ION EXCHANGE ADSORPTION DİLAN YAVUZ 21425283

ION EXCHANGE Ion exchange (IE) is a water treatment method used to remove unwanted dissolved impurities from water and other liquid solutions. The process by which this is accomplished is through the exchange of ions from the contaminant with the ions from a desirable substance. Ion exchange is the reversible exchange of ions between a liquid and a solid.

Usage areas It is used for water softening in drinking water treatment systems. It is used as ion exchanger and catalyst in chemical analysis. It is used in the production of fruit juices in the food sector. Used in sugar industry, in production.

In ion exchange, resin is used to remove unwanted ions from the liquid In ion exchange, resin is used to remove unwanted ions from the liquid. Resin is a chemical material with anionic or cationic character, which is water-insoluble, in the form of small bubbles, in colors between light yellow and orange, containing various polymers cross-linked in the body.

TYPES OF THE RESİN Cation Exchange Resins Anion Exchange Resins Mixed Bed Resins

ANION AND CATION EXCHANGE RESINS With cations hydrogen and sodium, the anions are replaced by hydroxide ions. Ion exchange resins that change positive ions are cationic, and ion exchange resins that change negative ions are called anionic resins.

The main component of ion exchange equipment is a microporous exchange resin. At water softening, usually done with sulfonated polystyrene beds that are supersaturated with sodium to cover the bed surface. As water passes through this resin bed, ions attach to the resin beads.

Ion Exchange Process

Cationic ion-exchange resins used in hardness removal are sodium (Na) based resins which retain the calcium (Ca) and magnesium (Mg) in the water and give sodium (Na) ions in their own constituents to the water.

In this manner Ca and Mg ions in the softened water is absent, it is higher Na ion concentrations. However, the high Na concentration does not adversely affect the availability of water (except for those who are medically sensitive).

REGENERATION After a time, the beds become saturated and the exchange resin must be regenerated or recharged. To regenerate, the ion exchange resin is flushed with a salt brine solution. The salt water contacts the resin and the Na ions in the brine are replaced by the Ca and Mg ions on the resin. The resin reloaded with Na ions is renewed and ready for reuse.

TANK DESIGN

It is recommended to work with at least two columns It is recommended to work with at least two columns. When one of them is working, the other is rejenered or kept in reserve. Pressure tanks are used for small ion exchange columns, while large- scale applications use systems that operate with gravity flow. Fiberglass and steel are generally used as tank material. Fiberglass tanks are usually less than 2.5 m in diameter and steel tanks can be up to 3.6 m in diameter. Steel tanks cost more than fiberglass tanks. Column heights are usually less than 4m. Column use higher than 4m is not suitable due to resin pressure difference limitation. During backwashing, the bed should be as high as the column to allow it to expand. The size limits of the manufactured tanks are determined by the highway conditions such as the turning diameter and the underpass height.

PIPING While pvc pipes are mostly used in small systems, plastic pipes or stainless steel pipes are used in large systems.

MAINTENANCE In addition to routine maintenance of pumps and valves, periodic resin cleaning or replacement is required. For cleaning, the resin must be left out of service for 8 hours or more. Unusual regeneration of the resin may be required after cleaning. The working life of cationic resins used for softening purposes is 10 years, while the time for anion exchange resins is 3-5 years. If it is damaged, it is expected to shorten its service life.

ADSORPTION Adsorption is most commonly implemented for drinking water preparation, process water or as tertiary cleansing after, for example, biological water purification. Adsorption is a process where a solid is used for removing a soluble substance from the water

Adsorbents of using specific aplications Active carbon Natural or synthetic zeolites it has a very homogeneous pore distribution and polar bonding sites. Zeolites are a lot more selective than active carbon; Natural clay minerals used for the adsorption of very polar organic and inorganic matter Silica gel and activated aluminium Silicic acid

Active carbon is by far the most commonly used adsorbent and is particularly suited to the removal of apolar compounds. The common application area of active carbon is the organic matter, color, odor, taste and chlorine removal present in the water.

Active carbon is a material with a very large surface area(1000-1500 m2/gr) The size of the surface area is a very effective factor in removing the pollution since the polluting substances will be held on the surface of the active carbon.

The best active carbons currently used for wastewater treatment are derived from various coals and natural materials. These include: stone coal, charcoal, peat, lignite, wood, bone; Coconut, hazelnut and rice husks; fruit seeds and oil products. The active carbons obtained from these materials are usually hard and chewy. They can be used for a long time without decomposition in water. Activated carbons can be produced in various shapes.

Active Carbon Types Powder Activated Carbon (PAC) Granular Activated Carbon (GAC)

Active carbons in powder form are obtained, resulting in chemical activation of the carbon. Activated carbons in powdered form are the most active carbon in the treatment of wastewater nowadays, while activated carbon in granular form gives very good results in wastewater treatment systems. These activated carbons have also been used for years to remove waste water containing biologically treated wastewater and organic- derived industrial wastes. 

ACTIVE CARBON FILTERS Active carbon filters are physico-chemical treatment units that work with the principle of adsorption. It runs fully automatically without human intervention.

Depending on the degree of contamination of the water passing through it and the amount of water passing, after a while the active carbon filter loses its bed adsorption property and needs to be cleaned by backwashing. To this end, the automation valve takes the filter bed in reverse rinsing for 15-20 minutes with pressurized water in certain periods

It removes the contaminants attached to the activated carbon surface and re-adsorbs the filter bed. The backwash process also distributes the water channels likely to occur during the filtration process and ensures that the water to be treated passes through the filter bed in a homogeneous flow, the filter runs at high efficiency on this count.

There is a risk that the activated carbon bed will create a suitable environment for bacterial reoccurrence. Active carbon holds organic substances in water, and these organic substances are food sources for bacteria. Bacteria fed with organic substances multiply rapidly and cause "bacteria leak". For this reason, disinfection is recommended before and after the application of activated carbon filters.

Factors that influence the performance of active carbon in water: The type of compound to be removed. Compounds with high molecular weight and low solubility are better absorbed. The concentration of the compound to be removed. The higher the concentration, the higher the carbon consumption. Presence of other organic compounds which will compete for the available adsorption sites. The pH of the waste stream. For example, acidic compounds are better removed at lower pH.