H3PO4 Medium Research Articles

Assessment of acid hydrolysates of peat as substrate for Scytalidium acidophilum ATCC 26774 fungus

AbstractThe acid‐resistant fungus Scytalidium acidophilum ATCC 26774 was cultivated in submerged fermentation in hydrolysates of Sphagnum peat moss produced with H2SO4, HCl, HNO3 and H3PO4 acids. Hydrolysis with H2SO4 produced the highest concentration of total carbohydrates and reducing sugars in the hydrolysates. However, when Scytalidium acidophilum ATCC 26774 was grown in undiluted hydrolysates, the H3PO4 medium produced the best mycelial growth. The H2SO4 medium produced the highest dry biomass concentration (3.5 g dm−3) obtained with water‐diluted, non‐supplemented peat hydrolysates. Supplementation of diluted H2SO4 hydrolysates with 3 g dm−3 yeast extract and 0.4 g dm−3 MgSO4 considerably enhanced the growth, up to 5.9 g dm−3 dry fungal biomass.The biomass composition of Scytalidium acidophilum ATCC 26774 grown in the medium which produced the best growth was determined, revealing a relatively high protein content of 37.5% of the dry mycelial weight.

The fluorimetric determination of cerium and terbium

It has been found that phosphoric acid decreases the first excitation maximum of Ce(III) at 256 nm, increases the second excitation maximum at 297 nm and shifts the fluorescence maximum from 350 to 346 nm. Under optimum conditions, with λexc = 297 nm and λem = 346 nm, Ce(III) can be determined fluorimetrically with a detection limit of 1.2 ng ml-1 in 12M-H3PO4 medium. No interference was observed from a 20-200 fold excess of HCl, H2SO4, Na, K, NH4+, Al and the rare earth elements. HNO3 interferes and Ce(IV) and Fe(III) interfere strongly. It follows from the stereofluorograms of Ce and Tb that the spectra of the two elements are practically independent. The detection limit for Tb(III) in 0.02-2.5M-H2SO4 medium for λexc = 222 nm and λem = 494 nm is 33 ng ml-1. No interference was observed from a 5-20 fold excess of Al3+ and the other rare earth elements. The determination is slightly less sensitive in H3PO4 or HCl medium. The relative standard deviation of the measurement for 10 ng ml-1 Ce(III) or 50 ng ml-1 Tb(III) is about 3%.

Electrosynthesis of cobalt (III) ions in concentrated H3PO4 medium

The electrosynthesis of cobalt(III) ions from cobalt(II) ions has been studied in 29, 57 and 85 wt % H3PO4 solutions. It has been shown that the conversion of Co(II) to Co(III) is limited by the chemical reaction between Co(III) ions and water. A kinetic study demonstrated that this reaction becomes more rapid as the Co(III) ion concentration increases. In order to find the best conditions for the electrolysis, the effect of some experimental parameters on the current yield and the chemical efficiency has been examined. A comparison between gold and platinum anodes has also been made. The following conditions were found to be the best: anode material, gold; initial Co(II) ion concentration, 5×10−3 M; solvent, 85 wt % H3PO4 solution; current density, 1 mA cm−2; temperature, 20–30° C. Under these conditions the maximum value of current yield, and chemical efficiency are 66% and 48% respectively.

Determination of plutonium and uranium in the same aliquot by potentiometric titration

A potentiometric titration method was developed for the determination of plutonium and uranium in the same aliquot in nitric acid medium. Plutonium was first determined by oxidation to Pu/VI/ by fuming with conc. HClO4. Pu/VI/ formed was reduced to Pu/IV/ with known excess of Fe/II/ and the excess Fe/II/ was titrated with standard K2Cr2O7 to a potentiometric end point. Uranium in the same solution was determined by reduction to U/IV/ with Fe/II/ in conc. H3PO4 medium and titrating U/IV/ formed with standard K2Cr2O7 using the potentiometric end point detection technique. For the quantity of plutonium and uranium each in the range of 3–5 mg per aliquot a precision of ±0.2% and ±0.4%, respectively, was obtained.

Coulometric determination of uranium in perchloric acid medium and its applications

A cotrolled potential coulometric method has been developed in 1M HClO4 for the determination of uranium using an electrolysis cell and coulometer. A noteworthy feature of this method is its applicability even in the presence of large excess of calcium, barium and lead, situations where the commonly used coulometric method in 0.5M H2SO4 medium and the well known potentiometric method in H3PO4 medium are not applicable, Results of the determination of uranium in a number of aliquots of synthetic solutions of (U,Ca), (U, Ba) and (U, Pb) showed a precision of the order of 0.2% and the experimental values of uranium content agreed with the expected values within the precision limits. Similar results were obtained with samples of synthetic mixtures of U3O6 and CaF2 powder containing 1–5% U and 95–99% Ca. The method was then successfully used to determine the U-conten of some typical samples of CaF2 slag (containing 1–5% U) generated during the calciothermic reduction of UF4 to U-metal at conversion plants.

ChemInform Abstract: PROFENAMINE HYDROCHLORIDE AS A NEW REAGENT FOR THE SPECTROPHOTOMETRIC DETERMINATION OF VANADIUM AND ITS APPLICATION TO VANADIUM STEEL

Profenamine hydrochloride is proposed as a sensitive and selective reagent for the spectrophotometric detn. of V(V). It forms a red-colored species with V(V) instantaneously in 5.5-7.5M H3PO4 medium. An 11-fold molar excess of the reagent is necessary for the full development of color intensity. The red species exhibits absorption max. at 510 nm with molar absorptivity of 7.09 A� 103. The Sandell sensitivity is 7 ng/cm2. Beer's law is valid over the concn. range 0.1-6.0 I¼g V/mL. The influence of some common ions is reported. The proposed method was successfully used for the detn. of V in V steels. [on SciFinder(R)]

Analysis of mixtures of inorganic ions by ion exchange VI. Distribution coefficients for cations in H3PO4 media with Dowex 50 W X 8 resin

In this paper we present the behaviour of Ag(I), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Fe(III) in H3PO4 media at various concentrations with a strong cationic resin. We have examined particularly the Kd values and the column separation of Fe(III) from Ni(II) as well the limiting quantities of the two ions separable without overlapping of the chromatographic bands.