There is a significant amount of metals in their pure form and various compounds in the earth’s crust. The presence of bivalent iron in water is almost impossible to determine. It is in a dissolved state and does not affect transparency. However, in underground water sources in most regions of India, the content of this chemical element significantly exceeds acceptable standards.
Excess dissolved iron in water is a serious threat to human health. The body can assimilate only a certain amount of this metal, necessary to ensure its vitality. However, the surplus of this element is not completely excreted and accumulates in tissues, displacing or replacing other trace elements: copper, calcium, zinc, and others. This leads to various diseases such as diabetes mellitus and functional disorders of the central nervous system.
Compounds of bivalent iron in the water
In underground sources, this metal is present in soluble and insoluble forms. In water, bivalent iron is mainly in bicarbonate of oxide – Fe (HCO3)2. Another name is two-charred iron. This compound is not highly resistant and, due to the hydrolysis reaction, is destroyed and, with the loss of acid, turns into a hydrates Fe (OH)2.
The increased content of iron dissolved in water (two-valent) is characteristic, first of all, for underground aquifers. This is explained by the low concentration of oxygen in the liquid and the lack of contact with the atmosphere. The oxides are volatile and, when exposed to air, are promised by passing into other insoluble forms; this property is used in water purification methods.
Difference of bivalent iron from trivalent
This chemical element has one exciting feature – it has several degrees of oxidation, or rather two. This metal property is significant for geochemical processes. Bivalent iron and trivalent iron in water are present simultaneously in the form of compounds and have several differences:
- Oxides have a high solubility, and their presence is not determined visually.
- Trivalent iron – oxides can be in the form of a solution, weight, or colloidal particles.
- The bivalent iron can move into trivalent, oxidizing when exposed to oxygen. The reverse process is not possible under normal conditions.
A large amount of bivalent iron in the water from the well of conventional or artesian, as well as in the well – a phenomenon widespread. At the same time, in open sources, this metal is mainly present in a trivalent state. This element also has the ability to change the degree of oxidation during chemical reactions.
Causes of iron in water and current regulations
Complex geochemical processes determine the content of certain trace elements in the Earth’s crust. From what in the water, bivalent iron is insignificant quantities – an issue that requires careful consideration. The main causes of the soluble compounds of this metal in underground and surface sources include:
- Destruction and dissolution of rocks in water when it seeps into deep aquifers.
- The formation of organic compounds involving predominantly humic acids.
- The stock of industrial enterprises is especially metallurgical and chemical.
- Corrosive processes in steel pipelines of centralized and autonomous water supply systems.
The first two factors of water pollution are considered to be natural, and natural phenomena cause them. The remaining causes are artificial and are the result of human economic activity.
The content of bivalent iron in the water is not separately regulated. The current sanitary standards set a total figure. The quality of the liquid coming from the centralized water supply systems is determined by the requirements of SanPin 1.4.1074-01. According to the document, the maximum allowable concentration of this element is 0.3 mg/L.
Basic methods of determining the amount of iron in the water
With a significant excess of the content of this metal in surface and groundwater, this fact can be established without special equipment. The trivalent iron in the water is dissolved and gives the liquid a very unpleasant glandular taste and a specific smell. At concentrations of this element, more than 1 mg/l, its presence will be noticeable even in strong tea or coffee.
It is impossible to accurately determine the content of bivalent iron in the water described above by the organoleptic method. It is only used for a very approximate estimate. The photometric method used in specialized laboratories allows establishing metal concentration in the liquid with sufficient accuracy. It is based on the color dependence of the samples on the content of the complex connection.
How to purify water from dissolved iron
A large amount of this micronutrient is dangerous for human health and destructive for technology. Cleaning water from bivalent iron from a well is possible in various ways, both household and with the use of professional equipment. Let’s take a closer look at both ways and evaluate their effectiveness.
Household water treatment methods
At home, it is quite possible to reduce the content of this metal to the required values. You can clean water from dissolved iron at no particular cost using the following methods:
Defending in an open container. On the coming of the day, the bivalent iron will move into a trivalent state when exposed to air and form brown sediment on the bottom. Accelerate the process allows aeration – pumping air into the water with the help of an aquarium compressor.
Boiling for at least 10 minutes. Dissolved iron settles on the walls of dishes in the form of a rusty plaque. A side effect of this method is to reduce the stiffness of the water.
Having received an answer to how to clean the water from the iron dissolved in it, we are not in a hurry to rejoice. In addition, they are very inconvenient, wait a day and drain relatively clean water from the sediment is not the best solution.
Professional water filtration methods
Modern technologies apply to both centralized and autonomous water sources. When choosing a water filter with dissolved iron, you should consider not only its quantitative content but also its pH. The following cleaning methods are used for this purpose:
- Deforestation with aeration;
- Ion exchange resins;
- Reverse osmosis.
The ways to purify water from bivalent iron mentioned in the list are given descending order of their effectiveness. In assessing the effectiveness of these methods, the quality of the liquid received and the financial costs are taken into account.
Filters of deforestation and aeration
The rapid removal of dissolved iron from the water and reducing its content to the required level is achieved through reagent and reactive technologies. The first is usually used in industrial plants and, for their implementation, need high-quality dispensing equipment.
The basis of reagents methods is the principle of iron oxidation in water by air, which is fed into it in pressure or no-pressure way. The first version uses a high-pressure compressor, and excess gas is drained into the atmosphere through a special valve. In the second case, the filters use ejection (air sucker by the flow of liquid) or showering (spraying to increase the area of contact).
This method, combined with aeration, reduces the amount of bivalent iron in the water purification process to regulatory requirements. These methods of deforestation have become most common in the industry and everyday life due to high efficiency at relatively low initial and operating costs.
Ion exchange filters
High-quality water treatment from dissolved iron is possible through the use of innovative physical and chemical methods. Ekotar ion resins replace Fe ions2+ Na ion with the first binds and are held in porous cations pellets. As iron accumulates in the working environment, the efficiency of the process is reduced, and its regeneration is carried out by washing a rich solution of table salt.+
Ion exchange filters for water purification from dissolved iron are used at concentrations of the latter no more than 5 mg Fe/L. In this case, the liquid requires pre-treatment. It is necessary to remove trivalent iron, manganese, and hydrogen sulfide. The presence of these elements and compounds leads to rapid degradation of filling. Despite the shortcomings, this method is the second most popular, yielding to the palm of primacy with aeration.
Reverse osmosis installations
Effectively remove bivalent iron from the water allows a filter with a semi-permeable membrane. Reverse osmosis plants provide a complete clean-up of the liquid from all kinds of impurities, the concentrate of which merges into the drainage. The resulting permit does not contain minerals and trace elements and needs additional processing.
Reverse osmosis technology is quite expensive, for the installation requires high pressure, which then included pump provides. The system also has several prefiltration elements to purify water from mechanical impurities to preserve the cartridge resource.
Cleaning water from valence iron
We select equipment for decontamination with aeration, ion exchange resins, or reverse osmosis installations based on the customer’s technical requirements. The proposed water treatment systems will allow you to stay healthy and prevent premature failure of household appliances.