 morning, myself Dr. Sanjay Sarsamkar, working as an assistant professor in the Department of Humanities and Sciences, Walshan Institute of Technology, Sulapur. With our today's session, we are going to learn about water softening process that is ion exchange, de-avionization or demineralization process. One outcome of today's session, that is, at the end of this session, students will be able to define ion exchange raising, describe the ion exchange or demineralization process with neat labeled diagram and advantages and disadvantages of ion exchange method. So, content of today's lecture, we are going to learn about discussion of introduction process, regeneration, advantages and disadvantages of this ion exchange process. Introduction, ion exchange raisins, so what do you mean by this raisin? Basically raisins are insoluble, cross linked, long chain organic polymers with a micro porous structure. The functional groups attached to the chains are responsible for the ion exchanging properties. That is, if it is attached with acidic functional group, it exchanges the cations and if it is attached with alkaline functional group, basic functional group, then it exchange the anions present in hardness producing water, types of raisins. Basically, there are two types of raisins we are using for this particular process. First is known as cation exchange raising, also known as cation exchanger and the second one is anion exchange raising, also known as anion exchangers. First, cation exchange raising, raisins containing acidic functional groups like carboxylic acid, sulfonic acid, etc. are capable of exchanging their H plus ions with their cations, for example carbonates, bicarbonates, chlorides, etc., of calcium and magnesium which comes in their contact. So cations like calcium or magnesium can be removed by cation exchange raisins. And anion exchange raising, raisins containing basic functional groups like NH2, NHOH, etc., are capable of exchanging their anions with other anions which comes in their contact. Cations containing NH2, NHCH3, that is methyl amine, etc., are capable for exchanging the anionic portions of the minerals, it is called as anionic exchanger. So at this juncture, take a pause and answer this question. Cation exchange raisins are those raisins which contains A option, acidic functional groups, B basic functional groups, C both A and B and D only long chain hydrocarbons. Well, the answer for this is B basic functional groups. This is diagram for anion exchange process. It consists of columns, first column contains cation exchanger, the second column contains anion exchanger and these columns are also provided with acidic chamber and the second column that is anion exchange column is also provided with alkali chamber and these are provided just for the sake of regeneration process. The first column that is cation exchange raisin column, it receives raw water which is to be purified that is which is to be softened. The hard water comes in this particular cation exchange raisin, the reaction occurs, the exchange between cations occurs then whole of the content is passed through this passage column in the second column that is anion exchange raisin where the anions are removed with exchange and then after everything comes in this particular degasifier where the water it is boiled to remove all the dissolved gases like carbon dioxide present in this particular water. Whenever the water is obtained that is known as a pure water or a demineralized water, we shall discuss this in detail. The hard water is passed through the cation exchange column which removes all the cations like calcium and magnesium etcetera from it and equivalent amount of H plus ions are released from this column to water. Thus the reaction involved is this cation exchange raisin containing H plus ions reacts with the hardness producing substance in water in that the calcium that is cations combines with this raisin and that forms calcium raisin and H plus ions are released. Same is the case with magnesium containing compound, so magnesium also produces hardness in water, this magnesium from hardness producing substance combines with this raisin and releases H plus ions in water. After cation exchange column the hard water is passed through anion exchanger which removes all the anions like chlorides, sulphides etcetera present in water and equivalent amount of OH minus ions are released from this column to water. The reaction involved that is chlorides from hardness producing substance these are anions they combines with this ROH that is anion exchange raisin and it replaces this OH by Cl and this forms RCl and OH minus ions are released in water. Same is the case with this sulphate ions also, so this forms R2 SO4 and OH minus ions are released in water. Because H plus ions and OH minus ions released from cation exchanger and anion exchanger raisins respectively gets combined to produce water molecules H plus ions and OH minus ions these are combining together that forms of water molecule this is a reaction water coming out from anion exchanger is completely free from the cation as well as anions and then after it comes in gasifier where it is boiled for a certain time period to remove all the dissolved gases like carbon dioxide etcetera from water. Thus the water which is obtained from this particular process it is known as deionized or de mineralized water and it is the pure as distilled water regeneration. So after continuous use of these raisins they gets exhausted that is it forms calcium or magnesium raisin in case of cation exchanger or chloride or sulphate raisins in case of anion exchangers then after such a raisin is not available for further purification of water thus regeneration is necessary for this. So cation exchange raisins can be regenerated by passing hydrochloric acid through this column the reverse reaction occurs hydrochloric acid react with exhausted raisin and that forms RH and calcium chloride like materials. So this RH which is regenerated again it is made available for further process same as the case in case of anion exchange raisin also through this anion exchange raisin column the sodium hydroxide is passed that sodium hydroxide combines with RCl2 that is the raisin which is exhausted one and that again gets converted into this ROH twice and this forms sodium chloride also and this is made available for further reaction. Advantages and Disadvantages Advantages the process can be used for highly acidic or alkaline water also that is many times the water which comes out from various industries does contains high quantity of acids or alkalis such a water even can be processed with the help of this particular process and it is converted into usable form that is distilled water. Second water of nearly zero hardness can be obtained thus the efficiency of this particular process is very high. Disadvantages equipment is costly and expensive chemicals are needed so it requires raisins for regeneration we require acid alkalis etc that is why the cost is somewhat high. If water contains turbidity then the output of this process is reduced as we know the raisins are porous materials this turbid material gets clogged with such a micro porous nature of this raisin and it reduces the output of this particular process well references for this particular session I have used a textbook of engineering chemistry by Jane and Jane. Thank you.