Lime deposits

Polyelectrolytes based on ethyleneimine are also used to treat drinking water and process water, and as agents for preventing lime deposits (407) in water extraction. The binding power of PEI is utilized for the treatment of effluents (408). Biochemical reactions can be catalyzed by using the complex-forming properties of PEIs and their affinity for organic substrates (409). 

When fresh water, not condensation water, is used as operating liquid, there is always a risk of lime deposits forming in the channels of the control system. 

Use Intermediate for plasticizers, solvents, resins, flavors, pharmaceuticals, acidulant and preservative chrome plating solder flux stabilizer for calcium greases control of lime deposits. 

Phenomena. In the first step, one could clearly look at aggressive effects - the well-known phenomena of acidic and basic solutions. Concerning acids, one can demonstrate the spectacular reaction of concentrated sulfuric acid with sugar (see E7.1) or that of the behavior of acidic solutions with metals (see E7.2). One should discuss, in both cases, the statement that an acid is something which eats material away [5], and can demonstrate that other substances are produced by those acid reactions sulfuric acid and sugar produce black carbon and steam metals react to produce hydrogen and a salt solution, from which solid white salts may be obtained by the evaporation of water. In addition, acidic household cleaners like those that remove lime deposits could be introduced one could demonstrates that when lime deposit is removed by a cleaner solution, salt solution and carbon dioxide gas are produced (see E7.3). 

Murcuric NrrB. TE— Hg(NO,),—323.7—is formed when Hg or HgO is dissolved in excess of HNO, and the solution evaporated at a gentle heat A s Tupy liquid is obtained, wliich, over quick-lime, deposits large, deliquescent crystals, having the composition 2[Hg(NO,)J -t- Aq, while there remains an unciystillizable liquid, Hg(NOj, + 2 Aq. 

Sulfuric acid is a strong acid used in chemical manufacturing. This same acid is also used in car batteries. Phosphoric acid is a weaker acid, but it is also a strong cleaner. It can be used to remove lime deposits. 

The carbon dioxide content of seawater is determined in waters dose to the surface by exchange with atmospheric carbon dioxide. Plants consume CO2 in the process of photosynthesis. The solute carbon dioxide influences the balance of carbon-ate/hydrogen carbonate and thus the formation of lime deposits and covering layers. This balance is the basis for the buffering properties of seawater and its relatively high pH level. 

Brine Preparation. Sodium chloride solutions are occasionally available naturally but they are more often obtained by solution mining of salt deposits. Raw, near-saturated brines containing low concentrations of impurities such as magnesium and calcium salts, are purified to prevent scaling of processing equipment and contamination of the product. Some brines also contain significant amounts of sulfates (see Chemicals FROMBRINe). Brine is usually purified by a lime—soda treatment where the magnesium is precipitated with milk of lime (Ca(OH)2) and the calcium precipitated with soda ash. After separation from the precipitated impurities, the brine is sent to the ammonia absorbers. 

Hydrogen chloride in the lungs can cause pulmonary edema, a life threatening condition. In order for HCl in air to reach the lungs, it must be transported either as an aerosol or as a deposit on soot particles of less than 3 p.m in diameter. A procedure for the removal of 99% of the HCl from municipal waste incinerators has been developed (87). Lime is employed as a dry adsorbent which is collected in a filter bag system. 

Impurities. The chemical composition and properties of lime and limestone depend on the nature of the impurities and the degree of contamination of the original stone. The contaminating materials either were deposited simultaneously with the CaCO or entered during some later stage (6). 

Ammonium Ion Removal. A fixed-bed molecular-sieve ion-exchange process has been commercialized for the removal of ammonium ions from secondary wastewater treatment effluents. This application takes advantage of the superior selectivity of molecular-sieve ion exchangers for ammonium ions. The first plants employed clinoptilolite as a potentially low cost material because of its availability in natural deposits. The bed is regenerated with a lime-salt solution that can be reused after the ammonia is removed by pH adjustment and air stripping. The ammonia is subsequentiy removed from the air stream by acid scmbbing. 

A uniform coating of calcium carbonate deposited on the metal surfaces physically segregates the metal from the corrosive environment. To develop the positive LSI required to deposit calcium carbonate, it is usually necessary to adjust the pH or calcium content of the water. Soda ash, caustic soda, or lime (calcium hydroxide) may be used for this adjustment. Lime is usually the most economical alkaH because it raises the calcium content as weU as the alkalinity. 

Morta.r, Mortar, principally slaked lime and sand, sets because of the evaporation of water, the deposition of calcium hydroxide, and the absorption of water by the bricks or cement blocks, foUowed by hardening as a result of the absorption and reaction of carbon dioxide. 

In a study of the adsorption of soap and several synthetic surfactants on a variety of textile fibers, it was found that cotton and nylon adsorbed less surfactant than wool under comparable conditions (59). Among the various surfactants, the cationic types were adsorbed to the greatest extent, whereas nonionic types were adsorbed least. The adsorption of nonionic surfactants decreased with increasing length of the polyoxyethylene chain. When soaps were adsorbed, the fatty acid and the aLkaU behaved more or less independently just as they did when adsorbed on carbon. The adsorption of sodium oleate by cotton has been shown independently to result in the deposition of acid soap (a composition intermediate between the free fatty acid and the sodium salt), if no heavy-metal ions are present in the system (60). In hard water, the adsorbate has large proportions of lime soap. 

The lime feeding system may be controlled by an instrumentation system integrating both plant flow and pH of the wastewater after lime addition. However, it should be recognized that pH probes require daily maintenance in this application to monitor the pH accurately. Deposits tend to build up on the probe and necessitate frequent maintenance. The low pH lime treatment systems (pH 9.5 to 10.0) can be more readily adapted to this method of control than high-lime treatment systems (pH 11.0 or greater) because less maintenance of the pH equipment is required. In a close-loop pH-flow control system, milk of lime is prepared on a batch basis and... 

Humidification can be achieved by placing separate humidifiers directly in the conditioned space. In order to maintain the design conditions, however, humidity control should be incorporated into the system. When positioning humidifiers, care has to be taken to ensure that the leaving moisture does not impinge on adjacent surfaces, forming lime or algae deposits. 

Kalk-echtlieit. /. fastness to lime, -einlagerung, /. calcareous deposit, -eisengranat, m. lime-iron garnet, andradite. -eisenstein, m, ferruginous limestone, kalkempfindlich, a. sensitive to lime. Kalkempfindlichkeit, /. sensitiveness to lime, kalken, kalken, v.t. lime. 

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