Dilute Mineral Acid Solution Research Articles

Purification of sphene concentrate to remove phosphorus impurity with dilute mineral acids

Methods of crystal-optic, X-ray phase, chemical, and IR spectroscopic analyses were used to study the interaction of sphene and fluorapatite concentrates with dilute mineral acid solutions. The conditions under which the sphene concentrate can be purified to remove admixtures of phosphorus-containing compounds were found.

Voltammetric and XPS investigations of polynuclear ruthenium-containing cyanometallate film electrodes

Glassy carbon electrodes coated with thin films of mixed valence ruthenium-oxo-species stabilized by cyanoruthenate or cyanoferrate crosslinks were investigated by cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). Electrochemical deposition was accomplished in dilute mineral acid solutions (e.g. 10 mM H 2SO 4) containing millimolar concentrations of RuCl 3 + K 4Fe(CN) 6, or RuCl 3 + K 4Ru(CN) 6, or OsCl 3 + K 4Ru(CN) 6. Film deposition is attributed to growth of compact and conducting lattices with significant oxo- (MOM) and cyano-bridging (M′CNM), in which M represents Ru, or Os, while M′ refers to Ru or Fe. Particular attention was devoted to the polynuclear ruthenium oxide microstructure (RuORu) crosslinked with cyanoruthenate and cyanoferrate, designated as RuORuCN and RuoFeCN respectively. From an electrochemical point of view, the mixed metal RuOFeCN behaves in a manner analogous to the RuORuCN film electrode, and indeed these modified electrodes are capable of catalyzing the oxidation of several substrates in acidic solutions. Depending on the applied potential, two distinct and selective reactive sites are recognizable in the electro-oxidation processes of As(III) and 2-furaldehyde at both RuOFeCN and RuORuCN film electrodes. XPS characterization of these ruthenium-containing cyanometallate films shows clear evidence of the existence of two oxidation states of ruthenium (Ru 3d region), which are respectively attributed to oxo-ruthenium(IV) and dioxo-ruthenium(VI) or Ru(V) in the oxide framework of the inorganic lattice.

Selective extraction of Hg(II) from aqueous mineral acid solution containing iodide ions using 2-benzylpyridine in benzene

A method for the selective extraction of mercury has been developed. The extraction of Hg(II) by 2-benzylpyridine (BPy) in benzene from dilute mineral acid solution containing iodide ions has been investigated, and variables such as concentration of acids, iodide and the extractant have been optimized. The optimum conditions for the extraction of Hg(II) by 0.1M BPy/benzene are: 0.01M (HCl, HNO3, H2SO4)+0.01M KI. The distribution coefficients and separation factors of 19 elements relative to Hg(II), have been reported. Effect of anions such as ascorbate, acetate, citrate, oxalate and thiosulfate has also been studied. The method developed could find useful applications in selective extraction of small amounts of mercury from environmental samples.

Acid-catalyzed hydrolysis of 5-enolpyruvylshikimate 3-phosphate (EPSP) and some simple models of its vinyl ether functional group

Rates of hydrolysis of the vinyl ether functional groups of 5-enolpyruvylshikimate 3-phosphate (EPSP), α-methoxyacrylic acid, and methyl α-methoxyacrylate were measured in concentrated and dilute mineral acid solutions and carboxylic and buffers, and rate profiles were constructed from the data so obtained

Studies of selective adsorption resin. XXIV. Preparation and properties of macroreticular chelating resins containing both polyethylenepolyamine side chains and mercapto groups

The macroreticular chelating resins containing both polyethylenepolyamine side chains and mercapto groups were prepared by the reaction of 2,3-epithiopropyl methacrylate-divinylbenzene macroreticular copolymer beads with polyethylene-polyamine. The adsorption behavior of metal ions on the obtained resins was then investigated. The amination of the macroreticular copolymer beads could effectively be carried out by treatment of the polymer beads with polyethylenepolyamine in organic solvent (benzene, terahydrofuran) or in the absence of organic solvent at 80°C or 100°C for 60 min. It was found that the adsorption capacity of the resins for metal ions is not only affected by the ion exchange capacity of the resins but also by the porosity of the resins. Hg2+, Ag+, and Cu2+ were effectively adsorbed on the resins even at a pH below 3, whereas Co2+, Ni2+, and Cd2+ were adsorbed at a pH above 3, Mn2+ at a pH above 7, and Ca2+ at a pH above 8. These metal ions adsorbed on the resins could easily be eluted with dilute mineral acid solution or dilute mineral acid solution containing thiourea.

Studies of selective adsorption resin. XXIV. Preparation and properties of macroreticular chelating resins containing both polyethylenepolyamine side chains and mercapto groups

AbstractThe macroreticular chelating resins containing both polyethylenepolyamine side chains and mercapto groups were prepared by the reaction of 2,3‐epithiopropyl methacrylate‐divinylbenzene macroreticular copolymer beads with polyethylene‐polyamine. The adsorption behavior of metal ions on the obtained resins was then investigated. The amination of the macroreticular copolymer beads could effectively be carried out by treatment of the polymer beads with polyethylenepolyamine in organic solvent (benzene, terahydrofuran) or in the absence of organic solvent at 80°C or 100°C for 60 min. It was found that the adsorption capacity of the resins for metal ions is not only affected by the ion exchange capacity of the resins but also by the porosity of the resins. Hg2+, Ag+, and Cu2+ were effectively adsorbed on the resins even at a pH below 3, whereas Co2+, Ni2+, and Cd2+ were adsorbed at a pH above 3, Mn2+ at a pH above 7, and Ca2+ at a pH above 8. These metal ions adsorbed on the resins could easily be eluted with dilute mineral acid solution or dilute mineral acid solution containing thiourea.

The extraction of trace amounts of gold from different aqueous mineral acid solutions by diphenyl-2-pyridylmethane dissolved in chloroform

Diphenyl-2-pyridylmethane, a high molecular weight substituted pyridine has been examined and found to be a useful solvent extraction reagent. Its behaviour is similar to amines in that it forms salts with mineral acids. The acid ionization constant (pKBH+) determined spectrophotometrically has a value of 4.41±0.06 at 25 °C. A study of the partition behaviour of trace amounts of gold between mineral acid solutions and 0.1M diphenyl-2-pyridylmethane dissolved in chloroform indicates that the metal can be quantitatively extracted from dilute mineral acid solutions and also from concentrated hydrochloric acid media in a single extraction. Attempts have been made to gain an understanding of factors affecting the extraction of gold. Common anions have little effect on extraction in concentrations upto 1M. Separation factors of a number of metal ions relative to gold are reported for three mineral acid systems; and gold has been estimated in some synthetic samples using neutron activation technique by prior extraction with 0.1M solution of diphenyl-2-pyridylmethane dissolved in chloroform.

N-oxides of 4-(5-nonyl)pyridine and trioctylamine as extractants for cerium(IV) and its separation from thorium(IV)

Trace level cerium has been oxidized to the quadrivalent state with potassium dichromate and shown to be preferentially extracted from very dilute mineral acid solutions and also from moderate nitric acid media by 0.1M solutions of 4-(5-nonyl)pyridine oxide and trioctylamine oxide dissolved in xylene. The dependence of extraction on the type of N-oxide, acid concentration and the N-oxide concentration has been investigated. The influence of the concentration of salting-out agents is described. Separation factors for a number of metal ions relative to cerium(IV) are reported for 0.1 M 4-(5-nonyl)pyridine oxide/xylene-0.1M sulphuric acid system. The ratio of the D for Ce(IV) to that of Ce(III) is greater than 105, and the D for Ce(IV) is much greater than that for thorium(IV). Separation of cerium(IV) from thorium has been achieved from 0.1M sulphuric acid solutions using 0.1M 4-(5-nonyl)pyridine oxide/xylene as an extractant.

Determination of 2-oximinopropanoic acid in microorganisms

A gas chromatographic technique for quantitative determination of 2-oximinopropanoic acid in microorganisms is described. The method is based on the fact that α-oximino acids decompose to the lower nitriles and carbon dioxide in dilute mineral acid solution. Acetonitrile derived from 2-oximinopropanoic acid in aqueous solutions can be gas chromatographed on a column with 20% of DEGA containing phosphoric acid on Chromosorb W as stationary phase. The practical limit of sensitivity is about 2 μg oximino acid/ml aqueous medium.

Photo-reaction product of 5-aminotropolone in aqueous acid solution

Irradiation of 5-aminotropolone (I) in dilute mineral acid solution with a high-pressure mercury lamp affords 2-amino-5-oxocyclopent-1-enylacetic acid (II) in good yield. A possible mechanism for this reaction is discussed.

Action of Dilute Mineral Acid Solution on Pinene. IV

Action of Dilute Mineral Acid Solution on Pinene. IV

Action of Dilute Mineral Acid Solution on Pinene. V

Action of Dilute Mineral Acid Solution on Pinene. V

Action of Dilute Mineral Acid Solution on Pinene. III

Action of Dilute Mineral Acid Solution on Pinene. III

Action of Dilute Mineral Acid Solution on Pinene II

Action of Dilute Mineral Acid Solution on Pinene II

Action of Dilute Mineral Acid Solution on Pinene (I)

Action of Dilute Mineral Acid Solution on Pinene (I)