The solubility of iron in water. How to clean water from iron?

Iron is present in water in the form of two- and trivalent ions. How to clean drinking and technical fluid from these contaminants? An actual problem for an ordinary family and a large enterprise. Let's consider the reasons on which the solubility of iron in water depends, the forms of pollutants, the ways to remove ferro-compounds.

Why is the tap water yellow and brown?

Iron compounds give the water a yellowish color, often an unpleasant aftertaste, you can see pollution in the form of brown flakes. The listed phenomena are deterioration of the organoleptic properties of drinking water. Color change is something that water consumers pay attention to first. In addition, there are consequences for human health. Negatively affects the liver, teeth, the entire gastrointestinal tract, skin and hair consumption of poor quality water from the tap, in which there is iron.

Solubility in water is explained not only by the interaction of ferro-compounds from the rock composition with other substances in nature. The concentration of Fe ²⁺ and Fe ³⁺ ions is increasing due to the corrosion process, which is constantly going on in apparatuses and pipes of water supply made of iron alloys. Pipelines are gradually becoming unusable, the properties of products are changing, in the production of which water with an admixture of iron was used.

What is the solubility of iron in water?

The chemical element, which was given the Latin name Ferrum, is in second place after aluminum in terms of prevalence in the earth's crust. In large quantities on the planet there are deposits of iron pyrites or pyrite (its formula is FeS ₂₎ . Ferro compounds are found in rocks of volcanic and sedimentary origin in the form of hematite, magnesite, brown iron ore.

A simple substance is iron - a silvery-gray plastic metal, insoluble in water. Oxides and hydroxides, many iron salts also do not interact with water. The solubility of FeO in water is discussed in connection with its ability to be oxidized to ferric oxide. When they speak of an aqueous solution of FeO, we have in mind the content of ferrous ions. In some water sources, this figure reaches 50 or more milligrams per liter. This is a high concentration, such drinking water must be cleaned.

How does iron get into natural waters?

Physical and chemical erosion leads to crushing, dissolution and destruction of rocks containing iron compounds. As a result of reactions occurring in nature, Fe ²⁺ and Fe ³⁺ ions are liberated. They Actively participate in oxidation-reduction processes. The divalent ion is oxidized, gives up the electron and becomes triply charged. The solubility of iron in water is the presence of the Fe ²⁺ cation. As a result of the reactions occurring in the solution, different salts are obtained. Among them are soluble, for example sulfates, and insoluble (sulfides, carbonates). When the water is de-ironed, the soluble form passes into an insoluble form, and flocs form in the precipitate. Divalent iron is oxidized to trivalent iron in the presence of oxygen or other oxidizing agents (ozone, chlorine).

The transformation of ions eventually leads to the appearance of brown rust, which is stable to further oxidation, and its conditional composition can be represented in the following form: Fe ₂ O ₃ • nH ₂ O. Particles of Fe ³⁺ are part of complex inorganic and organic substances that occur in surface waters .

Is the content of ferro compounds in natural waters identical?

The concentrations of the chemical element and the types of iron in water depend on the rock composition of the earth's crust and the state of various sources. At the same time, two- and trivalent iron compounds, organic forms, such as ferrous bacteria and colloidal substances (soluble and insoluble) can be present.

If there are deposits of sulphate ores, it is more likely that ferrous iron will be present at high concentrations. The solubility in water of the ferro compounds increases with temperature near the volcanic regions. In rivers and lakes, the content of iron is higher, if there is a discharge of sewage from metallurgical and chemical plants.

How to clean water from iron?

Reactive and nonreagent methods are used to remove ferro-compounds. The basis of most processes is the oxidation of a divalent ion to a trivalent cation. Similarly, they are treated with other impurities in water - they are transferred to insoluble compounds and removed by means of a filter. This principle is based on the work of most industrial installations.

What is the solubility of iron in water is determined with the help of instruments. Then de-ironing with chemical reagents: oxygen, chlorine, ozone, potassium permanganate, hydrogen peroxide. There are chemical reactions of oxidation, and an insoluble precipitate is obtained. It can not only be filtered out, but can also be removed after settling by decantation (drain clean water from the sediment). During ozonation and chlorination, decontamination (disinfection) occurs simultaneously. It is believed that the use of ozone is a more promising method, because chlorine is dangerous to human health.

What are the ways of deferring small amounts of water?

At home, hydrogen peroxide and manganese can be used from the above reagents. How to clean water from iron, if you want to get a small amount in a short time? When the peroxide is added to the water, the sludge flakes fall out. It is necessary to wait for him to sink to the bottom of the tank and drain the water, or to pass it through an ordinary pitcher filter. Such water-free water is suitable for drinking and cooking.

With respect to organic forms of iron, these methods are ineffective. The reagents mentioned above do not precipitate colloidal particles quickly enough.

Ion exchange and catalysis - methods of deironing water

There are autonomous installations operating on the principles of catalysis, ion exchange. Devices are used to purify water in small industrial enterprises and in cottages.

Iron in the catalytic process is removed by means of a special backfill produced from natural and synthetic raw materials. A filter for deironing water is a metal container. Inside put the filling and let in water. The substance is a catalyst for the oxidation of ferrous iron, transferring it to an insoluble state from various forms.

In ion-exchange deironing, cation exchangers obtained from resin-ion exchangers, for example zeolite (mineral), are used. In recent years, the production of synthetic products for deironing water by ion exchange has been established.

Why do we need an alternative to reagents?

Dietary time chemicals are used, if there is this harmful impurity - iron in water. Types of iron are different, so you need to look for the optimal solution, a method suitable for purifying water from a particular source, for which forms and concentrations of iron are installed.

Chlorination is a thing of the past, this way adversely affects the quality of water and the health of the population. Aeration or water enrichment with air is a method practically devoid of shortcomings. Oxygen is passed through the water, iron is oxidized, and insoluble flakes of the precipitate can be removed by filtration or settling.

Iron removal is carried out without chemical reagents - using the electrochemical method. Two electrodes are immersed in a container of water, which must be cleaned. A negative electrode, the cathode, attracts and retains positively charged iron ions, in whatever form they are. Another non-reagent method is the use of special membranes.

Each of the above methods has not only advantages, but disadvantages. The choice of method depends on the form in which iron is present in the water.