Salinity alkali effects

On account of its chemical resistance, glass is generally excellent for water, saline solutions, acids, organic substances and even alkalis, so that in all these cases it is superior to most metals and plastics. Hydrofluoric acid, strong alkaline solutions and concentrated phosphoric add are the only chemicals that have a noticeably adverse effect on glass, particularly at high temperatures. 

Surfactant Mixing Rules. The petroleum soaps produced in alkaline flooding have an extremely low optimal salinity. For instance, most acidic crude oils will have optimal phase behavior at a sodium hydroxide concentration of approximately 0.05 wt% in distilled water. At that concentration (about pH 12) essentially all of the acidic components in the oil have reacted, and type HI phase behavior occurs. An increase in sodium hydroxide concentration increases the ionic strength and is equivalent to an increase in salinity because more petroleum soap is not produced. As salinity increases, the petroleum soaps become much less soluble in the aqueous phase than in the oil phase, and a shift to over-optimum or type H(+) behavior occurs. The water in most oil reservoirs contains significant quantities of dissolved solids, resulting in increased IFT. Interfacial tension is also increased because high concentrations of alkali are required to counter the effect of losses due to alkali-rock interactions. 

Hydrides are broadly of three types, saline, covalent and metallic. Saline hydrides are formed by the alkali metals (Gp. lA), the alkaline earths (Gp. IIA) and the lanthanides they have ionic lattices, high melting points and, when fused, are electrolytes. Elements of the B Groups from IIIB to VIIB have covalent hydrides, most of them gaseous at room temperature. The metallic hydrides characteristic of some of the transition elements are in effect alloys and usually lack the stoichiometric composition of normal chemical compounds. 

Because alkalis provide an additional somce of electrolytes, their presence in a surfactant solntion will reduce the optimum salinity. When Martin and Oxley (1985) investigated the effects of alkalis on surfactant phase behavior, they fonnd that for petrolenm sulfonate, alkali anion had little or no effect on the phase behavior, whereas cations were effective for decreasing the optimum salinity in this order potassinm > sodium ammonium (see Figure 8.4). For the solutions with and withont alkali, the optimum salinity decreased with the snrfactant concentration. In the presence of alkaline chemicals, Martin and... 

Martin and Oxley (1985) studied the effect of different alkalis on surfactant systems. They showed that the presence of any alkali lowered the optimum salinity of the surfactant system. This phenomenon is caused by two facts (1) alkali can provide electrolytes and (2) alkali reacts with crude oil to generate soap, and soap has lower optimum salinity (see the next section). Martin and Oxley found a linear relationship between the optimum salinity and sodium concentration. The addition of any alkali agents results in a decrease in the optimum salinity of the system. However, alkali anions have very little effect on the phase behavior. 

When an alkali is injected into a reservoir with acidic crnde oil, a fraction of acid components are converted into soap, which helps to solnbilize oil and water into the microemnlsion phase. Figure 12.18 shows the water and oil soln-bilization ratios at different effective salinities, based on the two dehnitions. One dehnition is the ratio of water or oil volume (V or Vo) to the volume of injected synthetic surfactant in the microemulsion phase. The other dehnition is the ratio of water or oil volume (V or Vo) to the total volume of injected... 

Saline soils that are not high in sodium are usually well flocculated as long as the dissolved salts are present. Even alkali soils usually remain flocculated if they contain considerable soluble salts, but if these are removed the deflocculating effect of sodium manifests itself rather quickly and the rate of movement of water through the soil is soon greatly reduced. 

Aluminum to sulfiir ratios in residues point to iron co-precipitation, such that an alunite-jarosite compound is formed, typically about two-thirds alunite and one-third jarosite. The sodium plus potassium to sulfur ratios indicate that 10 to 20% of the alunite-jarosite is in the hydronium form. Kyle [27] gives a useful summary of these phenomena while Johnson and co-workers [15, 16] have carried out detailed studies into the effects of alkali addition and leach liquor salinity on PAL. Some typical assays are shown in Table 2 and Table 3. 

Alkali addition for thermal O3 decomposition would require pH adjustments after treatment that could have negative effects on the salinity in drinking water applications. 

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