Adsorption salinity effect

Figure 5.50 shows the salinity effect on the permeability reduction factor, Fkr, predicted from Eq. 5.36. This figure shows that F j decreases with salinity. However, Figure 5.40 shows that higher salinity leads to higher polymer adsorption. Therefore, the salinity effect on permeability reduction factor is different from that on polymer adsorption. In other words, because of the salinity effect, the permeability reduction based on Eqs. 5.36 and 5.37 does not... 

Salinity Salinity plays at least two important roles, namely it maintains the integrity of the reservoir and it balances the physicochemical environment so that surfactant formulation stays close to optimal. Thus, ultra-low interfacial tension and oil solubilisation are very sensitive to salinity. Mixing of the surfactant slug with connate water may alter the surfactant formulation mainly due to dilution and to the incorporation of new electrolytes to the formula. Adsorption and desorption of electrolytes, particularly divalent cations, onto or from solid materials such as clay, will also change the salinity of the aqueous phases to some extent and may cause surfactant precipitation, which is however not always an adverse effect [151]. In order to attenuate the undesirable salinity effects on formulation, surfactants able to tolerate salinity changes [109], high salinity [150] and the presence of divalent ions [112] maybe used. 

The preflush (or preliminary injection) is a slug applied to prepare the reservoir to help in protecting the surfactants and polymers against salinity effects and adsorption on the... 

By 1980, research and development shifted from relatively inexpensive surfactants such as petroleum sulfonates to more cosdy but more effective surfactants tailored to reservoir and cmde oil properties. Critical surfactant issues are performance in saline injection waters, adsorption on reservoir rock, partitioning into reservoir cmde oil, chemical stabiUty in the reservoir, interactions with the mobiUty control polymer, and production problems caused by resultant emulsions. Reservoir heterogeneity can also greatly reduce process effectiveness. The decline in oil prices in the early 1980s halted much of the work because of the relatively high cost of micellar processes. 

In the 1990s, the thmst of surfactant flooding work has been to develop surfactants which provide low interfacial tensions in saline media, particularly seawater require less cosurfactant are effective at low concentrations and exhibit lower adsorption on rock. Nonionic surfactants such as alcohol ethoxylates, alkylphenol ethoxylates (215) and propoxylates (216), and alcohol propoxylates (216) have been evaluated for this appHcation. More recently, anionic surfactants have been used (216—230). 

For Yiv > YPv> where y v and Ypv are the surface tensions of liquid and protein, respectively, AFads increases with increasing ysv, predicting decreasing polymer adsorption. An example of this is phosphate buffer saline where y]v = 72.9 mJ/m2 and Ypv is usually between 65 and 70mJ/m2 for most proteins [5]. Therefore, supports for gel-permeation and affinity chromatography should be as hydrophilic as possible in order to minimize undesirable adsorption effects. 

Typical adsorption isotherms are shown in Figs. 16 and 17. Despite the large experimental scatter, a steep increase in adsorption can be seen at low concentrations, followed by a plateau at concentrations exceeding the CMC. Similar behavior has been observed before with model surfactants [49-54] and has also been predicted by modem theories of adsorption [54]. According to Fig. 16, adsorption increases modestly with salinity provided that the calcium ion concentration remains low. The calcium influence, shown in Fig. 17, cannot be explained by ionic strength effects alone but may be due to calcium-kaolinite interactions. 

The critical micellar concentrations of anionic/nonionic surfactant mixtures examined are low in a saline medium, so that, at the concentrations injected in practice, the chromatographic effects resulting from the respective adsorption of monomers are masked. Such surfactants propagate simultaneously in the medium in the form of mixed micelles. 

Results from our fatigue tests have shown that, in the one-to two-month accelerated fatigue tests, blood is a less severe environment than saline or air. This may be due to adsorption of the blood components into the microcracks, resulting in reduced stress concentrations. More work is anticipated to study the effect of blood on the fatigue life of elastomers. 

HPC exhibited a notable increase in adsorption with increasing NaCl concentration. Entrapment in the interlayer of recovered sodium montmorillonite did not vary with salinity the extent of entrapment was greater with the 4 M.S. HE and HP celluloses than either of the 2.0 M.S. polymers. Mixed ethers of HEC (2 M.S.) containing an anionic (carboxymethyl) or cationic (3-0-2-hydroxypropyltrimethylaramonium chloride) group at 0.4 M.S. levels did not adsorb from fresh water. Adsorption of these polar mixed ethers increased with increasing electrolyte until electrostatic and solvation effects were negated in 0.54N NaCl solutions and the adsorbed amounts typical of a 2 M.S. HEC were observed. Interlayer entrapments comparable to the equivalent M.S. HEC were observed at lower (0.18N) electrolyte concentrations. 

The long-term goal of this investigation is an understanding of the effect of a particular mode of adsorption on montmorillonite which ensures that under pressure the clay platelets align parallel to a solid surface even under saline conditions. This is an important phenomenon in petroleum recovery processes. 

Sodium Adsorption Ratio. Because of the swelling effects of Na+, the relative amount of sodium (sodicity) in the water quality especially in the irrigation water quality is an important measurement in soil science. Decreased permeability can interfer with the drainage required for normal salinity control and with the normal water supply and aeration required for plant growth. The relative sodium status of irrigation waters and soil solutions is often expressed by the sodium adsorption ratio (SAR)... 

Adsorption of a surfactant on solids is dependent, among other things, on the structure of both the hydro-phobic and hydrophilic portions of it. There are a number of mechanisms proposed for surfactant adsorption and an understanding of the effects of the structure of the surfactant can help in elucidating the role of these mechanisms. In this study, the effect on adsorption on alumina of some structure variations of sulfonates (chain length and the branching and the presence of ethyoxyl, phenyl, disulfonate and dialkyl groups) is examined above and below CMC as a function of surfactant concentration, pH and salinity. Co-operative action between an ionic alkyl sulfonate and a nonionic ethoxylated alcohol is also studied. 

Tsai WT, Lai CW, Hsien KJ (2003) Effect of particle size of activated clay on the adsorption of paraquat from aqueous solution. J Coll Interface Sci 263 29-34 Turner A (1996) Trace-metal partitioning in estuaries Importance of salinity and particle concentration. Marine Chemistry 54 27-39... 

Rysgaard, S., Thastum, P., Dalsgaard, T., Christensen, P.B., and Sloth, N.P. (1999) Effects of salinity on NH4+ adsorption capacity, nitrification, and denitrification in Danish estuarine sediments. Estuaries 22, 21-30. 

The effects of conditioning layers of two important blood serum proteins, albumin and fibrinogen were investigated. Protein adsorption was studied using bovine serum albumin (BSA) and fibrinogen (F) from Sigma. The samples were incubated for 3 h at 37°C in solutions of albumin (1 mg/mL) and fibrinogen (0.2 mg/mL) prepared in phosphate buffered saline (PBS, 0.01 M phosphate buffer, 0.0027 M KC1, 0.137 MNaCl, pH 7.4). After the incubation period, the samples were rinsed 3 times with PBS and analyzed by the various surface characterization techniques. 

Comparison of equilibrium adsorption (Figures 4 and 5) and minute protein adsorption/flocculation as a function of protein concentration, Cp, demonstrates strong but variable effects of pH and salinity.4 The equilibrium adsorption of proteins is as large as 1 mg/m2 (or 300 mg/g) at pH 3.5 (i.e. between pH(IEP) of silica and proteins) for bovine serum albumin (BSA) with 0.9 wt.% NaCl and gelatin without NaCl, or at pH(IEP) of protein for ovalbumin without NaCl. The lowest equilibrium adsorption (0.1-0.2 mg/m2) is typically observed at pH = 2, which is close to pH(IEPS o2) 2.2, and without NaCl (Figure 4). It should be... 

The ODN adsorption onto cationic polystyrene latexes as a function of NaCl concentration and at acidic pH was investigated [24] and found to be slightly influenced by the salinity as given in Fig. 5. At acidic pH, the adsorbed amount of ODN decreased markedly as the salinity increases, compared to the adsorption at basic pH. For such a highly charged colloidal system, the effect of salt was attributed to the reduction in the attractive electrostatic interaction. 

The ODN adsorption onto cationic microgel poly(N-isopropylacrylamide) particles was reported to be dramatically affected by the salinity of the incubation medium [9] as illustrated in Fig. 6. The observed result was related to (i) the reduction in attractive electrostatic interactions between ODN molecules and the adsorbent and (ii) the drastic effect of ionic strength on the physico-chemical properties of such particles [17, 27]. In fact, the hydrodynamic size, the swelling ability, the electrokinetic properties, and the colloidal stability are dramatically affected by pH, salt concentration, and the medium temperature [27]. 

Green-Pedersen, H., and N. Pind. 2000. Preparation, characterization, and sorption properties for Ni11 of iron oxyhydroxide-montmorillonite. Coll. Surf. A. 168 133-145. Green-Ruiz, C. 2009. Effect of salinity and temperature on the adsorption of Hg(II) from aqueous solutions by a Ca-montmorillonite. Environ. Technol. 30 63-68. 

The reduced adsorption of fibrinogen from plasma onto Silastic and poly (HEMA)/Silastic compared with that from pure buffered saline solutions could be caused by competition from other proteins for the adsorption sites. Albumin and y-globulin are both present in plasma in relatively high concentrations (about 45 and 10 mg/ml, respectively, compared with ca. 3 mg/ml for fibrinogen), so either might compete effectively with fibrinogen for adsorption. To test this, mixtures of I-fibrinogen... 

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