Salt: concentration, maximum allowable

Substituting Eq. (3.52) into Eq. (3.50) gives the operating equation for a desalinator that produces potable water with 0.05 wt% salt, the maximum allowable concentration ... 

The efficiency of water separation varies considerably from boiler to boiler. The purity of the steam supplied to a steam turbine should be checked. On the basis of the results, the maximum allowable salt concentration in the boiler water can be determined. This concentration may be much lower than the values given in the table. 

Toxicity data on niobium and its compounds are sparse. The most common materials, e.g., niobium concentrates, ferroniobium, niobium metal and niobium alloys, appear to be relatively inert biologically. Limited animal experiments show high toxicity for some salts, which arc related to disturbance of enzyme action, Niobium hydride lias moderate fibiogenic and general toxic action. Recommended maximum allowable concentrations arc 6 mg/m3. Recommended maximum permissible concentration of Nb ill reservoir water is 0.01 mg/L. The threshold for affecting clarity and biological oxygen demand (BOD) is 0.1 mg/L. 

The mobile-phase solution composition may have a strong viscosity dependence, particularly if organic modifiers or high. salt concentrations are in use, particularly in gradient operations. Depending on how close the operating pressure is to the maximum allowable pressure, the flow rate and thus the cycle time may be effected. 

The toxic dose levels of silver and silver compounds have been determined in animal toxicity studies (Sweet 1989). In mice, orally administered silver nitrate had an LD50 of 50 mg kg (the LD50 is the dose required to kill 50% of the test group), whilst silver sulfadiazene had an LD50 of 5000 mg kg. In occupational medicine, the MAK-value (maximum allowable concentration at the workplace) has been set at 0.1 mg m for metallic silver and 0.01 mg m for silver salts as Ag (DFG 2002). The same values were set as TLV (Threshold Limit Values) in the USA (ACGIH 2002). 

Thus, oxidation products are oxidized in their turn faster than the hydrocarbons themselves, and therefore the yields of the required intermediate products are usually low. In many cases the catalyst merely decreases the induction period, changing neither the mechanism nor the maximum rate of the process. This is typical of low catalyst concentrations in hydrocarbon media when the metal salt concentration, due to low solubility, does not exceed several hundredths of one percent. The use of polar solvents, e.g., acetic acid, trifluoroacetic acid, etc., allows for a considerable increase (100-1000 times) of the catalyst concentration. In this case the reaction can acquire new features. Not only the ratio but also the kinetics of the process can be markedly changed. Especially important is... 

In the preparation of nylon-6,6 salt, DuPont discloses a process for making highly concentrated solutions of nylon salt at maximum solubility [192], In the first step of this process, a concentrated salt solution for nylon-6,6 is made with 73.5-77.5 wt% of adipic acid and 22.5-26.5 wt% of hexamethylene diamine at 55-60°C. The solution contains 60-69.5 wt% solute as compared to an ordinarily stoichiometric solution containing 56% diacid and 44% diamine with a maximum solute concentration of about 59 wt%i. The second step is to remove water from the solution by evaporation to a solution concentration of 93-96 wt%. When the concentrated solution is ready to be polymerized, addition hexamethylene diamine is added to complete the reaction. A process with similar reaction modifications is developed to prepare an essentially anhydrous mixture of adipic acid and hexamethylene diamine [193], The reaction mixture is heated to 120-135°C to allow evaporation of water while reacting. The resulting product has a ratio of adipic acid to hexamethylene diamine of 81 19. The molten acid-rich mixture is withdrawn in a continuous process. 

This situation exists for only four known substances, water, bismuth, iron, and gallium, where the solid floats on the liquid at the melting point. Water is unique, however, since its maximum density is not at 0°C but at 4°C. This is illustrated in Fig. 15.3 where the partial structure of dimers and trimers due to hydrogen bond formation allows for a more structured arrangement of the water clusters. This structure is dismpted as salt is added, as shown in Fig. 15.4, where the maximum density drops from 4°C to — 1.33°C at 24.7 ppt (parts per 1,000). At higher salt concentrations, the density of water increases with decrease in temperature. Ice formed from saltwater is normally free of salt and has the normal density of ice, that is, 0.9170 g/mL. 

To calculate the blowdown, we must know the maximum allowable salt (inorganics) concentration factor, S, of the circulating water conpared with the makeup water. The definition of S is given in the following equation ... 

Equations (37)-(40) allow computation of i/ (z) from volume fraction profiles. The calculated density profile of adsorbed polyelectrolyte is qualitatively different on an uncharged polymer. At low ionic strength, the maximum of density appeared as the result of the high electric potential generated by the adsorbed molecules repelling other chains (Fig. 11). The adsorbed amount and the thickness of adsorption layer increase with increasing salt concentration in solution (Fig. 12). 

The oil droplets in the mayonnaise are electrostatically stabilized. The water phase can be taken here as an aqueous solution of NaCl. The surface potential is 10 mV. The composite (overall) potential between the oil droplets at a distance of 0.5 nm must be higher than lOksT. Calculate the maximum salt concentration that can be allowed in the mayonnaise. 

In a manner similar to nltrafiltration systems, concentration polarization effects need to be accommodated in designing RO systems. The maximum allowable value of the concentration polarization factor is 1.13—1.2as recommended by different RO membrane suppliers. The concentration polarization factor can be defined as the ratio of salt concentration at the membrane surface to the bulk concentration. 

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