Sulfate Ions In Water Research Articles

Electrically enhanced adsorption performance of functionalized aluminum-nitride nanotubes for removal of sulfate ions in water

Here, density functional theory(DFT) calculations were carried out to investigate the effect of applied electric field on the adsorption of sulfate ions in water by doped functional aluminum nitride nanotubes. The stable structure of the adsorption system, the adsorption energy of SO42− on the adsorbent, and the electronic and thermodynamic properties of the adsorption system under applied electric field were calculated and analyzed. The results show that the adsorption energy of boron doped aluminum nitride nanotubes (AlNNT-B) on SO42− can be greatly improved under the action of electric field (EF). The electric field promotes the electron transfer of SO42− to AlNNT-B, and gradually increases the Mayer bond levels of B-N25 and B-N27, indicating that the binding of B atoms to N atoms is enhanced. In addition, the thermodynamic analysis shows that the adsorption of SO42− on the surface of AlNNT-B is a spontaneous heat release process, and the trend of spontaneous heat release can be enhanced by EF. Our research results not only propose a novel method for removing sulfate ions from water, but also have significant implications for other applications of nanomaterials (such as delivery system of anticancer drugs).

Electrically enhanced adsorption efficiency of aluminum nitride nanotube for sulfate ion removal from water

Herein, the adsorption performance of sulfate ion in water on aluminum nitride nanotube(AlNNT) under the influence of an electric field was investigated using the density functional theory (DFT) calculation method. The model structure stability, adsorption energy, electronic and thermodynamic properties of sulfate ion adsorbed on the surface of AlNNT were studied. The calculation results indicate that sulfate ion reacts with multi-atoms on the surface of AlNNT, forming ionic bonds and undergoing chemical adsorption. As the electric field intensity increases, the adsorption energy and the transfer of electrons from sulfate ion to AlNNT increase, leading to a higher degree of hybridization of atomic orbitals and enhanced multi-atom interactions. Additionally, the thermodynamic data suggests that the adsorption between sulfate ion and AlNNT under electric field can occur spontaneously, the process of which is exothermic. The results of present study are expected to propose a novel method for separation and removal of sulfate pollutants from water.

Overlooked effect of ordinary inorganic ions on polyaluminum-chloride coagulation treatment

Application of poly-aluminum chloride (PACl) coagulant is a popular mode of water treatment worldwide because of the high capacity of PACl to neutralize charge. The manufacture and use of PACls with various basicities in different regions around the world suggest that the characteristics of the raw water are important determinants of the efficacy of PACl application. However, attention has not been fully paid to the effects of water quality other than the substances to be removed. In this study, two typical PACls with different basicities were used to investigate why the performance of PACls depends on the characteristics of the raw water. We focused on the concentrations of inorganic ions in the raw water. Use of high-basicity PACl (HB-PACl) with a high content of polymeric-colloidal species (Alb+Alc) resulted in very slow floc formation and little turbidity removal in raw water with low concentrations of sulfate ions. The performance of the HB-PACl was inferior to that of normal-basicity PACl (NB-PACl), although the charge-neutralization capacity of the HB-PACl was higher. Rates of floc formation were strongly correlated with the rate of aluminum precipitation by hydrolysis reaction, which was identified as an indicator for evaluating the compatibility of raw water with PACl treatment. Among the common ions in natural water, the sulfate ion had the greatest ability to hydrolyze and precipitate PACl because of its divalency and tetrahedral structure. This conclusion followed from experimental results showing similar effects for selenate and chromate ions as for sulfate ions and somewhat smaller effects for thiosulfate ions. Bicarbonate ions and natural organic matter affected PACl hydrolysis-precipitation, but chloride ions, nitrate ions, and cations had little effect on PACl hydrolysis-precipitation. Interestingly, the abilities of sulfate ions to hydrolyze HB-PACl and NB-PACl were very similar, but bicarbonate ions were less effective in hydrolyzing HB-PACl than NB-PACl, and bicarbonate ions contributed little to the hydrolysis-precipitation of HB-PACl in raw water with normal alkalinity. Therefore, sufficient coagulation with HB-PACl therefore usually requires a certain concentration of sulfate ions in water to be treated. The implication is that which anions are most influential to the hydrolysis-precipitation of PACl, and thus to PACl's coagulation ability depends on the constituents of the PACl.

Improving the quality of waste water treatment by flocculation

Flocculation using polyacrylamides is one of the most promising methods of industrial wastewater treatment. The aim of our research was to estimate the efficiency of the use of new types of polyacrylamide-based flocculants for industrial wastewater treatment. The objects of the study were the wastewaters of the enterprise LLC “Saratov Chemical Plant of Acrylic Polymers “ACRYPOL” and several flocculants (water-soluble polymers) obtained on the basis of acrylamide, acrylic acid and chitosan. It was established that the optimal dose of nonionic flocculant H600™ was 5 mg/dm3. Industrial wastewater treatment efficiency was studied on two samples of weakly cationic flocculants (215-2 and 233-2) synthesized in a laboratory way, as well as on a sample of nonionic flocculant H600™. It was found that the tested flocculants had no significant effect on the pH value and the content of sulfate ions in water. Flocculant 233-2 with the highest chitosan content was the best in terms of chemical oxygen demand, dry residue and the amount of suspended solids. Flocculant 215-2 with the lowest chitosan content had a slightly worse performance. The worst of the tested flocculants was the nonionic H600™, which does not contain chitosan.

Understanding the effect of sulphate in mining-process water on sulphide flotation

Water quality affects the flotation recovery of minerals and their separation. Mining-process waters become saturated with soluble salts after contact with minerals (oxidation and dissolution) during crushing, classification and flotation. Inorganic species, such as metal ions but also carbonate and sulphate ions, may have a positive or negative effect on mineral flotation. As sulphate ions are always found in high concentrations in process waters, their effects on the flotation of copper, molybdenum and zinc sulphides were investigated in single minerals and ores experiments with complementary mineral surface analysis and particle-bubble detachment studies. It was found that molybdenite flotation was more depressed than chalcopyrite flotation by the presence of sulphate ions in water as a result of increased surface oxidation which decreased particle-bubble attachment. Similar results were obtained in the flotation of two copper ores; however, the grade of chalcopyrite and molybdenite was much lower as a result of increased recovery of unwanted or gangue minerals (e.g., sphalerite, pyrite and quartz).

Effect of water flow characteristics on gypsum dissolution

Gypsum is one of the karstic rocks with many positive and negative characteristics. The most important defect of these rocks is solubility against water flow. The dissolution phenomenon in gypsum is accompanied by the release of the sulfate ion in water increasing its concentration, gradually. In this research, the effect of water flow temperature (T), Reynolds number (Re) and water head (H) on gypsum dissolution rate was evaluated, experimentally. In all of the experiments, gypsum samples were prepared approximately in the same dimensions and a circular hole was created inside the sample. Results showed that by increasing the temperature above $ T/T_{a}=1.30$ (Ta = temperature of the ambient air), the dissolution rate of gypsum was significantly increased. At the end of the experiment, the hole diameter (d) at the temperatures $ T/T_{a}=1.09$, 1.30, 1.52 and 1.74 has been increased about 90%, 137%, 141% and 148% from the initial hole diameter (di), respectively. The dissolution rate at $ T/T_{a}=1.09$ is about 50% less than the dissolution rate at temperatures $ T/T_{a}=1.52$ to 1.74. Moreover, the increasing rate of the outlet discharge for H/d = 333 is 1.89 times the increasing rate of the outlet discharge for $ H/d=167$.

SULFATE ION IN THE GROUNDWATER IN THE BASIN OF MAYMA RIVER (NORTHERN ALTAI, RUSSIA)

he relevance of the investigated problem is that the majority of the world's population suffers from a lack of drinking water. A significant part of the water on the surface of the Earth is characterized by low quality and is not suitable for home use. That is why it is important to investigate the causes of changes in the qualitative composition of water and find ways to influence it. The aim of the article is to study the content of sulfate ion in the waters of Northern Altai by the example of the Maima river basin. The data was analyzed from two different sources in two laboratories for more accurate results. The study showed that the content of sulfate ions in water is influenced by such factors as precipitation, geological features, landscape features. Different temperature and humidity conditions at different times of the year also affect this indicator. Ice and snow can accumulate sulfate ions created by anthropogenic factors, and, accordingly, during melting, sulfate ions get into groundwater and river waters. The studied indicator is also affected by air temperature and groundwater temperature, the increase of which can be caused by earthquakes. Due to the large number of factors affecting the content of sulfate ion in water, it is rather difficult to determine the exact cause of significant fluctuations. Therefore, the work proves the importance of a comprehensive analysis of factual materials and the study of all of the above factors. Article materials can be useful in further studying the qualitative composition of the waters of the Northern Altai, as well as for their practical application to improve the composition of drinking water.

Case investigation in safety and reliability of a family heat supply system

AbstractCorrosion investigation and reliability analysis of a family heat supply system has been carried out. Results indicate that the smoke emission steel pipe mainly suffers the corrosion at high temperature, and the corrosion components in the heat supply system undergo the atmospheric corrosion attack in indoor environment. Besides, safety and reliability related corrosion factors include water temperature, water oxygen concentration, pH value, carbon dioxide content, and chloride and sulfate ion in water have been discussed. It is concluded that the make‐up water quality is crucial to the safety and reliability of the heat supply system.

Experimental study on durability of FRP sheets under wet-dry cycles in various solutions

Abstract Fiber-reinforced polymer (FRP) is being extensively used in repair and rehabilitation of concrete structures due to their excellent performance and ease of application. Externally bonded FRP hydraulic structures in fluctuating backwater area are likely being exposed to wet-dry cycles and unavoidably being attacked by chloride ions, sulfate ions in water. Therefore, the long-term durability of FRP composites under wet-dry cycles in various corrosive solutions becomes a major consideration in the selection of these composites. This paper evaluates the durability of three kinds of FRP sheets under four kinds of wet-dry cycles, which represent the hydraulic structures various conditions. Tensile tests of FRP sheets for periods up to one year have been presented. Test results indicate that: (1) Degradation of FRP sheets is primarily observed on the level of tensile strength rather than of elastic modulus; (2) Degradation of FRP sheets under wet-dry cycles in sulfate and chloride solutions is more significant than in alkali and acid solutions; (3) AFRP sheets and CFRP sheets show better resistance against wet-dry cycles in various solutions than BFRP sheets.

A fluorescent probe for the selective detection of sulfate ions in water

A nicotinamide–anthracene conjugate based fluorescent probe 1 exhibits highly selective fluorescence enhancement at 535 nm only with sulfate in HEPES buffer–DMSO (9:1) at pH 7.4. The other anions viz. F−, Cl−, Br−, I−, AcO−, HSO4−, H2PO4−, CN−, OH−, NO3−, ClO4−, SCN−, even if present in excess, do not interfere in the estimation of sulfate. The limit of detection for sulfate ions by probe 1 is 0.5 μM. Probe 1 can also be used to determine the sulfate ions in tap water using EDTA as a metal ion masking agent. Titration experiments and Job's plot reveal the formation of a 1:1 stoichiometric complex between the probe 1 and sulfate ions and DFT studies show the electron transfer from SO42− to anthracene moiety responsible for the observed optical changes.

Potentiometric Determination of Ion-Pair Formation Constants for Cadmium, Calcium Salts, and Cadmium-18-crown-6 Ether Derivative Complexes with a Sulfate Ion in Water

Theoretical equations were derived for the determination of ion-pair formation constants (K0 in mol-1·dm3) for 2:2 (M2+X2-) and 2:1 electrolytes and MX with crown ethers (L) in water at an ionic strength of zero. The K0 values were determined potentiometrically at 25 °C; CdSO4, CdCl2, Cd(picrate)2, CaCl2, and Ca(picrate)2 were used as the electrolytes, and CdL2+SO42- with L = 18-crown-6 ether (18C6) and benzo-18C6 were used as the ion-pair complexes. By examining the validity of the equations directly or indirectly, the K0 values for CdSO4 and CdCl2 were compared with the corresponding literature. Consequently, it was evident that the derived equations are useful for the determination of K0.

The sulphate ion in aqueous solution: an X-ray diffraction study of a ZnSO4solution

Two distinct X-ray diffraction studies of ~2 mol dm−3 ZnSO4 solutions were carried out in order to assess the possibility of studying the state of the sulfate ion in water and to verify whether and how structural information depends on possible differences in experimental data. It is shown that the X-ray diffraction method is unable to provide results capable of unambiguous modelling of the SO2−4 coordination; even the complete omission of sulfate-water interactions does not lead to unsatisfactory synthetic structure functions. This conclusion does not seem to be affected by differences in the experimental data; however, some characteristics of the `best' models can be affected by differences in experimental data that are within the limits of experimental uncertainties.

Experimental evidence of interactions SO 2−4 −H 2O in an aqueous solution

The scattering of X-rays from a (NH 4) 2SO 4 aqueous solution has been measured and analysed at 25°C. It is shown that the sample may be considered as a solution of sulphate ions in water. In this way the existence of discrete SO −2 4 −H 2O interactions can be unambiguously demonstrated. Good agreement with experimental data is achieved through a model in which each oxygen atom in the sulphate ion gives rise to about two hydrogen bonds with water molecules.

Oxygen isotopic composition of sulfate ions in water from thermal springs

No relation has been found between δO 18(SO 4 2−), δO 18(H 2O) and t °C in the water from 34 thermal springs in Tuscany (Italy). The δO 18(SO 4 2−) measurements carried out on some Triassic and Miocene evaporites from the same area confirm that the Upper Triassic evaporites are the source of the sulfate dissolved in thermal waters.

Some Improvement on Barium Chloranilate Method.

In barium chloranilate method for determining sulfur oxides in air or sulfate ion in water proposed by Bertolacini (Anal. Chem. 29, 281 (1957)), the absorbance is always constant in the range of pH 5.2∼7.9, while at pH 4.0 the absorbance is affected by the little variation of pH. Therefore, the buffer solution of pH 5.2 gives the more reliable results than that of pH 4.0.

An Electron Microscopic Study on the Suspension for the Nephelometry of Sulfate Ion

The electron microscopic observation of suspended particles of barium sulfate revealed that the nephelometric method of the estimation of sulfate ion in water as barium sulfate gives different shape and size by the least change of concentration of sulfate ion. The authors obtained dendritic suspended particles of 0.6 × 0.15μ in size by the formation of the suspension in 50% alcohol and the suspended particles are uniform in shape and size within the limit of concentration of sulfate ion present in natural water. By the use of this method the error of estimation is minimized within several percent. The data of estimation by this nephelometry and by the gravimetric method were discussed.