Search

Esta revisão de literatura teve como objetivo abordar de forma sucinta o uso de caulim como marcador externo na estimativa de consumo de matéria seca de suplemento e excreção fecal bovinos a pasto. Muitos marcadores apresentam certas limitações de uso, e nesse contexto o caulim é um possível marcador com aplicabilidade, pois apresenta características aceitáveis. Sua quantificação é realizada indiretamente através do alumínio presente no composto, e o teor do mesmo, determinado pelo método analítico colorimétrico com aluminon. Atualmente, pesquisas em nutrição animal tem apresentado informações interessantes, porém, falhas na metodologia analítica do composto tem apresentado resultados não satisfatórios. Uma alternativa eficaz, é o método de digestão ácida com mistura nitroperclórica associado ao ácido fluorídrico. Assim, a busca por novas metodologias acessíveis, práticas, de baixo custo que promove resultados acurados, precisos e robustos para a quantificação do teor de Al no caulim, se faz necessário diante desse cenário.

Phytotoxicity of soil aluminum (Al), both directly to the plant growth as well as indirectly through the increase of soil potential acidity, is closely related to the occurrence of various soil soluble-Al species. Amongst them, Al3+ and monomeric-Al species are the primary causes of Al phytotoxicity in soils with high Al content. This study was aimed to evaluate the effects of soil amelioration with dolomite and base-activated lignite (BAL) on changes in soluble-Al species and other soil chemical properties, and vegetative growth of soybean (Glycine max Merr) on Ultisol of Jasinga (Al-dd 16,03 cmol(+)/kg). A green house experiment was conducted by applying a Completely Randomized Design with dolomite and BAL amelioration as the treatments, each with three levels of repectively 0, 1, 1,5 x exchangeable-Al and 0, 2,5, 5 tons BAL ha-1, and three replications. The ameliorants were incubated at field capacity of soil moisture content for one week before planting soybean for one month. Soil soluble-Al speciation was carried out using colorimetric aluminon method to determine concentrations of total soluble-Al, monomeric-Al, and polymeric-Al species. Monomeric-Al were further speciated into inorganic monomeric-Al and organic monomeric-Al species. The results revealed that only dolomite amelioration that significantly increased soil pH-H2O, pH-KCl, Ca- dd, Na-dd, and decreased exchangeable-Al concentration, except for those of all soluble-Al species that only showed a decreasing trend. Soil exchangeable-Al that was negatively and significantly correlated with soybean measure parameters were plant height, root length, total roots and shoots wet and dry weights, as well as Ca concentration. These results indicated that soil Al phytotoxicity evaluation could be relied on the result of routine analysis on soil exchangeable-Al concentration. Keywords: exchangeable-Al, inorganic monomeric-Al, organic monomeric-Al, polymeric-Al

A glassy carbon electrode (GCE) modified with polyaminobenzene sulfonic acid functionalized single-walled carbon nanotubes (f-SWCNT) and electropolymerized aluminon has been developed for the simultaneous determination of naringin and hesperidin. Polyaluminon has been obtained by potentiodynamic electrolysis in basic medium from 100 µmol L−1 monomer solution by 10-fold potential cycling from 0.1 to 0.8 V at potential scan rate of 100 mV s−1. The polyaluminon-based electrode provides a statistically significant increase in the naringin and hesperidin oxidation currents at the same potentials in comparison to the electrode modified with carbon nanotubes. The electrode has been characterized by scanning electron microscopy (SEM) and electrochemical methods. The polyaluminon-modified electrode has demonstrated a 1.5-fold increase in the effective surface area compared to the f-SWCNT/GCE as well as a 2.1-fold lower electron transfer resistance. The electrooxidation parameters of hesperidin and naringin, including the anodic transfer and diffusion coefficients and number of electrons, have been determined. Differential pulse voltammetry in phosphate buffer (PB) pH 5.0 has been employed for the simultaneous determination of naringin and hesperidin. The linear dynamic ranges from 0.10 to 2.5 and 2.5 to 25 µmol L−1 have been obtained for the both analytes with the detection limits of 0.020 and 0.029 µmol L−1 for naringin and hesperidin, respectively. The method has been employed for the analysis of orange and grapefruit juice.

Visible light irradiation of the readily available sandwich complex [(C5H5)Fe(C6H6)]BF4 with multidentate salicylate dyes such as Aluminon, Alumocresone, Chrome Azurol S, or Eriochrome Cyanine R produced intesively colored iron(III) complexes. Similar reaction can proceed on paper, cotton, or polyacrylamide hydrogel to give colored pH-sensitive patterns.

In this paper, a simple and effective electrochemical sensor was performed based on the magnetic beads (MBs) and aurintricarboxylic acid ammonium salt called Aluminon (ATA) for sensitive and selective detection of Cu(II) using square wave voltammetry. The ATA/MBs/GCE electrode exhibited enhanced electrochemical response because of the high affinity to Cu(II) of the deposited layer made of the electrodeposited MBs and ATA. Under optimal conditions, a good linear response in the range from $10^{\mathbf {-6}}$ to $10^{\mathbf {-4}}$ M with a detection limit of $1.7\,\,10^{\mathbf {-7}}$ M were obtained. The developed copper sensor was further validated and successfully applied to detect Cu(II) in real water samples. Besides, the copper sensor showed a good anti interference performance, high stability, and excellent regeneration ability.

An anodic aluminon oxide-based nano-honeycomb electrode was fabricated on a quartz crystal to increase the surface area binding with an analyte for using as a sensing device in a quartz crystal microbalance to monitor the protein–protein interactions (PPIs). As examples, we detected PPIs of anti-Bcl-2 and Bcl-2, and Bcl-2 and Bax in real time. A sensor with a flat Au electrode showed a tiny frequency shift upon sample injection. However, our fabricated device could detect Bcl-2 and Bax in sequence. Frequency shifts corresponding to the binding of Bcl-2 to anti Bcl-2 and that of Bax to Bcl-2 increased linearly.

The interfacial distribution of a number of organic photometric reagents in a water‒potassium bis(alkylpolyoxyethylene)phosphate (oxyphos B)‒ammonium sulphate splitting system is studied. It is found that alizarin complexone, 1-(2-pyridylazo)-2-naphthol-2 (PAN), bromothymol blue, rhodamine 6G, pyrogallol red, morin, fuchsine, malachite green, bromothymol blue, pyrocatechol violet (PCV), chromazurol S, and aluminon are extracted with partition coefficients higher than 100. A possibility of the extraction‒photometric determination of gallium with PCV and cobalt with PAN is shown. The proposed procedures do not require the use of fire-hazardous, volatile, and toxic organic solvents.

The paper presents the results of the study of the possibilities of using color metal complexes to detect the presence of chemical warfare agents (CWA) in liquid or aerosol form. Aluminon/Fe3+ and Eriochrome Cyanine R/Cu2+ coordination complexes and their ability to detect CWA in liquid phase are discussed. Detection systems have been demonstrated on instances of simple detection papers exposed to drops of real CWAs. Detection papers showed a positive response to G-series nerve agents and vesicant lewisite. Other liquid CWA do not interfere and the systems are also resistant to common organic solvents and a wide range of industrial chemicals.

Recent advances in the use of organic–inorganic hybrid perovskites have been investigated in a variety of applications, such as solar cells, photodetector, light emitting devices (LEDs), and lasers because of their outstanding semiconductor properties. Furthermore, the perovskite structure has the ability to host extrinsic elements, making it a promising candidate for battery field. Previous studies have shown that organic–inorganic hybrid perovskites can be a suitable anode material for both lithium- and sodium-ion batteries. However, the multivalent rechargeable batteries with perovskite material have not yet been realized. Herein, we studied the electrochemical performance of three-dimensional (3D) CH3NH3PbI3 and quasi-two dimensional (C4H9NH3)2(CH3NH3)3Pb4I13 thin films as electrode materials for rechargeable Al-ion batteries. In this work, these electrodes were successfully synthesis on carbon cloth through a feasible solution process. The (C4H9NH3)2(CH3NH3)3Pb4I13 electrode yield a specific capacity of 210 mAh g–1 at the current density of 50mA g−1 . It still delivered 81 mAh g–1 after 250 cycles at the current density of 200mA g−1 with a retention of as high as 95%, indicating a long cycling stability. Compared with the CH3NH3PbI3, the (C4H9NH3)2(CH3NH3)3Pb4I13 presented higher initial capacities, better reversibility, and more excellent high-rate capabilities, all demonstrating the vitally prominent role of isobutyl amine (C4H9NH3). which can be attributed to the unique hydrogen-bonding interaction of isobutyl amine could effectively hinder the shuttle effect of polyiodide. We anticipate that these results open a new direction for the use of organic–inorganic hybrid perovskites for new secondary aluminum ion batteries.

Heavy metal ion contamination is a severe threat to the environment; hence, the development of methods for its trace level detection is urgently required. To contribute to this area, we report a selective and sensitive colorimetric method for Al(III) detection using Aluminon functionalized silver nanoparticles. Upon the addition of Al(III) ions to the NPs solution, Aluminon silver nanoparticles (A–AgNPs) were quickly aggregated through metal-ligand interaction. This interaction results in color change and surface plasmon resonance (SPR) peak shifted from 410 to 438 nm. The FTIR, HRTEM, XPS, DLS, and zeta potential techniques further confirmed the aggregation of NPs. This method offers a wide linear range from 10 to 0.1 ppm with a detection limit of 0.001 ppm that can be easily visualized via naked eyes as well as by UV–vis spectrophotometer. Moreover, the method was found applicable to the rapid and selective detection of Al(III) ions in the real water samples.

The aluminon functionalized MNPs (Fe 3 O 4 @aluminon) as a novel magnetic nano-sorbent have been synthesized by a simple hydro-thermal method for the removal of Cr(VI) and Cr(III) from aqueous solution. Fe 3 O 4 @aluminon MNPs were characterized using SEM, HRTEM, FTIR, VSM and TGA techniques. The Fe 3 O 4 @aluminon nano-sorbent has good dispersibility and valuable magnetic property. The effects of pH, equilibration time, mass of nano-sorbent and initial concentration of adsorbate on the percentage recovery of Cr(VI) and Cr(III) by Fe 3 O 4 @aluminon were investigated. The adsorption equilibrium was attained in 20 min at 25 °C and the adsorption kinetics obeyed the pseudo-second order model. The experimental data for the adsorption of Cr(VI) and Cr(III) better fitted the Langmuir isotherm and the maximum adsorption capacities were 263.2 mg/g for Cr(VI) at pH 1.0 and 400.0 mg/g for Cr(III) at pH 7.0. The adsorption–desorption cycles revealed that Fe 3 O 4 @aluminon nanoparticles had high stability and appropriate reusability. The removal efficiencies of chromium ions from different water samples were successfully accomplished (∼ 95.0–96.7 ± 1.4–2.1%).

The simple colour reaction between aluminum(III) and aluminon reagent was transferred to an automated sequential injection system. The experimental conditions were optimized in detail and found to be: sample pH, 4; zone sequence, aluminon–sample–HCl–aluminon; sample volume, 50 μL; volume of 1 M HCl, 5 μL; volume of reagent, 25 μL. The interference caused by iron was eliminated by the addition of thioglycolic acid. The calibration plot was linear over the range of 100–800 μg L−1 Al(III) with limits of detection and quantitation of 13.0 and 43.3 μg L−1, respectively. The sample throughput was 36 samples per hour. The RSD values for repeatability tested on 200 and 600 μg L−1 Al(III) levels were found in the range of 1.97–2.36% and 1.69–2.57%, respectively. Nine real samples of well and pond water were examined and the results corresponded well with the commercially available colour test based on the chromazurol reaction. The recovery based on the standard addition method ranged from 100.00 to 103.41%. The developed method is intended to be applied for the quick screening of Al(III) content using a fully automated technique based on the sequential injection system.

Although aluminium (Al) is toxic for the vast majority of angiosperm plants, high concentrations of Al (i.e., < 1,000 mg·kg-1 dry mass) are found in some plants. Here, we investigate the Al accumulation behaviour in the temperate, deciduous species Symplocos paniculata, which belongs to a mainly tropical genus known to accumulate high levels of Al in its aboveground tissues. Based on a growing experiment in hydroponics with and without Al, we show that S. paniculata has the capacity to accumulate Al and that the absence of Al in the nutrient solution has a negative impact on the performance of saplings., Aluminium (Al) is a phytotoxic element affecting the growth and yield of many crop plants, especially in the tropics. Yet, some plants are able to accumulate high levels of Al. The monogeneric family Symplocaceae represents an Al accumulating family including many tropical and evergreen species with high Al levels in their above ground plant tissues. It is unclear, however, whether Al accumulation also characterises temperate species of Symplocos, and whether or not the uptake has a beneficial growth effect. Here, we investigate if the temperate, deciduous species Symplocos paniculata is able to accumulate Al by growing seedlings and saplings in a hydroponic setup at pH 4 with and without Al. Pyrocatechol-violet (PCV) and aluminon staining was performed to visualize Al accumulation in various plant tissues. Both seedlings and saplings accumulate Al in their tissues if available. Mean Al levels in leaves were 4107 (±1474 mg kg−1) and 4290 (±4025 mg kg−1) for the seedlings and saplings, respectively. The saplings treated without Al showed a high mortality rate unlike the Al accumulating ones. The seedlings, however, showed no difference in growth and vitality between the two treatments. The saplings treated with Al showed new twig, leaf and root development, resulting in a considerable biomass increase. PCV and aluminon staining indicated the presence of Al in leaf, wood and bark tissue of the plants. S. paniculata shares the capacity to accumulate Al with its tropical sister species and is suggested to be a facultative accumulator. Whether or not Al has a beneficial effect remains unclear, due to developmental differences between seedlings and saplings. Al is suggested to be transported via the xylem transport system into the leaves, which show the highest Al levels. Radial transport via ray parenchyma to bark tissue is also likely given the high Al concentrations in the bark tissue.

International audience; n this study we report the development of copper ion sensor based on the electrochemical modification of a glassy carbon electrode by aurintricarboxylic acid ammonium salt (Aluminon). The deposited Aluminon layer was characterized by cyclic voltammetry and electrochemical impedance spectroscopy methods. The sensitivity of the developed ion sensor towards some metallic ions was evaluated by square-wave voltammetry. Among some tested metal ions the modified GC electrode shows a high and stable response towards the copper ions with a sensitivity of 23.8 μA·M–1 and detection limit around 3.16 10–7 M. In addition, UV-Visible spectrophotometry technique was carried out to confirm the best affinity between ATA and Cu2+ ions. An association constant of the host-guest complex of 20.104 L·mol–1 was obtained. As a result, a good selective copper ions sensor was obtained with low detection limit.

The rheological responses of aqueous alumina suspensions, stabilized with an organic polyvalent salt dispersant called “Aluminon,” and including a poly(vinyl) alcohol (PVA) binder, are described in this study. It is observed that the addition of PVA, without any dispersant does not significantly influence the rheology. However, in the presence of the dispersant the rheology is affected significantly. At a given concentration of the dispersant, the viscosity, the storage and loss modulii all increase with the PVA concentration. Also, for a given concentration of the PVA, the viscosity, the storage and loss modulii values increases as the concentration of the dispersant is increased. At relatively low PVA concentrations, an excess concentration of the dispersant, causes flocculation of the particles in the suspension by a reduction of the electrostatic (double layer) effect. On the contrary, at higher concentrations of the PVA the flocculation of the suspension occurs via a depletion mechanism.

A novel optical disposable probe for screening fluoroquinolones in fish farming waters is presented, having Norfloxacin (NFX) as target compound. The colorimetric reaction takes place in the solid/liquid interface consisting of a plasticized PVC layer carrying the colorimetric reagent and the sample solution. NFX solutions dropped on top of this solid-sensory surface provided a colour change from light yellow to dark orange. Several metals were tested as colorimetric reagents and Fe(III) was selected. The main parameters affecting the obtained colour were assessed and optimised in both liquid and solid phases. The corresponding studies were conducted by visible spectrophotometry and digital image acquisition. The three coordinates of the HSL model system of the collected image (Hue, Saturation and Lightness) were obtained by simple image management (enabled in any computer). The analytical response of the optimised solid-state optical probe against concentration was tested for several mathematical transformations of the colour coordinates. Linear behaviour was observed for logarithm NFX concentration against Hue+Lightness. Under this condition, the sensor exhibited a limit of detection below 50 μM (corresponding to about 16 mg/mL). Visual inspection also enabled semi-quantitative information. The selectivity was ensured against drugs from other chemical groups than fluoroquinolones. Finally, similar procedure was used to prepare an array of sensors for NFX, consisting on different metal species. Cu(II), Mn(II) and aluminon were selected for this purpose. The sensor array was used to detect NFX in aquaculture water, without any prior sample manipulation.

Electrophoretic deposition (EPD) method has been developed for the deposition of carbon nanotube, graphene, TiO 2 and composite films. The method is based on the use of aluminon as an organic charging agent. It was found that aluminon can be used as a common dispersing and charging agent for different materials. Aluminon offers advantages of pH dependent charge, pH dependent solubility and exhibits good film forming properties. The film deposition from aluminon solutions was studied potentiodynamically and at constant voltage deposition conditions. The deposition yield was studied by quartz crystal microbalance (QCM). The films were analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetry, differential thermal analysis (DTA), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The method allows co-deposition of different materials and control of deposit composition. The deposition mechanism is discussed.

Aluminum is the third most abundant metal in the Earth’s crust. Despite its ubiquitous nature it is present in small amount in living organisms. Aluminum toxicity has been implicated in the pathogenesis of renal distinct clinical syndromes, including progressive and fatal encephalopathy and bone diseases. In the present study, Al was selected for the analysis by complexometric method. This method was based on the formation of a red colored ternary complex by the reaction of Aluminum with Aluminon (Aurin tricarboxylic acid triammonium salt) in the presence of micellar medium. The ternary complex of Aluminum with the surfactant Triton X-100 shows a maximum absorbance at 530 nm wavelength at pH 4.0 while with the sodium dodecyl sulfate it shows a maximum absorbance at 525 nm and at pH 5.0. The reaction was proceeded by the variation in pH and concentrations of surfactants, aluminon, aluminum. Their effects on the reaction of aluminum with aluminon complex in micellar media were recorded by UV-visible spectrophotometer. The reaction was found to be extremely rapid at room temperature. The system obeys Lambert Beer’s law between 0.24 and 21.74 μg/mL concentrations with Triton X-100. The values of slope, intercept and correlation coefficients were 0.07, 0.348 and 0.989, respectively. The concentration varied between 0.24 and 24.14 μg/mL with sodium dodecyl sulfate and the values of slope, intercept and correlation coefficients were 0.029, 0.148 and 0.962, respectively. The foreign ion effect was also tested by keeping the constant concentration of metal ion and determining its concentration in the presence of different foreign ions. The method was also applied for the determination of Al(III) in pharmaceutical formulations and water samples, which showed an excellent resemblance between reported and obtained results.

A sensitive preconcentration procedure for spectrophotometeric determination of aluminum was developed. Aluminum as aluminon complex is adsorbed on microcrystalline naphthalene. The naphthalene containing the complex is dissolved in 3 mL of acetone and its absorbance is measured at 544 nm. The effect of various factors on the preconcentration of aluminum was investigated. The calibration graph was linear in the range of 1-60 mg L-1. The limit of detection was 0.52 mg L-1 and relative standard deviation for the determination of 5 mg L-1 was 2.65%. The proposed solid phase extraction procedure was applied to determination of aluminum in food samples.

A technique of microwave-assisted preparation of natural and commercial silicate materials for subsequent spectrophotometric determination of the major rock-forming components (silicon, aluminum, iron, titanium, and phosphorus) is described. The total duration of analysis is several times less than for a standard technique. In particular, the time taken for the digestion is shortened to 1 h for ten samples undergoing digestion simultaneously; the time of complexation of aluminum with aluminon and of phosphorus with molybdenum heteropoly acid is reduced from a few hours to 12 min.

Aluminon has been investigated for the separation of iron(III) by flotation technique. This reagent formed a 1:1 stable complex in aqueous solution. An intense violet layer is formed after flotation using oleic acid (HOL). A highly selective and sensitive spectrophotometric procedure is proposed for the determination of Fe(III) after overcoming all interferences. Preliminary studies show the possibility of forming a complex with Fe(II) to an extremely low extent. Trials have been carried out to separate Fe(II) and Fe(III) using NH 4 SCN or NaF. To prevent the oxidation of Fe(II), NaBH 4 is used. The separation of Fe(III) and Fe(II) can be achieved using 0.6 mg L -1 NaBH 4 . The flotation- determination method was carried out at pH 2-3. The formation constant is 1.3×10 7 L mol -1 with molar absorptivity of 0.2×10 5 L mol -1 cm -1 and detection limit of 5×10 -6 mol L -1 . The effect of foreign ions is avoided using excess aluminon and 0.5 mg L -1 NaBH 4 . The proposed procedure was applied to synthetic mixtures [Fe(III) + Fe(II)], Fe(III) and some cations, wastes of power stations, simulated samples and real ores.

In the present article, a procedure for the simultaneous separation and preconcentration of trace amounts of cadmium and zinc is proposed. It is based on the adsorption of cadmium and zinc ions onto a column of Amberlite XAD-4 resin loaded with aluminon reagent. Cadmium and zinc ions are quantitatively retained on the column in the pH range from 6.5―7.5, at a flow rate of 2 mL min ―1 . The cadmium and zinc ions are eluted with 5.0 mL of 5 mol L ―1 HN0 3 solution. Cadmium and zinc are measured by flame atomic absorption spectrometry (FAAS). In the present case, 0.1 μg of cadmium and 0.5 μg of zinc can be concentrated in the column from 1000 mL of aqueous sample, where their concentrations are as low as 0.1 and 0.5 ng mL ―1 , respectively. The relative standard deviations, for seven replicated determinations of 1.0 μg mL ―1 of cadmium and zinc, are 1.2 and 1.1%, respectively. The detection limits for cadmium and zinc in the original solution are 0.02 and 0.11 ng mL ―1 , respectively. The interference of a large number of anions and cations has been studied and the optimized conditions are utilized for the determination of trace amounts of cadmium and zinc in different environmental and standard samples.

A simple and sensitive method is presented for solid phase extraction (SPE) and preconcentration of trace quantities of beryllium using octadecyl silica gel modifed with aurin tricarboxylic acid (aluminon). Beryllium is then determined by flame atomic absorption spectroscopy. Parameters affecting SPE such as pH, sample solution and eluent flow rate, type, concentration and volume of eluent, interfering ions and breakthrough volume, were investigat- ed. Under optimal conditions, the beryllium ions were retained on the sorbent at pH 6-6.7, while 3.0 mL of 0.05 mol L �1 HNO3 is sufficient to elute the ions. The limit of detection (LOD) based on 3σ was 0.8 µg L �1 for 250 mL sample solution and 5 mL 0.05 mol L �1 HNO3 as eluent. The LOD can reach 0.1 µg L �1 for 1 L sample solution and 3 mL of 0.05 mol L �1 HNO3. The accuracy and precision (RSD %) of the method is >90% and

Exchangeable aluminium (AlKCl) and CaCl2-extractable aluminium (AlCaCl2) have approximately the same value in the prognosis of detrimental effect on plants. Additional, more in-depth research should show which of the two applied methods of exchangeable Al determination is more suitable (after Sokolov or using aluminon). The contents of total Al and amorphous Al increase with depth and percentage clay. Crystalline Al oxides and CuCl2-extractable aluminium (AlCaCl2) and EDTA-extractable aluminium (AlEDTA) represent the more mobile reserves of Al and they depend mostly on changes in the acidity parameters of the soil. Exchangeable Al is on average 4.3-4.7 times lower than the contents of AlCaCl2 and AlEDTA, 8 times lower than crystalline Al and 35 times lower than amorphous Al. Some methods are not sufficiently selective, hence further research is required to achieve more favorable methods for the determination of the different forms of Al.

In the present work the influence of the addition of some dispersing agents employed for maximizing the solid loading of alumina concentrated suspensions has been investigated. Three commercial deflocculants were used: a sodium salt of a benzenedisulfonic acid (Tiron), a sodium polyphosphate, and an aurintricarboxylic acid, triammonium salt (Aluminon). Rheological tests were carried out at 25°C under continuous flow conditions by using the rate-controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device SV2P with serrated surfaces. The application of rheological techniques permitted evaluating the efficiency and optimum dosage of the dispersing agents employed on the alumina slips examined, i.e., the critical concentration at which the maximum reduction in viscosity is detected.

Strong and permeable macro-porous α-Al2O3 membrane supports are made by colloidal filtration of 20 vol% dispersions of α-Al2O3 with an average particle size of 600 nm. Intact compacts with very good surface quality were obtained at an optimum pH of 9.5 and dosage of 0.2 wt% ammonium aurintricarboxylate (Aluminon), based on dry alumina. The colloidal stability of the aluminon-stabilized slurries is confirmed by ξ potential measurements. Slight sintering of dense-packed α-Al2O3 compacts was found to result in >67% packing density and a bimodal pore-size distribution as derived from shrinkage behavior and gas adsorption studies. Non-stationary single gas permeation measurements showed improved gas permeability, compared with α-Al2O3 compacts prepared using powder with a smaller particle size (300 nm). The strength of the disk-shaped alumina compacts within the porosity range of 30%–20% increased from 100 to 300 MPa with a standard deviation of 20 and 50 MPa, respectively.

Supported zirconia–zircon composite microfiltration layers produced by the dip-coating procedure are introduced for the first time. These can be produced using commercial grade monoclinic-zirconia powders having high silica content. Such membranes have the advantage of enhanced sintering due to a liquid-phase mechanism. These were prepared through dip-coating α-alumina supports with slips of zirconia powder stabilized with ‘aluminon’ and further sintering (1050–1200 °C). Optimum dispersant concentration and pH had been found based on sedimentation tests and UV–vis spectroscopy method. The effect of slip concentration, sintering temperature and number of coatings on the membrane characteristics has been studied. There exists a maximum sintering temperature of 1150 °C for the creation of minimum pore diameters lower than 0.2 μm with a reasonable surface microhardness of Hardness Vickers at 50 g force pyramidal load (ca. 110 HV50) and no observable crack. This work includes a comparative study with membrane layers produced with an analogous preparatory method using high purity monoclinic zirconia with a similar particle size distribution.

In the present work, the influence of the addition of some dispersing agents employed for maximizing the solid loading of calcium carbonate concentrated suspensions was investigated. Three commercial deflocculants were used:a sodium salt of a benzenedisulfonic acid (Tiron), a sodium polyphosphate, and an aurintricarboxylic acid, triammonium salt (Aluminon). Calcium carbonate aqueous suspensions were prepared at various solid volume fractions (0.270 to 0.382). Rheological tests were carried out at 25°C by using the rate-controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-oscillatory, measuring device SV2P with serrated surfaces. The tests were performed under both continuous and oscillatory flow conditions. The application of rheological techniques permitted highly accurate evaluation of the optimum dosage of the deflocculants, i.e., the critical concentration at which the maximum reduction in viscosity is detected. Generally, Aluminon and sodium polyphosphate behaved as the best ...

One of the main factors limiting agricultural production in tropical climate regions is mainly related to the presence of exchangeable aluminum (Al3+) in highly weathered acid soils. Four methods of Al3+ determination extracted with neutral 1 mol L¹ KCl solution were evaluated: three colorimetric methods (aluminon plus ascorbic acid, and eriochrome cyanine R by FIA) and the usual titrimetric method with back-titration. Surface samples from 20 soils of different Brazilian regions, with active acidity (0.01 mol L¹ CaCl2 pH) ranging from very high to medium (3.82 to 5.52), were used. The variance analysis revealed significant interaction among Al3+ determination methods and soil. Mean methods comparisons within each soil (Tukey, P < 0.05) indicated that, for most of the soils, the methods differed among each other, although there were high correlations between the obtained values. Al3+ values determined for soil samples by titration varied between 0.15 and 14.71 mmol c dm³. The colorimetric methods showed higher values than the titration method, mainly for those with aluminon (up to 18.75 mmol c dm-3). The Al3+ contents of colorimetric methods correlated quadraticaly with the titration values, for the soil samples with Al3+ > 10 mmol c dm³. Among colorimetric methods, in operational terms, the eriochrome with FIA method presented analytical performance up to 50 samples per hour, easiness and sensibility for routine Al analysis in soil samples. However, due to the specificity, the titration/back-titration method should be used, despite the moroseness, when the Al3+ ions are the objective. Um dos principais fatores que afetam a produção agrícola em regiões de clima tropical, é a presença de alumínio trocável (Al3+) em solos ácidos altamente intemperizados. Foram avaliados quatro métodos de determinação de alumínio trocável em solução neutra de KCl 1 mol L¹: três métodos colorimétricos (aluminon, aluminon + ácido ascórbico e eriocromo cianina R por FIA) e o método titulométrico usual com retrotitulação ácida. Para obtenção dos extratos de KCl, foram usadas amostras superficiais de 20 solos de diferentes regiões brasileiras, com acidez ativa (pH em CaCl2 0,01 mol L¹) variando de muito alta a média (3,82 a 5,52). A análise de variância revelou interação significativa entre os métodos de determinação e amostras de solos. O teste de médias (Tukey, P < 0,05) de métodos dentro de amostras evidenciou, para a maioria das amostras de solos, que os métodos analíticos diferenciaram entre si, embora tenha havido forte correlação entre os valores obtidos. Os valores de Al3+ determinados por titulação variaram de 0,15 a 14,71 mmol c dm³. Os métodos colorimétricos apresentaram valores superiores aos da titulação, notadamente aqueles com aluminon (até 18,75 mmol c dm³). Os teores de Al3+ dos métodos colorimétricos se relacionaram quadraticamente com os teores obtidos por titulação, em amostras de solos com Al3+ > 10 mmol c dm³. Dentre os métodos colorimétricos, o reagente eriocromo cianina R, em sistema FIA, mostrou-se operacionalmente confiável e eficiente para a análise de Al, de amostras de solos, em rotina, com freqüência analítica de 50 determinações por hora. Todavia, devido à especificidade, o método titulométrico com retrotitulação deve ser usado, não obstante a morosidade, quando o objetivo é a determinação do íon Al3+.

Spodic horizon in Spodosols often restricts growth of plant roots. Generally the Spodic horizon is acidic with high levels of aluminum (Al). In this study soil solution Al was characterized in the Spodic horizon and the respective surface horizon of three Spodosols in the major citrus production region in Florida. The soil pH ranged from 4.92 to 5.14, and 4.82 to 5.50 in the Spodic and top soil samples, respectively. The modified aluminon analytical technique was used to measure the concentrations of Al in the soil solution as monomeric Al which includes both organic and inorganic monomeric Al complexes, and as reactive Al (which excludes most of the organically complexed Al). The organically complexed Al was estimated by the difference between the above two concentrations. The concentrations of total Al in soil solutions were measured by the aluminon technique. The polymeric Al was estimated by the difference between the total and monomeric Al concentrations. Further, the activities of different...

The application of polyethylene (PE) powder to the adsorption of complexing dyes has been studied. Rhodamine B, aluminon, o-phenanthroline and dithizone were used as model substances of cationic, anionic, slightly polar, and apolar species, respectively. The influence of PE type, solvent, pH, and ionic strength on the adsorption was investigated. The results showed that high-density PE adsorbs polar dyes, preferentially cationic dyes, from aqueous solutions, whereas low-density PE adsorbs apolar dyes from an apolar milieu. The adsorption of polar species occurs probably at negatively charged sites on the PE surface, whereas the apolar ones occurs at the apolar parts of the surface. Presence of salts and pH influence the adsorption, mainly of anionic dyes; for these, the lower the pH the higher the adsorption, showing that the undissociated anionic dye is adsorbed. The adsorption in ethanolic solutions was very weak, probably because ethanol, differently from water, wets PE and therefore competes with the ...

In this study the interactions between an atomic force microscope (AFM) tip and a sapphire surface are investigated in the presence and absence of a dispersant, Aluminon, and a binder, poly(vinyl alcohol) (PVA). The results showed that attractive interactions are noted in the absence of the dispersant, but that these interactions become repulsive in its presence. Upon addition of binder to the system a weaker attractive interaction, which is preceded by a smaller repulsive interaction, is noted. The results of the AFM work are also compared to rheological studies that have been carried out on alumina dispersions stabilised by the aforementioned materials.

It was demonstrated that light-emitting materials can be produced by the photochemical dissolution of aluminum in composites based on a cresol–formaldehyde novolak resin and CBr4in the presence of triphenylmethane dyes such as aluminon, pyrocatechol violet, and malachite green. The electroluminescence (EL) is due to the formation of organoaluminum complexes. The SnO2(anode)/novolak resin + pyrocatechol violet/Al (cathode) diodes exhibited the highest EL intensity. Compositions based on aluminon are characterized by weak EL, which increased by a factor of 30 upon the additional introduction of silica gel into the composition. As a result of supporting a PVA film on the diode surface (on the cathode side), the EL increased by a factor of 1.5 and became as high as ∼10 cd/m2. This value is comparable to the EL of pyrocatechol violet–containing diodes. The possible mechanism of the influence of silica gel and the importance of a PVA film for increasing the EL intensity are discussed. In the aluminon-based compositions, the dependence of EL on the diode storage time both with and without an applied voltage was measured.

Uranium(VI) complexed with aluminon (3-[bis(3-carboxy-4-hydroxy-phenyl)methylene]-6-oxo-1,4-cyclohexadiene-1-carboxylic acid triammonium salt) was determined by adsorptive cathodic stripping voltammetry (ACSV) using a hanging mercury drop electrode. Trace uranium(VI) and zinc(II) can be simultaneously determined in a single scan in the presence of aluminon and urea. Optimal conditions were found to be: accumulation time; 180–200 s, accumulation potential; 50 mV versus Ag/AgCl, scan rate; 40 mV s−1, supporting electrolyte; 0.1 M sodium acetate buffer at pH 6.5–7.0, and concentration of aluminon; 1×10−6 M. The linear range of uranium(VI) and zinc(II) were observed over the concentration range 2–33 and 30–120 ng ml−1, respectively. The detection limit (S/N=3) are 0.2 ng ml−1 (uranium) and 30 ng ml−1 (zinc). A good reproducibility shows RSDs of 2.5–4.0% (n=10). The procedure offers high selectivity, with the presence of urea masking some metal ions.