Sodium hydroxide effluent

The reactor effluent, containing 1—2% hydrazine, ammonia, sodium chloride, and water, is preheated and sent to the ammonia recovery system, which consists of two columns. In the first column, ammonia goes overhead under pressure and recycles to the anhydrous ammonia storage tank. In the second column, some water and final traces of ammonia are removed overhead. The bottoms from this column, consisting of water, sodium chloride, and hydrazine, are sent to an evaporating crystallizer where sodium chloride (and the slight excess of sodium hydroxide) is removed from the system as a soHd. Vapors from the crystallizer flow to the hydrate column where water is removed overhead. The bottom stream from this column is close to the hydrazine—water azeotrope composition. Standard materials of constmction may be used for handling chlorine, caustic, and sodium hypochlorite. For all surfaces in contact with hydrazine, however, the preferred material of constmction is 304 L stainless steel. 

Naphthalenol. 2-Naphthol or p-naphthol or 2-hydroxynaphthalene/7i3 -/5 -i7 melts at 122°C and boils at 295°C, and forms colorless crystals of characteristic, phenoHc odor which darken on exposure to air or light. 2-Naphthol [135-19-3] is manufactured by fusion of sodium 2-naphthalenesulfonate with sodium hydroxide at ca 325°C, acidification of the drowned fusion mass which is quenched ia water, isolation and water-washing of the 2-naphthalenol, and vacuum distillation and flaking of the product. A continuous process of this type has been patented (69). The high sulfate content ia the primary effluent from 2-naphthol production is greatiy reduced ia modem production plants by the recovery of sodium sulfate. 

Active fractions are combined and concentrated in vacuo to about 5 liters. The concentrate is then adjusted to a pH of 8.0 with 6N sulfuric acid and passed through a column packed with 1 liter of an anion exchange resin, Dowex 1X2 (OH form). The column is washed with about 5 liters of water and the effluent and the washings containing active substance are combined and are concentrated to 1/15 by volume. The concentrate is adjusted to a pH of 10.5 with 6N sodium hydroxide and 5 volumes of acetone is added thereto. The resultant precipitate is removed by filtration and the filtrate is concentrated to 500 ml. The concentrate is adjusted to a pH of 4.5 with 6N sulfuric acid and 2.5 liters of methanol is added thereto. After cooling, a white precipitate Is obtained. The precipitate is separated by filtration and washed with methanol. After drying in vacuo, about 300 g of white powder is obtained. 

Fill a 250 mL separatory funnel with ca 0.25M sodium sulphate solution. Allow this solution to drip into the column at a rate of about 2 mL per minute, and collect the effluent in a 500 mL conical flask. When all the solution has passed through the column, titrate the effluent with standard 0.1 M sodium hydroxide using phenolphthalein as indicator. 

The electrolyte is nominally potassium diacid fluoride, KF-2HF. We use it slightly rich in HF, 20.75 to 20.95 meq of HF per gram of electrolyte, as determined by titration with standard sodium hydroxide solution to the phenolphthalein end point running slightly rich eliminates the formation of a layer of the salt on the bottom of the cell lid and in effluent ports. 

It should be noted that if sodium hydroxide is used instead of lime, the chemical cost will be higher, less sludge will be produced, and effluent sulfate concentration will be higher.15... 

Ke and Regier [71] have described a direct potentiometric determination of fluoride in seawater after extraction with 8-hydroxyquinoline. This procedure was applied to samples of seawater, fluoridated tap-water, well-water, and effluent from a phosphate reduction plant. Interfering metals, e.g., calcium, magnesium, iron, and aluminium were removed by extraction into a solution of 8-hydroxyquinoline in 2-butoxyethanol-chloroform after addition of glycine-sodium hydroxide buffer solution (pH 10.5 to 10.8). A buffer solution (sodium nitrate-l,2-diamino-cyclohexane-N,N,N. AT-tetra-acetic acid-acetic acid pH 5.5) was then added to adjust the total ionic strength and the fluoride ions were determined by means of a solid membrane fluoride-selective electrode (Orion, model 94-09). Results were in close agreement with and more reproducible than those obtained after distillation [72]. Omission of the extraction led to lower results. Four determinations can be made in one hour. 

Martin AD (1992) Sodium hydroxide production by the electrohydrolysis of aqueous effluent streams containing sodium salts, Inst Chem Eng Symp Series, 1992,127 (Electrochem Eng En 92), 153 Chem Abstr 117 (1992) 19458H... 

Kvaerner Chemetics have developed a novel, patented process [1] for the removal of multivalent anions from concentrated brine solutions. The prime market for this process is the removal of sodium sulphate from chlor-alkali and sodium chlorate brine systems. The sulphate ion in a brine solution can have a detrimental effect on ion-exchange membranes used in the production of chlorine and sodium hydroxide consequently tight limits are imposed on the concentration of sulphate ions in brine. As brine is continuously recycled from the electrolysers back to the saturation area, progressively more and more sulphate ions are dissolved and build up quickly in concentration to exceed the allowable process limits. A number of processes have been designed to remove sulphate ions from brine. Most of these methods are either high in capital or operating cost [2] or have large effluent flows. 

The effluent stream leaving the reactor is cooled and then treated with caustic (sodium hydroxide) and water to remove the catalyst. The cleaned up stream then contains about 35% unreacted benzene, 50% EB,.15% polyethylbenzene (PEB), and a small amount of miscellaneous heavy materials. 

The dimerization (Aldol condensation) takes place at temperatures of 175—250°F in the presence of a dilute solution of sodium hydroxide. After the reaction, the mixture is passed to a separator tank where the dimer is separated then sent to a reactor to be hydrogenated over a nickel catalyst. Reaction conditions have temperatures of 300°F and 2500 psi. Distillation of the effluent gives purified 2-EH in 95% yield. 

In this method, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, or sodium aluminate can be fed to the spent fixer for precipitation of silver ions as insoluble silver hydroxide precipitates. Figure 7 indicates that the residual silver concentration in the hydroxide precipitation treated effluent can be about 1 mg/L at pH 12 [19]. 

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