Basic Sulfate Research Articles

Enrichment and immobilization of heavy metal ions from wastewater by nanocellulose/carbon dots-derived composite

Heavy metal ions (HMIs) have been widely applied in various industries because of their excellent physicochemical properties. However, their discharging without appropriate treatment brought about serious pollution problems. So it is desirable but challenging to rapidly and completely clean up these toxic pollutants from water, especially utilizing environmentally friendly and naturally rich biomass materials. In this work, we prepared nanocellulose/carbon dots/magnesium hydroxide (CCMg) ternary composite using cotton via a simple hydrothermal method. The removal mechanism towards Cd2+ and Cu2+ was investigated using a combination of experimental techniques and density functional theory calculations. CCMg shows a good ability to remove HMIs. It is realized that the interaction between each component of CCMg and cadmium nitrate is mainly of hydrogen/dative bonds. Cadmium nitrate is preferentially enriched by the Mg(OH)2 moiety, proved by calculated thermodynamics, interfacial interactions and charges. After transformation, the cadmium carbonate precipitate is fixed on the surface by nanocellulose (NC) via chemical coupling; and of interest is that copper ion precipitates in the form of basic sulfate. Due to its high adsorption effect and simple recovery operation, CCMg is having a wide range of application prospects as a water treatment agent.

Aqueous Rechargeable Zn/ZnO Battery Based on Deposition/Dissolution Chemistry.

Recently, a novel electrochemical regulation associated with a deposition/dissolution reaction on an electrode surface has been proven to show superiority in large-scale energy storage systems (ESSs). Hence, in the search for high-performance electrodes showcasing these novel regulations, we utilized a low-cost ZnO microsphere electrode to construct aqueous rechargeable batteries (ARBs) that supplied a harvestable and storable charge through electrochemical deposition/dissolution via a reversible manganese oxidation reaction (MOR)/manganese reduction reaction (MRR), respectively, induced by the inherent formation/dissolution of zinc basic sulfate in a mild aqueous electrolyte solution containing 2 M ZnSO4 and 0.2 M MnSO4.

Electrochemical performance of novel Pb alloys reinforced with Ni-coated fly ash microballoon composite foams in Lead Acid Battery

Novel Pb composite foams comprising hybrid gas pores and Ni-coated fly ash microballoons were produced by direct melt foaming method. Pb composite foams were designed to have a lower weight and larger surface area to be used in the Lead Acid Battery (LAB) as alternative to the traditional Pb grids, offering benefits in the transportation industry. The Ni-coated fly ash microballoons were added to Pb alloy melt to serve as thickening agent and pores, which were wholly enclosed within the microballoons, as well as reinforcements. The electrochemical performance of Pb grids used in traditional LAB and Pb composite foams produced in the present work was investigated for comparing purposes. The cured plates form positive and negative electrodes of Pb grid and Pb composite foams were characterized by X-ray diffraction to identify the different Pb compounds and phases. The morphology of the cured plate was found to contain flakes and dendritic structure. Zones were formed from a network of Pb particles in the negative electrode covered with PbSO4 crystals. The PbSO4 crystals exhibited miscellaneous morphology. The matrix of lead basic sulphate crystals was converted into aggregates of PbO2 particles in the positive electrode morphology, which maintained the form of the original substance. Cyclic voltammetry measurements (CV) were conducted in 3 M H2SO4 to study the anodic oxidation and cathodic reduction peaks of Pb, PbSO4 and PbO2. The galvanostatic polarization for oxidation and reduction steps was measured at different current densities. It revealed the benefit that the Pb matrix composite foam showed a longer period for oxidation of Pb into PbSO4. The composite foams exhibited a greater specific discharge electrical capacity than the Pb alloys used in traditional LAB.

Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made to extract vegetable tannins from Xylocarpus granatum bark using different solvents (e.g., water, methanol, ethanol, and chloroform) and compare with conventional vegetable tanning agents such as mimosa and quebracho. The highest extraction efficiency was observed 31.22% by methanol. The presence of tannin content and polyphenolic compounds, e.g. (-)epicatechin (503 mg/100 g dry extract), catechin hydrate (218 mg/100 g dry extract), catechol (29 mg/100 g dry extract) were ensured by UV–Vis, FT-IR spectroscopy and HPLC. Again, condensed tannins, moisture content, and pH of the methanol extracted tannin were found 47.80%, 5.82%, and 3.97 respectively. The leather tanned by Xylocarpus granatum tannin showed a shrinkage temperature of 86.34 ± 1.52 °C. Other properties such as tensile strength, tear strength, grain cracking load, and distention at grain cracking were comparable to conventional vegetable-tanned leather. The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy (SEM) which revealed a compact structure of the leather fibers. In light of the findings from the study, X. granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.Graphical

Bioleaching of Enargite/Pyrite-rich “Dirty” Concentrate and Arsenic Immobilization

Bioleaching of arsenic (As)-rich, so-called “dirty” concentrates can produce additional Cu value from the flotation waste while simultaneously releasing toxic As. This study bioleached three such concentrates of varying pyrite/enargite ratios ([Py]/[Ena] = 0.7, 1.3 and 2.4) at a pulp density of 20%. The dissolution behavior of Cu and As in relation to the solution redox potential (Eh) was studied with and without activated carbon (AC) as a potential Eh-controlling catalyst. At this high pulp density, Eh was naturally suppressed, without a need for AC dosing, to <700 mV (a rapid pyrite dissolution is prevented in this Eh range). The effect of AC dosing on Eh varied depending on the type of concentrate; Eh was further reduced only in the case of the most enargite-rich concentrate, DC-I. Among the three concentrates, the highest Cu dissolution (35%) was seen in DC-I (without AC dosing), which simultaneously achieved the lowest As solubilization. Arsenic was immobilized as amorphous precipitates, likely in a mixture of ferric arsenate, cupric arsenate, basic ferric sulfate and sulfur. Arsenic immobilization became increasingly ineffective as the pyrite content increased in the concentrate. Based on these results, setting a lower [Py]/[Ena] ratio prior to the dirty concentrate bioleaching could be a useful approach to promote Cu dissolution and As immobilization simultaneously.

Influence of intensity of ultrasound on morphology and hardness of copper coatings obtained by electrodeposition

The influence of various intensities of ultrasound applied for the electrolyte stirring on morphological and mechanical characteristics of electrolytically produced copper coatings has been investigated. The copper coatings produced by the galvanostatic regime of the electrodeposition from the basic sulphate electrolyte and the electrolyte with added levelling/brightening additives at the low temperature were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques (surface morphology and topography, respectively) and by Vickers microindentation (hardness). The roughness of coatings increased with the increasing intensity of ultrasound, indicating that morphology of the coatings worsened with the enhanced application of ultrasonic waves. This is attributed to the strong effect of ultrasound on hydrodynamic conditions in the near-electrode layer, which is manifested by the increase of share of the activation control in the mixed activation-diffusion control of electrodeposition with increasing the intensity of ultrasound. The concept of "effective overpotential" originally proposed to explain a change of surface morphology in the conditions of vigorous hydrogen evolution is also applicable for a change of morphology of Cu coatings under the imposed effect of ultrasonic waves. Hardness analysis of the coatings showed that an intensity of applied ultrasound did not have any significant effect on the hardness, especially for the Cu coatings produced from the basic sulphate electrolyte.

Structural, Mechanical and Electrical Characteristics of Copper Coatings Obtained by Various Electrodeposition Processes

Mechanical (hardness and adhesion) and electrical (sheet resistance) characteristics of electrolytically produced copper coatings have been investigated. Morphologies of Cu coatings produced galvanostatically at two current densities from the basic sulfate electrolyte and from an electrolyte containing levelling/brightening additives without and with application of ultrasound for the electrolyte stirring were characterized by SEM and AFM techniques. Mechanical characteristics were examined by Vickers microindentation using the Chen–Gao (C–G) composite hardness model, while electrical characteristics were examined by the four-point probe method. Application of ultrasound achieved benefits on both hardness and adhesion of the Cu coatings, thereby the use of both the larger current density and additive-free electrolyte improved these mechanical characteristics. The hardness of Cu coatings calculated according to the C–G model was in the 1.1844–1.2303 GPa range for fine-grained Cu coatings obtained from the sulfate electrolyte and in the 0.8572–1.1507 GPa range for smooth Cu coatings obtained from the electrolyte with additives. Analysis of the electrical characteristics of Cu coatings after an aging period of 4 years showed differences in the sheet resistance between the top and the bottom sides of the coating, which is attributed to the formation of a thin oxide layer on the coating surface area.

Recovery of red iron oxide pigment from zinc plant hematite precipitates

ABSTRACT Hematite precipitates during zinc hydrometallurgy contain a certain amount of Zn and S impurities, which limit its applications. To remove these impurities and prepare high-value red iron oxide, a two-part study was carried out by atmospheric water washing and high-temperature hydrothermal treatment. The results showed that Zn2+ and SO4 2− existed two forms: adsorbed on the surfaces of hematite precipitates and via physical inclusions; as insoluble sulfates, jarosite, and basic ferric sulfate. During the high-temperature hydrothermal reactions (240°C, 6h, 10g/L H2SO4, 6 mL/g liquid-to-solid ratio), the non-iron phases in hematite precipitates transformed into iron oxides. The iron content in the product increased from 58.7% to 68.8%, the sulfur content decreased from 2.96% to 0.63%, and the zinc content decreased from 1.03% to 0.07%. The specific surface area increased from 0.39m2/g to 1.44 m2/g. These products met the application requirements of ISO 1248-C-II-2-a for red iron oxide.

Recovery of valuable metals from copper smelting open-circuit dust and its arsenic safe disposal

In this research, an integrated hydrometallurgical process for comprehensive recovery of valued metals and safe disposal of arsenic from copper smelting open-circuit (CSO) dust was developed. By sulfuric acid leaching, Cu, As, Zn and Cd can be selectively extracted into leachate while Pb and Bi were remained in the residue. Then, iron powder cementation, iron salt precipitation and Na2CO3 neutralization precipitation were adopt to successively recover Cu as sponge copper, remove As mainly as thermodynamically stable ferric arsenate and recover Zn and Cd as basic sulfate. Afterwards, the obtained ferric arsenate residue was solidified by cement with additive fulvic acid (FA). FA had an excellent performance and it can reduce arsenic leachability to 1.5 mg/L. The zeta potential, FTIR and SEM analyses indicated that FA chemically adsorbed onto the surfaces of ferric arsenate residue and cement hydrates through carboxylate groups. FA promoted the deposition of cement or cement hydrates on the surface of ferric arsenate residue, thereby enhancing the physical encapsulation of arsenic residue. This research demonstrates the possibility of comprehensively recovering metals and safely disposing arsenic from hazardous waste CSO dust by the developed integrated hydrometallurgical process, and thus it has good industrial application prospect.

Green synthesis, structure feature and energy transfer of yellow‐emitting (Y,Gd)2O2SO4:Dy phosphors

AbstractA green chemical precipitation route was used to yield a hydrated basic sulfate precursor upon calcination at 1000°C into a series of (Y,Gd)2O2SO4:Dy particles. The phosphors exhibited characteristic Dy3+ emissions from 4F9/2→6HJ (J = 15/2, 13/2, 11/2) transitions under ultraviolet light excitation; the quenching concentration of Dy3+ was determined to be 2.5 at.%. Substitution of Gd3+ for Y3+ led to an additional strong sharp band at ~277 nm (8S7/2→6IJ transition of Gd3+) in the photoluminescence excitation spectra, upon which the (Gd0.975Dy0.025)2O2SO4 phosphor achieved a ~2.8‐fold higher photoluminescence intensity via an effective energy transfer from Gd3+ to Dy3+ compared with the 354 nm excitation of Dy3+. Both the photoluminescence and photoluminescence excitation intensities of (Y,Gd)2O2SO4:Dy phosphors increased with rising Gd3+ concentration and calcination temperature in the range 750–1000°C. A higher Gd3+ concentration slightly prolonged the effective fluorescence lifetime.

The effect of stirring speed and reactant residence time in the bench scales CSTR on the reaction conversion of ZBS

The bench scales continuous stirred tank reactor (CSTR) for the synthesis of zirconium basic sulfate (ZBS) is one of the prototypes of research and development for the manufacture of nuclear-grade zirconium products in Center for Accelerator Science and Technology (CAST). The use of bench scale CSTR is to reduce the impurities of U, Th, Fe, Ti from zirconium oxychloride (ZOC) at certain pH conditions through the ZBS precipitation process. The purpose of this study is to test the CSTR of bench scale for ZBS synthesis by studying the effect of stirring speed of 100, 150, 200, 250, 300 rpm and residence time of 60, 75, 90, 105, 120 min on the conversion of ZBS synthesis. The bench scales of CSTR for ZBS synthesis was carried out by reacting to a 0.2 M ZOC solution with (NH4)2SO4 0.08 M at a mole ratio of Zr/SO4- = 5/2 and the pH of ZBS formation about 1.8─2.0. The experimental results show that at a stirring speed of 250 rpm and a reactant residences time of 120 min gives a ZBS formation conversion of 0.5059. It can be concluded that the greater the stirring speed and space-time the greater the conversion of ZBS.

Physicochemical and Calorimetric Study of Aluminocopiapite and Thermodynamic Properties of Copiapite-Group Minerals

The natural basic aqueous aluminum and iron sulfate, aluminocopiapite (Al0.60 $${\text{Fe}}_{{0.07}}^{{3 + }}$$ ) $${\text{Fe}}_{{4.00}}^{{3 + }}$$ [SO4]6.03(OH)1.95 ⋅ 19.54H2O (Blyava, South Urals, Russia), was studied using powder X‑ray diffraction, infrared and Mossbauer spectroscopy, and thermal analysis. The enthalpy of formation from the elements $${{\Delta }_{f}}H_{{el}}^{0}$$ (298.15 K) = −11 826 ± 58 kJ/mol was determined by high-temperature melt solution calorimetry on a Tian-Calvet high-temperature heat-flux microcalorimeter “Setaram” (France). Standard entropies and Gibbs energies of formation were estimated for the studied aluminocopiapite and other copiapite-group minerals.

High-Potential Pseudocapacitive Energy Storage System: Iron-Based Polyferric Sulfate Electrolyte and Partially Sacrificial Graphite Electrode

Tremendous research works including nanofabrication techniques and crystal defect preparation approaches have been applied to enhance the capacitance of bulk materials. However, a comprehensive understanding of active sites in the reaction process is an enigma for all researchers. This work reported an environmentally friendly system with a basic polymerized ferric sulfate (BPFS) electrolyte and electroactive graphite electrode, which achieved high area capacitance and showed the different characteristics of active sites. This enhanced energy storage system shows the evidence that carbon materials are electrochemically activated as a result that active groups could react with iron groups in aqueous solutions. A high area specific capacitance of 12 F cm-2(1255 F g-1) is obtained in a mixed BPFS at 5 mV s-1 in a potential window of 2.1 V in a three-electrode cell. In an aqueous solution capacitor, a capacity of 4.8 F cm-2 at 30 mA from 0 V to 1.5 V is achieved at room temperature. It has the potential to develop a low-cost, high energy storage, and high safety system, which can be a lead-acid battery substitute.

Phase composition of autoclave oxidation products and its effect on gold coating

This paper describes the mineralogical studies of the solid products of autoclave oxidation. These products were obtained during autoclave pilot tests at a temperature of 225 oС and total pressure 3.25 МPa. Autoclave tests were carried out on the samples of sulfide gold-bearing concentrate of the Malomyr deposit. Mineralogical studies were provided using Mossbauer spectrometry, scanning electron microscope, X-ray fluorescence and X-ray diffraction analysis. It was found that the solid autoclave residues consist of basic ferric arsenate sulfate (Fe(AsO4)x(SO4)y(OH)z·wH2O), sodium jarosite (KFe3(SO4)2(OH)6), basic ferric sulfate (Fe(OH)SO4) and gangue minerals (muscovite, quartz, feldspars and others). The main relationships of the phase transformations in the autoclave oxidation process were described. Data obtained during these studies shows that some part of the gold may be associated with a secondary arsenic-containing phase formed in the autoclave oxidation process. This gold may be isolated from cyanidation solution and remain in the tailings. It was considered to subject the autoclave slurry to an additional treatment — Hot Cure process. This can minimize the loss of the precious metal during autoclave aftertreatment. As a result, a part of the secondary soluble phases (up to 10–50%) decomposes and dissolves. After that gold becomes accessible to the cyanide solution during sorption cyanidation. The increase in precious metal recovery is 2–5% for various samples.

Performance of BMSC column with large eccentricity under natural exposure conditions

As a new type of concrete material, basic magnesium sulfate cement concrete (BMSC) has the advantages, such as early strength, high strength, good toughness and crack resistance. However, it is unclear about the degradation of the mechanical properties of BMSC columns, which is exposed to the natural environment for several years. In order to apply this new concrete to practical engineering, six large-eccentricity compressive columns of BMSC were studied. The mechanical properties such as the crack propagation, failure morphology, lateral displacement and bearing capacity of BMSC column were studied. The results show that the degradation rate of ultimate load of BMSC column is from 6% to 7%. The degradation rate of the stiffness of the column is from 6% to 13%. With the increase of compressive strength of BMSC, the axial displacement and lateral displacement are gradually reduced. The calculation model of bearing capacity of the BMSC column under the large eccentric compression is proposed. This paper provides a reference for the application of BMSC columns in the civil engineering.

Hyper oxidized V6O13+x·nH2O layered cathode for aqueous rechargeable Zn battery: Effect on dual carriers transportation and parasitic reactions

The origin of parasitic reaction formed/dissolved during the electrochemical reaction at the interface and the conformity role of H+/H2O carrier during electrochemical reaction in aqueous Zn salt electrolyte medium of aqueous rechargeable zinc-ion batteries (ARZIBs), is almost recognized halfway; albeit the consequence of this side reaction is not established yet. Through operando X-ray diffraction analyses in two different electrolytes, the parasitic phases and the dual carriers are recognized in a hyper non-stoichiometry layered oxide of V6O13+x.nH2O as cathode. Indeed, galvanostatic intermittent titration (GITT) and operando potentiostatic electrochemical impedance spectroscopy (PEIS) techniques are utilized to clearly show the parasitic phase of thick ZBS (zinc basic sulfate) layer negatively influence the reaction kinetics at the interface in ZnSO4 electrolyte and hence the performance, especially at low current surges. Thus, the layered cathode demonstrated exceptional stability especially in Zn (CF3SO3)2 electrolyte. For example, in a 1 M ZnSO4/1 M Zn (CF3SO3)2 aqueous electrolyte, nearly 80/65% capacity retention over 2,000/5000 cycles at 15 C is exhibited. Comparative GITT investigations on the overpotential and electrochemical kinetics in ZnSO4 and water electrolytes offer strong evidence for the continuous and reversible co-intercalation of dual carriers of Zn2+and H+/H2O.

Influences of silica additive on sintering and Hall effect of novel transparent In2O3 semiconductive ceramics

Polycrystalline transparent In2O3 semiconductive ceramics are successfully fabricated by oxygen atmosphere sintering for the first time. The starting rounded In2O3 particles are obtained via pyrolyzing the nanoplate-like hydrated basic sulfate precursor prepared by a chemical precipitation route using hexamethylenetetramine as the precipitant. The silica additive dissolves into the In2O3 lattice to form an interstitial solid solution, which promotes the diffusion rate during high-temperature densification process and thus helps to achieve good optical quality for In2O3 ceramics. The created interstitial oxygen further compensates the oxygen vacancy in the ceramic body to result in a higher resistivity and lower carrier concentration / carrier mobility. The optical qualities of In2O3 ceramics are also found to have slight effects on the resistivity, carrier mobility, carrier concentration, and Hall coefficient.

Basic Sulfate Precipitation of Zirconium from Sulfuric Acid Leach Solution

H2SO4 was ensured to be the best candidate for Zr leaching from the eudialyte. The resulting sulfuric leach solution consisted of Zr(IV), Nb(V), Hf(IV), Al(III), and Fe(III). It was found that ordinary metal hydroxide precipitation was not feasible for obtaining a relatively pure product due to the co-precipitation of Al(III) and Fe(III). In this reported study, a basic zirconium sulfate precipitation method was investigated to recover Zr from a sulfuric acid leach solution of a eudialyte residue after rare earth elements extraction. Nb precipitated preferentially by adjusting the pH of the solution to around 1.0. After partial removal of SO42− by adding 120 g of CaCl2 per 1L solution, a basic zirconium sulfate precipitate was obtained by adjusting the pH to ~1.6 and maintaining the solution at 75 °C for 60 min. Under the optimum conditions, the loss of Zr during the SO42− removal step was only 0.11%, and the yield in the basic zirconium sulfate precipitation step was 96.18%. The precipitate contained 33.77% Zr and 0.59% Hf with low concentrations of Fe and Al. It was found that a high-quality product of ZrO2 could be obtained from the basic sulfate precipitate.

Vacuum sintering of novel transparent Tm2O3 ceramics: Effect of silica additive and thermal performance

Polycrystalline transparent Tm2O3 ceramics are successfully fabricated by means of chemical precipitation route plus vacuum sintering technique. Hexamethylenetetramine as the precipitant is dripped into thulium sulphate system to directly result in a hydrated basic sulphate precursor with an approximate chemical composition of Tm(OH)1.7(SO4)0.65∙2.1H2O, followed by pyrolysis to yield a sphere-like Tm2O3 powder with an average particle size of ∼165 nm. During high-temperature sintering, the silica additive induces lattice distortion via the formation of interstitial solid solution and helps to achieve a uniform microstructure together with good optical quality. The best Tm2O3 ceramic sample has in-line transmittances of ∼71 % at 880 nm and ∼76 % in partial middle infrared spectral region with maximal infrared cut-off at ∼11 μm. The thermal diffusion and thermal conductivity of the bulk both decrease as the temperature increases.

Fast high-pressure tanning of animal skins by accelerated chromium sulphate complexation

In the conventional leather production process, basic chromium sulphate (BCS) penetrates fully inside the collagen matrix during tanning and forms oligo-nuclear complexes that stabilize the skin structure during basification. Accelerated chromium sulphate complexation by basifying the BCS before full penetration leads to surface tanning and low leather qualities. Therefore, long processing times of 16 h for tanning and basification are common in modern tanneries. We used sodium hydrogen carbonate to basify BCS before penetration. However, instead of conventional tanning we performed CO2 tanning at 30 bar. The influence of accelerated chromium sulphate complexation on the leather quality was investigated. To estimate the structures of the formed chromium complexes, we considered the pH trend of the tanning solution during basification depending on the amount of basifying agent. The distribution of chromium oxide (Cr2O3) and the shrinkage temperature (Ts) in three different layers of the cross section were analysed. The analytics allowed the assessment whether the tanning agent penetrates through the whole cross section or adheres to the surface during CO2 tanning. We show that CO2-intensified tanning allows accelerated chromium sulphate complexation and a reduction in the tanning time from 16 to 4 h. The Cr2O3 is equally distributed, and Ts above 100 °C meets the standards of high-quality wet blue. However, the pH value of the tanning solution must not rise above 4.5 during basification. Otherwise, the Ts decrease dramatically. The feasibility of the process is demonstrated in a 1700-L drum, with a batch size of about 500 kg. The CO2-intensified tanning process has high potential to save time and chemicals and reduce emissions in industrial applications and is commercially competitive.Graphic abstract