Produced water treatment equations

Environmental regulations prohibit disposal of produced water without primary and. in some instances, secondary treatment. Corrugated-plate interceptors, cross-flow separators, flotation units and other specialized equipment is required to reduce hydrocarbon content to acceptable levels. Authors discuss various equipment used in water treating. Next month, equations and empirical rules to help the engineer select appropriate treating equipment wilt be provided. 

For these industrial uses, H2 is produced in situ (because the very low density and boiling point make transport costs unacceptably high). The reagents in reaction 9.11 are collectively called synthesis gas the mixture is manufactured by the water-gas shift reaction - reaction of carbon or a hydrocarbon (e.g. CH4) with steam followed by partial treatment of the CO produced with water vapour (equation 9.12). 

When water is added to quicklime (CaO), slaked lime, or Ca(OH)2, is produced. Figure 13.11 lists four major uses of slaked lime, including as mortar, for water treatment (softening temporarily hard water), in the paper and pulp industries, and for bleaches. The major equations pertaining to these uses. Equations (13.24) through (13.27), are listed in the figure. 

Coumarin was first produced synthetically by Perkin. He made it by heating salicylic aldehyde, CgH (OH)i(COH), acetic anhydride, and sodium acetate. The whole solidifies to a crystalline mass, from which, on treatment with water, an oil separates containing coumarin and aceto-coumaric acid. This acid on heating is decomposed into acetic acid and coumarin, so that the product of distillation is principally coumarin. Perkin s synthesis proceeds according to the following equation —... 

Equation (4.15) should be considered the final oil-treatment stage, in which a 0.5 to 1% water cut in treated oil is produced. Here a heater-treater-type horizontal vessel is more commonly used. A direct-fired burner-heater is normally placed in a front section of the horizontal treater. Controlling the system temperature for viscosity is important and may be mandatory for successful water dehydration. 

Treatment of an alkene with a strong acid, such as sulfuric acid, that has a relatively nonnucleophilic conjugate base results in the addition of the elements of water (H and OH) to the double bond. This reaction has many similarities to the addition of the halogen acids described in Section 11.2. First H+ adds to produce a carbocation and then water acts as the nucleophile. The reaction follows Markovnikov s rule and the stereochemistry is that expected for a reaction that involves a carbocation—loss of stereochemistry. Some examples are provided in the following equations. Note that the mechanism is the exact reverse of the El mechanism for acid-catalyzed dehydration of alcohols described in Section 10.13. 

It has been long known that the over-simplified Poisson-Boltzmann equation is accurate in predicting the double layer interaction only in a relatively narrow range of electrolyte concentrations. One obvious weakness of the treatment is the prediction that the ions of the same valence produce the same results, regardless of their nature. In contrast, experiment shows marked differences when different kinds of ions are used. The ion-specific effects can be typically ordered in series (the Hofmeister series [36]), and the placement of ions in this series correlates well with the hydration properties of the ions in bulk water. 

A new solvent was investigated for the introduction of amine nucleophiles onto the selenophene nucleus via nucleophilic aromatic substitution. Treatment of 5-bromoselenophene-2-carboxaldehyde 53 with secondary amines in water produced 5-aminoselenophenes 54 (Equation 6) <1999T6511>. 

Less than 15% of the ore is transformed into chromium compounds, principally chromates, dichromates, chromium(VI) oxide, chromium(III) oxide, and so on. Alkaline oxidative roasting of chromite in rotary kilns yields sodium chromate (see equation 1), which is leached out with water and typically converted into sodium dichromate with sulfimc acid (equation 2) or carbon dioxide (equations). Fiuther treatment of sodium dichromate with sulfuric acid yields chromium(VI) oxide ( chromic acid ), while its reduction (with carbon, sulfur, or anuuo-nium salts) produces chromium(III) oxide. Finally, basic chromium(III) salts, for example Cr(0H)S04, which are used as tanning agents for animal hides, also result from reduction of sodium dichromate. Heterogeneous chromium catalysts are used for the polymerization of ethylene. 

Sections 15.4 and 15.5 outline methods for calculating equilibria involving weak acids, bases, and buffer solutions. There we assume that the amount of hydronium ion (or hydroxide ion) resulting from the ionization of water can be neglected in comparison with that produced by the ionization of dissolved acids or bases. In this section, we replace that approximation by a treatment of acid-base equilibria that is exact, within the limits of the mass-action law. This approach leads to somewhat more complicated equations, but it serves several purposes. It has great practical importance in cases in which the previous approximations no longer hold, such as very weak acids or bases or very dilute solutions. It includes as special cases the various aspects of acid-base equilibrium considered earlier. Finally, it provides a foundation for treating amphoteric equilibrium later in this section. 

Hydroboration of terminal alkynes, e.g. 1 -hexyne, 1 -octyne or cyclohexylacetylene, with a dialkylborane, such as bis(l, 2-dimethylpropyl)borane, followed by copper(I)cyanide and copper(II) acetate in HMPA containing a trace of water, gives isomerically pure ( )-l-cyanoalk-l-enes (equation 29)133. Successive treatment of 1-bromo-l-alkynes with dialkylboranes and sodium methoxide results in the borinate esters 208, which are converted into ( )-alkenes of greater than 99% isomeric purity by protonolysis. The action of alkaline hydrogen peroxide on the borinates produces ketones (equation 30)134. 

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