ION EXCHANGE

ION EXCHANGEUTILITAS 20124/10/20131FUNDAMENTALIon exchange is the giving and receiving of ions between an ion exchange material and a process liquidFor water treatment applications, the ion exchange material is a resin and the process fluid is waterIt takes place as the process liquid flows through the ion exchange materialAs process water passes through the unit, undesirable ions are exchanged for the mobile (and more desirable) ions in the resin When the ion exchange resin bed can no longer remove undesirable ions, it is exhausted. It must then be regenerated before it is able to remove ions again.4/10/20132SEJARAHZEOLITE (ALUMINOSILIKAT SINTETIK) MERUPAKAN PENUKAR ION YANG PERTAMA KALI DIGUNAKANGREENSAND (BAHAN ALAMI) PENGGANTI ZEOLITESULFONATED STYRENE DIVINYLBENZENE STRONG ACID CATION EXCHANGERSULFONATED COAL CATION EXCHANGER (CARBONACEOUS ZEOLITE)DLL

4/10/20133JENIS PENUKAR IONSAC (STRONG ACID CATION)WAC (WEAK ACID CATION)SBA (STRONG BASE ANION)WBA (WEAK BASE ANION)4/10/20134STRONG ACID CATIONDapat menukarkan kation di air yang terikat dengan anion kuat maupun lemahAplikasinya di proses softening dan demineralisasi totalAda yang menggunakan siklus Na untuk proses softening atau siklus H untuk proses dekationisasiGugus fungsinya adalah sulfonat

Na4/10/20135STRONG BASE ANION

Gugus fungsi dari amonium kuartener Ada dua tipe Tipe I, seperti gambar di sebelahTipe II, salah satu gugus metil digantikan oleh golongan alkohol Tipe I lebih stabil dan memiliki kemampuan menukar lebih banyak anion lemah Tipe II efisiensi regenerasi dan kapasitanya lebih besar dibanding tipe I4/10/20136REAKSI PERTUKARAN SBA DALAM BENTUK HIDROKSIDA

4/10/20137WEAK ACID CATIONGUGUS FUNGSI IALAH GRUP KARBOKSILAT (COOH)DIGUNAKAN DALAM SOFTENING, DEALKALISASI AIR SANGAT SADAH, ALKALINITAS TINGGI,BEKERJASAMA DENGAN SAC SIKLUS Na DALAM SISTEM POLISHINGBERSAMA DENGAN SAC DIGUNAKAN DALAM DEMINERALISASI TOTAL

4/10/20138WEAK BASE ANIONGUGUS FUNGSINYA AMINA PRIMER, SEKUNDER DAN TERSIERREAKSI PERTUKARANNYA

4/10/20139APLIKASI ION EXCHANGERSOFTENINGDEMINERALISASIDEALKALISASIPOLISHER KONDENSAT4/10/201310SOFTENING

4/10/201311DEMINERALISASI, SAC DAN SBA

4/10/201312DEALKALISASIDIPAKAI BILA BIAYA DEMINERALISASI TIDAK TERJANGKAUSPLIT STREAM DEALKALIZATIONSODIUM ZEOLITE/CHLORIDE ANION DEALKALIZATIONWEAK ACID CATION DEALKALIZATION4/10/201313Split stream dealkalizationIn a split stream dealkalizer, a portion of the raw water flows through a sodium zeolite softener. The remainder flows through a hydrogen-form strong acid cation unit (hydrogen zeolite). The effluent from the sodium zeolite is combined with the hydrogen zeolite effluent. The effluent from the hydrogen zeolite unit contains carbonic acid, produced from the raw water alkalinity, and free mineral acids. When the two streams are combined, free mineral acidity in the hydrogen zeolite effluent converts sodium carbonate and bicarbonate alkalinity in the sodium zeolite effluent to carbonic acid Carbonic acid is unstable in water. It forms carbon dioxide gas and water. The blended effluents are sent to a decarbonator or degasser, where the carbon dioxide is stripped from the water by a countercurrent stream of air.4/10/201314Sodium Zeolite/Chloride Anion DealkalizationStrong base anion resin in the chloride form can be used to reduce the alkalinity of a water. Water flows through a zeolite softener and then an anion unit, which replaces the carbonate, bicarbonate, sulfate, and nitrate ions with chloride ions The chloride anion dealkalizer reduces alkalinity by approximately 90% but does not reduce total solids. When the resin nears exhaustion, treated water alkalinity increases rapidly, signaling the need for regeneration.4/10/201315Weak Acid Cation DealkalizationWeak acid resins are similar in operation to strong acid cation resins, but only exchange for cations that are associated with alkalinityThe carbonic acid (H2CO3) formed is removed by a decarbonator or degasser as in a split stream system.4/10/201316Advantages of Dealkalization SystemsIon exchange dealkalization systems produce hardness-free, low-alkalinity water at a reasonable cost, and with a high degree of reliability. They are well suited for processing feedwater for medium-pressure boilers, and for process water for the beverage industry. Split stream and weak acid cation systems also reduce the total dissolved solids. 4/10/201317Limitations of Dealkalization Systemsdealkalizers do not remove all of the alkalinity and do not affect the silica content of a waterdealkalizers require the same influent purity as other ion exchange processes; filtered water that is low in potential foulants must be usedthe water produced by a dealkalization system using a forced draft decarbonator becomes saturated with oxygen, so it is potentially corrosive

4/10/201318Counterflow Cation ExchangersIn a counterflow regenerated cation exchanger, the regenerant flows in the opposite direction of the service flow. As a result, the most highly regenerated resin is located where the service water leaves the vessel. The highly regenerated resin removes the low level of contaminants that have escaped removal in the top of the bed. This results in higher water purity than co-current designs can produce. To maximize contact between the acid and resin and to keep the most highly regenerated resin from mixing with the rest of the bed, the resin bed must stay compressed during the regenerant introduction. 4/10/201319This compression is usually achieved in one of two ways:a blocking flow of water or air is used the acid flow is split, and acid is introduced at both the top and the bottom of the vessel

4/10/201320Mixed Bed ExchangersA mixed bed exchanger has both cation and anion resin mixed together in a single vessel. As water flows through the resin bed, the ion exchange process is repeated many times, "polishing" the water to a very high purity.

4/10/201321During regeneration, the resin is separated into distinct cation and anion fractions. The resin is separated by backwashing, with the lighter anion resin settling on top of the cation resin. Regenerant acid is introduced through the bottom distributor, and caustic is introduced through distributors above the resin bed.4/10/201322The regenerant streams meet at the boundary between the cation and anion resin and discharge through a collector located at the resin interface. Following regenerant introduction and displacement rinse, air and water are used to mix the resins. Then the resins are rinsed, and the unit is ready for service.

4/10/201323