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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of acidity on the precipitation of various bivalent metal 8-selenoquinoline and 8-mercaptoquinoline complexes has been systematically studied and compared. The metal ions were Zn(2+), Cd(2+), Pb(2+), Mn2+, Ni(2+), Cu(2+) and Co(2+). Most of the metal ions, except copper(II) and cobalt(II), precipitate as a. 1:2 complex, metal :ligand. However, in hydrochloric acid solution cadmium precipitates as CdR(2).2HCl and lead as PbR(2).2HCl or PbR.Cl. Copper(II) is reduced to copper(I) and precipitates as CuR.RH at pH above 2.0 and as CuR in strongly acidic solution. Cobalt(II) does not give a precipitate of composition but appears to precipitate as a mixture of CoR(2).RH and fixed CoR(2) or as other complexes. The reasons for the formation of the various types of precipitate are considered.
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PMID:Formation and composition of the precipitates of various metal 8-selenoquinoline complexes. 1896 Oct 76

The effects of acidity, fluoride concentration, temperature and concentration of manganese in the reaction between KMnO(4) and Mn(II) were studied potentiometrically. The rate of reaction is increased by increasing the fluoride concentration and/or decreasing the acidity of the solution. The formal redox potentials of the MnO(-)(4)/Mn(III) and the Mn(III)/Mn(II) systems were determined at different pH values. The E degrees values obtained by extrapolation to pH = 0 were 1.58 and 1.52 V respectively. The amount of Mn(II) determined was varied from 5 to 56 mg. The net reaction can be represented as MnO(-)(4) + 10HF(-)(2) + 4Mn(2+) right harpoon over left harpoon 5MnF(-)(4) + 2H(+) + 4H(2)O.
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PMID:Oxidation with permanganate in presence of fluoride potentiometric determination of manganese(II). 1896 13

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.
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PMID:Separation of molybdenum from interfering elements by extraction as phosphomolybdenum blue. 1896 58

The oxidation of mandelic acid, ethylene glycol, glycerol and d-mannitol by the pyrophosphate complex of manganese(III) and with manganese(III) sulphate was studied. It was shown that benzaldehyde is formed by oxidation of mandelic acid, which undergoes no further oxidation. In the case of ethylene glycol, glycerol and d-mannitol the reactions do not follow a simple course and therefore are not of analytical utility. The effect of acidity and time on the course of the reactions was found and a procedure for the indirect titrimetric determination of mandelic acid with both reagents proposed.
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PMID:The oxidation of organic substances by compounds of tervalent manganese-I Oxidation of mandelic acid, ethylene glycol, glycerol and d-mannitol by the pyrophosphate complex of manganese(III) and by manganese(III) sulphate. 1896 35

Poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber was synthesized from polyacrylonitrile fiber and used for enrichment and separation for traces of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions from solution samples. The acidity, rate, re-use, capacity and interference on the adsorption of ions on the chelating fiber as well as the conditions of desorption of these ions from the chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry. The results show that 10-100 ngml(-1) of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions can be quantitatively enriched by the chelating fiber at a 2 mlmin(-1) of flow rate in the range pH 4-5, and desorbed quantitatively with 20 ml of 5 M HCl for In(III), Bi(III), Zr(IV), V(V), Ga(III), Ti(IV) and 20 ml of 4 M HCl+2% CS(NH(2))(2) solution for Au(III), Ru(III) (with recovery>95%). 50- to 500- fold excesses of Fe(III), Al(III), Mg(II), Mn(II), Ca(II), Cu(II), Ni(II) ions cause little interference in the concentration and determination of analyzed ions. When the fiber was reused for 8 times, the recoveries of the above ions enriched by the fiber were still over 87%. The relative standard deviations (RSDs) for the enrichment and determination of 10 ngml(-1) Au, Ru, In, Bi, Ga and 1 ngml(-1) Zr, V, Ti were lower than 3.0%. The results obtained for these ions in real solution samples by this method were basically in agreement with the given values with average errors of less than 6.3%. FT-IR spectra show that existence of NNCNHNH, OCNHNH and NO(2) functional groups are verified in chelating fiber, and Au(III) or Ru(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelate complex.
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PMID:Efficiency and application of poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber for pre-concentrating and separating trace Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) from solution samples. 1896 25

Water sample were collected from six different point of the Mouri River Khulna, Bangladesh with a regular intervals in the months of January-March 2002 for the analyzing different physicochemical parameters of the water. Total 22 different physicochemical parameters were investigated. Correlation and the t value among the parameters were also determined. In the present investigation the minimum and maximum value of water temperature, Transparency, Turbidity, TSS, TDS, Electric Conductivity, water pH, dissolve oxygen, free Carbon dioxide, Alkalinity, Acidity, Hardness, BOD, COD, Sulphate, Phosphate, Nitrite, Sodium, Calcium, Potassium, Manganese and Iron were noted as 21.6 and 32.2 degrees C; 15 and 66 cm; 16 and 22 NTU; 74 and 125 mg L(-1); 255 and 305 mg L(-1); 159 and 275 microS cm(-1); 1.10 mg L(-1) 8.18 mg L(-1); 7.5 and 8.3; 1.1 and 8.3 mg L(-1); 27.5 and 35.5 mg L(-1); 350 and 610 mg L(-1); 32.4 and 171 mg L(-1); 310 and 529 mg L(-1); 13 and 31 mg L(-1); 290 and 365 mg L(-1); 42046 and 57.35 mg L(-1); 4.89 and 11.46 mg L(-1); 0.54 and 1.82 mg L(-1); 16.8 and 33.9 mg L(-1); 1.5 and 6.9 mg L(-1); 49 and 94 mg L(-1); 31 and 59 mg L(-1); 2.6 and 3.8 mg L(-1), respectively. River water did not show any significant pollution during the present study. During the study period dissolved oxygen show direct relation with water temperature but inverse with BOD and COD.
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PMID:Study on the physico chemical properties of water of Mouri River, Khulna, Bangladesh. 1906 52

The persimmon cv. Hachiya (Diospyros kaki) fruits were analysed for some physical properties (fruit dimensions, fruit mass, fruit volume, fruit density, aspect ratio, geometric mean diameter, sphericity, spread area, projected area, bulk density, skin and flesh firmness, skin and flesh colour as L, a and b values, coefficient of static friction on different surfaces and porosity), chemical properties (moisture, ash, pH, acidity, vitamin C, total soluble solids) and nutritional properties (phosphorus, potassium, calcium, magnesium, sodium, iron, manganese, copper and zinc). The fruit characteristics ranged from 169 g for average fruit mass, 65.97 mm for the geometric mean diameter, 1.03% for sphericity and 180 cm3 for volume of fruit. The bulk density, fruit density and porosity were determined as 5,817 N/m3, 9,300 N/m3 and 38.06%, respectively. The present study also revealed important nutritional values of persimmon fruits.
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PMID:Persimmon cv. Hachiya (Diospyros kaki Thunb.) fruit: some physical, chemical and nutritional properties. 1938 48

Bromelia pinguin L. is a plant native to Sinaloa, Mexico, where its fruit is used as food or as a phytotherapeutic agent. The fruits of B. pinguin were characterized and they could be considered as a functional food. These fruits show an average weight of 13.7 g and a yellow color of high luminosity (b* = 43.2, L* = 74.5). The values for acidity (4.6%, as citric acid) and pH (3.7) of B. pinguin fruit are similar to those of citrics. The edible portion is characterized by a high content of vitamin C (126 mg/100 g), ash (10.6 g/100 g d.w.), crude fiber (3.4 g/100 g d.w.), calcium (1290 mg/100 g d.w.), magnesium (500 mg/100 g d.w.), manganese (2.95 mg/100 g d.w.) and it is a good source of zinc (2.8 mg/100 g d.w.). Polar fractions extracted from the pulp fruit showed activity against several genera of human pathogenic-bacteria (Staphylococcus, Streptococcus, Enterococcus, Salmonella, Shigella, Escherichia and Pseudomonas).
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PMID:Physicochemical, nutritional and antibacterial characteristics of the fruit of Bromelia pinguin L. 1953 51

Three industrial by-products (fly ash, phosphogypsum and blast furnace slag), were evaluated for their potential re-use as soil amendments to reduce methane (CH(4)) emission resulting from rice cultivation. In laboratory incubations, CH(4) production rates from anoxic soil slurries were significantly reduced at amendment levels of 0.5%, 1%, 2% and 5% (wt wt(-1)), while observed CO(2) production rates were enhanced. The level of suppression in methane production was the highest for phosphogypsum, followed by blast slag and then fly ash. In the greenhouse experiment, CH(4) emission rates from the rice planted potted soils significantly decreased with the increasing levels (2-20 Mg ha(-1)) of the selected amendments applied, while rice yield simultaneously increased compared to the control treatment. At 10 Mg ha(-1) application level of the amendments, total seasonal CH(4) emissions were reduced by 20%, 27% and 25%, while rice grain yields were increased by 17%, 15% and 23% over the control with fly ash, phosphogypsum, and blast slag amendments, respectively. The suppression of CH(4) production rates as well as total seasonal CH(4) flux could be due to the increased concentrations of active iron, free iron, manganese oxides, and sulfate in the amended soil, which acted as electron acceptors and controlled methanogens' activity by limiting substrates availability. Among the amendments, blast furnace slag and fly ash contributed mainly to improve the soil nutrients balance and increased the soil pH level towards neutral point, but soil acidity was developed with phosphogypsum application. Conclusively, blast slag among the selected amendments would be a suitable soil amendment for reducing CH(4) emissions as well as sustaining rice productivity.
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PMID:Effect of industrial by-products containing electron acceptors on mitigating methane emission during rice cultivation. 1956 Mar 34

Adsorption of different volatile organic compounds (trichloroethylene, TCE; 1,2-dichloroethane, DCE; n-hexane) over different manganese-zirconia mixed oxides (Mn(x)Zr(1-x)O(2)) - widely used as combustion catalysts - was studied by inverse gas chromatography. Adsorption isotherms (calculated in the Henry region), adsorption enthalpies (DeltaH(ads)), and dispersive (gamma(S)(D)) and specific (I(sp)) components of the surface energy have been determined at infinite dilution for the investigated compounds. Both the adsorption enthalpy and the specificity of the interaction of TCE and DCE over Mn(x)Zr(1-x)O(2) catalysts depend strongly on manganese content. Thus, the adsorption strength of the reactants over the active sites is closely related with both the surface acidity and the accessibility of the lattice oxygen. A great influence of the specific interaction on the catalytic pattern has been also noticed. Since I(sp) depends on the redox properties, it has been proved that the specific interaction is determined by the presence of bulk Mn(3)O(4), which hinders the mobility of the oxygen lattice, and MnO(x), with the contrary effect. Finally, the selectivity to oxidation products has been correlated with both the enthalpy of adsorption and the specific interaction parameter, decreasing the selectivity to HCl with the increase of the enthalpy of adsorption.
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PMID:Inverse gas chromatography as a technique for the characterization of the performance of Mn/Zr mixed oxides as combustion catalysts. 1974 84


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