Hard water

Have you ever noticed that always basic kettle to boil the water you use? The longer base of the kettle will be increasingly thick. why ? Crust formed on the base of the kettle will cause heat delivery is retarded, so as to heat water heating would requires a longer time.

Crust formed on the base of the kettle is caused by hard water. Hard water is water that contains ions Ca2 + or Mg2 +. Water is not aware of dangerous waters, because these ions can be dissolved in water. However, with high levels of Ca2 + which will cause water to become turbid.

Although not dangerous, it turns hard water can cause some harm, among others:

Soap become less bubbly. This happens because the ions Ca2 + or Mg2 + can react with soap to form sediment.

Ca2 + (aq) + 2RCOONa (aq) -> Ca (RCOO) 2 (s) + 2Na + (aq)

With the formation of sediment, then the soap function as a binder dirt to become less or even ineffective. Soap will be bubbly again after all the ions Ca2 + or Mg2 + contained in the water settles. Another case with detergent, detergents do not react with the ions Ca2 + or Mg2 + so that the detergent is not affected by hard water.

Hard water can cause the formation of crust at the bottom of the kettle that always used to heat water. So that is needed to heat water heating is longer. This is a waste of energy. The emergence of crust on the steam pipes can cause a blockage so feared tersbut pipes will burst.

Hard water is classified into two types, based on the type of anion bound by cations (Ca2 + or Mg2 +), ie hard water temporary and permanent hard water.

Temporary hard water
While hard water is hard water containing bicarbonate ions (HCO3-), or may be water containing a compound of calcium bicarbonate (Ca (HCO3) 2) and / or magnesium bicarbonate (Mg (HCO3) 2). Water containing ions or compounds called temporary hard water because kesadahannya can be eliminated by heating the water, so water is free from ion or Ca2 + and Mg2 +. By heating these compounds will settle to the bottom kettle. The reaction is: Ca (HCO3) 2 (aq) -> CaCO3 (s) + H2O (l) + CO2 (g)

Permanent hard water
Permanent hard water is hard water that mengadung anions other than bicarbonate ions, for example to form ion Cl-, NO3-and SO42-. Means that soluble compounds may be in the form of calcium chloride (CaCl2), calcium nitrate (Ca (NO3) 2), calcium sulfate (CaSO4), magnesium chloride (MgCl2), magnesium nitrate (Mg (NO3) 2), and magnesium sulfate (MgSO4 .) Water containing these compounds called permanent hard water, because kesadahannya not be eliminated simply by heating. To free it from the hardness of water, must be done by chemical means, namely by reacting water with certain chemical substances. Reagent used is a solution of carbonate, which is Na2CO3 (aq) or K2CO3 (aq). The addition is intended to precipitate a solution of carbonate ion or Ca2 + and Mg2 +.
CaCl2 (aq) + Na2CO3 (aq) -> CaCO3 (s) + 2NaCl (aq)
Mg (NO3) 2 (aq) + K2CO3 (aq) -> MgCO3 (s) + 2KNO3 (aq)
With the formation of precipitate CaCO3 or MgCO3 means the water has been liberated from the ion Ca2 + or Mg2 + or in other words the water has been free of hardness.

In industries that use steam boilers, water used must be free of hardness. The process of removal of water hardness that is often conducted in industries is through screening by using the substances as follows:

1. Cation and anion resin binder.

Hardness is generally removed using ion exchange resins. Commercial water softener resin can be used on a small scale, though not effectively used for large scale. Resin is a substance that has a large pore and act as ion exchange derived from polysterol, or polyakrilat a granular form or a small ball which has a basic structure that joins with cationic functional groups, non-ionic / anionic or acid. Often times the resin used to remove large molecules from water such as acid humus, liqnin, sulfonic acid. For the regeneration of used alkaline salts or sodium hydroxide, hydrochloric acid can also be used if the resin with acid properties. In regeneration it produced organic eluent containing a high concentration. For the process of drinking water until now hunya used resin with anionic character.

Synthetic ion exchange resin is a polymer that consists of two parts, namely the functional structure and the matrix resin is difficult to dissolve. These ion exchange resins made by condensing phenol with formaldehyde which is then followed by a sulfonation reaction to obtain a strong acid ion exchange resins.

As for the strong base ion exchange resin obtained by phenilendiamine condense with formaldehyde and has been shown that both the cation exchange resin and anion exchange resin synthesis results can be used to separate or take salt - salt.

In general, compounds that are used for the basic framework of a strong acid ion exchange resin and strong base styrene polymer is a compound divinilbenzena. Chemical bonds in polymers is very strong so it is not easily soluble in acidic and alkaline properties are high and remain stable at temperatures above 150oC.

This polymer is prepared by reacting styrene with divinilbenzena, having formed the framework of the ion exchange resin will be used for attachment of cluster ions to be exchanged.

Cation exchange resin prepared by reacting the base compound with a cluster ion that can produce (release) positive ions. Cluster ions are commonly used in strong acid cation exchange resin is a sulfonic group and a way of making the sulfonated polymer polistyren divinilbenzena (matrix resin).

Exchange resin on which reacted with the cluster ions that can release negative ions obtained by anion exchange resins. Anion exchange resins are made with the same matrix with cation exchange resin but the cluster ions can be inserted to remove the negative ions, for example-N (CH3) 3 + or other group or in other words after the formation of copolymer styren divinilbenzena (DVB), then later diaminasi diklorometilasikan to obtain anion exchange resin.

Cluster ions in ion exchange is a group of hydrophilic (water soluble). Ions dissolved in water is the ion - ion are interchangeable because of this group attached to the polymer, then he can pull all the polymer molecules in water, the polymer resin is bonded by crosslinking (cross linked) with other polymer molecules, the result will swell in water .

The mechanism of ion exchange resins, although the non-crystallization is very similar to the exchange of crystal lattice ions. With ion exchange resin is happening on the overall structure of the gel from the resin and is not confined to surface effects. In the anion exchange resin, the exchange occurs due to covalent acid absorption. If anion exchange is poliamin, amine content of the resin is a measure of the total exchange capacity.

In the ion exchange process if electrolyte comes in contact directly with ion exchange resins will occur in a stoichiometric exchange of a number of ions - ions that are exchanged with ions - ions with the same charge will be exchanged with ions - ions with the same charge also with a comparable amount.

Ion exchange materials is the main form of grains or granular with the structure of long molecules (the co-polymerization), by inserting the functional group of sulfonic acid, carboxyl ions. These compounds will be joined by ion pairs such as Na +, OH-or H +. This compound is a porous structure. This compound is a positive ion exchange (cationic) to exchange ions with electrolyte the same charge (positive) and vice versa negative ion exchange (anionic) to exchange anions contained in water treated in the unit, "Ion Exchangers".

Ion replacement process could be "reversible" (to return), which means that ion exchange material can be regenerated. As an example for the regeneration material cationic form Na + exchanger can be regenerated with concentrated NaCl solution, H + form regenerated using HCl solution anionic exchanger material while the OH-form can be regenerated with NaOH solution (see the user manual from the factory that sells this material.)

Regeneration is a rejuvenation, penginfeksian with new strength against the ion exchange resin has been exhausted when it works or already overburdened, it has been saturated. Regeneration of ion exchange can be done easily because the ion exchange is a reversible process that should be attempted only for the ongoing regeneration reaction in the opposite direction of the ion exchange.

2. Using Zeolites.

Zeolite has the chemical formula Na2 (Al2SiO3O10) .2 H2O or K2 (Al2SiO3O10) .2 H2O. zeolite has a three-dimensional structures have pores that can dikewati water. Ion Ca2 + and Mg2 + ions will be exchanged with Na + and K + from the zeolite, so the water is free of hardness.

The easiest way to find out the water that you always use is water conscious or not using soap. When the water you use is hard water, the soap will be difficult berbiuh, even if bubbly, berbuihnya little. Then to know what types of water hardness is by heating. If you find that after heating, foaming soap remains difficult, meaning the water that you use is hard water remains.

To remove the temporary hardness or hardness is still on the water you use at home can be done by using a zeolite. You simply provide a keg which can accommodate a zeolite. At the bottom of the vat was made faucet. Water that you will use is passed on first zeolite. Water that has passed through the zeolite can be used for domestic purposes, spserti washing, bathing and cooking purposes.

Zeolite has the capacity to exchange ions, which means you can not use the same zeolite forever. So at a certain time frame you have to replace it.