Presence Of Sulfate Anions Research Articles

Retention of Iodide by Chloride Green Rust and Magnetite.

Green rust (GR), a layered double hydroxide (LDH) containing Fe, and magnetite can be found in natural and engineered environments. The ability of chloride GR (GR-Cl) and magnetite to retain iodide as a function of various parameters was investigated. Sorption equilibrium is achieved within 1 day of contact time between iodide and preformed GR-Cl in suspension. pHm variations (7.5-8.5) have no significant influence, but the iodide sorption decreases with increasing ionic strength set by NaCl. Sorption isotherms of iodide suggest that the uptake operates via ionic exchange (IC), which is supported by geochemical modeling. The short-range binding environment of iodide associated with GR is comparable to that of hydrated aqueous iodide ions in solution and is not affected by pHm or ionic strength. This finding hints at an electrostatic interaction with the Fe octahedral sheet, consistent with weak binding of charge balancing anions within an LDH interlayer. The presence of sulfate anions in significant amounts inhibits the iodide uptake due to recrystallization to a different crystal structure. Finally, the transformation of iodide-bearing GR-Cl into magnetite and ferrous hydroxide resulted in a quantitative release of iodide into the aqueous phase, suggesting that neither transformation product has an affinity for this anionic species.

Predicting and modelling availability of fluoride in soil from sorption properties

AbstractUsage of alkaline and saline groundwater with elevated concentrations of fluoride (F−) for irrigation of pastures requires an assessment of the mobility of F− within the plant‐water‐soil continuum. Factors influencing F− sorption and desorption in 95 Australian soils were examined. Pronounced differences in F− sorption were observed across the soils, but these differences could not be explained by differences in soil pH, electrical conductivity or organic carbon. Rather, sorption was correlated with the content of Fe/Al hydrous oxides and kaolinite in soil. Sorption of F− onto soils increased the solution pH and the ratio of (F− adsorbed) to (OH− desorbed) was consistently below 1, thereby indicating that adsorption of F− results in the release of water and hydroxyl groups from, or co‐adsorption of protons to, the sorbent surface. Maximum sorption occurred at pH values of approximately 5–6, whilst sulphate slightly increased (<5%) F− sorption. Desorption was slightly decreased (~3%–7%) in presence of sulphate anions. Hence, it is unlikely that irrigation of soil with alkaline and saline groundwater, in combination with soil applications of gypsum and sulphur to limit pH fluctuations, would increase mobility of F− in soil. Finally, the irrigation of soil columns with 1200–1500 mm of alkaline and saline groundwater containing 0.18 mM F−, as would commonly occur in irrigation systems using coal seam gas associated water in Australia, resulted in a F− concentration of 0.05 mM at 10 cm depth and the measured values were in excellent agreement with modelled F− movement based on sorption parameters. Thus, sorption parameters can be used to identify soils which minimize movement of F− because of their strong F− sorption. Based on these results, safe limits for irrigation of soil can be established which avoid F− toxicity risks to plants, animals and contamination of water resources.

Environmental Persistence of the Antidepressant Fluoxetine and Its Pharmaceutical Alternative: Kinetics of Oxidation and Mathematical Simulations

To investigate the impact of antidepressants (ANT) in water, estimates of the direct and indirect photolysis of standard fluoxetine hydrochloride (FLX) and a pharmaceutical alternative, fluoxetine sulfate (FLXSO4), were evaluated. The second-order kinetic constants of the ANT and reactive photoinduced species (RPS) (singlet oxygen, 1O2; hydroxyl radicals, HO•; and triplet excited states of chromophoric dissolved organic matter, 3CDOM*) were obtained by competition kinetics under simulated solar radiation. These parameters were used in combination with water characteristics to assess the environmental persistence of the ANT based on mathematical kinetic simulations. The results indicated that the reactions with HO• (kFLX,HO• = (2.54 ± 0.06) × 109 L mol−1 s−1; kFLXSO4,HO• = (3.07 ± 0.03) × 109 L mol−1 s−1) and 3CDOM* (kFLX,3CDOM* = (2.67 ± 0.05) × 109 L mol−1 s−1; kFLXSO4,3CDOM* = (1.48 ± 0.03) × 109 L mol−1 s−1) play a more important role in the degradation of ANT compared to the reactions with 1O2 (kFLX,1O2 = (1.37 ± 0.07) × 107 L mol−1 s−1; kFLXSO4,1O2 = (1.63 ± 0.33) × 107 L mol−1 s−1). The main removal pathways were biodegradation and direct photolysis with persistence in the following order FLX > FLXSO4. Therefore, the presence of sulfate anions can contribute to the degradation of fluoxetine in sunlit environmental waters.

Atomistic Insight into the Behavior of Ions at an Oil-Bearing Hydrated Calcite Surface: Implication to Ion-Engineered Waterflooding

This research provides an atomistic picture of the role of ions in modulating the microstructural features of an oil-contaminated calcite surface. This is of crucial importance for the rational design of ion-engineered waterflooding, a promising technique for enhancing oil recovery from carbonate reservoirs. Inspired by a conventional lab-scale procedure, an integrated series of molecular dynamics (MD) simulations were carried out to resolve the relative contribution of the major ionic constituent of natural brines (i.e., Na+, Cl–, Mg2+, Ca2+, and SO42–) when soaking an oil-bearing calcite surface in different electrolyte solutions of same salinity, namely, CaCl2, MgCl2, Na2SO4, MgSO4, and deionized water (DW). In all cases, we observed the gradual detachment of polar oil molecules (mimicked by decanoate) already paired to Na+ cations, covering the calcite substrate in such a way that carboxylate groups were in contact with the treating solution. The appearance of such a negatively charged interface in conjunction with the bare calcite/brine surface is a likely nanometric source for the disparity of surface characteristics of oil-bearing rocks reported in the literature. The MD results showed the affinity of divalent cations (Ca2+ or Mg2+) for pairing with negatively charged carboxylate functional groups, thereby facilitating desorption of decanoates. Having a compact solvation shell, Mg2+ was not as effective as Ca2+ cations; however, its performance was enhanced in the presence of sulfate anions. We further figured out the tendency of SO42– anions to shielding Na+ sites over the calcite surface, thus limiting the chance of readsorption of carboxylate compounds. Consistent with lab experiences, sulfate was found to assist the access of magnesium cations to the calcite surface as well. Altogether, the present results provide us with a molecular-level validation for the well-known multicomponent ion exchange mechanism proposed for the wettability alteration of carbonate rocks through enriching the divalent ionic content of the injection brine solution.

Treatment of two sartan antihypertensives in water by photo-electro-Fenton using BDD anodes: Degradation kinetics, theoretical analyses, primary transformations and matrix effects

Degradation of two representative antihypertensives, losartan (LOS) and valsartan (VAL) in water by photo-electro-Fenton (PEF), using a BDD anode in presence of sulfate anion was evaluated. PEF showed a fast elimination of these pollutants (>95% at 30 and 60 min of treatment for LOS and VAL, respectively). The main elimination route was the attacks of radicals produced in the system, having pseudo-first-order rate constants of 0.154 and 0.054 min−1 for LOS and VAL, correspondingly. Theoretical analyses of atomic charges were performed to rationalize the antihypertensives reactivity toward the electrogenerated degrading agents. Afterwards, the primary transformation products were assessed. The transformation products revealed that the degrading species attack the biphenyl-tetrazole, imidazole, and alcohol moieties on LOS. Meanwhile, carboxylic and amide groups, plus the central nucleus, were modified on VAL. These moieties corresponded well with the electron-rich sites indicated by the theoretical calculations. Also, the PEF process removed between 33 and 38% of total organic carbon after 5 h of electrolysis. Finally, it was considered LOS treatment in presence of oxalic acid (a typical organic waste of pharmaceutical industry), in addition to the pollutant degradation in effluents from municipal sewage treatment plants by PEF at pH ∼5. Oxalic acid accelerated LOS degradation. Meanwhile, in the effluent, the process led to 64% of LOS removal after 120 min of treatment, indicating the high potentiality of PEF to degrade antihypertensives in water containing organic and inorganic substances.

Early stage in situ detection of polynuclear aluminum phases in aqueous solution

Polynuclear cationic aluminum hydroxide phases are known intermediates in the formation of aluminum oxides or (oxide)hydroxides upon hydrolysis of aluminum salt solutions. In the presence of sulfate anions, these aluminum polyoxocations (Al13) can form crystalline Al13 sulfates with varying chemical composition. The formation of these Al13 sulfates in aqueous solution has been poorly understood. Here, we investigate the early stage crystallization of Al13 clusters in a sulfate-containing solution, in situ and in real time. Dynamics associated with Al13 sulfate formation have been obtained for the first time, using synchrotron X-ray diffraction (XRD) of solutions suspended by acoustic levitation. Time-resolved in situ data show that the cubic phase, Na[(AlO4)Al12(OH)24(H2O)12](SO4)4·10H2O, forms after only minutes. The formation mechanism of Al13 sulfates was found to depend on the sulfate:aluminum (SO4:Al) ratio. Ex situ XRD of the product Al13 sulfates in solution shows that for SO4:Al ratio ≤1.5 two other crystalline phases form, and convert to the cubic phase upon washing and drying. In situ XRD for the same ratio shows transient formation of an intermediate during the crystallization process.

Comparing the photocatalytic activity of N-doped and S-doped titanium dioxide nanoparticles for water splitting under sunlight radiation

The objective of this research is to compare the photocatalytic activity of nanoparticles of N-doped and S-doped titanium dioxide in water splitting by using sunlight radiation for hydrogen production. The sol–gel method was used for the preparation of nanoparticles of doped TiO2 and the weight percent of doping element was 2, 4, 6 and 8. The prepared nanoparticles were identified by absorbance spectra of UV–Vis and FT-IR, TGA, XRD patterns, FE-SEM images and EDX spectra. The nanoparticles of S– $${\text{TiO}}_{2}$$ indicated the lower band gap and lesser particle size versus N– $${\text{TiO}}_{2}$$ nanoparticles. Nevertheless, the nanoparticles of N– $${\text{TiO}}_{2}$$ showed the higher photocatalytic activity in hydrogen production process. The activity of doped samples with sulfur (S– $${\text{TiO}}_{2}$$ ) was reduced by the presence of sulfate anions, and the absorption of radiation in the samples surface was due to a decrease in the number of electron–hole pair in photocatalyst. The photocatalytic activity of N– $${\text{TiO}}_{2}$$ was also increased with the increasing in weight fraction of N atoms, and the highest hydrogen production was obtained in 6 wt% of nitrogen.

Investigating injection of low salinity brine in carbonate rock with the assist of works of cohesion and adhesion and spreading coefficient calculations

Low salinity (LS) and smart water (SW) flooding processes which receive a great interest as cost-effective and environmental friendly techniques are relatively new enhanced oil recovery methods. Although shifting carbonate surfaces towards a water-wet state is the main mechanism behind these methods, effects of controlling factors (for instance: ion type or salinity) are already remained unsettled. In this regard, the effects of sulfate ion types (i.e. Na2SO4, MgSO4 and CaSO4) and their concentrations (i.e. 0–45,000 ppm) on wettability alteration are investigated using contact angle (CA) measurement technique. In addition, work of cohesion, work of adhesion and spreading coefficient of all examined salts are calculated based on the experimental interfacial tension (IFT) and CA measurements. The results reveal that reduction of salinity of the aqueous solution and presence of sulfate anion at high salinity conditions (15,000–45000 ppm) are two important parameters for wettability alteration.

Adsorption and Selective Recovery of Citric Acid with Poly(4-vinylpyridine).

Citric acid (CA) is an important organic acid that is produced on a large scale by fermentation. Current methods to recover CA from the fermentation broth require large amounts of chemicals and produce considerable amounts of waste, while not all CA can be recovered. The use of adsorbents can increase the degree of product recovery and reduce chemical consumption and waste generation. In this work, poly(4-vinylpyridine) (PVP) is evaluated as an adsorbent for CA recovery. It has a high adsorption capacity (>30 wt %) at low pH and a high selectivity for CA at moderate pH in the presence of sulfate anions, two conditions that are frequently encountered during CA recovery. PVP could be efficiently regenerated after adsorption using simple alcohols like methanol and ethanol. Considering selectivity and regeneration, PVP distinctly outperforms more common adsorbents for organic acids, including commercial strongly and weakly basic anion exchangers. The desirable adsorptive features of PVP for CA can be attributed to the low basicity of the pyridine group.

EFFICIENT REMOVAL OF Cr(VI) BY POLYELECTROLYTE-ASSISTED ULTRAFILTRATION AND SUBSEQUENT ELECTROCHEMICAL REDUCTION TO Cr(III)

This work is focused on the removal of Cr(VI) ions from aqueous solution using water-soluble poly(diallyldimethylammonium chloride), PDDA, coupled to an ultrafiltration membrane of regenerated cellulose and subsequent electrochemical reduction of Cr(VI) to Cr(III). The removal of Cr(VI), using the washing mode, was studied as a function of pH, the molar ratio of polymer:Cr(VI), and the presence of interfering ions. The enrichment mode was used to determine the maximum retention capacity of the polymer, and the release of Cr(VI) and regeneration of the polymer were analysed by sorption-desorption process. Subsequently, the electroanalysis of Cr(VI) was conducted by linear sweep voltammetry and full electrolysis at controlled-potential in acidic media and in the presence of PDDA. The results show an efficient removal of Cr(VI) (95%, 30 mg/L in the feed) using PDDA at pH 9 and a polymer:Cr molar ratio of 20:1. The retention capacity of the polymer was decreased by the presence of sulphate anions. The maximum retention capacity of PDDA was 33 mg Cr/g polymer at pH 9. Using the sorption–desorption process, the results indicated that this water-soluble polymer can release Cr(VI) and be regenerated. Finally, the electrolysis of Cr(VI) to Cr(III) was performed successfully in the presence of PDDA.

Interfacial rheological insights of sulfate-enriched smart-water at low and high-salinity in carbonates

Lowering the injection water salinity or modifying its chemistry can improve waterflooding displacement efficiency. This water modification has been frequently alluded to increase rock water-wetness. However, the presence of sulfate anions in the aqueous phase is shown here to also alter the crude oil–water interfacial rheology drastically, in ways similar to that associated to the reduction of water salinity. Under the right conditions, oil recovery could, in principle, be increased to a considerably degree by alteration of fluid–fluid interactions at high salinity. The purpose of this research is to contrast oil recovery behavior in cases when smart-water is designed based on either increasing the sulfate anion concentration in a high-salinity brine or by decreasing salinity considerably, when using seawater as the base aqueous phase. Interfacial rheological and coreflooding results are compared to the case of seawater injection. The effect of various ions on the interfacial shear rheological response of several crude oils and modified seawater were examined. Carefully designed corefloods using Indiana Limestone were run to evaluate the effect of each brine on recovery behavior. Mild temperature and short ageing time were imposed to hinder wettability alteration. Interfacial rheological results show that the visco-elasticity of the crude oil-brine interface is higher for a low-salinity brine compared to the higher-salinity counterpart represented by seawater. However, when the sulfate anion concentration is increased, the interfacial visco-elasticity increases noticeably. Coreflooding results show that brines leading to more a visco-elastic interface, including low salinity and sulfated seawater, yield higher oil recovery factor. Ion analysis of the effluent brine shows that for the model rock used, brine composition does not change significantly from contact with rock surfaces. The recovery response is found to be consistent with changes in interfacial rheology. After the injection of high salinity smart-water in secondary mode, the low-salinity water injection in tertiary mode apparently triggers connection and mobilization of oil ganglia, as hypothesized from the recovery response. Tracking water droplet size distribution seems to support this hypothesis. Low-salinity brine injection is generally conducive to increasing oil production. On the other hand, our findings reveal that the injection of sulfate-enriched water can modify fluid–fluid interactions and consequently the final oil recovery. However, this smart-water appears to lose effectiveness entirely, if injected as residual oil saturation is reached, indicating an apparent threshold in the oil saturation to draw benefits of high-salinity sulfated-water.

Tripodal squaramide conjugates as highly effective transmembrane anion transporters

Two tripodal squaramide conjugates having 4-(trifluoromethyl)phenyl and 3,5-bis(trifluoromethyl)phenyl substituents were synthesized and found to exhibit highly efficient transmembrane anion transport with the EC50 values being 0.14 and 0.75mol%, respectively. Though one of them has been reported to act as a strong anion receptor, in particular for sulfate anions, these two compounds exhibit no significant selectivity with respect to the tested monovalent anions and a very low level of activity in the presence of sulfate anions.

Uranium Removal from Aqueous Solution Using Ion-exchange Resin DOWEX® 2x8 in the Presence of Sulfate Anions

The current study was attributed to uranium (VI) ions adsorption using a anion exchanger resin, Dowex®2x8, in the presence of sulfate anions. Evaluation of operational parameters including contact time, pH, initial concentration of uranium ions, and presence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution was assessed on sorption performance of Dowex 2x8. Employing the Langmuir and Freundlich binding models, isotherm analysis was performed to clarify the relation between uranium ions adsorbed on the resin and the concentration of remaining uranium ions in the aqueous phase. To reveal the rate-limiting step of the sorption process, kinetics modeling using pseudo first-order and pseudo second-order equations was also carried out. Maximum sorption capacity for Dowex 2x8 anionic exchanger resin on uranium removal process was found to be 303.03 mmol g-1. It was also disclosed that existence of diverse anion contents in the solution could affect the uranium sorption using Dowex 2x8 anion exchanger resin.

Effects of the large distribution of CdS quantum dot sizes on the charge transfer interactions into TiO2 nanotubes for photocatalytic hydrogen generation

Hydrogen fuels generated by water splitting using a photocatalyst and solar irradiation are currently gaining the strength to diversify the world energy matrix in a green way. CdS quantum dots have revealed a hydrogen generation improvement when added to TiO2 materials under visible-light irradiation. In the present paper, we investigated the performance of TiO2 nanotubes coupled with CdS quantum dots, by a molecular bifunctional linker, on photocatalytic hydrogen generation. TiO2 nanotubes were obtained by anodization of Ti foil, followed by annealing to crystallize the nanotubes into the anatase phase. Afterwards, the samples were sensitized with CdS quantum dots via an in situ hydrothermal route using 3-mercaptopropionic acid as the capping agent. This sensitization technique permits high loading and uniform distribution of CdS quantum dots onto TiO2 nanotubes. The XPS depth profile showed that CdS concentration remains almost unchanged (homogeneous), while the concentration relative to the sulfate anion decreases by more than 80% with respect to the initial value after ∼100 nm in depth. The presence of sulfate anions is due to the oxidation of sulfide and occurs in greater proportion in the material surface. This protection for air oxidation inside the nanotubular matrix seemingly protected the CdS for photocorrosion in sacrificial solution leading to good stability properties proved by long duration, stable photocurrent measurements. The effect of the size and the distribution of sizes of CdS quantum dots attached to TiO2 nanotubes on the photocatalytic hydrogen generation were investigated. The experimental results showed three different behaviors when the reaction time of CdS synthesis was increased in the sensitized samples, i.e. similar, deactivation and activation effects on the hydrogen production with regard to TiO2 nanotubes. The deactivation effect was related to two populations of sizes of CdS, where the population with a shorter band gap acts as a trap for the electrons photogenerated by the population with a larger band gap. Electron transfer from CdS quantum dots to TiO2 semiconductor nanotubes was proven by the results of UPS measurements combined with optical band gap measurements. This property facilitates an improvement of the visible-light hydrogen evolution rate from zero, for TiO2 nanotubes, to approximately 0.3 μmol cm–2 h–1 for TiO2 nanotubes sensitized with CdS quantum dots.

Uranium Ions Removal Using Amberlite CG-400 Anion Exchanger Resin in the Presence of Sulfate Anions

Uptake of uranium (VI) ions using an anion exchanger resin, namely amberlite CG-400, was studied through this work in the presence of sulfate anions. Impact of various parameters including pH, contact time, initial concentration of uranium ions and intrusion with different anion contents (phosphate, chloride,sulfate, nitrate and fluoride) was examined on the sorption performance of the resin. An estimation of sorption process was also performed using isotherm and kinetics equations, which led to conformity of Freundlich and pseudo second-order models with experimental data, respectively. The maximum adsorption capacity (qmax) was found to be 63.29 mg g-1. Presence of various anions species in solution show that uranium sorption using amberlite CG-400 anion exchange resin could strongly be affected.

Application of Graphene Nanoparticles in Removal of Fluoride from Aqueous Solution in Presence of Sulfate Anion

Application of Graphene Nanoparticles in Removal of Fluoride from Aqueous Solution in Presence of Sulfate Anion

Entrapment of Cyclic Fluoride–Water and Sulfate–Water–Sulfate Cluster Within the Self-Assembled Structure of Linear meta-Phenylenediamine Based Bis-Urea Receptors: Positional Isomeric Effect

meta-Phenylenediamine based two linear bis-urea anion receptors, L1 (meta-nitro) and L2 (para-nitro), have been synthesized which showed strong binding affinities toward halides as well as planar and tetrahedral oxyanions. In the presence of excess fluoride anion, L1 self-assembles to entrap a cyclic fluoride–water tetrameric cluster within its tetrameric pillar-like assembly of each urea arm (complex 1a). In the presence of sulfate anion, L1 self-assembles in an identical fashion to entrap the bigger tetrahedral anion (complex 1b), whereas two urea moieties of two different receptor molecules of L1 have been structurally authenticated to be sufficient to stabilize the simple Y-shaped acetate anion in complex 1c. On the other hand, receptor L2, with a bis(para-nitro urea) functional group, especially in the presence of sulfate anion, self-assembles like long straight pillars entrapping sulfate–water–sulfate cluster {SO42–-(H2O)3-SO42–} (complex 2a). Additionally, L2 forms a host–guest assembly with the ca...

Adsorptive Behavior of an Amberlite Anion Exchanger Resin for Uranium (VI) Sorption in the Presence of Sulfate Anions

Uranium (VI) sorption using an anionic exchanger resin in the presence of sulfate anions, namely amberlite 910, was the subject of current study. Batch sorption experiments were carried out to evaluate the influence of operational parameters such as pH, contact time, initial concentration and existence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution on amberlite 910 sorption behavior. Kinetics study revealed that the pseudo-second-order model showed better curve-fitting regression of the experimental data than the pseudo-first-order one. Freundlich isotherm was also provided well mathematical description of sorption process than the Langmuir one. It was also revealed that the existence of various anion species in the solution could strongly affect the sorption of uranium using amberlite 910 anion exchanger resin.

M-Al-SO4 layered double hydroxides (M=Zn, Mg or Ni): synthesis, characterization and textile dyes removal efficiency

Mg–Al, Zn–Al, and Ni–Al layered double hydroxides (LDH) materials with molar ratio (M2+/Al3+) of 3 were synthesized via co-precipitation method. The as-synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and simultaneous thermogravimetric–differential thermal analysis (TGA/DTA). XRD analyses showed that Zn–Al-SO4 had the greatest lattices parameters followed by Mg–Al-SO4 and Ni–Al-SO4. FTIR confirmed clearly the presence of sulfate anions in the structure of LDHs with the presence of carbonate impurity in the interlayer. TGA/DTA analysis indicates a better thermal stability of Zn–Al-SO4 vs. Ni–Al-SO4 and Mg–Al-SO4. The capability of the materials for textile dye removal was investigated using methyl orange (MO) as a model dye and an industrial textile effluent. Experimental results showed that pH is the most affecting factor in dye removal. The effective pH range for dye removal was between 3.5 and 5. The adsorption process can be well described by the pseudo-second-order kinetic model. The Langmuir model fit equilibrium data with exceptional maximum adsorption capacities for MO of 2,758, 1,622, and 800 mg/g, respectively, in the case of Zn–Al-SO4, Mg–Al-SO4, and Ni–Al-SO4. Color and chemical oxygen demand (COD) reduction from industrial textile effluent increased with the increase in the amount of LDHs. The optimum color and COD reduction were obtained by Zn–Al-SO4.

Positively charged and bipolar layered poly(ether imide) nanofiltration membranes for water softening applications

Poly(ether imide) (PEI) ultrafiltration membranes were chemically modified with branched poly(ethyleneimine) to obtain nanofiltration (NF) membrane Cat PEI with a positive charge in the pH range below 9. An oppositely charged polyelectrolyte layer was deposited on the resulting membrane surface by using sodium polystyrene sulfonate (PSSNa) and sodium polyvinyl sulfonate (PVSNa) to prepare a bipolar layered membrane NF Cat PEI_PSS and Cat PEI_PVS having a negatively charged surface and positively charged pores. Cat PEI exhibited good performance to remove multivalent cations (more than 90% of Ca2+) from single salt solutions except in presence of sulfate ions. Adding an anionic polyelectrolyte layer onto the positively charged surface resulted in a significant enhancement of rejection performance even in presence of sulfate anions. Application of the prepared membranes in water softening of natural complex mixtures was successful for the different studied membranes and a large decrease of hardness was obtained. Moreover, Cat PEI_PSS showed a good selectivity for nitrate removal. Fouling experiments were carried out with bovine serum albumin, as model protein foulant. Cat PEI_PSS showed much better fouling resistance than Cat PEI with a quantitative flux recovery ratio.