Influence Of Sulfate Ions Research Articles

Influence of sulfate ion on fluoride removal from flue gas scrubbing wastewater using lanthanum salts

Batch experiments were conducted to remove fluoride from simulated flue-gas scrubbing wastewater using La(NO3)3·6H2O. The effects of SO42− concentration and addition sequence on residual fluoride concentration and precipitates properties (mass, morphology, phase structure and composition) were investigated using fluorine ion-selective electrode, SEM, EDS and XRD. The results show that precipitates obtained in the presence of SO42− mainly consisted of LaF3 in irregular bulk shape with high crystallinity. However, amorphous particles were observed in the precipitates, which were speculated to be La[SO4]F. Due to the smaller stoichiometric coefficient of F/La in La[SO4]F compared to that in LaF3, the residual fluoride concentration increased as the SO42− concentration ascended. Subsequent addition of SO42− after lanthanum salt could inhibit the formation of amorphous particles, and further reduce the residual fluoride concentration. At a La/F molar ratio of 1:3.0, the subsequent addition of SO42− (0.02 mol/L) after La(NO3)3∙6H2O could obtain a residual fluoride concentration of 6.9 mg/L, lower than the required fluoride emission level. Further increasing the La/F molar ratio could reduce residual fluoride concentration to below 2 mg/L, while the risk of retaining La3+ would emerge.

Comparative Analysis of High Water Hydraulic Fluid for Hydraulic Support

In view of the use and existing problems of high water cut hydraulic fluid for hydraulic support in Shendong mining area, the water quality of each mine in Shendong mining area was analyzed. The influence of mine water quality on hydraulic fluid was analyzed, including the influence of water hardness, the influence of impurities in water, the influence of sulfate ions and chloride ions, the influence of pH value, the influence of conductivity, and the comparison of different raw liquids and different hydraulic fluids. The matters needing attention in daily use and maintenance of hydraulic fluids were put forward. The corresponding hydraulic fluid should be scientifically selected and reasonably proportioned according to the mine water quality. The real-time monitoring of the hydraulic fluid should be paid attention to. The changes in the water quality, concentration, pH value and microbial situation of the hydraulic fluid should be monitored daily. The maintenance and management of the problems should be carried out in time according to the situation, so as to prevent equipment corrosion and ensure the working stability of the hydraulic system. It can provide reference for the selection, proportioning and maintenance of the high water-cut hydraulic fluid of the mine hydraulic support and ensure the safe and efficient production of the working face.

Influence of sulphate ions on the crystal chemistry of white cement mortars with a high content of marble filler powder

Objects of this research are white cement mortars, characterized by both of high content of addition of marble powder and reduced water-cement ratio. The hardened cement mortars, formed after 28-and 120-day curing under standard conditions, are studied. The newly formed phases, containing [SO4]2-, [CO3]2-, [OH]-, etc., are identified using X-ray powder diffraction, infrared spectroscopy and thermal analysis (coupled with analysis of the outgoing gas mixture by mass spectrometry). Based on of the formed calcium silicate hydrates, calcium aluminate hydrates, the influence of sulphate ions is analysed and the mechanism of the thermal decomposition reaction at high temperatures in an oxidizing gas environment is studied. This allows us to establish that the hydration of Portland cement depends on the addition of marble powder (technically calcium carbonate CaCO3), as well as mono- and hemicarboaluminates are formed instead of monosulphoaluminates.

Influence of Sulfate Ions on the Combined Application of Modified Water and Polymer Flooding—Rheology and Oil Recovery

Oil recovery using modified/smart water technology can be maximized by optimizing the composition of the injected water. Brine optimization is also believed to improve polymer flooding performance. This chapter assesses and defines the potential impact of combining low-salt-modified water with polymer flooding, based on the presence of sulfate in the injection water. Hence, we evaluated the influence of sodium sulfate on (1) polymer viscoelasticity, under the assumption that the phenomena exists, and (2) oil recovery and pressure response. Mainly, a comprehensive rheological evaluation and two-phase core flood experiments are the focus of this work. Composition of injection brine is optimized after having synthetic seawater as a base brine. Core-flood experiments were performed in a secondary, tertiary and a sort of post-tertiary (quaternary) mode to evaluate the feasibility of applying both processes (modified water and polymer flood). Obtained data was subsequently cross-analyzed and as an overall observation, sodium sulfate helped with improving polymer viscosity compared to sodium chloride or divalent cation presence. Moreover, optimized modified water, with the higher amount of sulfate ions, showed an additional oil recovery in both secondary and tertiary mode of about 5.0%. Additionally, polymer injection in tertiary mode, after modified-water injection, showed significant additional oil recovery.

Experimental investigation on the effect of sulfate attack on chloride diffusivity of cracked concrete subjected to composite solution

The presence of crack and sulfate ion will significantly affect the chloride diffusivity of concrete resulting in the performance degradation of concrete material and structure. This paper experimentally investigated the chloride diffusivity of cracked concrete subjected to the chloride solution and the composite attack of sulfate and chloride ions. The concentration distributions of both the total and free chloride ions in the cracked concrete are tested to evaluate the influences of sulfate and crack on the chloride diffusivity of concrete material. The experimental observation indicated that the presence of crack resulted in a 2-D chloride diffusion in concrete and the crack width has a notable impact on the chloride diffusion rate. It is found that the presence of sulfate ion decelerated the chloride diffusion in cracked concrete with a lower concentration of both free and total chloride ions. This influence of sulfate ion on the chloride diffusion was enhanced with the elapsed immersion time. Moreover, the chloride binding capacity of concrete material was found decreased by the action of sulfate ion in solution. Finally, the evaluation of corrosion products by X-ray diffraction (XRD) during the erosion process provide a sound mechanism validation for the experimental observations. This study laid an experimental foundation for the upcoming numerical modeling of the diffusivity of cracked concrete material.

Influence of sulfate ion and associated cation type on steel reinforcement corrosion in concrete powder aqueous solution in the presence of chloride ions

State of rebar corrosion in concrete powder aqueous solution contaminated with chloride and sulfate ions has been determined by conducting a potentiodynamic polarization test. XRD analysis and FTIR spectroscopy were also performed. From the results, different zones of corrosion in terms of potential ranges have been identified. The presence of Na2SO4 has mitigated the effect of chloride ions whereas the presence of MgSO4 has stimulated the effect of chloride ions on reducing the passivity of steel reinforcement in a chloride environment. Ordinary Portland cement performed better against Mg-oriented sulfate attack whereas Portland pozzolana cement performed better against Na-oriented sulfate attack in the presence of chloride ions.

The influence of sulfate ions on the electrodeposition of Ni–Sn alloys from acidic chloride–gluconate baths

Codeposition of nickel and tin from acidic gluconate baths of various compositions was investigated. It was found that cathodic process was seriously affected by sulfate ions resulting in lower nickel percentages in the deposits, changes in the phase composition as well as improved surface morphology of the alloys. Partial cathodic polarization curves have shown that tin ions were reduced under limiting current. Chronoamperometric studies indicated nucleation of the alloys according to the instantaneous mechanism. Anodic stripping analysis confirmed phase composition of the alloys – NiSn and Ni3Sn4 were formed in the chloride bath, while NiSn phase was produced in the presence of sulfate anions. It was accordant with thermodynamic predictions. Equilibrium speciation of the baths was also calculated.

Influence of anions on the geotechnical properties of soils treated with hydraulic binders: Individual and coupling effects

The treatment of soils with hydraulic binders improves their physical and mechanical characteristics, allowing the soils to be reused in several geotechnical applications such as road construction. The aim of this research study is to assess the influence of sulfate, chloride, nitrate and phosphate ions, introduced as CaSO4·2H2O, NaCl, NH4NO3 and KH2PO4, on the physical and mechanical properties of a treated soil under accelerated curing conditions. Then, the influence of sulfate ions is determined in the presence of another anion.Regarding the influence of each anion on the soil considered, only phosphate ions have a deleterious effect on the stabilization at concentrations between 3 and 10gkg−1 of dry soil. The sulfate ions induce an important volumetric swelling at 10gkg−1.However, the combination of one anion with sulfate ion induces important disturbances on both volumetric swelling and indirect tensile strength: these interactions must be taken into account in the determination of the stabilization of disruptive parameters.

Chemistry of the calcite/water interface: Influence of sulfate ions and consequences in terms of cohesion forces

Calcite suspensions are used to mimic the behavior of more complex cementitious systems. Therefore the characterization of calcite–water interface in strong alkaline conditions, through ionic adsorption, electrokinetic measurements, static rheology and atomic force microscopy is a prerequisite. Calcium, a potential determining ion for calcite, adsorbs specifically onto the weakly positively charged calcite surface in water. This leads to an increase of the repulsive electric double layer force and thus weakens the particle cohesion. Sulfate adsorption, made at constant calcium concentration and ionic strength, significantly increases the attractive interactions between the calcite particles despite its very low adsorption. This is attributed to a lowering of the electrostatic repulsion in connection with the evolution of the zeta potential. The linear relationship found between the yield stress and ζ2 proves that the classical DLVO theory applies for these systems, contrary to what was previously observed with C–S–H particles under the same conditions.

Influence of seawater composition on SCC behavior of anodized 1050 Al‐alloy

PurposeThe purpose of this paper is to study the stress corrosion cracking (SCC) behaviour of anodized 1050 Al‐alloy in marine environments at different concentrations of sulphate ions.Design/methodology/approachThe SCC experiments were performed by measuring the time to failure in 3.5% NaCl solution, or in the presence of three different concentrations of sulphate ions under conditions of applied anodic current. For the interpretation of the results, changes in potential during SCC tests and optical microscope micrographs of stress corrosion tested specimens at various periods of time, were obtained.FindingsThe influence of seawater composition on the SCC behaviour of the anodized 1050 Al‐alloy depends on the concentration of sulphate ions, the oxide thickness and the stress level. At the higher stress levels and low concentrations of sulphate ions, increased times to failure were observed. These results were attributed to the inhibitory action of sulphate ions. At a low stress level and higher concentration of sulphate ions, the increased times of exposure and the more intensive corrosive environment led to partial destruction of the anodic coatings and a decrease in the time to failure. Better protective properties were observed at an oxide thickness of 10 μm. The thicker oxides did not protect so well because they were more brittle, cracking under strain and allowing corrosive species to reach the metal surface.Research limitations/implicationsThe hypothesised mechanism of the effect of seawater composition on the SCC behaviour of anodized Al‐alloys depended on the concentration of sulphate ions and the stress level remains yet to be confirmed.Practical implicationsThe selection of suitable anodic coatings for the protection of aluminium alloys against stress corrosion cracking depends on the composition of the marine environment.Originality/valueThe paper provides information regarding the influence of sulphate ions on the anticorrosive properties of electrolytically prepared anodic coatings on aluminium alloys.

Influence of sulfate ions on properties of co-precipitated Y 3Al 5O 12:Nd 3+ nanopowders

A new precursor of yttrium aluminum garnet with an approximate composition of NH 4AlY 0.6(CO 3) x (OH) y (SO 4) z · nH 2O has been synthesized via a reverse strike co-precipitation method with ammonium hydrogen carbonate as the precipitant and ammonium aluminum sulfate as the sulfate ions source. The evolution of phase, chemical composition and morphology of the precursor during calcination has been studied by means of XRD, XPS, DTA–TG, BET methods and FT-IR spectroscopy. The loosely agglomerated powders with narrow size distribution, spherical shapes and diameter of 50–60 nm have been obtained by calcination of the sulfate-containing precursor at 1100 °C for 2 h. The doping by sulfate ions enhances densification of Y 3Al 5O 12:Nd 3+ nanopowders compared to undoped ones. This leads to improved microstructure and optical transmittance of vacuum sintered ceramics prepared from sulfate-doped nanopowders.

Influence of sulfate ions on the interaction between fatty acids and calcite surface

The effect of sulfate ions on adsorption/displacement of long chain fatty acids onto/from calcite surface is investigated. The fatty acids used in this work are stearic acid (SA), oleic acid (OA) and 18-cyclohexyl-octadecanoic acid (CHOA). The main methods are thermogravimetric analysis for determining the extent of surface modification and vapour adsorption isotherm to evaluate the wetting behaviour. An appreciable reduction of adsorbed amount of fatty acids is observed in presence of sulfate ions. This is interpreted by the high affinity of the sulfate ions for the active sites of the calcite. In addition, they modify the calcite surface to a negative charge, as indicated by zeta potential measurements, hence reducing the availability of the active sites for carboxylate ions. The ability of sulfate ions to displace the pre-adsorbed fatty acids from the calcite surface is also demonstrated. It is mostly related to the molecular structure of the fatty acids, where the percentage of displacement by 0.1 M sulfate is found to be 7 and 10 for stearic acid and oleic acid, respectively. This work shows that the sulfate ions changed the wettability of calcite to more water-wet as indicated by water vapour adsorption isotherms.

Influence of sulphate ions on corrosion mechanism of carbon steel in calcareous media

The corrosion of carbon steel in contact with synthetic calcareous natural waters containing sulphate ions was investigated. Since the diffusion process is a determining factor in the corrosion kinetics through the reduction of dissolved oxygen, use was made of a rotating disc electrode. The development of the open circuit corrosion potential showed two distinct time domains indicating two corrosion processes: one at the bare electrode and another at the accumulation of corrosion products. Electrochemical impedance spectroscopy measurements at the open circuit potential allowed study of three main phenomena relating to the corrosion of mild steel and the influence of sulphate ions: (i) the formation of a poorly protective surface layer, the double layer capacitance indicating the accumulation of corrosion products; (ii) the charge transfer resistance, allowing evaluation of the corrosion rate; and (iii) mass transport processes through the hydrodynamic layer in the vicinity of the electrode surface, and through the corrosion products.

Influence of Sulfate Ions on Conversion of Fe(OH)<SUB>3</SUB> Gel to β-FeOOH and α-Fe<SUB>2</SUB>O<SUB>3</SUB>

Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and chemical analyses were used for characterizing the effect of sulfate ions on the conversion rate of condensed Fe(OH) 3 gel, prepared from FeCl 3 and NaOH solution, to β-FeOOH and α-Fe 2 O 3 particles by aging at 100°C. Fine particles and supernatant solution were sampled from the aged suspensions containing colloidal particles. XRD profiles and TEM observation showed that β-FeOOH was formed from the gel and subsequently converted into α-Fe 2 O 3 . It was revealed that the addition of sulfate ions accelerated the β-FeOOH formation from the gel, but delayed the conversion from β-FeOOH to α-Fe 2 O 3 . The concentration changes of sulfate and chloride ions in the supernatant solution phases were in agreement with the conversion from Fe(OH) 3 gel to β-FeOOH and α-Fe 2 O 3 Particles.

Phisico-Chemical Investigation on a 32-Year-Old Concrete Marine Struture

A 32-year-old concrete marine structure was phisico-chemically investigated, in order toevaluate its durability.The influence of sulfate ion on concrete must be synthetically determined by ettringite, Friedel's salt and monosulfate. A great difference was found in the distribution of calcium carbonate and calcium hydroxide between concrete exposed to sea air and concrete exposed to sea water.

Influence of sulfate ions on the formation of interphase layers in weak acid zinc electrolytes

Influence of sulfate ions on the formation of interphase layers in weak acid zinc electrolytes

Influence of Sulfate Ions on Chloride-Induced Reinforcement Corrosion in Portland and Blended Cement Concretes

AbstractReinforced concrete structures serving in marine environments and in soils contaminated with high concentrations of chloride and sulfate salts are prone to two problems, namely reinforcement corrosion and sulfate attack. While a substantial number of studies have been carried out on reinforcement corrosion in pure chloride environments, practically no data exist on the influence of sulfate ions on chloride-induced reinforcement corrosion in plain and blended cement concretes.In this study, the effect of chloride and sulfate ions, or both on reinforcement corrosion in plain and blended cement concretes was investigated. Reinforcement corrosion was evaluated by measuring corrosion potentials and corrosion current density at periodic intervals. The mechanisms of chloride-induced reinforcement corrosion in the presence of sulfate ions was elucidated by extracting and analyzing the pore solution.The time to initiation of reinforcement corrosion was observed to be strongly related to the mobility and diffusivity of the chloride ions. Once the chloride and sulfate ions reach the steel-concrete interface, the concomitant presence of sulfates and chlorides generally increases the corrosion rate of steel in both plain and blended cements. Despite the very aggressive internal chemical environment in silica fume cement concrete, the corrosion current density was the lowest and generally below the threshold level. The longer time to initiation of corrosion and lower corrosion current density observed in silica fume cement concrete, even in very aggressive environments marked by high chloride and sulfate concentrations, emphasizes its usefulness in aggressive media.

The influence of sulfate ions on the surface enhanced raman spectra of passive films formed on iron

Surface enhanced Raman (SER) spectra were obtained from the passive films formed on iron in aqueous solutions of sulfate (pH 5 and pH 10) andborate + sulfate. The results indicate that the identities of the passive films are dependent on the pH of the solution, the identity of the anions present and the potential of iron. Either Fe(OH) 2, or a species similar to Fe(OH) 2 and which is produced by the oxidation of Fe(OH) 2, was present in all the films including those formed in the active region of the sulfate solution at pH 5. In the passive state additional species were present but could not always be unambiguously identified. The passive films formed in the sulfate solutions of pH 5 and pH 10 appeared to contain a mixture of Fe 3O 4 and γ-Fe 2O 3. In thesulfate + borate solution the passive film contained α-Fe 2O 3. The widths of the peaks in the SER spectra suggested that the constituents in the films were either microcrystalline or amorphous. In addition, in all solutions examined sulfate ions and, when present in the bulk solution, borate ions, appear to adsorb on the surface of the passive films. In the case of the films formed in the sulfate solution of pH 5, sulfate ions were covalently bonded in the films in a bidentate configuration.

Structural features of sulfate-vanadate-phosphate glasses

The introduction of sulfate ions into vanadate-phosphate glasses may lead to a rearrangement of structure and the acquisition of new properties by the glass. In [i] we reported initial results from an investigation of the structure of glasses of the pseudoternary system Na2P206-V2Os-Na2SO4, using ESR with a vanadium(IV) spin probe. The work reported here was aimed at studying the influence of sulfate ions on the structure of vanadate-phosphate glasses, using intrinsic and radiation-induced paramagnetic centers :(PMC) with vanadium(IV).

Technical Note:The Influence of Sulfate Ion on the Corrosion Potential of Type 304 Stainless Steel in High-Temperature Water

The corrosion potential of type 304 SS in high-temperature water has been measured in relation with the DO content and the trace level of sulfate ion, which is a common impurity in BWR coolant