Effect Of Different Salts Research Articles

Recovery of organic acids from lactic acid-enriched fermentation broth via salting-out assisted solvent extraction

The organic acids (OAs) market has been expanding due to their versatility and wide range of uses in several industrial applications, thus prompting a transition from chemical to biological approaches to generate such high-value products. Nevertheless, downstream processes to separate OAs from the fermentation broth represent, to date, the main cost in biological OAs manufacturing. With the goal of limiting this issue, the present study investigated OAs separation from a lactic acid (LA)-rich fermentation broth through physical, i.e., using ethyl acetate (EA), and physico-chemical, i.e., using tributyl phosphate (TBP), solvent extraction. In addition, the salting-out effect of different salts on OAs recovery was investigated. Among the investigated conditions, a combination of pure TBP and 40% ammonium sulfate ensured the highest LA extraction efficiency of 65%. Besides, mixing TBP with EA (50:50) enabled to maintain the same LA extraction efficiency while reducing the process costs, limiting the toxicity of the chemicals involved, and obtaining an extracted OAs mix with lower co-metabolites, i.e. volatile fatty acids, compared to using pure TBP. Overall, solvent extraction assisted by salting-out agents were shown to be a promising method to separate OAs from a fermentation broth in liquid form, especially for fermentation processes operated at low pH.

Effect of different salts on the foaming properties of model protein systems for infant formula

This multiscale study aimed to evaluate the effects of different salts (NaCl, KCl, MgCl2, and CaCl2) on the foaming capacity (FC) and foam stability (FS) of model protein systems (MPS) for infant formula via changes in surface and structural properties. Our results showed that the FC and FS of MPS were increased with the addition of NaCl, KCl, and MgCl2, whereas CaCl2 significantly decreased FC (79.5 ± 10.6%) and increased FS (93.2 ± 2.2%). The surface hydrophobicity was increased and the net charge and surface tension were reduced after the addition of salts. Structural analysis revealed the reduction of intensity of intrinsic fluorescence spectroscopy and UV absorption, and the conversion of α-helix into β-strand, which was attributed to protein agglomeration. Additionally, MgCl2 and CaCl2 exhibited larger size and lower net charge compared with NaCl and KCl, indicating a greater ability to bind to charged amino acids and form larger aggregates. Correlation analysis indicated that FC was positively related to adsorbed protein and β-turn and negatively correlated with particle size. In addition, FS showed a positive correlation with β-strand, apparent viscosity, and zeta potential. However, it exhibited a negative correlation with β-turn, α-helix, and sulfhydryl content. These results provide a theoretical reference for further understanding of the effect of salts on the foaming properties of MPS.

Comparative study on the effect of different salts on surimi gelation and gel properties

The effects of four representative salts, KCl, NaCl, CaCl2 and MgCl2, on surimi gel properties were comprehensively investigated. During gelation, monovalent salts are prone to convert α-helix to β-sheet while divalent salts tend to change α-helix to β-turn, thus altering the protein conformation differently. Monovalent salts extract and swell myofibrillar proteins more effectively, generating an ordered and smooth gel network with appreciable water-holding capacity (WHC). Ca2+ activates transglutaminase (TGase) to crosslink surimi proteins by forming ε-(γ-glutamyl) lysine bonds, while Mg2+ forms salt bridges with adjacent proteins, leading to a gel with more developed protein complexes. However, excessive divalent salts would induce serious protein coagulation, forming poor networks and lowering water retention. Ionic strength within 0.2–0.5 effectively reinforced the gel structure, while the WHC of surimi gels reached its peak with an ionic strength of around 0.6. At the optimal salt concentration of 1.5%, K+ with a larger ionic radius showed inferior effects on forming ionic bonds among proteins, whereas other metal ions induced more hydrophobic interactions within surimi gels. Mg2+, with higher oxidability than other metal ions, could enhance the formation of disulfide bonds and inhibit the browning caused by the Maillard reaction, thus improving gel whiteness. This study provides new insides into the roles of common salts during surimi gelation and gel properties and is expected to guide further gelation innovation and gel product development.

On the startup behavior of wormlike micellar networks: The effect of different salts bound to the same surfactant molecule

We report on shear startup data for two wormlike micellar solutions, differing only in concentration and type of two binding aromatic sodium salts. The surfactant molecule is cetylpiridinium chloride at a fixed concentration (100 mM). Sodium salicylate (NaSal) and diclofenac sodium (Diclo) are used as binding salts at concentrations 68 mM NaSal and 52 mM Diclo such that both systems are fully entangled and their linear viscoelastic response is essentially identical. Both systems show the linear response typical of a wormlike micellar solution, with terminal behavior at low frequencies, a well-defined moduli crossover, and a plateau modulus. In the nonlinear regime, however, the behavior of the two systems is totally different, suggesting that the molecular structure difference of the salts and their binding activity to the surfactant molecule are both crucial to determine the fast flow behavior. The NaSal solution shows a very complex rheological response, with strain hardening and very sharp stress peaks, whereas the solution containing Diclo behaves much like ordinary linear polymers, exhibiting pronounced overshoots as well as moderate undershoots in the transient shear viscosity, before approaching the steady state. This polymerlike behavior has also been proved by successfully comparing data with predictions of a constitutive equation recently adopted for both entangled polymers and linear wormlike micelles. As far as NaSal is concerned, a phenomenological model based on rubber network theory is developed, which describes the flow singularities. A physical interpretation of the different behavior in the nonlinear regime is also suggested.

Investigating the effect of different salts on the thermal efficiency of a solar pond device

This article describes an experimental method for determining the physicochemical properties of NaCl, MgCl2, and KCl salts to establish a salinity gradient in an experimental solar pond located at Karshi engineering-economics institute. During the experiments, separate brine solutions of each salt were prepared in the solar pond device in order to establish the density profile, concentration, and heat capacity of these salts. Based on the study of samples taken from different points of the pond, the density profile of each salt was studied and graphs were constructed. Using an adiabatic colorimeter made for the experiment, the heat capacities of each salt brine were studied in the temperature range of 20оС-70оС and at values of brine concentration of 5%-28%, and the change graphs at different temperatures were presented.

Nature of Cations Critically Affects Water at the Negatively Charged Silica Interface.

Understanding the collective behavior of ions at charged surfaces is of paramount importance for geological and electrochemical processes. Ions screen the surface charge, and interfacial fields break the centro-symmetry near the surface, which can be probed using second-order nonlinear spectroscopies. The effect of electrolyte concentration on the nonlinear optical response has been semi-quantitatively explained by mean-field models based on the Poisson-Boltzmann equation. Yet, to explain previously reported ion-specific effects on the spectroscopic response, drastic ion-specific changes in the interfacial properties, including surface acidities and dielectric permittivities, or strong ion adsorption/desorption had to be invoked. Here, we use sum-frequency generation (SFG) spectroscopy to probe the symmetry-breaking of water molecules at a charged silica surface in contact with alkaline metal chloride solutions (LiCl, NaCl, KCl, and CsCl) at various concentrations. We find that the water response varies with the cation: the SFG response is markedly enhanced for LiCl compared to CsCl. We show that within mean-field models, neither specific ion-surface interactions nor a reduced dielectric constant of water near the interface can account for the variation of spectral intensities with cation nature. Molecular dynamics simulations confirm that the decay of the electrochemical potential only weakly depends on the salt type. Instead, the effect of different salts on the optical response is indirect, through the reorganization of the interfacial water: the salt-type-dependent alignment of water directly at the interface can explain the observations.

Effect of Sodium Salicylate on Improving the Lubricating Properties of [C18imC9]Br Wormlike Micelles in Glycerol/Propylene Glycol at Low Temperatures

The formation of long cylindrical wormlike micelles at low temperatures (near 0 °C) is relatively rare. In this work, the effect of different salts on the viscoelasticity of the formed wormlike micelles by the ionic liquid surfactant (1-octadecyl-3-nonyl imidazolium bromide, [C18imC9]Br) and glycerol/1,2-propanediol mixture at low temperature was studied. The rheological measurements revealed that only sodium salicylate (NaSal) can increase the viscoelasticity of [C18imC9]Br wormlike micelles by up to 15 times and the existence of temperature range. When the [C18imC9]Br concentration is fixed, the viscoelasticity of the [C18imC9]Br/NaSal wormlike micelles increases and then decreases with the increase of NaSal concentration. Tribological results show that the [C18imC9]Br/NaSal wormlike micelles have excellent friction reduction and antiwear properties for steel/steel contact at 6.00 °C. The friction coefficient and wear volume of [C18imC9]Br/NaSal wormlike micelles first decrease and then increase with the increase of the NaSal concentration. In addition, their tribological properties are significantly better than those of pure [C18imC9]Br wormlike micelles under the same conditions. The lubrication effect of [C18imC9]Br/NaSal wormlike micelles at low temperatures is improved due to the adhesion of [C18imC9]Br/NaSal wormlike micelles and the protective film formed by the tribochemical reaction.

Effect of Different Salts on Nutrients Uptake, Gene Expression, Antioxidant, and Growth Pattern of Selected Rice Genotypes.

Climate change leads to soil salinization, and the dynamic scarcity of freshwater has negatively affected crop production worldwide, especially Oryza sativa. The association among ion uptake, gene expression, antioxidant, biomass, and root and shoot development under different salt stress are not fully understood. Many studies are related to the effect of NaCl only. This study used two salts (CaCl2 and MgCl2) along with NaCl and analyzed their effects on mineral uptake (macronutrients and micronutrients), gene expression, seed germination, antioxidants, plant growth, and biomass in different rice genotypes. CaCl2 (up to 200 mM) slightly increased the germination percentage and seedling growth, whereas, 150 mM MgCl2 in the soil increased the root, shoot length, and fresh and dry weight in cultivars IR 28 and Cheongcheong. All agronomic traits among rice genotypes were drastically reduced by NaCl stress compared to other salts. Different salt stress differentially regulated ion uptake in the roots and shoots among different rice genotypes. Under different salt stress, a consistent decrease in Ca2+, Mn2+, and Fe2+ ions was observed in the roots of Cheongcheong, Nagdong, and IR 28. Similarly, under different salts, the stress in the shoots of Cheongcheong (Ca2+, Na+, and Zn2+) and Nagdong (Ca2+, Mg2+, Na+, and Zn2+) and the shoots of IR 28 (Ca2+ and Mg2+) consistently increased. Under different salts, a salt stress-related gene was expressed differentially in the roots of rice genotypes. However, after 6 and 12 h, there was consistent OsHKT1, OsNHX1, and OsSOS1 gene upregulation in the shoots of Nagdong and roots and shoots of the salt-tolerant cultivar Pokkali. Under different salt stress, glutathione (GSH) content increased in the shoot of IR 28 and Nagdong by NaCl, and MgCl2 salt, whereas, POD activity increased significantly by CaCl2 and MgCl2 in cultivar Cheongcheong and IR 28 shoot. Therefore, this study suggested that Pokkali responded well to NaCl stress only, whereas, the plant molecular breeding lab cultivar Nagdong showed more salt tolerance to different salts (NaCl, CaCl2, and MgCl2). This can potentially be used by agriculturists to develop the new salt-tolerant cultivar “Nagdong”-like Pokkali.

Effect of bacteria on oil/water interfacial tension in asphaltenic oil reservoirs

Microbial enhanced oil recovery (MEOR), due to the formation of biofilm and the presence of biosurfactants generated by microorganisms in the reservoir, can play a role in reducing interfacial tension (IFT) and wettability alteration. In this work, the fluid-fluid interaction by measuring the IFT has been evaluated for combining two EOR methods, including low salinity water and MEOR, due to the high importance of fluid-fluid interaction in EOR. GeoBacillus stearothermophilus has been used as a bacterium to study changes in IFT. The effect of different salts, including monovalent and divalent cations and anions at different salinities, on biosurfactant performance, is investigated using IFT measurements. Also, the type of oil is evaluated in terms of its acidic and basic properties on the performance of biosurfactants. According to the results of this study, injection of GeoBacillus stearothermophilus bacteria reduces interfacial tension in acidic oil by 10.26% and in basic oil by 5.26%. According to the results, increasing salinity in the presence of oil-containing asphaltene with basic properties increases the IFT of the solution containing GeoBacillus stearothermophilus bacteria, but in the presence of acidic oil, a decrease in IFT is observed. The most significant effect of reducing the IFT of acidic oil and solution containing GeoBacillus stearothermophilus is obtained in the presence of the following salts, respectively: CaCl2 > MgCl2 > NaCl. The results show that with increasing CaCl2 concentration, the IFT between basic oil and GeoBacillus stearothermophilus solution gradually increases. This ascending trend is in the presence of NaCl salt with a lower slope. However, in the presence of MgCl2 salt, dual behavior is observed before and after the concentration of 1000 ppm, so that before this concentration, the IFT increases and then decreases. The findings of this study can help for a better understanding of the interaction of bacteria with asphaltenic oils in the presence of effective salts for low salinity water injection. The results of this study showed that by combining low salinity water with bacteria, less IFT could be obtained than low salinity water or bacteria alone.

Preparation of chitosan/sodium alginate conductive hydrogels with high salt contents and their application in flexible supercapacitors

Conductive hydrogels (CHs) are a potential material for flexible electronics. However, most of CHs display disadvantages of low ionic conductivities and intolerance to low temperatures. Herein, a novel physical CHs with salt contents as high as 30 wt% was prepared with chitosan (CTS) and sodium alginate (SA) by combining the anti-polyelectrolyte effect and semi-dissolution acidification sol-gel transition (SD-A-SGT) method. The obtained hydrogels show extremely high ionic conductivities up to 2.96 × 10−1 S·cm−1 at room temperature and 4.9 × 10−2 S·cm−1 at −20 °C. The effects of different salts on the ion mobility and electrochemical properties of CTS/SA CHs were predicted and analyzed. The flexible supercapacitor assembled using CTS/SA CHs as the electrolyte exhibits the specific capacitance as high as 405 F·g−1 at the current density of 0.25 A·g−1 and satisfying electrochemical stability with 74.91% capacitance retention in 1000 cycles. Our work has provided a new strategy for constructing green CHs with high ionic conductivities.

Ion-specific Limitations of Sodium Chloride and Calcium Chloride on Growth, Nutrient Uptake, and Mycorrhizal Colonization in Northern and Southern Highbush Blueberry

Excess salinity is becoming a prevalent problem for production of highbush blueberry (Vaccinium L. section Cyanococcus Gray), but information on how and when it affects the plants is needed. Two experiments, including one on the northern highbush (Vaccinium corymbosum L.) cultivar, Bluecrop, and another on the southern highbush (V. corymbosum interspecific hybrid) cultivar, Springhigh, were conducted to investigate their response to salinity and assess whether any suppression in growth was ion specific or due primarily to osmotic stress. In both cases, the plants were grown in soilless media (calcined clay) and fertigated using a complete nutrient solution containing four levels of salinity [none (control), low (0.7–1.3 mmol·d−1), medium (1.4–3.4 mmol·d−1), and high (2.8–6.7 mmol·d−1)] from either NaCl or CaCl2. Drainage was minimized in each treatment except for periodic determination of electrical conductivity (EC) using the pour-through method, which, depending on the experiment, reached levels as high as 3.2 to 6.3 dS·m−1 with NaCl and 7.8 to 9.5 dS·m−1 with CaCl2. Total dry weight of the plants was negatively correlated to EC and, depending on source and duration of the salinity treatment, decreased linearly at a rate of 1.6 to 7.4 g·dS−1·m−1 in ‘Bluecrop’ and 0.4 to 12.5 g·dS−1·m−1 in ‘Springhigh’. Reductions in total dry weight were initially similar between the two salinity sources; however, by the end of the study, which occurred at 125 days in ‘Bluecrop’ and at 111 days in ‘Springhigh’, dry weight declined more so with NaCl than with CaCl2 in each part of the plant, including in the leaves, stems, and roots. The percentage of root length colonized by mycorrhizal fungi also declined with increasing levels of salinity in Bluecrop and was lower in both cultivars when the plants were treated with NaCl than with CaCl2. However, leaf damage, which included tip burn and marginal necrosis, was greater with CaCl2 than with NaCl. In general, CaCl2 had no effect on uptake or concentration of Na in the plant tissues, whereas NaCl reduced Ca uptake in both cultivars and reduced the concentration of Ca in the leaves and stems of Bluecrop and in each part of the plant in Springhigh. Salinity from NaCl also resulted in higher concentrations of Cl and lower concentrations of K in the plant tissues than CaCl2 in both cultivars. The concentration of other nutrients in the plants, including N, P, Mg, S, B, Cu, Fe, Mn, and Zn, was also affected by salinity, but in most cases, the response was similar between the two salts. These results point to ion-specific effects of different salts on the plants and indicate that source is an important consideration when managing salinity in highbush blueberry.

Improving aeration systems in saline water (part II): effect of different salts and diffuser type on oxygen transfer of fine-bubble aeration systems.

The objective of the present study is to investigate the different effects on the oxygen transfer of fine-bubble aeration systems in saline water. Compared to tap water, oxygen transfer increases due to the inhibition of bubble coalescence. In Part I of the present study, we investigated in laboratory-scale experiments the effect of design of diffuser membrane. The objective of Part II is the assessment of effects of different salts, diffuser type and diffuser density. We measured the concentration of various salts (MgCl2; CaCl2; Na2SO4; NaCl; KCl) above which coalescence is fully inhibited and oxygen transfer reaches its maximum (referred to as the critical coalescence concentration; CCC). For this purpose, we developed a new analytical approach, which enables investigation of the coalescence behaviour of any aeration system and (mixed) salt solution quickly and easily by evaluating the results of oxygen transfer tests. To investigate the transferability to large scale and the effect of diffuser type and density, we repeated lab-scale experiments in a 17,100 L pilot-scale test tank and carried out additional tests with tube and plate diffusers at different diffuser densities. The results show that despite the higher pressure drop, diffusers with dense slit density and smaller slits are to be recommended in order to improve efficiency of aeration systems in saline water.

Molecular dynamics simulation of the effects of different salts on methane hydrate formation: an analysis of NaCl, KCl and CaCl2

The formation of hydrates in seawater is of great significance for hydrate prevention and control and seawater desalination. Molecular dynamics simulations were performed to investigate the spontaneous methane hydrate formation in 3.5wt % (seawater salinity) NaCl, 3.5wt % KCl and 3.5wt % CaCl2 solution, respectively. Results indicated that salt inhibited the formation of hydrates, and the strength of inhibition followed the sequence of 3.5wt % CaCl2 > 3.5wt % NaCl > 3.5wt % KCl. Salt inhibited nucleation and growth of hydrates by suppressing methane dissolution and reducing the number of tetrahedral water molecules in the methane hydration layer. It was observed that Na+, K+ and Cl- can replace the water molecules in the hydrate cage to participate in the formation of the cage. Compared with the pure water system and KCl system with a fast hydrate growth rate, the randomness of hydrate crystallization was smaller in the NaCl system and CaCl2 system with slow hydrate growth rate.

Farklı Tuz Uygulamalarının Makarnalık (Triticum duum L.) Buğdayda Kadmiyum ve Çinko Alımı Üzerine Etkisi

Cadmium (Cd), an important environmental polluter reaching into soils from different sources, is not an essential element in animal and human nutrition. Cadmium, when present in high concentrations, is an element with toxic effect to humans, animals and plants. One of the important factors affecting Cd accumulation in plants is salinity status of the soils. In this study, it was determined how different salts effected Cd accumulation in plants. 
 When increasing rates of NaCl, Na2SO4 and CaCl2 applied into the soil, it was determined that Cd accumulation capacity of the plants increased only with the forms of Cl-1 salts, particularly with NaCl. It was found that, among different salts applied with increasing ratios (NaCl, Na2SO4 ve CaCl2), NaCl salt remarkably increased green part Cd concentration. With comparing the effects of different salts on Cd uptake, green part Cd concentration in the Cl-1 salt applied condition was higher than those of the plants treated with SO4-2 salt. The Cd concentration of the plants was affected differently when the salt was applied as NaCl and CaCl2 forms. The increasing effect of chlorine on Cd concentration mostly occurred when it was applied as Na form. With the present of calcium, the increasing effect of Cl on Cd uptake was less comparing to Na ion. In conclusion, the application of Cd and different salts with increasing rates decreased dry matter yield of green part but increased Cd accumulation by plant.

An aminated silver orthophosphate/graphitic carbon nitride nanocomposite: An efficient visible light sonophotocatalyst

An Aminated silver phosphate/graphitic carbon nitride (NH2–Ag3PO4/g-C3N4) nanocomposite with favored band gap energy was produced via facile co-precipitation and thermal pyrolysis processes. The synthesized nanomaterials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), field scanning electron microscopy (FESEM), transmittance electron microscopy (TEM), and photoluminescence spectroscopy (PL) analyses. The sonophotocatalytic activity of the prepared NH2–Ag3PO4/g-C3N4 in the removal of methylene blue (MB) was investigated. The influence of such effective parameters as NH2–Ag3PO4/g-C3N4 dosage (50–250 mg L−1), the initial MB concentration (3–10 mg L−1), the initial solution pH (4–10), the effect of different salts, and ultrasound power (50–150 W L−1) on the sonophotocatalytic treatment of MB was investigated. The removal efficiency (R%) of 82% was attained at 150 mg L−1 of NH2–Ag3PO4/g-C3N4, 7 mg L−1 of MB, the solution pH of 7, and the power of 150 W L−1 after 100 min ultrasound irradiation. Additionally, the removal efficiency was enhanced by visible light irradiation due to more radical hydroxyls production via the photocatalytic process. However, the results showed that the addition of benzoquinone and EDTA significantly decreased it, confirming that the main active radicals were hole and superoxide. Moreover, the phytotoxicity study via L. minor growth showed an increase in the number of fronds from 70 to 78 in the treated solution. The kinetic of the treatment process was found to follow a second-order rate law.

Thermodynamic modeling of [formula omitted] solubility in saline water using NVT flash with the cubic-Plus-association equation of state

The accurate estimation of CO2 sequestration potential in deep saline aquifers requires the knowledge of CO2 solubility in brine, thus placing importance on reliable thermodynamic models that account for the effect of different salts and their mixtures over wide ranges of pressure, temperature and salt concentration. Most literature investigated CO2 solubility in a single-salt solution as a replacement of real saline water, which may significantly overestimate CO2 sequestration potential through solubility trapping. In order to accurately estimate CO2 sequestration potential over geological conditions, the Peng-Robinson Cubic-Plus-Association (PR-CPA) equation of state (EOS) is used in this study to model both aqueous and nonaqueous phases. A promising flash technique at given moles, volume and temperature, known as NVT flash, is employed and the salting-out effect is reproduced by correcting the chemical potential of aqueous nonelectrolyte components. To represent real saline environments, five salts are considered, including sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), magnesium chloride (MgCl2) and sodium sulfate (Na2SO4). With taking into account the electrostatic contribution caused by salts, the combination of the salt-based PR-CPA EOS and NVT flash accurately models the solubility behavior of CO2 in mixed-salt solutions and the numerical results agree with experimental data very well. Moreover, the proposed CPA model exhibits neck-to-neck accuracy to the more sophisticated electrolyte CPA EOS, thus making it promising to accurately estimate carbon sequestration potential in saline aquifers through solubility trapping.

Effect of Added Tetraalkylammonium Counterions on the Dilational Rheological Behaviors of N-Cocoyl Glycinate.

Ion specific effect, which is also known as Hofmeister effect, has been reported in numerous systems including ionic surfactant aggregates. Acyl amino acid surfactants have attracted growing attentions in the field of novel surfactants research due to their environmentally benign characteristics. The objective of this study was to investigate the effect of different salts containing NH4+ and tetraalkylammonium (TAA+), where alkyl = methyl (TMA+), ethyl (TEA+), and propyl (TPA+), cations on the dilational rheological properties of interfacial film are stabilized by potassium N-cocoyl glycinate (KCGl). The interfacial behaviors were studied using oscillating drop shape analysis method. The interfacial tensions (IFTs) and dilational rheological parameters results illustrate that KCGl in the presence of salts has better interfacial activity and stronger intermolecular interaction, indicating that added cations contribute to denser molecular packing at oil-water interface. Ion specific effects were observed in the system. Among the cations, KCGl shows highest dilational modulus in the presence of NH4+. The overall interaction between cations and headgroups of KCGl decreases in the sequence NH4+ >TMA+ >TEA+ ≈TPA+, which follows Hofmeister series. The increasing hydrophobicity of TAA+ prevents the interaction between cations and KCGl's headgroup, and therefore prevent amphiphiles from packing closely at interface. The results present a theoretical origin for useful application of KCGl in cosmetics, petroleum and daily chemical industries.

Evaluation of Different Salts and Heavy Metal Concentrations on Bacterial Biofilm from Selected Surface and Borehole Water Samples

Biofilms in drinking water systems can serve as significant environmental reservoirs for pathogenic bacteria associated with gastro-enteric diseases. The evaluation of the effects of different salts and metal concentrations on bacterial biofilm from surface and borehole water samples was conducted. Water samples were collected, from 10 selected water sources of economic importance, aseptically using sterile containers. The physicochemical properties were investigated before the biofilm generation process. The collected water samples were allowed to stand in a secluded environment for four (4) weeks at 27°C±2°C for biofilm generation. The isolates were characterized culturally, morphologically, biochemically and molecularly. The isolates were identified as Stenotrophomonas pavanii, Stenotrophomonas maltophilia, Chromobacterium violaceum, Bacillus cereus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. It was observed that the isolates exhibited growth at a wide range of temperature, salts, pH, and metal salt concentrations. To determine the metal tolerance of the isolates, different concentrations (0.05, 0.1, 0.5, and 1.0%) of four metal salts; ferrous chloride (FeCl2), zinc chloride (ZnCl2), calcium chloride (CaCl2), and magnesium oxide (MgO) was used in nutrient broth. Their ability to grow in medium containing different salt (NaCl) concentrations was also evaluated. Different concentrations of NaCl ranging from 2.0% to 10.0% were used in nutrient broth seeded with 0.1ml of the inocula and incubated at 37°C for 48 and 24hours respectively. Growth was measured in terms of OD at 660 nm using spectrophotometer. Results showed a decline in the growth of the isolates with percentage increase in concentrations of all the metal salts. The result of the effect of NaCl salt on growth showed a decrease in growth with an increase in NaCl concentration from 2% to 10%. For Stenotrophomonas pavanii, FeCl2 is negatively correlated with pH r=-.998 but there is positive correlation between CaCl2 and NaCl with r=889.

A mechanistic experimental study on the combined effect of Mg2+, Ca2+, and SO42- ions and a cationic surfactant in improving the surface properties of oil/water/rock system

More than half of the discovered hydrocarbon reservoirs in the world are the oil-wet carbonates. Enhanced oil recovery (EOR) from these reservoirs is challenging because of their tendency to retain oil at the rock surface. The use of low salinity (LS) water injection to recover more oil from these types of oil reservoirs has been recommended by several researchers. There are possible mechanisms concerning LS water flooding that have been introduced in the literature; a distinct lack of experimental investigation to enhancing the efficiency of this method is still felt. In this work, a detailed and comprehensive study was carried out on using LS + surfactant (LSS) to improve the surface and interface properties of oil + water + calcite rock samples. In the first step, the point of zero charge of the rock sample was determined. Then, the effect of different salts including MgCl2, CaCl2, and Na2SO4 at different concentrations on improving the oil-water interfacial tension and wettability alteration of the rock surfaces was investigated in the presence and absence of a cationic surfactant, cetyl methylammonium bromide (CTAB), in the operational range of pH. Emulsion formation and adsorption measurement tests were performed for a deep investigation of the performance of the cationic surfactant in the presence of different salts. Finally, waterflooding experiments were carried out and the water/oil relative permeabilities, amount of recovery and wettability alteration were thoroughly investigated for three different injection scenarios.The results showed that the co-presence of magnesium, calcium and sulfate ions all in the presence and absence of CTAB surfactant causes a significant reduction in IFT and contact angle values, especially at the lower ranges of salinity. The addition of divalent cations, i.e., Mg2+ and Ca2+, could reduce the amount of surfactant adsorbed on the calcite rock surfaces, especially in the low ranges of salinities. Also, in flooding tests, an increase in differential pressure between the inlet and outlet faces of the core samples from about 2.9 MPa for LS to about 4.7 MPa for LSS flooding, at the breakthrough time, was observed which was related to the formation of water in oil emulsions during LSS flooding. Comparison of the ratio of the residual to initial oil saturation (Sor/Soi) for different flooding scenarios (i.e., injection of saline water (SW), LS and LSS solutions) indicates that as the salinity of water reduces, the efficiency of CTAB surfactant in improving oil recovery increases.

Substitution effects of NaCl by KCl and CaCl2 on Lipolysis of Salted Meat.

The objective of this study was to investigate the reduction and partial substitution effects of sodium chloride (NaCl) by potassium chloride (KCl) and calcium chloride (CaCl2) on lipolysis and lipid oxidation in salted meat aiming at reducing sodium content. To evaluate the effect of different salts on lipid oxidation thiobarbituric acid-reactive substances (TBARs) assay was performed along 180 days. Furthermore, ESI-MS/MS and GC analysis were conducted to detect and identify oxidized lipids, volatile compounds and free fatty acids profiles during the meat processing time. Lipid profiles from different salted meat demonstrated that CaCl2 salt have inducted more lipid oxidation when compared to the combination of NaCl and KCl salts, highlighting the implication of CaCl2 on increased lipolysis reactions. Moreover, the obtained results from both the analyses suggest that a combination of NaCl and KCl salts can be a good alternative for reducing the sodium content without compromising the quality of the salted meat.