PH-adjusting agents

PHA depolymerases, 20 253, 256 pH adjusting agents, 12 61-62 Phage cloning, DNA isolation for,... 

Acidity regulator/acid, alkali, base, buffer, buffering agent, pH adjusting agent... 

Compared to silica, ceiia particles polish the planar surfaces more effectively. It has been shown that some ceria slurries exhibit the reverse-Prestonian behavior on certain polishing platforms and not for silica-based slurries. Ceria-based slurries often contain additives that are specifically designed to alter the surface charge on the abrasive particle and/or wafer surface, whereas silica slurries generally do not contain additives other than dispersion stabilizers and pH-adjusting agents. 

Meglumine is an organic base used as a pH-adjusting agent and solubilizing agent primarily in the preparation of soluble salts of iodinated organic acids used as X-ray contrast media. 

X Food additives that may be used as pH adjusting agents, acid-reacting materials and water correcting agents... 

Case study I RM-10 is a proprietary blend of clay minerals, polymers and pH adjusting agents, which allow one-step entrapment of emulsified oils and dissolved metals from various waste streams. CETCO Oilfield Services has been the industiy leader in clay-based flocculants and for over 30 years has provided the trusted line of RM-10 products to remove the following contaminants from waste streams ... 

In a back titration, a slight excess of the metal salt solution must sometimes be added to yield the color of the metal-indicator complex. Where metal ions are easily hydrolyzed, the complexing agent is best added at a suitable, low pH and only when the metal is fully complexed is the pH adjusted upward to the value required for the back titration. In back titrations, solutions of the following metal ions are commonly employed Cu(II), Mg, Mn(II), Pb(II), Th(IV), and Zn. These solutions are usually prepared in the approximate strength desired from their nitrate salts (or the solution of the metal or its oxide or carbonate in nitric acid), and a minimum amount of acid is added to repress hydrolysis of the metal ion. The solutions are then standardized against an EDTA solution (or other chelon solution) of known strength. 

Sodium bisulfate, NaHSO, is a convenient mild acid and is safe for uses as a household toilet-bowl cleaner, automobile-radiator cleaner, and for swimming pool pH adjustment. It is used for metal pickling, as a dye-reducing agent, for soil disinfecting, and as a promoter in hardening certain types of cement. 

Electroless solutions contain a metal salt, a reducing agent, a pH adjuster or buffet, a complexing agent, and one or mote additives to control stabiHty, film properties, deposition rates, etc. 

Buffers are necessary to adjust and maintain the pH. Buffering agents can be salts of a weak acid and a weak base. Examples are ammonium, potassium, sodium carbonates (caustic soda), bicarbonates, and hydrogen phosphates [1345]. Weak acids such as formic acid, fumaric acid, and sulfamic acid also are recommended. Common aqueous buffer ingredients are shown in Table 17-8. 

In addition to the sulfuric acid required for pH adjustment, some amount of acid is consumed by the reduction reaction (Equation 8.15). If sulfur dioxide is used as the reducing agent, it will provide all the acid consumed by this reaction, and additional acid will not be required. However, if sodium bisulfite or sodium metabisulfite is used, additional acid must be supplied to satisfy the acid demand. This acid requirement is stoichiometric and can be calculated from Equations 6.19 to 6.22. 

Ferrous sulfide acts as a reducing agent at pH 8 to 9 for reduction of hexavalent chromium and then precipitates the trivalent chromium as a hydroxide in one step without pH adjustment.5162 So, the hexavalent chromium in the nickel-chromium plating wastewater does not have to be isolated and pretreated by reduction to the trivalent form. The new process is applicable for removal of all heavy metals. All heavy metals other than chromium are removed as insoluble metal sulfides, M(II)S. 

This is a process mainly used in power plants for removal of soluble organics or chemically charged pollutants. The required chemicals are immiscible solvents that may contain chelating agents. It may require pH adjustments. The removal efficiency for inorganic pollutants is as follows ... 

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