Bicarbonates and Carbonates

Recovery of Ammonia. The filter Hquor contains unreacted sodium chloride and substantially all the ammonia with which the brine was originally saturated. The ammonia may be fixed or free. Fixed ammonia (ammonium chloride [12125-02-97]) corresponds stoichiometrically to the precipitated sodium bicarbonate. Free ammonia includes salts such as ammonium hydroxide, bicarbonate, and carbonate, and the several possible carbon—ammonia compounds that decompose at moderate temperatures. A sulfide solution may be added to the filter Hquor for corrosion protection. The sulfide is distilled for eventual absorption by the brine in the absorber. As the filter Hquor enters the distiller, it is preheated by indirect contact with departing gases. The warmed Hquor enters the main coke, tile, or bubble cap-fiUed sections of the distiller where heat decomposes the free ammonium compounds and steam strips the ammonia and carbon dioxide from the solution. 

Amino-2-hydroxybenzoic acid is manufactured by carboxylation of 3-amiaophenol under pressure with ammonium carbonate at 110 °C (182) or with potassium bicarbonate and carbon dioxide at 85—90°C (183) with subsequent acidification. 

Alkalinity. The alkalinity of a water sample is its acid-neutrali2ing capacity. Bicarbonate and carbonate ions are the predominant contributors to alkalinity in most waters, and their chemical equiUbria generally maintain the pH of 5—9. The presence of enough hydroxide ion to affect the alkalinity determination in natural waters is rare. SiUca, borate, or phosphate do contribute to the overall alkalinity if present in large enough quantities. 

Aikaiinity Bicarbonate (HCOs" ), carbonate (COs , and hydroxyl (OH ), expressed as CaCOs Foaming and carryover of solids with steam embrittlement of boiler steel bicarbonate and carbonate produce CO2 in steam, a source of corrosion Lime and lime-soda softening, acid treatment, hydrogen zeolite softening, demineralization, dealkalization by anion exchange, distillation, degasifying... 

The Pf and M,. tests are designed to establish the concentration of hydroxyl, bicarbonate, and carbonate ions in the aqueous phase of the mud. At a pH of 8.3, the conversion of hydroxides to water and carbonates to bicarbonates is essentially complete. The bicarbonates originally present in solution do not enter the reactions. 

The most important property of the dissolved solids in fresh waters is whether or not they are such as to lead to the deposition of a protective film on the steel that will impede rusting. This is determined mainly by the amount of carbon dioxide dissolved in the water, so that the equilibrium between calcium carbonate, calcium bicarbonate and carbon dioxide, which has been studied by Tillmans and Heublein and others, is of fundamental significance. Since hard waters are more likely to deposit a protective calcareous scale than soft waters, they tend as a class to be less aggressive than these indeed, soft waters can often be rendered less corrosive by the simple expedient of treating them with lime (Section 2.3). 

Bicarbonates and carbonates provide the total alkalinity in most MU waters. Normally, there is no free hydroxide alkalinity. 

The resulting ferrous bicarbonate and carbonate salts produced are not particularly stable and various secondary reactions subsequently take place, resulting in the formation of ferrous and ferric oxides,... 

The use of pretreatment equipment such as dealkalization or demineralization to remove bicarbonates and carbonates in the MU. 

In experiments where Mono Lake water was acidified to remove carbonate and bicarbonate ions and again adjusted to pH 10, more than 90 percent of the soluble plutonium moved to the sediment phase. When carbonate ion concentration was restored, the plutonium returned to solution—strong evidence of the importance of inorganic carbon to solubility in that system(13). Early studies with Lake Michigan water, which has low DOC, had also implicated bicarbonate and carbonate as stabilizing ligands for plutonium at pH 8(14). This latter research characterized the soluble species as mainly anionic in character. 

At equilibrium, the concentration of H+ will remain constant. When a strong acid (represented by H+ or HA) is introduced into solution, the concentration of H+ is increased. The buffer compensates by reacting with the excess H ions, moving the direction of the above reaction to the left. By combining with bicarbonate and carbonate ions to form the nonionic carbonic acid, equilibrium is reestablished at a pH nearly the same as that existing before. The buffer capacity in this case is determined by the total concentration of carbonate and bicarbonate ions. When no more carbonate or bicarbonate ions are available to combine with excess H+ ions, the buffer capacity has been exceeded and pH will change dramatically upon addition of further acid. 

Sodium hydrosulfite is produced through the Formate process where sodium formate solution, sodium hydroxide, and liquid sulfur dioxide reacted in the presence of a recycled stream of methanol solvent. Other products are sodium sulfite, sodium bicarbonate, and carbon monoxide. In the reactor, sodium hydrosulfite is precipitated to form a slurry of sodium hydrosulfite in the solution of methanol, methyl formate, and other coproducts. The mixture is sent to a pressurized filter system to recover sodium hydrosulfite crystals that are dried in a steam-heated rotary drier before being packaged. Heat supply in this process is highly monitored in order not to decompose sodium hydrosulfite to sulfite. Purging is periodically carried out on the recycle stream, particularly those involving methanol, to avoid excessive buildup of impurities. Also, vaporized methanol from the drying process and liquors from the filtration process are recycled to the solvent recovery system to improve the efficiency of the plant. 

Equation 8.26 predicts a concentration of CO2 in one litre of water at 25°C of 3.32 x 10-2 moll-1 at a pressure of 1 bar. The pH of the oceans is related to the amount of dissolved C02 but also to the equilibria controlling the formation of carbonic acid and the bicarbonate and carbonate ions ... 

The equilibrium constants for the formation of bicarbonate and carbonate are given by ... 

Dissolved carbon dioxide produces carbonic acid, which ionizes to bicarbonate and carbonate ions, the reactions for which are shown in Figure 5.2 (equations 1-3). This reaction sequence is extremely important because bicarbonate is a counterion to many cations, is active in buffering the soil solution, and is involved either directly or indirectly in many soil chemical reactions. Bicarbonates are generally more soluble than carbonates, which are generally insoluble. Adding acid to carbonates or bicarbonates results in the release of carbon dioxide and the formation of the salt of the acid cation. The acid is thus neutralized. 

It is reasonable to expect that because anions and most colloidal particles in temperate region soils have a negative charge, they will repel each other. The consequence is that anions will pass through soil and will not be adsorbed or even retarded. For the simple anions and some of the oxyanions, this is exactly what happens. All the halides, nitrite, nitrate, bicarbonate, and carbonate act in this fashion. However, there are some oxyanions that do not act as expected, and chief among them is phosphate. 

Of the nonmetal oxyanions, those of carbon have a different role in soil than nitrogen and phosphorus. Bicarbonate and carbonate can act as counterions to cations to keep the soil electrically neutral. They are also important because all pH changes in soil tend to involve either carbonate or bicarbonate, and thus, both are involved in soil pH and buffering. 

Puri and collaborators (3d, 59) found that the amount of CO2 given off on heating to 1200° was always equivalent to the Ba(OH)2 or NaOH neutralization. Evolution of COj was complete between 750 and 900°. Samples oxidized in liquid medium evolved more COg in relation to CO on heating than did samples treated with oxygen (3d, 55). Puri and Bansal (59) suggested that the neutralization of alkali was caused by carbon dioxide chemisorbed on the carbon surface ( COg complex ). If carboxyl groups were responsible, 1 mole of COg should be formed for each equivalent of alkali consumed. The author of this article thinks, as will be shown below, that very likely carboxyl groups of different environment are responsible for bicarbonate and carbonate neutralization as well as COg evolution. 

CO2 is measured by acidifying a seawater sample. This converts all the bicarbonate and carbonate ion into CO2. The CO2 gas is stripped out of the water sample by bubbling with an inert gas and then swept through either a coulometer or infrared analyzer for quantification. Alternatively, 2CO2 can be calculated from two easily measurable concentrations, pH and alkalinity. (See the online appendix on the companion website for the equations.)... 

In practice, the alkalinity of seawater is determined by titrating a sample until the pH drops to 3, well below the bicarbonate equivalence point (pH 4.5). Although most of the titratable negative charge is contributed by bicarbonate and carbonate, the other weak bases present in seawater do consume some acid above and below the bicarbonate... 

The formation and degradation of planktonic POC and PIC influence pH and C.A. as follows. The remineralization of POC produces CO2, which is rapidly hydrolyzed to carbonic acid, bicarbonate, and carbonate via the reactions given in Eqs. 5.53 through 5.57. Carbonic acid and bicarbonate are both weak acids, so their dissociation generates H. This acid enhances the dissolution of PIC through the following reaction ... 

Carbon dioxide is a symmetrical, linear triatomic molecule (0 = C=0) with a zero dipole moment. The carbon-to-hydrogen bond distances are about 1.16A, which is about 0.06A shorter than typical carbonyl double bonds. This shorter bond length was interpreted by Pauling to indicate that greater resonance stabilization occurs with CO2 than with aldehydes, ketones, or amides. When combined with water, carbonic acid (H2CO3) forms, and depending on the pH of the solution, carbonic acid loses one or two protons to form bicarbonate and carbonate, respectively. The various thermodynamic parameters of these reactions are shown in Table I. 

Ammonium carbamate is used as an ammoniating agent. It occurs as a mixed salt with ammonium bicarbonate and carbonate. 

The answer is C. Ingestion of an acid or excess production by the body, such as in diabetic ketoacidosis, may induce metabolic acidosis, a condition in which both pH and HCOj become depressed. In response to this condition, the carbonic acid-bicarbonate system is capable of disposing of the excess acid in the form of CO2. The equilibrium between bicarbonate and carbonic acid shifts toward formation of carbonic acid, which is converted to COj and HjO in the RBC catalyzed by carbonic anhydrase, an enzyme found mainly in the RBC. The excess CO2 is then expired by the lungs as a result of respiratory compensation for the acidosis (Figure 1-2). The main role of the kidneys in managing acidosis is through excretion of H" rather than CO2. 

Eluent degassing is important due to trap in the check valve causing the prime loose of pump. Eoss of prime results in erratic eluent flow or no flow at all. Sometimes only one pump head will lose its prime and the pressure will fluctuate in rhythm with the pump stroke. Another reason for removing dissolved air from the eluent is because air can get result in changes in the effective concentration of the eluent. Carbon dioxide from air dissolved in water forms of carbonic add. Carbonic add can change the effective concentration of a basic eluent including solutions of sodium hydroxide, bicarbonate and carbonate. Usually degassed water is used to prepare eluents and efforts should be made... 

In this method, the crystallized and anhydrous carbonates are mixod in such proportions as to leave a slight excess of water over what is necessary for the water of crystallization of the whole salt, when it is converted entirely into bicarbonate and carbonic acid is admitted to the bottom of the mixture by a tube proceeding from a pneumatic apparatus similar to a gasometer, so constructed that there can never be any waste of gas, The absorption is completed every twenty-four hours. 

If an alkaline carbonate be employed, all the earthy salts—calcareous and magnesian sulphates, chlorides, bicarbonates, and carbonates of the earths—are precipitated, while alkaline sulphates, chlorides, aod bioar-bonates which do not communicate hardness to water, aro left in solution. If carbonate of soda be employed, its reaction on sulphate of lime and chloride of magne slum will be as follows—... 

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