Ion exchange for water

The main uses of natural zeolite as adsorbent are as drying agents, deodorants, adsorbents for air separation, ion exchangers for water purification especially for removing ammonium ion and heavy metal ions and for water softening, soil upgrading and so on. 

In the water treatment sector, NaOH is used for the regeneration of ion exchangers for water purification, pH-adjustment, waste water treatment, drinking and swimming pool water disinfection by treatment with hypochlorite solution. 

Precipitation softening processes are used to reduce raw water hardness, alkalinity, siHca, and other constituents. This helps prepare water for direct use as cooling tower makeup or as a first-stage treatment followed by ion exchange for boiler makeup or process use. The water is treated with lime or a combination of lime and soda ash (carbonate ion). These chemicals react with the hardness and natural alkalinity in the water to form insoluble compounds. The compounds precipitate and are removed from the water by sedimentation and, usually, filtration. Waters with moderate to high hardness and alkalinity concentrations (150—500 ppm as CaCO ) are often treated in this fashion. 

Molecular sieve Zeolites used for ion exchange in water treatment. 

Supply of MU water for a medium-pressure (450 psig) WT boiler, from a surface water source with very variable suspended solids and hardness (sugar refinery, South Africa). The process used is a. carbonate removal using hot-lime precipitation softening coupled with silica adsorption by magnesia addition b. clarification in anthracite filters and c. cation ion-exchange for the balance of hardness removal. 

The quality of an ideally prepared coffee beverage can still be reduced or even spoiled if the water quality affects the coffee. Hardness is one of the main problems in the U.S. because it is usually associated with alkalinity. The acidity, which is a substantial part of the flavor character of coffee, is partly neutralized by hard water. Ion-exchange softened water is even worse, since the excess sodium ions present form soaps with the fatly acids in the roasted coffee. Demineralization of the water is the most effective way to obtain water for the preparation of a clean-flavored cup of coffee in hard-water areas. Oxygen in the water is easily removed by boiling. Chlorine in the water can spoil the flavor of a good coffee, as can organic matter and metal ions, such as iron and copper. 

Richard, J. J., and Junk, G. A., Steam Distillation, Solvent Extraction, and Ion Exchange for Determining Polar Organics in Shale Process Waters. Anal. Chem, 1984. 56 pp. 1625-1628. 

Application of ion exchange to the manufacture of dextrose has been in the process of development for several years. Numerous problems, not present in the application of ion exchange to water purification, were met which required solution. Although some problems remain,... 

Ultramarines are three-dimensional cage-like structures. They differ from feldspars and zeolites because of the large spaces within the structures that can contain cations and anions but not water, illustrating a natural buckeyball-like structure and cavity, and a diversity of environment between the internal and external cages. Ultramarines can act as ion-exchangers for both anions and cations. The blue color of ultramarines is due to the presence of the ion although a yellow ion S2 also exists in the same structure. 

Figure 4.14 — (A) Flow injection system for the preconcentration and determination of copper P peristaltic pumps A 0.5 M HNOj B sample q = 2.5 mL/min) C water (jq = 0.5 mL/min) E 1 M NaNOj/O.l M NaAcO, pH 5.4 q = 0.5 mL/min F 1 M NaAcO/2 x 10 M Cu pH 5.0 (9 = 1.0 mL/min) 3-5 valves ISE copper ion-selective electrode W waste I and II 2 and 3 mL of chelating ion exchanger for purification III 100 fil of chelating ion exchanger for metal ion preconcentration. (B) Scheme of the flow system for the determination of halides A 4 M HAcO/1 M NaCl/0.57 ppm F B 1 M NaOH/0.5 M NaCl C, mixing coil (1 m x 0.5 mm ID PTFE tube) Cj stainless-steel tube (5 cm x 0.5 mm ID) ISE ion-selective electrode R recorder. (Reproduced from [128] and [129] with permission of Elsevier Science Publishers and the Royal Society of Chemistry, respectively).

Insoluble polystyrene crosslinked with divinylbenzene can easily be converted by sulfonation to a usable ion exchanger. For this purpose a mixture of 0.2 g of silver sulfate and 150 ml of concentrated sulfuric acid are heated to 80-90 °C in a 500 ml threenecked flask fitted with stirrer, reflux condenser, and thermometer. 20 g of a bead polymer of styrene and divinylbenzene (see Example 3-41) are then introduced with stirring the temperature climbs spontaneously to 100-105 °C.The mixture is maintained at 100 C for 3 h,then cooled to room temperature and allowed to stand for some hours. Next the contents of the flask are poured into a 11 conical flask that contains about 500 ml of 50% sulfuric acid. After cooling, the mixture is diluted with distilled water, and the gold-brown colored beads are filtered off on a sintered glass filter and washed copiously with water. 

Dran, J.-C., Petit, J.-C., Trotignon, L., Paccagnella, A. Della Mea, G. 1989. Hydration mechanisms of silicate glasses Discussion of the respective role of ion exchange and water permeation. In Lut/.l, W. Ewing, R. C. (eds) Scientific Basis for Nuclear Waste Management XII. Materials Research Society Symposia Proceedings, 127, 25 - 32. 

The batch contact consisted of equilibrating stoichiometric quantities of waste and ion exchanger for 15 to 30 minutes. The solid product was then washed with water to remove most of the sodium ions. This step was necessary as high sodium content in... 

Many cooling system operators use either lean water, with very low natural hardness, or ion-exchange softened water as a makeup source. Also, there are some authorities that require softened water makeup, say less than 5 to 10 ppm total hardness (TH), for comfort cooling systems on the basis that this will minimize the risk of calcium carbonate deposits, the presence which could in turn increase the risk of Legionella proliferation. 

Fig. 2 The model of ion extraction/ion exchange for an optode based on a neutral ionophore and a lipophilic cationic dye in relation to the ion-optode response mechanism i+ cation to be extracted, H+ proton, S neutral ionophore, R lipophilic cationic additive, D color-changeable dye. The subscripts o and w represent the organic phase and the water phase, respectively)...

Voulgaropoulos and Tzivanakis used ion exchangers for the voltammetric determination of nitrilotriacetic acid and EDTA in natural waters [23],... 

Snyder DW, Snoeyink VL, Pfeffer JL. 1986. Weak-acid ion exchange for removing barium, radium, and hardness. Am Water Works Assoc J 78 98-104. 

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