Coagulant use

The water in many circuits often has sufficient natural levels of cations, especially multivalent ions of calcium and magnesium, to destabilise the repulsive surface charge on the finer sized particles to allow natural aggregation, suitable for secondary bridging flocculation. Where this is not the case, the application of inorganic or organic coagulants is employed. 

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Soluble iron or aluminum carryover ia the clarifier effiueat may result from inorganic coagulant use therefore, elimination of the inorganic coagulant can minimise the deposition of these metals ia filters, ion-exchange units, and cooling systems. 

Chemical precipitation is used in porcelain enameling to precipitate dissolved metals and phosphates. Chemical precipitation can be utilized to permit removal of metal ions such as iron, lead, tin, copper, zinc, cadmium, aluminum, mercury, manganese, cobalt, antimony, arsenic, beryllium, molybdenum, and trivalent chromium. Removal efficiency can approach 100% for the reduction of heavy metal ions. Porcelain enameling plants commonly use lime, caustic, and carbonate for chemical precipitation and pH adjustment. Coagulants used in the industry include alum, ferric chloride, ferric sulfate, and polymers.10-12... 

Any substance which will bring about coagulation. In the preparation of natural rubber the usual coagulants are acetic or formic acids. In the manufacture of dipped goods from latex, the coagulant used depends on the method of dipping employed. 

Aluminum is a metal which exists abundantly and widely in the earth and is commonly used in food packaging, antiperspirants, antiacid in digestion remedies, cosmetics and in beverages industries [2]. Aluminum sulfate is the most common aluminum-based coagulant used in purify water in many countries and it is found in most drinking water. WHO guidelines set its permissible level in drinking water at 200 ppb [3]. Upper levels can lead to serious problems such as Alzeheimer s disease. So, optimized preconcentration methods are required for the determination of trace amounts aluminum. 

Before World War II, hevea rubber accounted for over 99% of all elastomers used, but synthetic elastomers account for more than 70% of all rubber used today. NR and many synthetic elastomers are available in latex form. The latex may be used, as such, for adhering carpet fibers or for dipped articles, such as gloves, but most of the latex is coagulated and the dried coagulant used for the production of tires and mechanical goods. 

Still another important application of the concept of K equilibrium constants is the coprecipitation of EeP04 and Fe(OH)3 in the removal of phosphorus from water. As in the case of coagulation using alum, it is desired to have a final equation that is expressed only in terms of the constants and the hydrogen ion. Once this is done, the equation can then also be manipulated to obtain an optimum pH for the removal of phosphorus. 

For effective removal of the colloids, as much of the copperas should be converted to the solid Fe(OH)2(j). Also, as much of the concentrations of the complex ions should neutralize the primary charges of the colloids to effect their destabilization. Overall, this means that once the solids have been formed and the complex ions have neutralized the colloid charges, the concentrations of the complex ions standing in solution should be at the minimum. The pH corresponding to this condition is the optimum pH for the coagulation using copperas. 

The sludge production is in linear relation with the quantity of coagulant used. The influence of the mixing conditions and of the water quality is of second importance. 

P. C. Singer and K. Bilyk, Enhanced coagulation using a magnetic ion exchange resin. Water Research 36, 4009-4022 (2002). 

List I. Solids, Suspending Medium, and Coagulants Used... 

C2. Cannon, W. B., and Mendenhall, W. L., Factors affecting the coagulation time of blood. 1. The graphic method of recording coagulation used in these experiments. Am. J. Physiol. 84, 225-231 (1914). 

C6. Claeson, G., Aurell, L., Karlson, G., and Friberger, P., Substrate structure and activity relationship. In New Methods for the Analysis of Coagulation Using Chromogenic Substrates (I. Witt, ed.), pp. 37-54. De Gruyter, Berlin, 1977. 

Polymerization. Copolymers of tetrafluoroethylene/perfluoro(methyl vinyl ether) and the nitrile (1-4 mole ) have been prepared batch-wise in a stirred autoclave using an aqueous ammonium persulfate or ammonium persulfate-sodium sulfite redox couple system at 40°-100° C. The TFE/PMVE gas mixture was pressured, as required, to maintain the pressure and the nitrile pumped in solution in trichlorotrifluoro-ethane. After completion of the reaction, polymer was isolated from the latex (25-30 solids) by coagulation using ethanol and aqueous magnesium chloride solution. It was washed with alcohol/water solutions and dried at 70 °C in an oven under nitrogen. Mass balance indicated that most of the nitrile had been incorporated. 

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