Ammonium Alum Research Articles

Preparation of Uniform α-Alumina Microspheres by Catalytic Precipitation and Calcination Process

Uniform α-alumina microspheres with mean partice size about 5-6 μm were prepared by the catalytic precipitation and calcination process. The spherical hydrated alumina precursor was first synthesized by the precipitation using ammonium aluminum sulfate and urea. During the reaction process, the urea can be decomposed to the mediator urease, which acts as the catalyst to influence the precipitate formation. The as-prepared α-alumina microspheres exhibit a very good shaping ability and the green body shaped by the dry-press process has a low linear shrinkage rate 5.8% at the sintering process.

Determination of ammonium sulphate in ammonia alum by formaldehyde reaction

Existing methods for the estimation of ammonium salts in presence of hydrolysable salts have been reviewed. A new titrimetric method utilizing formaldehyde and potassium fluoride is described for its estimation in presence of aluminium sulphate. The method is accurate and rapid for routine analysis.

Preparation of α-Al2O3 Powder by Microwave Pyrolysis

A fast method of microwave pyrolysis was provided to prepare α-Al2O3 powders. Aluminum hydroxide and Aluminum ammonium sulfate doclecahydrate were used as raw materials to obtain α-aluminum oxide powder by microwave pyrolysis, respectively. Thermo-Gravimetric/Differential Thermal Analyzer (TG/DTA) and X-ray Diffraction (XRD) analysis were employed to investigate pyrolysis process and the transformation of metastables Al2O3 in the process of heating different precursors. Meanwhile, Flied Emission Scanning Electron Microscopy (FESEM) was applied to observe microstructure and grain growth, and the phase composition was characterized by XRD. The results indicated that the high purity α-Al2O3 was obtained which met the demands of market, and the sample obtained from aluminum hydroxide performed high purity, small particle size and, while the sample from ammonium aluminum sulfate showed lower purity and larger grain size.

Magnetic Shielding of an Adiabatic Demagnetization Refrigerator for TES Microcalorimeter Operation

We are developing a compact adiabatic demagnetization refrigerator (ADR) dedicated for TES X-ray microcalorimeter operation. Ferric ammonium alum (FAA) was grown in a stainless-steel container in our laboratory. This salt pill was mounted together with a superconducting magnet and a conventional mechanical heat-switch in a dedicated helium cryostat. Using this system, we achieved \({ }20\) h below 100 mK. Initially, we used a 3 mm thick silicon steel shield around the ADR magnet and a Nb/Cryoperm double shield around the detector. However, this silicon steel shield allowed a \({\sim }50\) mT field at the detector position when a full field (3 T) was applied, and caused the Nb shield around the detector to trap a magnetic field. The observed transition curve of a TES was broad (\({\sim }20\) mK) compared to \({\sim }4\) mK obtained in a dilution refrigerator. By increasing the shield thickness to 12 mm, transition width was improved to \({\sim }4\) mK, which suggests that the shields work as expected. When we operated a TES microcalorimeter, energy resolution was \(14.5\pm 0.7\) eV (FWHM) at 5.9 keV.

Morphology Evolution in Hydrothermal Synthesis of Mesoporous Alumina

Boehmite with varied morphologies was successfully synthesized from aluminum ammonium sulfate hy- drate and urea, as well as poly-glycol-2000 by hydrothermal method. The experimental results show that boehmite mi- crospheres, microfibers and 3D hierarchical structured AlOOH can be fabricated only by adjusting hydrothermal tem- perature. SEM images indicate that boehmite decomposes into γ-Al2O3 phase after heat-treatment through a topotacti- cal process. TEM studies present that the mesopores are formed in γ-Al2O3 particles. Based on these investigations, a temperature-dependent morphology formation mechanism is proposed. Besides, the as-synthesized alumina excited at 325 nm shows emission in the range of 380 nm to 500 nm, centered at 409 nm and 467 nm.

Phase Separation Characteristics of Ammonium Alum Hydrates with Poly Vinyl Alcohol

Phase Separation Characteristics of Ammonium Alum Hydrates with Poly Vinyl Alcohol

Crystal Growth and Viscosity Behaviors of Ammonium Alum Hydrate Solution with PVA in Shear Flow

Crystal Growth and Viscosity Behaviors of Ammonium Alum Hydrate Solution with PVA in Shear Flow

Self‐Assembled 3D Hierarchically Structured Gamma Alumina by Hydrothermal Method

Self‐assembled γ‐Al2O3 with hierarchical structure was successfully obtained via thermolysis of γ‐boehmite (γ‐AlOOH) particles, which was hydrothermally derived from aluminum ammonium sulfate hydrate (NH4Al(SO4)2·12H2O), urea, poly‐glycol (PEG)‐2000, and deionized water. SEM observations indicate that the as‐synthesized γ‐AlOOH has hierarchical flower‐like structure, composing of needle‐like building blocks. After calcinations at 800°C, it converts to cubic γ‐Al2O3 with hierarchical structure retained by a topotactical process. N2 adsorption and desorption reveal that the obtained γ‐Al2O3 has a BET surface area of 101 m2/g with a narrow mesoporous size of about 13 nm and a broad macroporous‐size distributions of 200–500 nm, respectively. The as‐generated γ‐Al2O3 with hierarchical structure shows good capacities for removing Congo red from wastewater, indicating that 3D hierarchical structure has excellent adsorption ability.

The Role of Inorganic Metal Salts in Wastewater Clarification

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

The Role of Inorganic Metal Salts in Wastewater Clarification

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

Photoluminescent properties of new up-conversion phosphors of Yb/Tm co-doped (Gd1−xLux)3Al5O12 (x=0.1–0.5) garnet solid solutions

Abstract The metastable garnet lattice of gadolinium aluminate garnet (Gd3Al5O12, GdAG) has been effectively stabilized by doping with significantly smaller Lu3+, which then allows a facile incorporation of rare earth activators for opto-functionality explorations. Carbonate precursors of Yb/Tm codoped (Gd,Lu)3Al5O12, with an approximate composition of (NH4)xLn3Al5(OH)y(CO3)z·nH2O (Ln = Gd, Lu, Yb and Tm), were coprecipitated from the mixed solution of ammonium aluminum sulfate and rare earth nitrates, using ammonium hydrogen carbonate as the precipitant. The resultant [(Gd1−xLux)0.948Yb0.05Tm0.002]3Al5O12 (x = 0.1–0.5) garnet solid-solution particles, with good dispersion and fairly uniform particle morphologies, exhibit a strong blue emission centered at ∼487 nm (the 1G4→3H6 transition of Tm3+) and a weak red emission centered at ∼650 nm (the 1G4→3F4 transition of Tm3+) under laser excitation at 978 nm. Meanwhile, the dependence of up-conversion emission intensity on the pumping power was discussed. Partially replacing Gd3+ with Lu3+ up to 50 at.% (x = 0.5) does not appreciably alter peak positions of the up-conversion emission bands but tends to yield decreased lattice parameters of the material and lowered emission intensities. The Yb/Tm codoped (Gd,Lu)AG garnet system developed herein may potentially be used as a new type of optical material.

Mechanical Properties and Wear Behaviour of Al2O3/SiCp Reinforced Aluminium-Based MMCs Produced by the Stir Casting Technique

In this study, initially Al2O3/SiC powder mix was prepared by reacting of aqueous solution of aluminium sulphate, ammonium sulphate and water containing SiC particles at 1200°C. 10 wt% of this hybrid ceramic powder with different sized SiC particles was added to a liquid Al matrix alloy during mechanical stirring between solidus and liqudus under inert conditions. Then hybrid Metal Matrix Composites (MMCs) was produced. The effect of reinforced particle size on tensile strength, bending strength, hardness resistance and wear resistance properties of hybrid reinforced MMCs were investigated. The mechanical test results revealed that bending, tensile strength and hardness resistance of the composites increased with decrease in ductility, with decrease size of the reinforcing SiC particulates in the aluminium alloy metal matrix. The wear behaviour of the hybrid ceramic reinforced aluminium matrix composites was investigated using pin-on-disc test at room temperature under dry conditions. Wear tests showed that the wear resistance of MMCs increased with increasing reinforced Al2O3/SiC particle size. Comparing the fine particle size MMCs with the coarse particle size MMCs were easily pulled out whole from the matrix. Microstructural examination showed that as well as coarse SiC particle reinforcement, a fine alumina particle reinforcement phase was observed within the aluminium matrix (A332).

Theoretical analysis of a seawater desalination process integrating forward osmosis, crystallization, and reverse osmosis

A hybrid forward osmosis (FO)/crystallization/reverse osmosis (RO) process for seawater desalination was proposed, and the theoretical analysis of the process was conducted. When the FO unit is considered as the main desalination unit, the crystallization and RO units can be regarded as a draw solute recovery process. First, in the FO process, fresh water is extracted from seawater and permeates into draw solution. This diluted draw solution is cooled down in the crystallization process and the draw solute is precipitated up to the saturation at low temperature. As a result, the feed stream of the RO process has lower concentration, and consequently, total energy consumption is expected to be reduced. In order to apply the proposed process in practice, the selection of suitable draw solute should be carefully determined. In the present work, five substances were suggested as draw solutes in the proposed system: ammonium oxalate, ammonium aluminum sulfate, sodium periodate, sodium phosphate and sodium sulfate. Based on properties of the substances, total energy consumption was analyzed for each draw solute. The total energy was calculated by the sum of cooling energy in crystallization process and pumping energy in RO process. Through the hybridization of these three unit processes, the energy requirement for fresh water production can be reduced to 2.15kWh/m3. Thus, it is concluded that the proposed process can be highly competitive.

Crystal Structure Stabilization of Gadolinium Aluminum Garnet (Gd<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>) and Photoluminescence Properties

To suppress the thermal decomposition and to stabilize the crystal structure of Gd3Al5O12 (GdAG) garnet, doping GdAG with smaller Ln3+ (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, respectively) to form (Gd,Ln)AG solid solutions was proposed in work. Carbonate precursors of (Gd,Ln)AG with an approximate composition of (NH4)x(Gd,Ln)3Al5(OH)y(CO3)z•nH2O were synthesized via coprecipitation from a mixed solution of ammonium aluminum sulfate and rare earth nitrate, using ammonium hydrogen carbonate as the precipitant. The precursors and the calcination derived oxides were characterized using FT-IR spectroscopy, DTA/TG, XRD, BET and FE-SEM. The results showed that smaller Ln3+ doping can indeed stabilize GdAG against its thermal decomposition to a mixture of GdAlO3 (GdAP) and Al2O3 phases at elevated temperatures and at the same time effectively lowers the temperature for garnet crystallization. The carbonate precursors are loosely agglomerated and the resultant (Gd,Ln)AG powders show good dispersion and a fairly uniform particle morphology. The (Gd,Ln)AG solid solutions exhibit decreasing lattice parameters along with decreasing radius of the dopant ions at the same dopant content of 50 at%. Photoluminescence properties of some of the garnet solid solutions are also studied. The materials developed herein may potentially be used for photoluminescent and scintillation applications.

Synthesis of Monodispersed Spherical Yttrium Aluminum Garnet (YAG) Powders by a Homogeneous Precipitation Method

Monodispersed yttrium aluminum garnet (YAG) powders have been synthesized via homogeneous precipitation method from the mixed solutions of yttrium nitrate, aluminum nitrate, and ammonium aluminum sulfate using urea as the precipitant. The molar ratio of aluminum nitrate to ammonium aluminum sulfate has a significant effect on morphology and particle size of the precursor powders. It was found that spherical precursor particles can be obtained when the ratio is 1:1. During the homogeneous precipitation process, aluminum ions precipitate first and form monodispered spherical powders, and then yttrium ions precipitate onto the surface of the existing spheres. Monodispersed spherical YAG particles with 500 nm in diameter were obtained by calcining the precursor powder at 1100°C for 5 h. The so‐prepared monodispersed spherical Nd:YAG powders have good sinterability, and can be sintered into transparent ceramics by vacuum sintering at 1650°C for 3.5 h.

Flow and heat transfer characteristics of ammonium alum hydrate slurries

Flow and heat transfer characteristics of ammonium alum hydrate slurries have been investigated. Ammonium alum hydrate has high latent heat of 251 kJ kg−1 and its melting temperature is 51 °C when the concentration of ammonium alum in water was set at 35 wt%. The friction and the melting heat transfer coefficients were measured in a pipe flow with 13 mm of diameter. From the results, it was found that the friction coefficient of ammonium alum hydrate slurry shows almost the same value as that of water. On the other hand, the slurry shows higher heat transfer than that of water. Especially, the heat transfer enhanced rate becomes high when the temperature difference between the slurry and the heating flow was set small. This is because of the temperature sustainability of phase change material slurries. From this, it was concluded that ammonium alum hydrate slurry can be a promising candidate for a heating system.

Synthesis of AlN Powder from Precipitation Precursor by Carbon Thermal Reduction in Flowing Nitrogen

Abstract. Aluminum nitride(AlN) powders were synthesized by carbonthermal reduction of Ammonium aluminum carbonate hydroxide(AACH). The AACH were prepared from ammonium alum and ammonium hydrogen carbonate by precipitation method and AACH adhere to carbon black during precipitation. The precursor has a high reaction activity (near 100% of nitridation ratio after heated in flow nitrogen at 1400°C, 2h). After carbon remove in muffle furnace at 700 °C, white color Aluminum nitride (AlN) powder attained and mean size is 100 nm. The specific surface area of the powders decreased with increasing of concentration of ammonium alum and ammonium hydrogen carbonate, which range from 22 m2/g to 7 m2/g, particle size vary from 58 to 120 nm. Phase presents in the products during heating in flowed nitrogen were observed by X-ray diffraction. The -Al2O3 formed when the precursor heated to 1200°C, AlN was founded at 1300°C and the reaction ended at 1400°C, the reaction temperature and annealing time were much lower than nitridate the mixture of Al2O3 and carbon black. Particle size was increased when reaction temperature increased from 1400°C to 1550°C.

Coagulation/Flocculation of Tannery Wastewater Using Immobilized Chemical Coagulants

Chemical coagulants were immobilized into bead form using sodium alginate to treat tannery wastewater samples. The used chemical coagulants were ammonium aluminium sulphate (NH4Al(SO4)2), aluminium sulphate (Al2(SO4)2, calcium carbonate (CaCO3), sodium citrate (Na3C6HsO7). The effect of the chemical coagulant dose and tannery wastewater pH was studied on wastewater electrical conductance (EC), total dissolved solids (TDS), sulphates, chlorides, phenolphthalein alkalinity, total alkalinity and chemical oxygen demand (COD). The quantity of various pollutants present in waste water was reduced after treatment. The optimized dose and pH for maximum decrease in EC and TDS were 5g/L and 7, respectively. The maximum reduction in the amount of sulphates and chlorides present in tannery wastewater was observed at dosage of 0.5g/L and pH 7. A dosage of 5g/L and pH 7 was also found most favorable for maximum reduction in values of COD, phenolphtalein and total alkalinity. The chromium concentrations in tannery wastewater before and after treatment were determined by atomic absorption spectrophotometer. A reduction in chromium concentration was observed after treatment. The promising results of the present study demonstrate that immobilization of chemical coagulants can make them more effective for wastewater treatment.

Aluminum ammonium sulfate dodecahydrate purified from traditional Chinese medicinal herb Korean monkshood root is a potent matrix metalloproteinase inhibitor

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases and key regulators for many physiological and pathological functions. The MMP inhibitors have been shown to modulate diseases such as cancer, inflammation, and cardiovascular diseases. In this paper we tracked the MMP inhibitory activities of the traditional Chinese medicinal herb Korean Monkshood Root. The purified active ingredient was identified by the elemental analysis, infrared spectrum (IR) and X-ray diffraction as aluminum ammonium sulfate dodecahydrate. This inorganic compound showed inhibitory activities toward a number of MMP family members. In particular, it has a strong inhibitory effect toward MMP-2 and MMP-9, with IC50 values of 0.54 and 0.50 μM, respectively. Further analysis suggested that the MMP inhibitory activity is mainly due to Al(3+). Cell viability assays using human fibrosarcoma HT1080 cells showed aluminum ammonium sulfate had minimal cyto-toxicity with a concentration up to 500 μM. However, within 50 μM, it exhibited significant inhibition of cell invasion. To our knowledge, there has been no previous report of inorganic form of the MMP inhibitor with strong inhibitory activity. Our results for the first time showed that aluminum ammonium sulfate is an inorganic form of MMP inhibitor with high potency, and can be used to interfere with MMP related cellular processes.

Conclusion on the peer review of the pesticide risk assessment of the active substance aluminium ammonium sulfate (approved as aluminium ammonium sulphate)

Conclusion on the peer review of the pesticide risk assessment of the active substance aluminium ammonium sulfate (approved as aluminium ammonium sulphate)