Amounts Of Aluminum Hydroxide Research Articles

Study on preparation and properties of alkali-free accelerator

As one of the main components of shotcrete, accelerator is widely used in housing construction, tunnel engineering and road emergency repair. In this paper, hydrofluoric acid, aluminum sulfate and aluminum hydroxide were used as main raw materials to prepare alkali free accelerator by liquid phase self reaction method. The influence of the amount of hydrofluoric acid, aluminum sulfate and aluminum hydroxide on the coagulation performance and stability of alkali free accelerator was mainly investigated. The test results are as follows: within the experimental range, the influence of aluminum sulfate on the coagulation performance of alkali free accelerator is greater than that of hydrofluoric acid. When the amount of 40% hydrofluoric acid is 100 g ∼ 160g, the amount of aluminum hydroxide is 50 g ∼ 80g, and the amount of aluminum sulfate is 320 g ∼ 400g, the alkali free accelerator products with main indexes of initial setting time ≤ 3 min and final setting time ≤ 6 min can be prepared, which meet the requirements of GB/T 35159-2017"Accelerator for shotcrete". The unit price of the optimized product is ¥1488 which is compared with the main products on the market, This product has good competitiveness.

New strategies to quantify aluminum hydroxide in powder coatings by thermogravimetric analysis and ATR-FT-MIR spectroscopy coupled with chemometrics

Powder coatings industry is a growing trade sector in our days and the process control phase is a critical step with the increasing necessity for rapid methods. In this research, we evaluated the possibility of aluminum hydroxide quantification in powder coatings using thermogravimetric analysis and ATR-FT-MIR spectroscopy. Spiked powder coatings sample standards were realized with a known amount of aluminum hydroxide from 0 to 22% in weight. The thermogravimetric analysis (TGA) was optimized, and the aluminum hydroxide content was determined with a stoichiometric formula based on the delta at the inflection point (DTG curve were derived) in TGA results. The spectroscopic data were acquired, and multivariate regression (Partial Least Squares Regression) was used to model the aluminum hydroxide content with respect to the spectral signal. Models were validated with an external set of real powder coating samples. In this article, a step-by-step model development procedure is illustrated as well as the issues addressed. In addition, models showed the possibility of identifying some additives and resins using only the spectroscopic information.

BRIGHT LUMINESCENCE OF FIRE RETARDANT ALUMINUM HYDROXIDE-SILICA SPHERE COMPOSITE

Bright luminescence was achieved with excess amount of aluminum hydroxide with silica spheres. Various amounts of aluminum hydroxide were attached to silica spheres to improve the performance of fire retardancy. Although silica spheres attached with 60[Formula: see text]wt.% of AlCl3 (AlOH-A) showed no color change and luminescent chromophores, silica spheres attached with 80[Formula: see text]wt.% of (AlOH-B) and 100% of (AlOH-C) of AlCl3 changed the color and produced luminescent chromophores. The solution colors became intense yellow and brown for AlOH-B and AlOH-C, respectively, after 15 days. The FTIR spectra showed the characteristic absorption peaks of Al–OH and Si–O–Al. The concentration dependent photoluminescence (PL) intensities were continuously increased until 242[Formula: see text]mg addition of the colored solution and then slightly decreased thereafter for both AlOH-B and AlOH-C. The PL peaks shifted toward red by increasing the excitation wavelength for both AlOH-B and AlOH-C. Large Stoke shifts, such as 73 and 68[Formula: see text]nm for AlOH-B and AlOH-C, respectively, were observed.

Enhancement of Fire Retardancy Using Surface-Modified Silica Spheres with Aluminum Hydroxide

Large surface area and fire-inert property of sub-micrometer silica spheres were employed to improve the fire retardant performance by attaching large number of Si–O–Al(OH)\(_{2}\) groups. Various amounts of AlCl\(_{3}\) were attached to the surface of silica spheres and the residual –AlCl\(_{2}\) was hydrolyzed by adding excess amount of KOH. Although the FESEM image of pure silica spheres showed smooth surface, the surface-modified silica spheres exhibited nanoparticles on the surface of silica spheres. The characteristic absorption peaks of Al–OH and Si–O–Al were detected by FTIR spectra. Silica spheres attached with Si–O–Al(OH)\(_{2}\) were uniformly distributed on the surface of cellulose acetate films. The performance of the fire retardant was greatly enhanced by increasing the amount of aluminum hydroxide.

Synergistic effect of combined dimethyl methylphosphonate with aluminum hydroxide or ammonium polyphosphate retardant systems on the flame retardancy and thermal properties of unsaturated polyester resin

ABSTRACTA series of flame-retardant unsaturated polyester resin (UPR) were prepared by the addition of dimethyl methylphosphonate (DMMP) with various amounts of aluminum hydroxide (ATH) or ammonium polyphosphate (APP) as the flame retardants. The combustion resistance effects of ATH/DMMP and APP/DMMP systems were evaluated by limiting oxygen index test and vertical burning test (UL-94). The thermal properties of UPR were investigated by thermogravimetric analysis. The structure of char was observed by scanning electron microscopy. DMMP incorporated with ATH or APP improved the flame retardancy and thermal properties of UPR. However, the fire-retardant mechanism of these two systems were different: The ATH/DMMP system provided synergistic effect in charring property of the UPR, produced great amount of residual char, and thus revealed the excellent flame retardancy. The APP/DMMP system further improved the flame retardancy of the UPR due to the change in the residual char structure rather than the increase in the production of char.

Aluminum hydroxide supported on zeolites for fluoride removal from drinking water

BACKGROUND Problems of fluorosis are still affecting millions of people around the world including Ethiopia. Hence the need to find sustainable solutions is still worth investigating. In this study, commercial zeolite Y (ZY) and natural stilbite (STI) from Ethiopia are evaluated as support for aluminum hydroxide (AO) and studied for fluoride removal from aqueous solution. The composites (STI-AO) and (ZY-AO) are synthesized at different zeolite to AO ratios by modifying the procedure used for synthesizing AO, reported earlier. RESULTS The X-ray diffraction profiles show that zeolite structures are stable during modification processes. The Si/Al ratio of composites decreases as the amount of AO is increased due to increase in Al content. The PZC of STI, initially at 2.5, increased to 9.2 in STI-AO. Textural properties of ZY and ZY-AO proved to block certain microporosity by the AO. Optimum conditions to reduce an initial fluoride concentration of 10 mg L−1 to below the WHO guideline value of 1.5 mg L−1 were 2 g L−1 for the 2:1 systems and 4 g L−1 for the 6:1 systems. CONCLUSION Zeolite-AO composites have very good equilibrium fluoride adsorption capacity compared with most reported materials. Hence these materials can be considered alternative adsorbents for the removal of fluoride from drinking water. © 2016 Society of Chemical Industry

Properties of Sintered Brick Containing Lignite Bottom Ash Substitutions

This study examined the feasibility of utilizing lignite bottom ash as a partial substitute for ball clay in an insulating brick composition. Lignite bottom ash is a waste byproduct that is high in alumina and silicates and is therefore a candidate material for replacing aluminosilicate minerals such as clay. The lignite bottom ash powder was obtained from the Mae Moh power plant, Thailand. Small brick specimens were produced by die pressing a mixture of lignite bottom ash, ball clay and aluminum hydroxide. The composition of the mixture contained a fixed amount of aluminum hydroxide, while the lignite bottom ash replaced from 30 to 70% of the ball clay. The pressed samples were sintered at 1300 oC for 1 hour in air. The density, porosity, strength and thermal properties of the samples were measured. A microstructural analysis of the sintered brick was also performed. It was found that the porosity of the samples increased from 35 to 45% with increased lignite bottom ash content. The modulus of rupture and the thermal conductivity of the bricks were reduced with increased lignite bottom ash content, likely due to the increased amount of porosity. Dilatometric analysis found that the thermal expansion increased with increased amounts of lignite bottom ash, possibly as a result of an increased amount of glassy phase. Despite the high thermal expansion coefficient at high temperature, the feasibility of using lignite bottom ash in the insulating brick composition was demonstrated.

Usability of three boron compounds for enhancement of flame retardancy in polyethylene-based cable insulation materials

It is known that for the production of halogen-free cable insulation materials based on polyethylene, very high amounts of traditional metal hydroxide flame retardants such as 65 wt% aluminum hydroxide are required to fulfill international directives. In this respect, the aim of this study was to reveal possible enhancement effects of three boron compounds on the flame retardancy of two cable insulation materials: low-density polyethylene and its blend with ethylene vinyl acetate both loaded with aluminum hydroxide. For this purpose, a certain fraction of aluminum hydroxide was replaced with various amounts of zinc borate, boron oxide, and boric acid. The materials were compounded by the melt mixing method with a twin-screw extruder, while specimens were shaped by compression and injection molding. Limiting oxygen index, UL-94 vertical burning and mass loss cone calorimeter analyses indicated that replacement of certain amount of aluminum hydroxide with boron compounds could lead to certain levels of enhancement in many flame retardancy parameters. Residue analyses revealed that these improvements were basically due to further contribution of boron compounds to the physical barrier mechanism of aluminum hydroxide in both gas and condensed phases.

Immobilisation matrices for intermediate level nuclear wastes using sulphate activated BFS/OPC and PFA/OPC composite cements

The highly alkaline pore solution of ordinary Portland cement composites currently used by the nuclear waste immobilisation industry causes corrosion of encapsulated reactive metals which generates hydrogen, causes loss of wasteform integrity and may release radioactive material to the environment. This work has investigated using near neutral salts as additives to composite cement powders in order to develop less alkaline cement pastes and reduce the corrosion of reactive metals. The effect of adding anhydrite and gypsum to ordinary Portland cement partially replaced by blast furnace slag or pulverised fuel ash was investigated. Adding the sulphate salts significantly changed the composition and microstructure of the bulk cement and the aluminium corrosion layer with ettringite the main phase detected. The amount of aluminium hydroxide formed during corrosion was significantly reduced by adding the sulphate salts as was the rate of hydrogen generation.

高純度アルミニウム箔の塩酸溶液中における交流エッチングで生ずる生成物と拡面倍率

During AC etching of aluminum foil used in electrodes for electrolytic capacitors, an anodic oxide film and a non-uniform aluminum hydroxide develop over the etched cell surface. The effects of these products on enlargement of surface area were investigated in 3.6wt% hydrochloric acid solution at 303K by applying AC with an asymmetrical triangular wave and a compound waveform of anodic current with a triangular wave and cathodic current with a square wave. The amount of aluminum hydroxide was measured using a stripping method and the thickness of the deposition layer was calculated assuming that the product is present homogeneously on the entire etched cells surface. Marked enhancement of specific surface area was obtained under condition where the deposition rate of the aluminum hydroxide at the half cycle of cathodic current was high and the pit nucleation potential at the half cycle of anodic current was maintained at about -0.2V (vs. SCE). Larger pits appear at a more noble potential and dissolution takes place on entire aluminum surface as a whole at a less noble potential. The breakdown behavior of anodic oxide film is affected by the cycle of cathodic current to controll the rate at which chloride ions are supplied to the etched cell surface.

Characterization of Abrasion Powder Worn from Alumina Balls by Wet Milling and Its Phase Transformation during Heating

Abrasion test of high and low purity alumina balls is conducted in different types of mills under wet condition. The abrasion powder produced by abrasion of high purity alumina balls gave extremely large value of specific surface area over 30m2/g. The powder includes α-Al(OH)3 of gibbsite type, while α-Al(OH)3 is not included in an abrasion powder worn from the low purity alumina one. A considerable amount of amorphous aluminum hydroxide is contained in both abrasion powders. The amount of aluminum hydroxide in the powder increased as the milling becomes moderate and as the balls' size is small. The aluminum hydroxide in the abrasion powder is transformed into a single phase of α-alumina without forming κ- and θ-alumina phases at a relatively low temperature of about 900°C. This is completely different from the phase transformation of an ordinary powder of α-Al(OH)3. The formation of α-alumina from abrasion powder at such low temperature is attributed to a seed-effect of fine α-alumina powder mixed uniformly in the abrasion powder. An abrasion powder worn in alcohol also enables us to sinter at comparatively low temperature.

Adverse Effects of Aluminum-Containing Antacids on Mineral Metabolism

The beneficial effects of aluminum-containing ant­ acids for the treatment of peptic ulcer are well rec­ ognized. However, these antacids can cause adverse reactions. It is the aluminum which interacts in the intestine with anions, such as phosphate and fluo­ ride, and affects the absorption of these dietary and possibly also endogenously secreted elements. Aluminum forms insoluble complexes with the diet­ ary phosphate which becomes unavailable for ab­ sorption. In addition to the interaction of aluminum with the dietary phosphate and fluoride, the absorp­ tion of aluminum from these antacids and the depo­ sition of aluminum in various tissues has been re­ ported in recent years. The biologic consequences of the interaction of aluminum with dietary phosphorus in animals have been reported almost half a century ago,l and similar effects were reported in humans as long as four dec­ ades ago!-4 Relatively large amounts of antacids in­ creased the fecal phosphorus excretion, decreased urinary phosphorus, and increased urinary calcium excretion. This inhibition of the intestinal absorp­ tion of phosphorus suggested the therapeutic use of aluminum hydroxide for preventing the recurrence of phosphate-containing kidney stones. 5 Although inhibition of phosphorus absorption and the associ­ ated hypercalciuria have been clearly demonstrated, these early observations were not related to the pos­ sible adverse effects of aluminum-containing ant­ acids on bone and to the potential development of skeletal demineralization. It was not until 1960 that severe bone pain, osteomalacia, and pseudofractures were attributed to chronic ingestion of large amounts of aluminum hydroxide for several years.6 Shortly thereafter, the intake of large amounts of aluminum-containing antacids was reported to be associated with the phosphorus depletion syndrome

The Adsorption of Serum Proteins to Aluminium Hydroxide Gel Examined by Means of Quantitative Immunoelectrophoresis

By means of crossed immunoelectrophoresis with intermediate gel containing a known amount of aluminium hydroxide the adsorption of the individual human serum proteins to the aluminium hydroxide was determined. The extent of adsorption varies considerably with the particular protein and is independent of the net charge, the molecular weight and the carbohydrate content of the proteins. The possible use of the method in connection with diagnosis and immunotherapy in human allergology is outlined.