Ammonium Hydrogen Sulfate Research Articles

Study on recovering the scattered metals from coal gangue by low-temperature activation and two-stage selective leaching

As metal deposits are developed on a large scale and at high intensity, the strategic metals under “protective measures” will inevitably face resource depletion. It becomes particularly important to sustainably and stably maintain the supply of strategic metals. A method is proposed to selectively extract Li and Ga from coal gangue through a process of ammonium sulfate roasting followed by stepwise leaching. Li and Ga in coal gangue are converted into metal sulfates or ammonium sulfates through low-temperature roasting, and then selectively extracted through a water-acid combined stepwise leaching process. Under the conditions of 450 °C and 2 h, with a coal gangue to ammonium sulfate ratio of 1:2.5, the leaching rates of lithium and gallium reach 88.35 % and 90.28 %, respectively. During the roasting process, ammonium sulfate decomposes into ammonium hydrogen sulfate, which enters the core through the pores of gangue and reacts with kaolinite to enhance activation. Li is converted into lithium sulfate ammonium and extracted through aqueous solution leaching, while metal gallium is first converted into gallium sulfate ammonium and then, with increasing temperature, into ammonium sulfate and extracted through dilute acid leaching.

Low temperature phase transitions in the visible and near-infrared (VNIR) reflectance spectra of (NH4)2HPO4 and (NH4)HSO4 salts

The detection of ammonium bearing crystalline solids in salt-water systems on icy bodies and solar system bodies could provide information about the ascent of these salts from a deep reservoir within the hydrosphere. Due to their chemical-physical properties, NH4+ compounds play a key role both in the internal dynamics of celestial bodies and in the potential habitability of ocean worlds. In this work we analysed the reflectance spectra of two synthetic NH4+ salts: ammonium hydrogen phosphate (NH4)2HPO4 and ammonium hydrogen sulphate (NH4)HSO4 in the 1–4.2 μm spectral range at low temperature, between 110 and 290 K. For (NH4)2HPO4 we also examined the effect of three different grain sizes (150–125 μm; 125–80 μm; 80–32 μm). The collected reflectance spectra show absorption features related to NH4+ group overtone and combination modes in the 1–2.5 μm range. In particular, the bands located at ∼1.09 μm (3ν3), ∼1.30 μm (2ν3 + ν4), ∼1.58 μm (2ν3), ∼2.02 μm (ν2 + v3) and ∼ 2.2 μm (v3 + v4) could be useful to discriminate these salts. The low temperature spectra, compared to those at ambient temperature, reveal finer structures, displaying sharper and narrower absorption bands. The selected NH4+-bearing salts are subjected to reversible low temperature phase transitions, which are revealed in the spectra by a progressive growth and shift of the bands toward shorter wavelengths with a drastic change of their depth. We performed laboratory measurements of ammonium (NH4+) compounds to address the limited data available expanding the existing database. The collected cryogenic spectra can be directly compared with remote sensing data from planetary missions of the upcoming decade such as NASA's Europa Clipper, and ESA's JUICE and the newly launched James Webb Space Telescope expanding the existing database of ammonium compounds at cryogenic temperature.

Properties of methylmercury and its physiological effect on the human body

With the development of Chemistry industry, more and more organic mercury compounds are now found in environment and the level of their exposure is increasing, polluting and harming the environment. Humans may be exposed to organic forms of mercury through inhalation, oral routes. Among them, the most common phenomenon is by eating fish and shellfish contaminated by methylmercury. Many methods are used in detecting the existence of mercury in the tissue of samples or the concentration of mercury in sediments of Minamata Bay, which is the origin of Minamata disease, such as using ammonium sulfide and hydrogen sulfate through the observation of brownish back granules. Generally, the effects of exposure to organic mercury are primarily on the nervous system, while many other organ systems may also be affected, including the gastrointestinal tract, respiratory system, liver, immune system, skin, and kidneys. The study investigates the physiological effect of the organic mercury and how to detect the existence of the organic mercury in the environment.

Growth process of boehmite with large particles in ammonia system

The development of a novel technology for extracting aluminum resources from coal fly ash through direct leaching with an ammonium hydrogen sulfate solution represents a significant advancement. A pivotal stage within this process is the reaction crystallization between NH4Al(SO4)2·12H2O solid and NH3·H2O. Despite its many benefits, the fine particle size of the resultant product has impeded its widespread adoption. To tackle this challenge, this study concentrated on examining the growth mechanism of boehmite with larger particles in the presence of ammonia. Analysis revealed a distinct morphological evolution process for large-particle boehmite, progressing from a flaky morphology to a flower-like nanostructure with flaky features, and then further transitioning into particles displaying flower-like nanostructures and culminating in the formation of large particles with smooth surfaces. Initially, the early stages of crystallization were governed by kinetic factors, followed by a self-assembly phase, ultimately resulting in the final morphology of large particles, dictated by thermodynamic considerations. Density functional theory calculations underscored the significant role of H2O molecule adsorption in boehmite's growth trajectory, leading to the formation of pseudo-boehmite and inducing shifts in the X-ray diffraction peaks. The growth units remained integral throughout the entirety of the crystal growth process.

Alkyl ammonium hydrogen sulfate immobilized on Fe3O4@SiO2 nanoparticles: a highly efficient catalyst for the multi-component preparation of novel tetrazolo[1,5-a]pyrimidine-6-carboxamide derivatives

In this, a three-component reaction for the preparation of novel tetrazolo[1,5-a]pyrimidine-6-carboxamide derivatives from N,N′-(sulfonylbis(1,4-phenylene))bis(3-oxobutanamide), aldehydes and 1H-tetrazol-5-amine is reported. The application of Fe3O4@SiO2-(PP)(HSO4)2 (A) as a catalyst afforded the desired products (a1–a18) in high yields in DMF as solvent as well as under solvent-free conditions.

Bonding Pretreatment of Aesthetic Dental CAD-CAM Materials through Surface Etching with a Mixed Aqueous Solution of Ammonium Fluoride and Ammonium Hydrogen Sulfate.

Hydrofluoric acid (HF) is commonly used as an etchant for the pretreatment of dental computer-aided design/computer-aided manufacturing (CAD-CAM) materials, such as glass-ceramics and resin composites. Despite its effectiveness, the harmful and hazardous nature of HF has raised significant safety concerns. In contrast, ammonium fluoride (AF) is known for its relatively low toxicity but has limited etching capability. This study explored the potential of ammonium hydrogen sulfate (AHS), a low-toxicity and weak acid, to enhance the etching ability of aqueous AF solutions for the bonding pretreatment of CAD-CAM materials. This study investigated five types of aesthetic CAD-CAM materials: lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, resin composites, and zirconia. Seven experimental etchants were prepared by varying the amount of AHS added to aqueous AF solutions, with each etchant used to etch the surfaces of the respective CAD-CAM materials. The treated surfaces were analyzed using scanning electron microscopy and confocal laser scanning microscopy. Additionally, the shear bond strength (SBS) of the CAD-CAM materials treated with a luting agent (resin cement) was evaluated. The results indicated that the AF1/AHS3 (weight ratio AF:AHS = 1:3) etchant had the most substantial etching effect on the surfaces of silica-containing materials (lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, and resin composites) but not on zirconia. The SBS of the materials treated with the AF1/AHS3 etchant was comparable to that of the commercial HF etchant. Hence, an AF/AHS mixed solution could effectively etch silica-containing CAD-CAM materials, thereby enhancing their bonding capabilities.

Leaching Kinetics of Limonite-Type Laterite Nickel Ore from Ammonium Hydrogen Sulfate Solution at Atmospheric Pressure

Leaching Kinetics of Limonite-Type Laterite Nickel Ore from Ammonium Hydrogen Sulfate Solution at Atmospheric Pressure

Exploiting Cation Structure and Water Content in Modulating the Acidity of Ammonium Hydrogen Sulfate Protic Ionic Liquids.

In this paper, we investigated the effect of cation structure and water content on proton dissociation in alkylammonium [HSO4]- protic ionic liquids (ILs) doped with 20 wt % water and correlated this with experimental Hammett acidities. For pure systems, increased cation substitution resulted in a reduction in the number of direct anion-anion neighbors leading to larger numbers of small aggregates, which is further enhanced with addition of water. We also observed spontaneous proton dissociation from [HSO4]- to water only for primary amine-based protic ILs, preceded by the formation of an anion trimer motif. Investigation using DFT calculations revealed spontaneous proton dissociation from [HSO4]- to water can occur for each of the protic ILs investigated; however, this is dependent on the size of the anion aggregates. These findings are important in the fields of catalysis and lignocellulosic biomass, where solvent acidity is a crucial parameter in biomass fractionation and lignin chemistry.

Development and antibacterial investigation of Linezolid loaded SPIONs and HPLC method development for quantitative analysis of Linezolid.

Linezolid (LNZ) is extremely prone to resistance. The development of resistance to LNZ should be taken into consideration when selecting this drug as a therapeutic option. By considering the hypothesis that reactive oxygen species (ROS) generated by iron oxide nanoparticles (MNPs) could kill the infecting bacteria. So, we hypothesized the synergistic antibacterial effect of iron oxide nanoparticles and LNZ. To study the release and antibacterial effects of LNZ loaded superparamagnetic iron oxide nanoparticles (SPIONs) on Staphylococcus aureus and Streptococcus pneumoniae. Ferrofluid containing SPIONs was synthesized via chemical co-precipitation method and stabilized by sodium lauryl sulphate (SLS). SPIONs were then loaded with LNZ and characterized for particle size, FT-IR, XRD, and entrapment efficiency. Further antibacterial activity of SPIONs and LNZ-loaded SPIONs was investigated. For the in-vitro release findings, a HPLC analytical method development and validation was performed. Isolation of LNZ was accomplished on a C-18 column with methanol: TBHS (Tetra butyl ammonium hydrogen sulphate, 50:50 v/v). The eluate was monitored at 247 nm with retention time of 4.175 min. The MNP's DLS measurement revealed monodispersed particles with an average size of 16.81 ± 1.07 nm and PDI 0.176 ± 0.012. In optimized formulation, 25 ± 1.75% (w/w) of the drug was found to be entrapped. XRD revealed uniform coating of oleic acid covering the entire magnetic particles surface with no change in its crystallinity. An effective antimicrobial activity was observed at the lowered dose of drug. A robust HPLC method was developed to quantify the LNZ in MNPs and outcomes showed that the reduced dose of LNZ incorporated in SPIONs was able to show similar activity as the marketed product. Successfully reduction of dose of LNZ was established with the aid of biocompatible MNPs to attain the equivalent antibacterial activity.

Acidic Ionic Liquid Bridge Supported on Nano Rice Husk Ash: An Efficient Promoter for the Conversion of Nitriles to Their Corresponding 5‐Substituted 1H‐Tetrazoles and Amides

AbstractIn this study, an efficient method is reported for the preparation of 5‐substituted 1H‐tetrazoles and amides using nano rice husk ash modified with an ionic liquid bridge [RHA‐[bip]‐NH2+ HSO4−] as a new heterogeneous catalyst. This reagent was obtained easily and simply from the preparation and consolidation of bis‐3‐(trimethoxysilylpropyl)‐ammonium hydrogen sulfate on nano rice husk ash and identified with different methods including FT‐IR, XRD, FESEM, TEM and TGA. All products using this catalyst were obtained in suitable times with excellent isolated yields without the formation of any by‐products. Heterogeneous nature of the reaction conditions, ease of the preparation of the catalyst and its stability and reusability are the other important features of this method.

New stability indicating liquid chromatographic method for the estimation of Valsartan in pharmaceutical dosage forms

Valsartan is an orally active antihypertensive agent which belongs to the category of angiotensin II type I receptor antagonists. Valsartan is used for the treatment of heart failure, hypertension, myocardial infraction and diabetic nephropathy. A new stability indicating RP-HPLC was proposed for the quantification of Valsartan by using an ion-pairing agent, tetra butyl ammonium hydrogen sulphate. Mobile phase mixture consisting of 10 mM tetra butyl ammonium hydrogen sulphate and methanol (25: 75, v/v) was selected with a flow rate of 1 ml/min using Agilent C18 column (Detection wavelength 250 nm). The LOD and LOQ were found to be 0.0291 μg/mL and 0.0897 μg/mL respectively. Linearity was observed over the concentration 0.1-50 μg/mL with linear regression equation, y = 36571x + 13532 and the method is precise, accurate and robust. Stress degradation studies were performed and the method was found to be selective and specific.

A new stability indicating RP-UFLC method for the quantification of Gemifloxacin tablets using an ion pairing agent

Gemifloxacin is a new broad-spectrum quinolone antibacterial with activity against both Gram-negative and Gram-positive organisms. A new stability indicating RP-UFLC method was proposed for the estimation of Gemifloxacin in pharmaceutical dosage forms (tablets). Shimadzu Model CBM-20A/20 Alite UFLC system with PDA detector and Zorbox C18 column were used for the chromatographic study. Mobile phase mixture consisting of Tetra butyl ammonium hydrogen sulphate and Acetonitrile in the ratio 68: 32, v/v with a flow rate 0.8 mL/min was chosen for the chromatographic elution of Gemifloxacin (Detection wavelength 273 nm). The method was linear over the concentration range 0.02-200 mg/ml with linear regression equation, y = 207068x + 19935 (R² = 0.9999). The LOD and LOQ were found to be 0.0553 mg/ml and 0.1693 respectively. Forced degradation studies were performed and the method was validated as per ICH guidelines.

Nano Rice Husk Ash Modified with Acidic Ionic Liquid Bridge: An Efficient Promoter for the Synthesis of 1,2,4-Triazolo Quinazolinones

In this study, a new heterogeneous catalyst was obtained easily and simply from the preparation and consolidation of bis-3-(trimethoxysilylpropyl)-ammonium hydrogen sulfate on nano rice husk ash [RHA-[bip]-NH2 + HSO4 –]. After identification this reagent using different techniques including FT-IR, XRD, FESEM, TEM, and TGA, its application as an efficient catalyst was investigated in the acceleration of the preparation of 1,2,4-triazolo quinazolinones. All reactions using this catalyst were performed under solvent-free conditions and all products were obtained in suitable times with high isolated yields without the formation of any by-products. Furthermore, the reusability of the catalyst was investigated during successive three runs.

Characteristics of Water-Soluble Inorganic Ions in PM2.5 in Typical Urban Areas of Beijing, China.

Following the implementation of “coal-to-gas conversion” policy in the Haidian District of Beijing during summer, the present comparative study was performed employing 41 PM2.5 samples as precursors to analyze the characteristics of water-soluble inorganic ions. The concentrations of water-soluble inorganic ions in PM2.5 were analyzed by ion chromatography, and the occurrence form of ions was characterized via time-of-flight secondary ion mass spectrometry (TOF-SIMS). Results revealed that the daily average mass concentration of PM2.5 in Beijing during the sampling period was 94.28 ± 52.49 μg/m3. As compared to the winter of 2016, the average daily PM2.5 concentration in Beijing decreased by 29 μg/m3 in 2017 (28.2% decrease), with a remarkable decline in the number of days with pollution. During the pollution period, the concentrations of NO3–, SO42–, and NH4+ were significantly higher in PM2.5 as compared to the cleaning period. The ratio of the concentrations of [NO3–]/[SO42–] was greater than 1, and the contribution from mobile sources was relatively large, indicating that the implementation of the “coal-to-gas conversion” policy in Beijing has led to the reduction of SO42– emissions from fixed sources, such as coal. Furthermore, TOF-SIMS analysis results showed that NH4+ tended to exist in the form of molecular ammonium sulfate or ammonium hydrogen sulfate during the period of pollution.

Effect of dilution on the performance of ionic liquids in milliflow solvent extraction applications: Towards integration of extraction, scrubbing and stripping operations with in-line membrane-based phase separation

The combination of ionic liquids (ILs) and millifluidic reactors is often suggested as a form of process intensification. The high viscosity of ILs has, however, raised concerns about hydrodynamics, mass-transfer enhancement and the ability to integrate several millifluidic operations. In the present study the performance of a quaternary ammonium hydrogensulfate IL, [A336][HSO4], in a millifluidic solvent extraction (SX) process was evaluated and compared with various, lower viscosity solutions of the IL in a diluent. Dilution of [A336][HSO4] significantly improved the slug flow hydrodynamics by reducing the film thickness, avoiding the loss of secondary recirculations inside the plugs and improving stability at elevated flow rates. The overall mass-transfer performance of the system was also improved upon dilution by a balancing of mass-transfer and reaction limitations. It was also observed that dilution reduced reagent consumption and improved the extraction selectivity. In addition, the decrease of the viscosity of the IL upon dilution facilitated the use of an in-line membrane-based phase separator. An integrated millifluidic set-up containing an extraction, scrubbing and stripping reactor was built using these in-line phase separators and applied to the SX purification of germanium from a synthetic zinc refinery residue leachate. The integrated reactor system was operated using a 30 vol% [A336][HSO4] dilution in p-cymene and successfully run for 4 h without any loss in separation performance or stability.

Decomposition of K-feldspar by potassium hydroxide solution in the hydrothermal system

A novel hydrothermal alkaline process combined with ammonium hydrogen sulfate solution leaching process for improving the comprehensive utilization value of the mineral K-feldspar was developed. In this technology, K-feldspar was first decomposed by the alkaline hydrothermal method, forming kalsilite in the resultant products, where potassium and aluminum were easily leached by ammonium hydrogen sulfate solution. The effects of hydrothermal temperature, concentration, and excess rate of potassium hydroxide on the leaching rate of alumina were investigated. The products obtained under various conditions were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray fluorescence (XRF) and Fourier transform infrared spectroscopy (FTIR). The results show that the hydrothermal temperature has a predominant influence on the hydrothermal decomposition of K-feldspar. With the hydrothermal time of 30 min, the leaching rate of alumina at 280 °C is 62.5 % higher than that at 220 °C. The K-feldspar is completely decomposed at 280 °C for 120 min. The concentration of potassium hydroxide has little effect on the decomposition of K-feldspar. The transformation of K-feldspar in the proposed hydrothermal process is as follows: Microcline → kaliophilite (as metastable materials) → kalsilite.

An exploratory study on strategic metal recovery of coal gangue and sustainable utilization potential of recovery residue

Coal gangue is a resource that is often improperly managed, especially during the current strategic metal element shortage. Achieving the efficient and green cooperative recovery of primary elements and strategic metal elements is critical, especially in the treatment without acid and alkali. In this study, the low-temperature combined roasting-DI water leaching method extracted valuable elements and prepared adsorption materials from coal gangue. The element migration and reaction mechanisms were investigated in detail. The results show that the primary reaction path includes the decomposition of ammonium sulfate into ammonium hydrogen sulfate, which reacts with kaolinite to form aluminum ammonium sulfate. Al, Fe, Ga, Li, Mg, Sr, Ti, and V were strongly correlated during roasting. The combined roasting of ammonium chloride and ammonium sulfate promoted the dissolution of Al and Li significantly. The specific surface area of water-leached gangue residue was adjusted by combined roasting, and its adsorption effect on lead ions was stronger than that of raw gangue and kaolinite. The present process presents an eco-friendly solution for the comprehensive utilisation of coal gangue.

Green and four-component cyclocondensation synthesis and in silico docking of new polyfunctionalized pyrrole derivatives as the potential anticholinesterase agents.

Synthesis of new substituted pyrrole scaffolds containing substituted thiadiazol-2-amine moiety was successfully developed through one-pot and multi-component tandem condensation reaction utilizing of triethyl ammonium hydrogen sulfate ([Et3NH][HSO4]) ionic liquid as a green media under solvent-free conditions. The chemical structures of all newly synthesized compounds were fully characterized by spectroscopic methods (IR, 1H NMR, 13C NMR) and elemental analyzes. The molecular docking studies were also performed to predict the possible binding sites of the derivatives on the active site gorge of cholinesterase enzymes (AChE and BuChE). The results showed that all the seventeen derivatives interact with the enzymes with high affinity and among them 7d and 7f possess the greatest ability to bind to AChE and BuChE, respectively.

A New stability indicating RP-HPLC method for the estimation of Gefitinib tablets using an ion pairing agent

Gefitinib is an anticancer drug used for the treatment of lung cancer, breast cancer and prostate cancer. A new stability indicating RP-HPLC method was proposed for the estimation of Gefitinib in pharmaceutical dosage forms (tablets). Shimadzu Model CBM-20A/20 Alite HPLC system with PDA detector and Agilent C18 column were used for the chromatographic study. Mobile phase mixture consisting of Tetra butyl ammonium hydrogen sulphate and Methanol in the ratio 50:50, v/v with a flow rate 0.8 mL/min was chosen for the chromatographic elution of Gefitinib (Detection wavelength 340 nm). The method was linear over the concentration range 0.1-80 mg/mL with linear regression equation, y = 70782x + 6171.6 (R² = 0.9999). The LOD and LOQ were found to be 0.2931 mg/mL and 0.8947 mg/mL respectively. Stress degradation studies were performed by exposing Gefitinib to various stress conditions and the method was validated as per ICH guidelines.

Chemometric Assisted Development and Validation of a Stability-indicating LC Method for Determination of Related Substances in Haloperidol Decanoate Injection

Abstract: Aim: Haloperidol decanoate injection is a phenyl butyl piperadine derivative with antipsychotic, neuroleptic, antiemetic effects and has multiple related substances as process and degradant impurities. Objectives: This study focuses on chemometric assisted liquid chromatographic approach to develop a stability indicating impurity profile of Haloperidol decanoate injection. Methodology: Dual experimental designs (combined mixture I-optimal design and response surface historical data design) were employed to resolve all thirteen known impurities of Haloperidol decanoate. Chromatographic separation was achieved on a Hypersil BDS C18 (100 x 4.0 mm) 3-μm column to attain separation of related compounds. Results: The optimum conditions for the chromatographic system resulted in a mobile phase consisting of tetra butyl ammonium hydrogen sulphate/ 1-decane Sulphonate sodium buffer solution and acetonitrile with linear gradient elution at a flow rate of 1.4 mL/min. Selectivity, forced degradation, linearity, accuracy and precision were demonstrated in a range of 0.75-30.0 μg/mL. Conclusion: The optimized method was able to resolve the ghost peak observed because of gradient change of mobile phase and is able to separate both polar and non-polar impurities within 60 min, in single method, with resolution of more than 2.0 between adjacent impurities. The inter-day precision for all impurities and haloperidol decanoate were evaluated and found to have a % RSD of less than 10. Key words: Design of Experiments, Haloperidol decanoate Injection, Stability indicating method, DoE aided chromatographic method development, Artifact optimization.