speed of the electrode process.

The practically measured exact value of EMF usually differs from the theoretically calculated one using the Nernst equation by a certain small amount, which is associated with potential differences that arise at the point of contact of different metals (“contact potential”) and different solutions (“diffusion potential”).

Contact potential(more precisely, the contact potential difference) is associated with different meaning electron work function for each metal. At any given temperature, it is constant for a given combination of metal conductors of a galvanic cell and is included in the EMF of the element as a constant term.

Diffusion potential occurs at the boundary between solutions of different electrolytes or identical electrolytes with different concentrations. Its occurrence is explained by different rates of diffusion of ions from one solution to another. The diffusion of ions is due to the different values ​​of the chemical potential of the ions in each of the half-elements. Moreover, its speed changes over time due to a continuous change in concentration, and therefore m . Therefore, the diffusion potential, as a rule, has an uncertain value, since it is influenced by many factors, including temperature.

With normal practical work the value of the contact potential is minimized by the use of installation with conductors made of the same material (usually copper), and the diffusion potential by the use of special devices called electrolytic(saline)bridges or electrolytic keys. They are tubes of various configurations (sometimes equipped with taps) filled with concentrated solutions of neutral salts. For these salts, the mobility of the cation and anion should be approximately equal to each other (For example, KCl, NH 4 NO 3, etc.). In the simplest case, an electrolytic bridge can be made of a strip of filter paper or an asbestos flagellum moistened with a KCl solution. When using electrolytes based on non-aqueous solvents, rubidium chloride is usually used as a neutral salt.

The minimum values ​​of contact and diffusion potentials achieved as a result of the measures taken are usually neglected. However, for electrochemical measurements that require great accuracy, contact and diffusion potentials should be considered.

The fact that a given galvanic cell has an electrolytic bridge is reflected by a double vertical line in its formula, located at the point of contact of two electrolytes. If there is no electrolytic bridge, then a single line is placed in the formula.