Polyether-based Polyurethane Foam Research Articles

Sorption of food dyes on polyurethane foam and aluminum oxide

The sorption of food dyes Sunset Yellow (E-110), Tartrazine (E 102), Ponceau 4R (E-124), Fast Green FCF (E-143) on polyether-based polyurethane foam, and α-Al2O3 from water solutions has been studied. It has been found that the maximum sorption is observed in the range of 0.2 M HCl-pH 2 on polyurethane foam and at pH 2–4 on aluminum oxide. Under the optimal conditions the recoveries on polyurethane foam and α-Al2O3 are 20–30% and 70–80%, respectively. It has been shown by diffuse reflectance spectroscopy that, for all dyes except for Fast Green FCF, only one form of the dye that dominates under these conditions in the aqueous solution is extracted on the sorbents in the range of 0.5 M HCl, pH 8.0. Possible models of the interaction between the dyes and the sorbent surface are proposed.

Optimizing the Properties of Polyether Based Polyurethane Foam

Effect of different chemicals and additives used in producing polyester foam was investigated. Reference samples were produced from polyol, toluene di isocyanate (TDI), amine stannous octoate distil water, and silicone oil using laboratory mix formulation based on 500 g polyether based polyol. Other samples were produced by consecutively varying the content of all the additives with the exception of polyol. Standard sample dimensions for density test, indentation test, compression set test, tensile strength and elongation tests were produced from the samples. The various tests were carried out on the samples using the ASTM-D3574 standards. It was observed that the degree of indentation affects the value of indentation hardness and increasing the percentage content of TDI results in acceptable compression set value for the polyester samples. It was concluded that Holding all other parameters constant, reducing the water content and increasing the TDI content will yield polyester foam of optimum properties.

The sorption behaviour and separation of some metal thiocyanate complexes on polyether-based polyurethane foam

The preliminary screening tests on the preconcentration of lanthanum(III), aluminium(III), molybdenum(VI), gallium(III) and tungsten(VI) thiocyanate complexes in aqueous media by unloaded foam indicated a reasonable percentage of metal ions were retained on the foam. The influence of various parameters affecting the retention of these complex species from the aqueous media by the foam were critically studied and the possible mechanisms of the sorption of the compounds were suggested. However, owing to the complex chemical nature of the polyether—polyurethane foam, several mechanisms may be involved simultaneously. Attempts for the quantitative retention and recovery of the tested complexes by the foam columns were also made and satisfactory results were obtained. The height equivalent to theoretical plates (HETP) of the foam columns were calculated from the chromatograms and break through capacity curve and were found in the range 1.8–2.3 mm at flow rates up to 15 cm 3/min. The proposed foam column method has been successfully used for the separation of a series of complex mixtures of the tested metal thiocyanate complexes in aqueous media. The membrane properties of the foam sorbents offer unique advantages over conventional bulk type granular sorbents in rapid, versatile effective separations and preconcentrations of different complexes from fluid samples.

Separation of antimony(III) with iodide and dithizone by sorption on polyurethane foam from sulphuric acid medium for its spectrophotometric determination in glasses

A method for quantitative separation of antimony(III) by sorption on polyether based polyurethane foam and its spectrophotometric determination has been described. The method involves formation of a pink—red complex of antimony(III) with iodide (0.045 M) and dithizone (2.3 × 10 −5 M) in 0.25–0.75 M H 2SO 4 medium, sorption of the complex on polyurethane foam (within 45 min) at room temperature followed by its elution with acidified acetone (acetone containing 0.008% H 2SO 4) and spectrophotometric measurement at 507.2 nm (ϵ = 2.56 × 10 4 l mol cm). The method obeys Beer's law from 0.1 to 6.0 μg antimony(III). Tolerance limits of other ions are Co (100 μg), Ni (100 μg), Fe (10 μg), Cu (0.5 μg), Sn (20 μg), Zn (100 μg), As (100 μg), Mn (200 μg), Pb (50 μg), Ti (100 μg), V (50 μg), etc. Interference by iron and copper have been eliminated by treating with KOH prior to the extraction of antimony. The method has been standardized with glass samples spiked with known amounts of antimony and applied to the determination of antimony in various glasses.

Extraction Kinetics of Uranium(VI) with Polyurethane Foam.

The extraction kinetics of uranium(VI) from aqueous nitrate solution with polyether-based polyurethane foam was investigated in a batch reactor with automatic squeezing. The extraction curves of uranium(VI) concentration in solution vs. extraction time exhibited a rather rapid exponential decay within the first few minutes, followed by a slower exponential decay during the remaining period. This phenomenon can be attributed to the presence of two-phase structure, hard segment domains and soft segment matrix in the polyurethane foam. A two-stage rate model expressed by a superposition of two exponential curves was proposed, according to which the experimental data were fitted by an optimization method. The extraction rate of uranium(VI) was also found to increase with increasing temperature, nitrate concentration, and hydration of the cation of nitrate salt.

Extraction Behavior of Uranium(VI) with Polyurethane Foam

Abstract The extraction of uranium(VI) from aqueous solution with polyether-based polyurethane (PU) foam was studied. The effects of the kinds and concentrations of nitrate salts, uranium(VI) concentration, temperature, nitric acid concentration, pH, the content of poly(ethylene oxide) in the polyurethane foam, and the ratio of PU foam weight and solution volume on the extraction of uranium(VI) were investigated. The interferences of fluoride and carbonate ions on the extraction of uranium(VI) were also examined, and methods to overcome both interferences were suggested. It was found that no uranium was extracted in the absence of a nitrate salting-out agent, and the extraction behaviors of uranium(VI) with polyurethane foam could be explained in terms of an etherlike solvent extraction mechanism. In addition, the percentage extraction of a multiple stage was also estimated theoretically.

Spectrophotometric determination of vanadium in glass and ceramics after extraction of the vanadium—salicylhydroxamic acid complex on polyurethane foam

A simple spectrophotomeric method was developed for the determination of traces of vanadium present in glass and ceramic raw materials. The method involves the formation of a vanadium-salicylhydroxamic acid complex in 1 M HF-H 2SO 4 medium, followed by extraction of polyether-based polyurethane foam and elution of the complex with acidified acetone (9.5 ml of acetone + 0.5 ml of 1 M HCl) for spectrophotomeric measurement at 520 nm. The method obeys Beer's law from 0.5 to μg V ml −1. The molar absorptivity was calculated to be 6.9 x 10 3 mol 1 −1 cm −1 at 520 nm. Interferences from other metals, viz., Fe, Co, Mo, Zr, Hf and Ti, were eliminated by using HF medium. The method was applied to several glass and ceramic samples.

Extraction of Mo, W and Tc with polyurethane foam and with cyclic polyether from SCN −/HCL medium

The extraction of molybdenum, tungsten and technetium by polyether-based polyurethane foam and by a cyclic polyether from aqueous thiocyanate solutions is described. The influence of the reductants stannous chloride and ascorbic acid has also been studied. The possibilities of the polyurethane foam for preconcentration and determination of molybdenum are discussed.

Studies on the extraction of phosphomolybdate by polyether foam

To establish the mechanism of heteropoly anion extraction, the sorption of phosphomolybdate by polyether-based polyurethane foam was investigated. The effect of several variables on the extraction was studied and the optimum conditions were ascertained. The results of this study indicate that the cation-chelation mechanism cannot account for the extraction of phosphomolybdate by polyether foam.

Extraction of monovalent and divalent cations by polyether-based polyurethane foam

The extraction of silver(I), thallium(I), barium(II), and lead(II) ions by polyester-based polyurethane foam from aqueous solution is described. The extraction equilibrium constants and the ion-pair formation constants for the picrate systems containing the four ions are reported. The sorption of these ion-pairs by polyether foam can be explained in terms of cation chelation.