Sulfate Crystals Research Articles

Effects of microwave and plastic content on the sulfur migration during co–pyrolysis of biomass and plastic

In order to reduce the risks of sulfur-containing contaminants present in biofuels, the effects of microwave and content of hydrogen donor on the cracking of C–S bonds and the migration of sulfur were studied by co–pyrolysis of biomass and plastic. The synergistic mechanism of microwave and hydrogen donor was explored from the perspective of deducing the evolution of sulfur–containing compounds based on microwave thermogravimetric analysis. By combining temperature–weight curves, it was found that microwaves and hydrogen radicals promoted the cracking of sulfur–containing compounds and increased the mass loss of biomass during pyrolysis. The mixing ratio of hydrogen donor (plastic) was the key parameter resulting in the removal of sulfur from oil. By adjusting the mixing ratio, the yield of co–pyrolyzed oil was three times higher than that of cow dung pyrolysis alone and the relative removal rate of sulfur reached 73.67%. The relative content of sulfur in the oil was reduced by 73.77% due to the escape of sulfur–containing gases (H2S, COS and C2H5SH) and the formation of sulfate crystals in the char. Microwave selectively heated sulfur–containing organics and hydrogen radicals stimulated the breaking of C–S bonds, which improved the cracking efficiency of the oil. This breaking will provide a theoretical and technological reference for the environmentally friendly treatment of biomass and biofuels.

Insight into the structural properties of methyl orange, hexamethyl pararosaniline chloride dyes doped potassium hydrogen phthalate ammonium sulfate crystals and their antibacterial applications

Insight into the structural properties of methyl orange, hexamethyl pararosaniline chloride dyes doped potassium hydrogen phthalate ammonium sulfate crystals and their antibacterial applications

Optimization of Ammonium Sulfate Crystallization Under Ammonium Nitrate Based on Response Surface Method

AbstractThe response surface method is used to study the influence mechanism of three factors (seed crystal concentration, pH value, and stirring rate) on ammonium sulfate crystallization (average particle size and coefficient of variation [C.V.] value) under ammonium nitrate to prove the effect of ammonium nitrate doping on ammonium sulfate crystallization. Regression equations between each response value and the influencing factors are established. Results show that the interaction between the seed crystal concentration and the stirring rate is stronger than that between the seed crystal concentration and the pH and that between the pH and the stirring rate. The error between the verified model values and the experimental values is minimized when the seed crystal concentration is 1.5%, the pH is 4.5, and the stirring rate is 250 r min−1, at which the average particle size is 1.238 mm, and the C.V. value is 73.53. After optimization, the crystal morphology changes from needle‐ and flake‐like crystals to cubes, resulting in crystals with large average particle size, uniform distribution, regular morphology, and diffraction peak intensity that is close to that in the analysis of pure ammonium sulfate.

Separation of phosphoric acid and magnesium from wet process phosphoric acid by solvent extraction

ABSTRACT Wet process phosphoric acid (WPA) contains a high concentration of metal cations. Our research group developed a P-15 extractant that can effectively remove metal cations in WPA. Different metal cations supported by the extractant are stripped and recycled by different stripping agents. In this study, ammonium sulfate is used as a stripping agent to separate magnesium ions from the extractant. So that phosphoric acid and magnesium ions can be separated and separately prepared into their own products. To determine the optimal operation parameters of the magnesium ion stripping process, single factor experiments are conducted. Under the reaction temperature of 333.15 K, stirring speed of 300 rpm, phase ratio (A/O) of 1/2, ammonium sulfate concentration of 3.305 mol/L, and reaction time of 30 min, the stripping efficiency reaches 75%. A stripping equilibrium curve at 333.15 K is plotted to determine the optimal reaction order for countercurrent stripping. Through two-stage countercurrent stripping, the magnesium ion concentration in the extractant could be reduced to approximately 0.0018 mol/L when A/O = 1/2. Magnesium ion concentration in extraction can be reduced from 0.0419 mol/L to 0.0026 mol/L through two-stage stripping countercurrent cascade. The concentration of each kind of impurity ion in ammonium magnesium sulfate crystals is all below 500 ppm.

Dynamics of the Phase Transition in the Dielectric Spectra of Pure and Chrome-Doped Triglycine Sulfate Crystals

Dynamics of the Phase Transition in the Dielectric Spectra of Pure and Chrome-Doped Triglycine Sulfate Crystals

Optimizing laser induced nonlinear optical, dielectric and microscopic traits of copper sulfate crystal by glycine for photonic device applications

• First comparative article on pure and glycine doped copper sulfate crystal has been reported. • Glycine enhanced optical transmittance of copper sulfate by 8% within 300-698 nm. • Glycine optimized third order nonlinear optical properties of copper sulfate crystal. • Glycine enhanced the laser induced damage threshold energy of copper sulfate by 55 mJ. • Glycine significantly reduced the dielectrics of copper sulfate crystal. Novel investigation reports mono crystal growth of pristine and glycine (C 2 H 5 NO 2 ) doped copper sulfate (CS) by slow solvent evaporation method. The structural analysis has been performed by single crystal X-ray diffraction technique. The presence of various chemical components has been qualitatively established by energy dispersive spectroscopy. The UV-visible spectroscopy has been employed within 200-1000 nm to evaluate the rise in optical transmittance of CS crystal due to glycine. Influence of glycine on third order nonlinear optical response of CS crystal has been examined at 632.8 nm by means of He-Ne laser assisted Z-scan technique. The laser induced surface damage tolerance limit of pure and glycine doped CS crystal has been comparatively investigated at 1064 nm. The impact of glycine and temperature on dielectric traits of CS crystal has been investigated by means of dielectric studies. A comparative etching analysis has been done to investigate surface attributes of pure and glycine doped CS crystal.

Folded, undulating, and fibrous doxorubicin sulfate crystals in liposomes

High-resolution cryogenic transmission electron microscopy (cryo-TEM) evidenced that doxorubicin sulfate crystals in liposomes (prepared by remote loading with ammonium sulfate) form folded, undulating, and fibrous crystals with a diameter of approximately 2.4 nm. An undulating, fibrous crystal considered to be undergrowth, in addition to bundles of fibrous crystals, was also observed in doxorubicin-loaded liposomes. This explains the validity of the formation of doxorubicin sulfate crystals of various shapes, e.g., curved, U-shaped, or circular, in addition to cylinder and/or rod-like crystals reported in the literature. Liposomes that do not contain crystals have inner aqueous phases with high electron density, suggesting that the doxorubicin is remotely loaded and remains as a solute without precipitation.

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.

Acceleration of methane hydrate nucleation by crystals of hydrated sodium dodecyl sulfate

It was shown that hydrated crystals of sodium dodecyl sulfate (SDS), which precipitate from dilute SDS solutions sharply accelerate nucleation of methane gas hydrate. This finding adds significant details to the available information on the mechanisms of hydrate formation from SDS solutions and can form the basis for the development of a new class of kinetic promoters of hydrate formation.

Structural and Dielectric Investigations on Pure and Doped Triglycine Sulfate (TGS) Crystals

Abstract: In this paper, a single crystal triglycine sulfate (TGS) doped with copper sulfate was synthesized using the slow evaporation technique. Structural characterization was carried out using X-ray diffraction and FTIR techniques. Thermal studies revealed that the addition of copper sulfate did not affect the thermal stability of the TGS. In addition, intensive dielectric investigation has been carried out, which showed that the addition of copper sulfate enhances the dielectric permittivity. A change in Curie temperature has been observed upon doping TGS with copper sulfate. Keywords: TGS doping, Copper sulfate, Dielectrics, Cole-Cole plot.

Synthesis, Characterization and Catalytic Applications of Chitosan Based Schiff Base Complexes of Copper (II)

Abstract: Chitosan Schiff Base was synthesized using conventional method and its corresponding metal complex was synthesized using Copper sulphate crystals. CSB and the metal complex were characterized using analytical and spectroscopic techniques like FT-IR and SEM. The excellent catalytic activity of the synthesized CSB-Cu complex was studied with Knoevenagel Reaction

Portland cement hydration in the vicinity of electrically polarized conductive surfaces

Hardening of Portland cement-based materials in vicinity of electrically conductive surfaces, especially when the surfaces are electrically or galvanically polarized, can lead to both morphological and chemical changes in cement close to the surfaces due to combined electrochemical and electrophysical processes.Cement hydration products close to graphite and steel surfaces being positively (anode) and negatively (cathode) electrically polarized (direct current) were studied. Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy were used to compare structure and atomic composition of cement hydration products on cathode, anode and a reference surface with no electrical polarization.The application of direct current (DC) potential in aqueous Portland G cement dispersion significantly affects cement hydration products close to cathode and anode and different products were found at the anode compared to the cathode surfaces. At the graphite anode, calcium sulphate crystals along with calcium hydroxide were most abundant, while the graphite cathode was mainly covered with calcium hydroxide. The calcium hydroxide carbonated upon exposure to air during drying. When steel electrodes where used, the most significant adsorption occurred at the anode, in contrast to graphite where the largest amount of the adsorbed material was found on the cathode. The observed differences were explained in view of electrophysical (electrophoresis, electroosmosis) and electrochemical (reduction and oxidation) processes occurring at electrode surfaces upon application of DC current.The knowledge gained in this work is important for engineering of electrically conductive cement nano-composites where typically the contact surface of an electrically conductive filler and a cementitious matrix is high.

Exfoliation of stone cultural relics under the microclimate in the Yongling Mausoleum of the Former Shu Dynasty

Many degradation processes of cultural heritage objects are associated with unsuitable microclimatic conditions. One of the most ubiquitous deteriorations is the crystallization of salts in pores, which can accelerate the erosion rate of masonry historical relics. In this study, the microclimate of the burial tomb and exfoliation of sandstone in the Yongling Mausoleum of the Former Shu Dynasty in Chengdu were monitored for 1 year to determine the development of the degradation. We established a connection between the monitoring data and exfoliation variations of the stone with time. To predict the deterioration of the stone, a three-dimensional computational finite element model was used to simulate the detailed process of the thermo-hygrometric performance that led to salt crystallization and artwork deterioration. Two results were obtained. In the simulation of the microclimate, the temperature ranged from 15 to 22.6 °C, and the relative humidity was heterogeneous and varied between 60 and 100%. The other was the relationship between the microclimate and exfoliation. It was found that the exfoliation was more severe in the higher relative humidity areas where the water vapor frequently interacted with the relics. The crystallization and hydration of sulfate produced stress, which damaged the stone relics. These results provide a rationale analysis and a reference for better management of the environmental interactions and reduction of the environmental impacts in the subsequent scientific conservation of ancient Chinese cultural relics in tombs.

Impact of colloidal iron hydroxide and colloidal silicon dioxide on calcium sulfate crystallization in the presence of antiscalants

Impact of colloidal iron hydroxide and colloidal silicon dioxide on calcium sulfate crystallization in the presence of antiscalants

Exploration of process optimization for recovery of sodium and ammonium sulfate crystals from vanadium precipitation wastewater

In this paper, we have studied vanadium precipitation wastewater in two stages of the fractional crystallization process. In order to extract sodium sulfate and ammonium sulfate products with large particle size and uniform particle size distribution from the rear end vanadium precipitation wastewater and to realize the resource reuse of vanadium precipitation wastewater, the effects of various operating parameters (seeding amount, evaporation rate, stirring rate, growing time) on the particle size and particle size distribution of sodium sulfate and ammonium sulfate products were investigated. Better separation and crystallization conditions of sodium sulfate and ammonium sulfate were obtained. The optimized crystallization conditions of sodium sulfate are: the addition amount of ammonium sulfate seeding with a particle size of 40 μm is 1.17 %, the evaporation rate is 100 mL/h, the stirring rate is 80 rpm, the crystal growth time is 60 min, and the main particle size M.S. value of sodium sulfate crystals is 242.23 μm; The optimized crystallization conditions of ammonium sulfate were as follows: the addition amount of sodium sulfate seeding with a particle size of 80 μm was 0.68 %, the evaporation rate was 160 mL/h, the stirring rate was 150 rpm, and the crystal growth time was 30 min. The M.S. value of the final ammonium sulfate crystal was 880 μm.

Development of a recurrent neural networks-based NMPC for controlling the concentration of a crystallization process

Crystallization is a separation and purification process relevant to industrial sectors, such as pharmaceuticals. The maximum possible recovery of solute amount is one of its goals, and the temperature profile is crucial to achieve this. In this work, neural networks-based models were developed to predict the solute concentration of a batch crystallization process and used as internal model in a nonlinear model predictive controller. Three different neural network architectures were considered: the multilayer perceptron (MLP) network, the echo state network (ESN), and the long short-term memory (LSTM). The dataset used for training and testing applied a co-teaching learning algorithm, which uses simulated and experimental data from the batch crystallization of the potassium sulfate (K2SO4). The three network structures were trained to predict the solute concentration one step ahead, using the current temperature and concentration values as feed, and the predictive performances were evaluated for larger prediction horizons. A nonlinear model predictive controller (NMPC) based on the ESN, the most efficient neural network design, was successfully applied to the batch crystallization process to maintain the solute concentration on its desired trajectories by manipulating the operating temperature. The controller's behavior was studied for three different set-points of concentration and supersaturation, varying the initial concentration. The performance of the proposed NMPC was compared to a controller based on a more traditional approach, using the MLP network as internal model.

Investigations on the Growth and Characterization of L-Leucine Doped Rubidium Sulfate Nonlinear Optical Single Crystal

Objectives: To grow crystal of inorganic material Rubidium sulfate by doping with an organic material L-leucine. Methods: Crystal has been grown by solution method. Crystallographic studies were done. Mechanical studies were carried out to find the mechanical strength and other parameters. Dielectric studies of L-leucine doped rubidium sulfate crystals were carried out to evaluate dielectric constant, dielectric loss and activation energy. UV-visible- NIR spectral studies were done in the wavelength range 200-1100 nm. Second order Non Linear Optical (NLO) studies of the grown crystal of LLRS were carried out by Kurtz-Perry technique. Findings: The grown LLRS crystal is observed to be crystallizing in orthorhombic structure by single crystal XRD studies. The optical band gap of LLRS crystal was found to be slightly more than that of undoped rubidium sulphate crystal. The SHG efficiency of LLRS crystal is observed to be 0.61 times that of the reference KDP sample. Dielectric parameters are found to decrease with increase in frequency. Dielectric constant and dielectric loss factor increase when the temperature of the samples increases. AC conductivity increases with increase of temperature. Activation energy is increasing when the frequency increases. The band gap value is found to be 4.43 eV for undoped rubidium sulfate crystal. For L-leucine doped rubidium sulfate (LLRS) crystal, the optical band gap is 4.48 eV. From the Microhardness teat, it is observed that the hardness increases with increase of the applied load for both the samples and this is due to reverse indentation size effect. Novelty: In this study, as a novel work, a very first attempt has been made to combine an organic material L-leucine with an inorganic crystal viz. rubidium sulfate to alter its physical and chemical properties. Keywords: Inorganic Single Crystal; Crystal Structure; Mechanical Properties; Dielectric properties; Optical Properties; Spectral Properties

Influence of sulfate crystallization on bond-slip behavior between deformed rebar and concrete subjected to combined actions of dry-wet cycle and freeze-thaw cycle

The bond-slip behavior of deformed rebar with medium embedded length and surrounding concrete without stirrup under sulfate salt, dry-wet cycle and freeze–thaw cycle was investigated in this study. Physical crystallization of sulfate was produced by using a 3:1 drying/wetting time ratio in erosion specimens. Different concentrations of sodium sulfate solution (CSSS), different drying and wetting cycles (DWC), and different freeze–thaw cycles (FTC) were considered as environmental variables in central pull-out tests. The bond characteristics of post-yielding rebar and surrounding concrete under combined environmental factors were obtained. Scanning electron microscope and x-ray diffraction analysis were conducted to identify reaction products. The experimental results showed that CSSS and DWC had both beneficial and adverse effects on the bond strength.1% CSSS and 25 DWC were the turning points of increasing and decreasing of bond strength. The expansion force caused by Na2SO4 physical crystals improved the bond strength in the initial stage, but impaired it after the crack of pore wall of concrete in the later stage. After superimposed FTC, the bond strength was greatly reduced. Sulfate crystallization significantly accelerated the deterioration of bond strength under freeze–thaw cycles. The prediction models of the bond strength between deformed rebar and surrounding concrete after yielding in terms of single and multiple environmental factors had been established. The models can be used to predict the bond strength of post-yielding rebar and surrounding concrete in complex environments of sulfate, dry-wet cycle and freeze–thaw cycle.

CRYSTAL GROWTH IN SOLUTION AND CHARACTERIZATION OF RUBIDIUM SULFATE SINGLE CRYSTALS DOPED WITH L-LEUCINE

Rubidium sulfate crystal is an inorganic material and it is doped with an organic material viz. L-leucine to improve the various properties of the host crystal. L-leucine doped rubidium sulfate (LLRS) crystals have been grown by solution method. LLRS crystals have been harvested after the growth period of 30 days. The grown LLRS crystal is observed to be crystallizing in orthorhombic structure by single crystal XRD studies. Mechanical studies were carried out to find the mechanical strength and other parameters. Dielectric studies of L-leucine doped rubidium sulfate crystals were carried out to evaluate dielectric constant, dielectric loss and activation energy. UV-visible-NIR spectral studies were done in the wavelength range 200-1100 nm and linear optical properties like transmittance, absorption coefficient and extinction coefficient of samples have been evaluated. Second order Non Linear Optical (NLO) studies of the grown crystal of LLRS were carried out by Kurtz-Perry technique. The fundamental absorption was noted at 280 nm and at 278 nm for undoped and L-leucine doped rubidium sulphate crystals respectively. The optical band gap of LLRS crystal was found to be slightly more than that of undoped rubidium sulphate crystal. The SHG efficiency of LLRS crystal is observed to be 0.61 times that of the reference KDP sample.

Studies on growth and characterization of a nonlinear optical crystal: Zinc sulfate-doped L-alanine

Single crystals of zinc sulfate doped L-alanine (LAZ) were grown by adopting the slow evaporation technique at room temperature. The crystal structure of LAZ was determined using single-crystal X-ray diffraction. The functional groups of LAZ were identified by FT-IR spectroscopy analysis. UV–Visible–NIR transmittance study was carried out, and the bandgap energy was found. A fluorescence study was performed to get the emission spectrum of the LAZ crystal. The Vickers microhardness test is used to determine the LAZ crystals mechanical behavior. Thermogravimetric and differential thermal analyses have also been studied to investigate the thermal property of the LAZ crystal. The efficiency of the title crystal’s second harmonic generation (SHG) was investigated. The electrical properties were estimated by impedance study.