Analytical applications of condensed phosphoric acid-I Determination of ferrous and total iron in iron ores after decomposition with condensed phosphoric acid

A simple method is described for the determination of ferrous and total iron in iron ores. Iron ores are dissolved by condensed phosphoric acid (CPA) very rapidly without any tedious and time-consuming manipulations such as elimination of silica and filtration. Under the proposed conditions (amount of sample 100 mg, amount of CPA added 10 g, heating temperature 290 degrees , heating time 30 min), magnetite, limonite and hematite are completely dissolved. The iron content can be determined in the presence of condensed phosphoric acid by titration with dichromate solution, if a slight modification is made. The total iron in iron ores, determined by the present method, is in agreement with that found by the JIS method. The ferrous iron in iron ores can be determined by dissolving the samples with CPA in a nitrogen atmosphere and titrating with dichromate solution. Chelatometric titration of iron after solvent extraction with MIBK from solutions prepared by use of CPA is found to be accurate for samples such as pyrite cinder. The ability of CPA to dissolve various materials has been investigated.     

Analytical applications of condensed phosphoric acid-III Iodometric determination of sulphur after reduction of sulphate with sodium hypophosphite and either tin metal or potassium iodide in condensed phosphoric acid

Novel methods for the reduction of sulphate to hydrogen sulphide with hypophosphite-tin metal or hypophosphite-iodide in condensed phosphoric acid (CPA) are proposed. The reduction of sulphate with hypophosphite alone does not proceed quantitatively. Sulphate, however, is quantitatively decomposed with hypophosphite when tin metal or potassium iodide is used together with it. The determination of sulphur by the hypophosphite-tin metal-CPA and tin(II)-CPA methods is interfered with by copper on account of the stabilization of copper(I) sulphide, but this interference can be eliminated by adding iodide, e.g. potassium and lead salts. Alum and barytes are quantitatively decomposed within 15 min at 140 and 280 degrees , respectively. The hydrogen sulphide evolved is absorbed in zinc acetate solution at pH 4.5 and then determined by iodometry.     

Spectrophotometric and inductively coupled plasma atomic emission spectrometric determination of titanium in ilmenites after rapid dissolution with phosphoric acid

The use of 85% phosphoric acid in borosilicate conical flasks for the dissolution of ilmenites at 230 +/- 10 degrees C is reported. The samples were quantitatively dissolved in less than 13 min. Titanium was determined by both spectrophotometry and inductively coupled plasma atomic emission spectrometry ICP-AES. Vanadium and iron were determined by ICP-AES. In several samples of ilmenites analyzed, the TiO(2) concentration was in the range 10.6-57.5% and those of FeO and V(2)O(5) were in the ranges 31.6-51.4% and 0.39-1.32%, respectively. In the spectrophotometric method, vanadium interference occurs only when the Ti V concentration ratio is <4. In all samples analyzed this ratio was around 12, resulting in no interferences due to vanadium. Hence the ilmenite dissolution procedure using phosphoric acid was compatible with titanium quantification by both spectrophotometry and ICP-AES.     

Gravimetric determination of beryllium with n-benzoylphenylhydroxylamine

N-Benzoylphenylhydroxylamine has been employed in the gravimetric determination of beryllium and in its separation from iron, aluminium and titanium. After suitable adjustment of pH iron, aluminium or titanium is precipitated quantitatively with the reagent; beryllium is subsequently precipitated after raising the pH of the filtrate. The metal may be determined by either igniting the precipitate to beryllium oxide or weighing it as Be(C₁₃H₁₀O₂N)₂.     

Analytical applications of condensed phosphoric acid-IV Iodometric determination of sulphur in sulphate and sulphide ores and minerals and other compounds after reduction with sodium hypophosphite and tin metal in condensed phosphoric acid

Sulphate in sulphate ores, e.g., alunite, anglesite, barytes, chalcanthite, gypsum, manganese sulphate ore, is reduced to hydrogen sulphide by the hypophosphite-tin metal-CPA method, if a slight modification is made. Sulphide ores, e.g., galena, sphalerite, are quantitatively decomposed with CPA alone to give hydrogen sulphide. Suitable reducing agents must be used for the quantitative recovery of hydrogen sulphide from pyrite, nickel sulphide, cobalt sulphide and cadmium sulphide, or elemental sulphur is liberated. Iodide must be used in the decomposition of chalcopyrite; the copper sulphide is too stable to be decomposed by CPA alone. Molybdenite is not decomposed in CPA even if reducing agents are added. The pretreatment methods for the determination of sulphur in sulphur oxyacids and elemental sulphur have also been investigated.     

The determination of alumina in silicates (Rocks and Refractories)

New procedures have been developed for determining the alumina contents of silicate material (rocks and refractories). The material is first taken into solution by a peroxide sinter technique, followed by dissolving the sinter in warm water and the addition of sufficient hydrochloric acid to render the solution acid to litmus. A different technique is used for silicates containing less than 5% alumina. The majority of the silica is first removed by treating with hydrofluoric-sulphuric acids and the residue is fused with potassium bisulphate. Extractions with cupferron are next employed to remove iron, titanium, zirconium etc., and the aluminium is subsequently separated from other sample constituents by precipitating as its insoluble benzoate. After filtration the aluminium benzoate is dissolved in hydrochloric acid and the aluminium concentration determined volumetrically with ethylenediaminetetraacetic acid.     

Extraction with long-chain amines-X Complexometric determination of titanium after extraction of its ascorbate complexes

A highly selective extraction of titanium as its ascorbate complexes from slightly acidic medium into trioctylmethylammonium sulphate is described. After stripping into nitric acid, titanium is determined complexometrically. The method allows separation of titanium from large amounts of iron, aluminium and bivalent metals. The procedure for the determination of iron and aluminium after the titanium extraction is also given. The method has been applied to the determination of titanium in special alloys and minerals.     

Thermometrische Schnellanalyse von Martin- und Hochofenschlacken sowie anderen Silicaten

Summary A novel method has been developed for the rapid analysis of silicates. Each component is determined from the temperature variation of the solution resulting from the addition to the test solution of a selectively reacting reagent. By suitable construction of the instrument the concentration of the component to be determined can be read directly in per cent. The determination of a component takes usually 4 to 8 minutes.In the test solution a temperature change proportional to the concentration of the component to be determined has been produced by the following reagents: sulphuric acid for barium, ammonium peroxodisulphate for iron, hydrogen peroxide for titanium, hydrofluoric acid for silicic acid, potassium permanganate for sulphur, ammonium molybdate and hydrogen peroxide for phosphate, potassium permanganate for manganese, potassium oxalate for calcium, diammonium hydrogenphosphate for magnesium, ascorbic acid for chromium. The above components can be determined without any separations. Only in the case of aluminium a separation of silicic acid from aluminium by dehydrating with perchloric acid in necessary. Thereafter the aluminium can be determined with hydrofluoric acid.The precision of the determinations is practically identical with the precision of the usual plant methods.     

Using NAA to the Determination of Antimony in Trichlorosilane with Substoichiometric Extraction

Neutron activation analysis has been applied to the determination of trace of antimony based on the substoichiometric extraction of Sb(III) with BPHA (N-benzoyl-N-phenyl hydroxylamine). The antimony contens in trichlorosilane or high purity silicon can be determined by the proposed method down to ppb range. The effect of acid concentration, shaking time, the amount of carrier and the decontamination factors were studied.     

The polarographic determination of traces of titanium-(IV) in the presence of n-benzoyl-n-phenylhydroxylamine

The polarographic behavior of the titanium(IV)-N-benzoyl-N-phenyl-hydroxylamine (BPHA) system in acidic medium and in water-ethanol mixtures has been studied. In (1+3) water-ethanol containing 2 M sulfuric acid and 0.05 M BPHA, titanium(IV) gives a single kinetically controlled wave. Titanium(IV) can be determined at concentrations as low as 5·10^-6M, in the presence of Fe(III), Cu(II), V(V), etc., but Cd(II), Sn(II and IV), As(V), U(VI) and Mo(VI) interfere.     

Photometric determination of aluminium with alizarin fluorine blue

In order to decide whether Alizarin Fluorine Blue (alizarin complexan, 3-amino-methylalizarin-N,N-diacetic acid) is a suitable reagent for the spectrophotometric determination of aluminium, values of the stability constants for some reactions of this reagent with aluminium(III) and iron(III) have been determined spectrophotometrically in a medium containing 20 % dioxan and 80 % water at ionic strength 0.1. The values of the constants that were determined are log K(Al)(AlHL) = 14.3, log K(2Al)(Al2L) = 25.3 and log K(Fe)(FeHL) = 19.6. These results were employed in the design of a method for the spectrophotometric determination of aluminium in the presence of iron and titanium. The Sandell sensitivity is 0.01 mug/cm(2) and the coefficient of variation for 34 determinations was 0.9 %.     

The use of trioctylphosphine oxide for solvent extraction recovery and purification of transplutonium elements

Extraction of trivalent curium, berkelium, californium, einsteinium, and europium with trioctylphosphine oxide (TOPO) from nitric acid solutions as well as extraction of curium and cerium from lactic acid solutions containing DTPA depending on aluminium nitrate concentration have been studied. The distribution of cobalt, nickel, chromium, iron, aluminium, titanium, zirconium, and niobium ions has been studied and coefficients of berkelium purification from the elements studied have been determined under the conditions of extraction-chromatographic recovery of berkelium. The influence of weighed amounts of the same impurities on the yield of berkelium in its extraction-chromatographic separation has been studied. Some examples of the practical application of the extraction-chromatographic techniques using TOPO are given.     

Separation of molybdenum from interfering elements by extraction as phosphomolybdenum blue

A simple method is described for the separation of molybdenum from titanium, zirconium, chromium, manganese, iron, cobalt, nickel, uranium and aluminium in a wide variety of samples in <30 min. Phosphomolybdenum blue is produced by boiling for 2 min a molybdate solution containing phosphate to give Mo/P = 20-37 (w/w) with hydrazine sulphate in 0.1N sulphuric acid. The volume and acidity are adjusted to give a molybdenum concentration of 0.6-5 my/ml in 0.4-0.5N sulphuric acid. The phosphomolybdenum blue is 99.5% extracted with methyl isobutyl ketone in a single extraction. The residual molybdenum and hydrazine in the aqueous phase are oxidized with a few drops of liquid bromine and the molybdenum is quantitatively extracted with the same solvent from 1N sulphuric acid as its reddish brown thiosulphato complex. The molybdenum is stripped by ammonia-hydrogen peroxide solution. The back-extract is heated to boiling and filtered to remove the insoluble hydroxides of traces of accompanying elements. The thiosulphate in the filtrate is destroyed by boiling for 4-5 min with excess of hydrogen peroxide in slightly ammoniacal medium. The molybdenum is determined finally by cerimetry or other standard methods.     

Complexometric determination of aluminium in iron ore,sinter, concentrates and agglomerates

A method for the complexometric determination of aluminium in iron ore, sinter, concentrates and agglomerates encountered in international trade is described. The sample is fused in a zirconium crucible with a mixed flux of sodium carbonate and sodium peroxide. The fused mass is completely soluble in hydrochloric acid. The R₂O₃ oxides are then precipitated with ammonia and redissolved in hydrochloric acid. Elements such as iron, titanium and zirconium are separated from aluminium by solvent extraction with cupferron and chloroform. After removal of traces of organic matter from the aqueous phase, the solution is treated with an excess of EDTA, which is then back-titrated with zinc solution (Xylenol Orange as indicator). Addition of ammonium fluoride then releases EDTA equivalent to the aluminium and this is titrated with zinc solution. The method is rapid. The precision and accuracy are excellent, and the results comparable with those obtained by the referee method.     

Extraktiv-photometrische Bestimmung von Titan in Aluminium und Aluminiumlegierungen mit 4,4′-Diantipyrylmethan

(DAPM). The use of DAPM as a spectrophotometric reagent for the determination of titanium in aluminium and aluminium alloys was investigated. To the solution, 0.5 N in hydrochloric acid, a 2% solution of DAPM in 0.5 N hydrochloric acid is added to form the yellow complex of titanium(IV) with DAPM. The addition of 20% solution of tin(II)chloride in 0.5 N hydrochloric acid yields a yellow precipitate, which is extracted by chloroform. The absorbance of the extract is measured at 390 nm. 0.01–0.1% of titanium have been determined in pure aluminium and Al-Mg-Zn alloys by the method suggested (standard deviation ±0.0004 to 0.0008%).     

Wet ashing of coal with perchloric acid mixed with periodic acid for the determination of sulphur and certain other constituents

A method is described for the determination of sulphur and some other inorganic constituents of coal. Organic matter is destroyed by wet combustion with perchloric acid and periodic acid. The method is rapid and efficient. Silica and sulphur are determined gravimetrically, iron, aluminium, vanadium, titanium, phosphorus, and arsenic spectrophotometrically, and calcium and magnesium volumetrically. No loss occurred by volatilisation. The complete analysis scheme devised was applied to a bituminous coal of Iowa origin.     

Flow-injection analysis of silicate rocks for total iron and aluminium

A flow-injection method is described for the spectrophotometric determination of total iron and aluminium in silicate rocks. Rock samples are opened up by fusion with a mixture of lithium carbonate and boric acid, the melt is taken up in 1M hydrochloric acid and the resulting solution is used for the determination of both iron and aluminium. The flow system for the determination of iron needs no particular reagents, involving simply measurement of the absorbance of the chloro-complex of iron(III) at 335 nm. The system for aluminium consists of the reduction of iron(III) to iron(II), colour development with Xylenol Orange (XO), destruction of XO-chelates other than that of aluminium by addition of EDTA and subsequent measurement of the absorbance of the aluminium-XO complex at 506 nm. The systems permit semi-automatic, rapid analysis of silicate rocks for iron and aluminium. Results obtained for standard rocks were in good agreement with the recommended values. The precision ranged from 0.1 to 0.9% for iron and from 0.3 to 0.7% for aluminium.     

Coulometric argentometric determination of microamounts of sulphur in iron and steel after reduction to hydrogen sulphide with iron(II) in strong phosphoric acid medium

A coulometric method was developed for the determination of microamounts of sulphur in iron and steel. Hydrogen sulphide is quantitatively evolved by reduction with iron(II) in strong phosphoric acid medium and is titrated with electrolytically generated silver ion from a silver anode. Microamounts of sulphide (2.96–224.3 μg) in sodium sulphide standard solutions could be determined with an error of only a few percent. Sulphur in a potassium sulphate standard solution is quantitatively reduced to hydrogen sulphide and could be separated from the solution by heating and determined accurately. Trace amounts of sulphur (7–100 μg g^?1) in iron and steels could be determined with a standard deviation of 0.7–2.1 μg g^?1.     

Determination of major and minor elements in silicates by inductively coupled plasma emission spectrometry

A simple rapid method for the determination of major and minor elements in silicates is reported. Powdered sample (50 mg) is treated with hydrochloric and hydrofluoric acids in a small sealed Teflon vessel. After addition of boric acid, silicon, aluminium, iron, titanium, manganese, calcium, magnesium, sodium, and potassium are determined by inductively coupled plasma emission spectrometry. The method is satisfactory for a variety of standard silicate materials.     

Assessing the Influence of Electrode Polarity on the Treatment of Poultry Slaughterhouse Wastewater

Electrochemical methods have been increasingly gaining popularity in the field of wastewater treatment. However, the performance of these methods can be highly affected by the polarity direction as determined by the electrodes arrangement (anode to cathode or cathode to anode); as well as the characteristics of the wastewater to be treated as determined by the type of wastewater. The presented research work investigated the relationship between polarity direction and the removal of pollutants from poultry slaughterhouse wastewater using titanium and aluminium electrode materials. In the first case, the wastewater was exposed to the Ti (anode)-Al (cathode) combination, whereas in the second case the wastewater was subjected to the Al (anode)-Ti (cathode) arrangement. The two cases were designed to see if the polarity direction of the chosen electrode materials affected the removal of pollutants. The removal efficiencies were computed as a ratio of the remaining concentration in the treated effluent to the concentration before treatment. It was observed that the production processes generate highly fluctuating wastewater in terms of pollution loading; for instance, 422 to 5340 Pt-Co (minimum to maximum) were recorded from color, 126 to 2264 mg/L were recorded from total dissolved solids, and 358 to 5998 mg/L from chemical oxygen demand. Also, the research results after 40 min of retention time showed that both electrode arrangements achieved relatively high removal efficiencies; Whereby, the aluminium to titanium polarity achieved up to 100% removal efficiency from turbidity while the titanium to aluminium polarity achieved a maximum of 99.95% removal efficiency from turbidty. Also, a similar phenomenon was observed from total dissolved solids; whereby, on average 0 mg/L was achieved when the wastewater was purified using the aluminium to titanium arrangement, while on average 2 mg/L was achieved from the titanium to aluminium arrangement. A little higher removal efficiency discrepancy was observed from ammonia; whereby, the aluminium to titanium arrangement outperformed the titanium to aluminium arrangement with average removal efficiencies of 82.27% and 64.11%, respectively.