Aqueous Ammonium Sulfate Solutions Research Articles

Dispersion copolymerization of acrylamide and sodium 2-acrylamido-2-methylpropanesulfonate in aqueous salt solution stabilized with a macro-RAFT agent

Dispersion copolymerization of acrylamide (AM) and sodium 2-acrylamido-2-methylpropanesulfonate (AMPSNa) in aqueous ammonium sulfate (AS) solution was performed without mechanical stirring using a macro-RAFT agent sodium poly(2-acrylamido-2-methylpropanesulfonate) trithiocarbonate (PAMPSNa-TTC) as the stabilizer and 2,2′-azobis(2-methylpropionamide) dihydrochloride as the initiator. The effects of various polymerization parameters were systematically investigated regarding dispersion stability, particle size, molecular weight and apparent viscosity. A new mechanism for particle formation and the particle stability of aqueous dispersion polymerization was proposed.

Design of Bulk Protein Crystallization Based on Phase Diagrams Accounting for the Presence of Interfacial Water

An effective procedure for design of protein crystallization was proposed, in which binary and ternary phase diagrams were exploited to evaluate the process performance. A method for the construction of phase diagrams that accounted for the presence of water associated with the protein crystalline phase (interfacial water) was described. The model system for the study included ovalbumin and lysozyme, which were crystallized from aqueous solutions of ammonium sulfate. The design procedure consisted of the determination of the operating window on the plane of the protein and salt concentrations, quantifying the protein phase behavior within the window, and the construction of the corresponding phase diagrams to select operating conditions that ensure a high yield of the operation. The analysis of the solid phase behavior was supported by differential scanning calorimetry, which was used to evaluate the amount of interfacial water in the protein dense phase, thus, to determine the solid phase composition. Th...

A Role for 2-Methyl Pyrrole in the Browning of 4-Oxopentanal and Limonene Secondary Organic Aerosol.

Reactions of ammonia or ammonium sulfate (AS) with carbonyls in secondary organic aerosol (SOA) produced from limonene are known to form brown carbon (BrC) with a distinctive absorption band at 505 nm. This study examined the browning processes in aqueous solutions of AS and 4-oxopentanal (4-OPA), which has a 1,4-dicarbonyl structural motif present in many limonene SOA compounds. Aqueous reactions of 4-OPA with AS were found to produce 2-methyl pyrrole (2-MP), which was detected by gas chromatography. While 2-MP does not absorb visible radiation, it can further react with 4-OPA eventually forming BrC compounds. This was demonstrated by reacting 2-MP with 4-OPA or limonene SOA, both of which produced BrC with absorption bands at 475 and 505 nm, respectively. The formation of BrC in the reaction of 4-OPA with AS and ammonium nitrate was greatly accelerated by evaporation of the solution suggesting an important role of the dehydration processes in BrC formation. 4-OPA was also found to produce BrC in aqueous reactions with a broad spectrum of amino acids and amines. These results suggest that 4-OPA may be the smallest atmospherically relevant compound capable of browning by the same mechanism as limonene SOA.

Synthesis of Cross-Linked Poly(acrylamide) Microspheres by Dispersion Polymerisation in Aqueous Ammonium Sulfate Solution

Cross-linked poly(acrylamide) microspheres, i.e. PAMBA, with mean diameters ranging from 169.7 to 525.2 nm were prepared by dispersion polymerisation of acrylamide in aqueous ammonium sulfate (AS) solution. N,N′-methylenebis(acrylamide) (MBA), sodium dodecyl sulfate (SDS), and potassium persulfate (KPS) were selected as the cross-linking agent, stabiliser, and initiator, respectively. The basic conditions for producing PAMBA microspheres, such as the salt concentration and monomer concentration, were optimised based on the precipitation behaviour of the polymer and the state of the product obtained after polymerisation. The optimum AS concentration and monomer concentration were determined as 300 and 88 g L−1, respectively. The effects of parameters, such as SDS concentration, MBA concentration, initiator concentration and temperature, on the product morphology and particle size were investigated by dynamic light scattering and transmission electron microscopy. The results show that the optimum conditions for the generation of microspheres are concentrations of 2.2–8.8 g L−1 for SDS, 4–6 g L−1 for MBA, 0.3–1.0 wt-% based on acrylamide for KPS, and the temperature should be kept at 35–45°C. The mean diameter of the microspheres decreases with an increase in SDS concentration and increases with an increase in MBA concentration. The polydispersity of the microspheres increases when SDS concentration exceeds 6.6 g L−1 as well as when MBA concentration increases. The formation mechanism of the products was discussed based on the results.

Paired Electro-Synthesis of PbO2 and Pb As Lead Storage Battery Active Materials Using PbSO4 As a Precursor

Given the toxicity and economy of lead, it is important to achieve good recovery in the recycling of waste lead storage batteries. Lead sulfate (PbSO4), which plays an important part in reactions of the lead storage battery, is formed in accordance with Faraday's law during discharge. PbSO4, is the main component in a waste battery paste and account for up to 50% of the paste by weight. PbSO4 can be isolated from the waste battery paste as raw material by the nitrate acid leaching-ammoniacal ammonium sulfate leaching-refining and solid-liquid separation process. First, the paste was treated by nitrate acid leaching to convert PbO to lead nitrate (Pb(NO3)2), then leach residue containing lead sulfate and lead dioxide was leached with ammoniacal ammonium sulfate, based upon the solubility of PbSO4 in aqueous ammoniacal ammonium sulfate solution. After solid-liquid separation the solution is then purified, PbSO4 was obtained by removal of free ammonia and heating. The paired electro-synthesis of PbO2 and Pb as lead storage battery active materials using PbSO4 as a precursor was investigated. Optimal synthesis conditions were determined by investigating the effect of the particle diameter and distribution of the precursor, current density, temperature, and operating time. Experimental results show that lead can be recovered effectively as PbSO4, and as a precursor, can be readily converted to PbO2 and Pb for directly making lead-battery pastes by controlling the electrochemical process and the particle diameter and distribution of the precursor in microscale powders. Results in this work are used to underpin the development of a new process that can be used for recovering lead from lead battery pastes. The route is suitable for large scale operations which in turn entail large scale movement of battery waste materials. The new process can avoid both smelting, desulphurisation and electro-winning. PbSO4, as a precursor, can be readily converted to PbO2 and Pb for directly making lead storage battery pastes for achieving lead recovery simultaneously. Key words : paired electro-synthesis, lead storage battery, lead sulfate, lead monoxide, lead dioxide

Toward a Green Generation of Oxidant on Demand: Practical Electrosynthesis of Ammonium Persulfate

The electrolysis of aqueous solution of ammonium sulfate has been systematically investigated in a two-compartment electrolytic flow cell for the potential applications for green and efficient synthesis of ammonium persulfate. A commercial boron-doped diamond (BDD) coated anode (active area of 10 cm2) was used and electrolysis was operated under batch recirculation. Under a flow rate of 3.33 mL min–1, the flow pattern is well described by a flow model with axial dispersion in the reaction compartment. The electrosynthesis was found not to be mass transport-limited in the present system at flow rates of ≥50 mL min–1 with a current density of ≤150 mA cm–2. The charge transfer-controlled reaction was subsequently modeled, taking into account bubble coverage effects. Thereafter, the productivity of persulfate was investigated under different current densities, electrolyte compositions and concentrations. It was found that a high current efficiency can be obtained at the initial stage (∼93%, 150 mA cm–2, ≤1 h)...

Observation of attachment ratio of fission products on solution aerosol

Attachment behavior of fission products to solution aerosols has been observed to elucidate the role of chemical effects in the generation mechanism of fission-product aerosols. Primary aerosols generated from aqueous solution of sodium chloride or ammonium sulfate were passed through a fission-product chamber, and radioactive aerosols were generated by attaching fission products to the primary aerosol particles. Attachment ratios of the fission products on aerosols were estimated from activity measurements. It was found that the attachment ratio of the sodium chloride solution aerosol is larger than that of the ammonium sulfate solution aerosol.

Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single-droplet basis

Abstract. An experimental setup has been constructed to measure the collection efficiency (CE) of sub-micrometer aerosol particles by cloud droplets. Droplets of a dilute aqueous ammonium sulfate solution with an average radius of 21.6 μm fall freely into a chamber and collide with sub-micrometer polystyrene latex (PSL) sphere particles of known sizes and concentrations. Two relative humidity (RH) conditions, 15 ± 3 % and 88 ± 3 %, hereafter termed "low" and "high", respectively, were varied with different particles sizes and concentrations. After passing through the chamber, the droplets and aerosol particles were sent to the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument to determine chemical compositions on a single-droplet basis. "Coagulated droplets" (droplets that collected aerosols) had mass spectra that contained signatures from both an aerosol particle and a droplet residual. CE values range from 2.0 × 10−1 to 1.6 for the low-RH case and from 1.5 × 10−2 to 9.0 × 10−2 for the high-RH case. CE values were, within experimental uncertainty, independent of the aerosol concentrations. CE values in this study were found to be in agreement with previous experimental and theoretical studies. To our knowledge, this is the first collection experiment performed on a single-droplet basis with atmospherically relevant conditions such as droplet sizes, droplet charges and flow.

Isolation of rare earth elements from ammonium salts solutions

It has been shown that nonradioactive concentrate containing up to 97–99 wt % rare earth elements (REEs) oxides after calcinations might be isolated from the strippant based on concentrated aqueous solution (275–300 g/L) of ammonium sulfate or ammonium nitrate obtained during the REE extraction from phosphogypsum or phosphoric acid. A REE loss in thorium-containing precipitate does not exceed 0.1–0.5% in the hydrolytic precipitation of thorium.

Effects of High Magnetic Fields on Thermal Convection Using Feeble Magnetic Conductive Aqueous Solutions

Abstract Effects of magnetic fields on thermal convection in conductive aqueous solutions at ambient temperatures have been studied through heat transport measurements. The suppression of thermal convection by a magnetic field in conductive paramagnetic aqueous solutions of copper nitrate was observed and confirmed as an effect of the Lorentz force by comparing with diamagnetic aqueous solutions of ammonium sulfate. The effect of the Lorentz force and magnetic force on the thermal convection in conductive fluids was separately evaluated by changing the magnetic field environment. The results obtained show that the behavior of liquid metals under magnetic field can be investigated by using electrolyte aqueous solutions combined with a superconducting magnet.

Effects of high magnetic fields on thermal convection of conductive aqueous solution

Effects of magnetic fields on the thermal convection in conductive aqueous solutions at ambient temperatures have been studied through heat transport measurements combined with shadowgraph technique-based visualization. The suppression of thermal convection by magnetic field was in fact observed in conductive diamagnetic aqueous solutions of ammonium sulfate. The magnitude of the suppression was found to depend on the applied magnetic field and the electrical conductivity of the sample fluid. These effects are qualitatively understood by assuming that Lorentz force acting on the fluid is a main player. Based on these results, a control method of heat transfer process using high magnetic fields has been demonstrated. It seems feasible to understand the behaviors of liquid metals by using electrolytes aqueous solution combined with a superconducting magnet, since flow conditions thereby are regarded as similar to those for liquid metals in industrial electromagnets.

Effect of hydrophobic monomer on the aqueous dispersion polymerization of acrylamide with quaternary ammonium cationic monomer

Aqueous dispersion polymerization has been considered as a promising green technology for preparing water-soluble polymers such as cationic polyacrylamide (CPAM). Dispersion copolymerization of acrylamide and 2-methylacryloylxyethyl trimethyl ammonium chloride was generally carried out in aqueous ammonium sulfate solution with poly(2-methylacryloylxyethyl trimethyl ammonium chloride) as the stabilizer. In this study, we reported the potential influence of a small amount of hydrophobic monomer, methyl methacrylate (MMA), on the above-mentioned aqueous dispersion polymerization system. It was found that MMA could play an important role in the polymerization process by significantly affecting the particle formation and stabilization, as well as the viscosity evolution of the reaction mixture during polymerization. With the addition of a small amount of MMA, the particle formation was accelerated and the viscosity of the polymerization system decreased significantly. With the increase in MMA addition, the final copolymer particle size was reduced and its size distribution became narrower; meanwhile, the particle morphology tended to be spherical. Moreover, it was found that the addition of MMA could favor the production of CPAM with high charge density. The flocculation performance of the resulting CPAM dispersion was also examined in detail and it was found that the introduction of MMA unit into CPAM molecular chain could improve its flocculation efficiency.

Characterization of Kaolinite (Al2Si2O5 (OH)4) and Lansoprazole (C16H14N3F3O2S) for Developing a Structured Coating

The phenomenon of corrosion is impaired and the different materials. Industrially it has worked in the protection of these, however, efforts can increase costs if the methods and mechanisms are not adequate and therefore inefficient. Currently, several studies focus on the development of new coatings that act as corrosion inhibitors from natural sources with no toxic properties. Kaolinite (Al2Si2O5 (OH) 4) is considered a "green" low cost material and promotes it to be used as a container of polymeric materials because of their porous characteristics. Moreover, some drugs such as omeprazole (C17H19N3O3S), pantoprazole (C16H15N3F2O4S) for their inhibitory properties in acidic environments are ideal candidates for use as corrosion inhibitors to replace those that are typically toxic as chromate lithium (Li2CrO4).In this paper the development of a structured coating consisting of kaolinite (Al2Si2O5 (OH) 4) doped with lansoprazole (C16H14N3F3O2S) and a polymer film with the purpose of protecting metallic materials such as steel is presented. The objective of this work is to characterize kaolinite (Al2Si2O5 (OH) 4) in the raw natural state and heat treated at 350, 400, 450 and 560 ° C by Scanning Electron Microscopy (SEM). Lansoprazole ((C16H14N3F3O2S)) was characterized by electrochemical techniques: polarization curves and electrochemical impedance spectroscopy (EIS).The results show that the kaolinite in its natural state has amorphous and crystalline particles with impurities. When the heating process mesoporous particles were obtained. Lansoprazole effectiveness at different concentrations (50, 75, 100, 125, 150 and 200 ppm) was evaluated in an aqueous solution of ammonium sulfate ((NH)4 SO4) with sodium chloride (NaCl) at pH 7 and 25 ° C using mild steel.The results suggest that at 500 °C mesoporous kaolinite particles which may be applied as inhibitory container obtained lansoprazole, gave the better electrochemical response. Moreover lansoprazole has the highest efficiency as a corrosion inhibitor at 125 ppm.

Enhanced high-temperature ice nucleation ability of crystallized aerosol particles after preactivation at low temperature

In cloud chamber experiments with crystallized aqueous ammonium sulfate, oxalic acid, and succinic acid solution droplets, we have studied a preactivation mechanism that markedly enhances the particles' heterogeneous ice nucleation ability. First cloud expansion experiments were performed at a high temperature (267–244 K) where the crystallized particles did not promote any heterogeneous ice nucleation. Ice nucleation at this temperature, however, could be triggered by temporarily cooling the crystallized particles to a lower temperature. This is because upon crystallization, residuals of the aqueous solution are trapped within the crystals. These captured liquids can freeze when cooled below their respective homogeneous or heterogeneous freezing temperature, leading to the formation of ice pockets in the crystalline particles. When warmed again to the higher temperature, ice formation by the preactivated particles occurred via depositional and deliquescence-induced ice growth, with ice active fractions ranging from 1 to 4% and from 4 to 20%, respectively. Preactivation disappeared above the eutectic temperature, which for the organic acids are close to the melting point of ice. This mechanism could therefore contribute to the very small fraction of atmospheric aerosol particles that are still ice active well above 263 K.

Partial Molar Volumes of Glycine and dl-Alanine in Aqueous Ammonium Sulfate Solutions at 278.15, 288.15, 298.15 and 308.15 K

Partial Molar Volumes of Glycine and dl-Alanine in Aqueous Ammonium Sulfate Solutions at 278.15, 288.15, 298.15 and 308.15 K

Salting‐out thin‐layer chromatography and computational analysis of some oral hypoglycemic drugs

A quantitative structure-retention relationship study of some oral hypoglycemic drugs was carried out using a salting-out thin-layer chromatographic technique. Aqueous solution of ammonium sulfate and acetonitrile was used as a mobile phase. It was established that the applied mobile phase has different effects on retention of the studied oral antidiabetic drugs. The factors that affect the salting-out process were determined. In this study a good correlation between the structures of the investigated drugs with the retention data and molecular descriptors was established throughout computational analysis and using molecular operating environment software, focusing on octanol/water partition coefficient, molar refractivity, total hydrophobic surface area, hydrophobic volume, Van der Waals energy and solvation energy. Quantitative structure-retention relationship modeling for the separation of the investigated drugs was carried out, validated and evaluated.

Partial Molar Volumes of l-Serine and l-Threonine in Aqueous Ammonium Sulfate Solutions at (278.15, 288.15, 298.15, and 308.15) K

In this study, the partial molar volumes of l-serine and l-threonine in aqueous solutions of ammonium sulfate at (0.0, 0.1, 0.3, 0.7, and 1.0) mol·kg−1 are reported between 278.15 and 308.15 K. Transfer volumes and hydration numbers were obtained, which are larger in l-serine than in l-threonine. Dehydration of the amino acids is observed, rising with the temperature and salt molality. The data suggest that interactions between ions and charged/hydrophilic groups are predominant, and by applying the McMillan and Mayer formalism, it was concluded that they are mainly pair wise. The combination of the data presented in this study with solubility and molecular dynamics data suggests a stronger interaction of the ammonium cation with the zwitterionic centers of the amino acids when compared to the interactions of those centers with the sulfate anion.

Synthesis of hydrophobically modified flocculant by aqueous dispersion polymerization and its application in oily wastewater treatment

A hydrophobically modified cationic flocculant, in the form of aqueous dispersion, has been successfully synthesized via dispersion copolymerization of acrylamide (AM), 2‐methylacryloylxyethyl trimethyl ammonium chloride (DMC), and methyl methacrylate (MMA) in aqueous ammonium sulfate (AS) solution. The molecular structure of the prepared copolymer was characterized by nuclear magnetic resonance spectroscopy (NMR). Meanwhile, the influence of hydrophobic comonomer (MMA) on the viscosity and microstructure of this aqueous dispersion was investigated. It was found that both the viscosity and the particle size were decreased with increasing content of MMA. Thereafter, this flocculant was used to treat the oily wastewater, and its oil removal ability was assessed under various conditions. It was demonstrated that the hydrophobically modified flocculant has obvious superiority for oily wastewater treatment. POLYM. ENG. SCI., 55:1–7, 2015. © 2014 Society of Plastics Engineers

Photochemical Aging of Light-Absorbing Secondary Organic Aerosol Material

Dark reactions of methylglyoxal with NH4(+) in aqueous aerosols yield light-absorbing and surface-active products that can influence the physical properties of the particles. Little is known about how the product mixture and its optical properties will change due to photolysis as well as oxidative aging by O3 and OH in the atmosphere. Here, we report the results of kinetics and product studies of the photochemical aging of aerosols formed by atomizing aqueous solutions of methylglyoxal and ammonium sulfate. Experiments were performed using aerosol flow tube reactors coupled with an aerosol chemical ionization mass spectrometer (Aerosol-CIMS) for monitoring gas- and particle-phase compositions. Particles were also impacted onto quartz windows in order to assess changes in their UV-visible absorption upon oxidation. Photooxidation of the aerosols leads to the formation of small, volatile organic acids including formic acid, acetic acid, and glyoxylic acid. The atmospheric lifetime of these species during the daytime is predicted to be on the order of minutes, with photolysis being an important mechanism of degradation. The lifetime with respect to O3 oxidation was observed to be on the order of hours. O3 oxidation also leads to a net increase in light absorption by the particles due to the formation of additional carbonyl compounds. Our results are consistent with field observations of high brown carbon absorption in the early morning.

Granulation by spray coating aqueous solution of ammonium sulfate to produce large spherical granules in a fluidized bed

Spherical 2–4mm granules of ammonium sulfate (NH4)2SO4 are promising fertilizer for practical use, though only much smaller grains are being produced in industry. This work used coating granulation to produce large spherical granules of (NH4)2SO4 in a fluidized bed by spraying its aqueous solution onto 0.9–1.6mm (NH4)2SO4 core particles. However, the overall coating efficiency was only 58% due to loss as dust by attrition of (NH4)2SO4 in the vent gas. By adding CaCO3 or SiO2 particles into the feed solution, the coating efficiency was increased to over 90%. This increase in coating efficiency was due to a change in the crystallization mechanism of (NH4)2SO4. The added CaCO3 or SiO2 particles provided a heterogeneous surface that induced (NH4)2SO4 to crystallize uniformly to form a more compact structure less susceptible to attrition.