Alkaline Ammonium Research Articles

Causes for the reduced reactivity of phosphate rock residues in partially acidulated phosphate rocks

The agronomic effectiveness of partially acidulated phosphate rock (PAPR) fertilizers depends on the proportion of water soluble P present and the long-term release of P from the unacidulated residual phosphate rock (water-insoluble residue) in the soil environment. The relative reactivity of water-insoluble residues in a range of partially acidulated phosphate rock (PAPR) fertilizers was assessed according to chemical solubility, and was found to be lower than the corresponding original PRs. Two causes were identified for the reduced formic acid solubility of water-insoluble residues: (i) some preferential dissolution of more reactive apatite components (i.e. higher carbonate substituted apatite) during partial acidulation as indicated by reductions in the molar apatite C:P ratio of the residual PRs compared with the corresponding original PRs, and (ii) acid-insoluble metal (Fe-Al-Mg)phosphate and/or fluoride complexes formed on the surface of residual PRs during partial acidulation with commercial-grade phosphoric acid, which were partially soluble in alkaline ammonium citrate. These two mechanisms accounted for most of the solubility differences observed for 'medium' reactive PRs (Khouribga, Arad), compared with only half for more reactive PRs (North Carolina, Gafsa). The conclusion from this study is that partial acidulation may not be an ideal method for the manufacture of fertilizers containing fast and slow release (i.e. PR) components, particularly when highly reactive PRs such as North Carolina are used.

An investigation of extraction procedures for assessing the phosphate rock residue in multicomponent fertilisers

Five chemical extractants-water, neutral ammonium acetate, neutral ammonium citrate (hot and cold) and alkaline ammonium citrate-have been assessed on their ability to efficiently isolate the residual phosphate rock present in multicomponent fertilisers without affecting the phosphate rock. Phosphoric acid-based partially acidulated phosphate rocks (PAPRs) were manufactured along with several LONGLIFE (LL, single superphosphate to which “reactive” phosphate rock is added ex-den) materials for the assessment of these extractants.

Development of molybdena catalysts supported on γ-alumina extrudates with four different Mo profiles: Preparation, characterization, and catalytic properties

The main goal of this work is to prepare, characterize, and determine the catalytic properties of molybdena supported γ-alumina extrudates with four Mo profiles. Concerning preparation, a procedure was established allowing us to prepare (both axially and radially) egg-shell, egg-white, egg-yolk, and uniform profiles with the same, relatively high, Mo loading. The preparation of the egg-shell and uniform profiles was achieved by impregnating γ-alumina extrudates with acidic and alkaline ammonium heptamolybdate solution, respectively. Moreover, it was found that an egg-white (egg-yolk) profile may be achieved from an egg-shell (uniform) profile by successive pore volume or simple nondry impregnations of the Mo-supported extrudates with NH 4OH aqueous solutions. A qualitative mechanism, based on the relative rates of desorption and diffusion of the MoO 4 2− ions occuring in the NH 4OH impregnation, was developed to interpret the influence of desorption time, concentration of NH 4OH solution, drying, and mode of impregnation on the characteristics of the egg-white and egg-yolk profiles obtained. The physicochemical characterization of the Mo/γ-alumina extrudates for which radial profiles have been achieved, done by using a number of techniques, showed a progressive increase of the “Mo supported-support” interactions and Mo dispersion following the order egg-yolk < uniform < egg-white < egg-shell. A similar trend (uniform < egg-yolk < egg-white < egg shell) was obtained for the number of active sites as estimated by the amount of the adsorbed NO. The trends mentioned above were related with the values of the preparative parameters used for obtaining each profile. Kinetic experiments were done, using the hds of thiophene as a probe reaction, over the characterized samples being in the form of extrudates and powders produced by crushing the extrudates. It was found that hds activity was mainly determined by the number and the quality of active centers and not by the type of Mo profile, though these suggested the presence of no significant diffusional effects. The relative yield of butane, produced by the hydrogenation of the unsaturated hydrocarbons formed during hds, increased with the distance of the maximum of the Mo profile from the periphery of the extrudate to its center. Finally, it is important to note that the most active radial profile proved to be the egg-white for hds and the egg-yolk for hydrogenation.

Analysis of tropane alkaloids with thermospray high-performance liquid chromatography—mass spectrometry

A thermospray high-performance liquid chromatography—mass spectrometry method for analysis of hyoscyamine and scopolamine in plant cell culture samples is described. The alkaloids were separated on a polymeric reversed-phase column with an alkaline ammonium acetate buffer—acetonitrile eluent. Selected-ion recording of the protonated molecular ions was used for quantitation of the compounds. The compounds were fragmented by discharge-assisted ionization and elevated thermospray capillary temperatures or ion repeller potentials.

Investigations on interactions of phosphorus compounds in partially acidulated phosphate rock and fertilizer effectiveness

Khouribga phosphate rock was partially acidulated with 50 and 70% of the required H2SO4 for complete acidulation. The unreacted rock residue was isolated by subsequent extractions with water and alkaline ammonium citrate solution. P solubility in 2% formic acid of this residues was reduced as compared to the original Khouribga phosphate rock. This ‘loss in reactivity’ consistently increased with the degree of acidulation. Plant response to fertilizer application emphasized the negative effect of partial acidulation in an acid soil. Mixtures of superphosphate and phosphate rock were more effective than partially acidulated phosphate rock.

Properties of unreacted rock residues in partially acidulated phosphate rocks affecting their reactivity

The nonacidulated P fraction of partially acidulated phosphate rocks (PAPR) was obtained by extraction with alkaline ammonium citrate solution. Investigations on this unacidulated rock residues using standard analytical techniques and electronbeam microanalysis showed a surface “coating” with highly increased fluorine content surrounding the unreacted phosphate rock particles. The coating may be responsible for low reactivity of the residues and their inferior agronomic effectiveness as compared to the original mother rock phosphate. Furthermore, the existence of dicalciumphosphate and Fe—Al—P compounds in PAPR products make solubility tests based on alkaline ammonium citrate appropriate to gauge the acidulated and easily plant available P fraction. Only after the removal of these compounds with citrate solution is an assessment of the potential agronomic value of the nonacidulated rock residues in 2% formic acid possible.

ChemInform Abstract: CHEMISTRY OF TETRAVALENT NICKEL AND RELATED SPECIES. 4. THE SITUATION WHERE NICKEL(III) IS STABILIZED BY AMINE‐IMINE‐OXIME LIGANDS AND NICKEL(IV) IS NOT FORMED

AbstractDie durch 1:1‐molare Umsetzung entsprechender Diketonmonoxime mit Tetraethylenpentamin erhaltenen sechszähnigen Liganden bilden mit Ni(II)‐perchlorat die pseudooktaedrischen high‐spin‐Komplexe (I).

Chemistry of tetravalent nickel and related species. 4. The situation where nickel(III) is stabilized by amine-imine-oxime ligands and nickel(IV) is not formed

New hexadentate ligands (HRR'Y) generated by reaction of isonitroso ketones with tetraethylenepentamine in 1:1 ratio yield pscudooctahedral nickel(II) complexes Ni(HRR'Y)(CIO 4 )Dq≈1250 cm -1 ;μ eff ≈3μ B ). These are oxidized by alkaline ammonium persulfate to produce red crystals of Ni(RR'Y)(CI0 4 ) 2 which (i) oxidize iron(II) to iron(III), the reaction stoichiometry being Fe:Ni=1:1, (ii) have μ eff ≈2.1 μB, (iii) exhibit polycrystalline EPR spectra characteristic of S=1/2 in axial field (gp≈2.04; g⊥≈2.14), and (iv) undergo a ono-electron electrochemical reduction but no oxidation. Thus Ni(RR'Y)2+ contains nickel in the oxidation state +3. Extensive cyclic voltammetric studies have led to the identification of the following quasi-reversible process near pH 6: Ni(RR'Y) 2+ +e - + H + Ni(HRR'Y) 2+ with E°′ 298 ≈0.68 V vs. SCE. No sign of the formation of nickel( IV) species could be detected up to +0.9 V. Comparison of the ocnnplexing behavior of the various amine-imine-oxime ligands described in this paper and elsewhere and the various oxidation states of nickel achievable with each suggests that for each unit increase (above +2) in the oxidation state of the metal, the presence of at least one oxime function is needed. The HRR'Y ligand system having only one oxime function stabilizes nickel(III) but not nickel(IV). The low-spin iron(II) complexes Fe(HRR'Y)(C10 4 ) 2 are also reported. The IR and electronic spectra of these and the nickel(II) and nickel(III) complexes are described and compared. The iron(II) and nickel(III) complexes exhibit MLCT and LMCT transitions, respectively, in the visible region (∼500 nm).

Stratigraphy of two sandrocks at rainbow beach, Queensland, Australia, and a note on humate composition

Two intervals of coastal sandrock development are proved by the occurrence of sandrock boulders in a fossil beach that is itself preserved in sandrock. The fossil beach also contains driftwood, and carbon dates obtained by previous workers indicate that its age is greater than 40,000 years. The ancient beach rises 3 m above the present ocean beach and is the highest Pleistocene shoreline recognized on Queensland's southern coast. It is therefore likely to represent the warmest interval of the last two million years. Several lines of evidence indicate that the fossil beach is hundreds of thousands of years old. This is in agreement with tentative correlations with other Pleistocene events described in a previous paper where an age of 400,000 years was attributed to it. Large amounts of aluminium can be extracted with alkaline ammonium citrate from the two sandrocks, which are composed of quartz sands cemented with organic matter. Gibbsite is present in the older sandrock and in the boulders of older sandrock in the fossil beach. There is much less C relative to Al than in the younger sandrock. This is possibly due to decomposition of Al-humate by loss of organic matter, leaving Al in situ. If the rate of decomposition could be calibrated, by for example radiocarbon dating of the younger sandrock, it might be possible to use the C/Al ratios to date the older sandrock.

Calcined Christmas Island C-grade rock phosphate fertilizers: Mineralogical properties, reversion and assessment by chemical extraction

Calcination of Christmas Island C-grade ore at temperatures up to 1050�C produces phosphorus fertilizers that differ greatly in effectiveness as determined by citrate extraction and plant growth. Maximum effectiveness is obtained by calcination at temperatures between 500� and 650�C, and is best predicted by extractions of between 1 and 3 h duration in neutral ammonium citrate. Alkaline ammonium citrate and citric acid are poorer indicators of phosphorus availability. The mineralogical and chemical properties of the calcines may be used to explain variations in amounts of citrate soluble phosphorus for different temperatures of calcination. Incubation of moist 500�C calcined C-grade ore induces recrystallization (i.e. reversion) of some crandallite, resulting in a decrease in the solubility of phosphorus in neutral ammonium citrate and its availability to plants.

Evaluation of phosphate in fertilizers by means of the alkaline ammonium citrate extraction according to Petermann.

The phosphate extraction with alkaline ammonium citrate solution for the control of phosphate in fertilizers was subjected to a critical examination. The contribution of inferior phosphate forms such as tricalcium phosphates and apatites to the available P2O5 percentage can be excluded to a great extent by using a narrow sample solvent ratio. However, the dissolution rate of dicalcium phosphate in alkaline ammonium citrate solution limits the narrowing of the ratio. The dissolution rate of dicalcium phosphate can be increased, if instead of intermittent manual shaking, mechanical shaking is applied. Extraction of 1.0 g sample with 200 ml of alkaline ammonium citrate solution at 65 deg C under mechanical shaking for 1.5 hours is preferred to other methods for quality control of phosphate in fertilizers. The extraction method with neutral ammonium citrate solution is not reliable, because this method makes little or no distinction between high quality and low quality fertilizers. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Free Energy of Formation of Carbonate Apatites in Some Phosphate Rocks

AbstractA constant ion‐activity product or solubility‐product constant for carbonate apatite (KCA) was found within a certain pH range in dilute HCl solutions equilibrated with each of a group of phosphate rocks that had been treated with an alkaline ammonium citrate solution to remove alkaline‐earth carbonates. The KCA values generally increased with an increase in the number of moles of carbonate/mole of apatite. As predicted theoretically, the free energies of formation calculated for the carbonate apatites (ΔG°f,CA) in various phosphate rocks increased linearly with an increase in the number of moles of carbonate/mole of apatite. The apatites in phosphate rocks extensively pre‐extracted with HCl had lower KCA values and lower ΔG°f,CA values than the apatites in phosphate rocks pre‐extracted with alkaline ammonium citrate solution. Empirical equations developed to relate the ΔG°f,CA values to the number of moles of carbonate/mole of apatite make possible the estimation of KCA for other phosphate rocks for which the empirical molecular formula of the apatite is known.

Clinical significance of intraluminal pH in intestinal ammonia transport

1. 1. In the canine small intestine the ammonia furnished by the relatively alkaline ammonium acetate (pH 7.1) is absorbed at a faster rate than is ammonia from a comparable quantity of the relatively acid dibasic ammonium citrate (pH 4.8). 2. 2. In the canine and human colon ammonia can be dialyzed more efficiently by an acid medium (Impersol) than by saline and much more efficiently than by an alkaline medium (THAM). 3. 3. Passive non-ionic diffusion appears to be the mechanism of ammonia transport in the colon and canine small bowel. 4. 4. Acid dialysis by Impersol in the acute situation or by lactulose for chronic use is suggested for the management of portasystemic encephalopathy.

A routine method for the determination of low caesium-137 activities in biological samples.

A routine method for the determination of low fall-out activities of caesium-137 in biological materials is described. Radiocaesium is extracted by adsorption on ammonium molybdophosphate. The usual radiochemical purification of the alkaline ammonium molybdophosphate solution by anion exchange is omitted and caesium precipitated directly with bismuth tri-iodide in the presence of citric acid as complexing agent. A caesium chloroplatinate source is prepared for β-counting.

Relative Availability of Phosphorus in Fertilizers Varying in Solubility of the Phosphorus

AbstractTwenty‐eight NPK fertilizers varying in solubility of the phosphorus were compared by band application and cropping to corn (Zea mays L.) in the greenhouse. Phosphorus uptake and per cent superphosphate equivalent were determined for each of two crops and for a combination of both crops. The per cent superphosphate equivalent ranged from 14 to 135 in the first crop, from 15 to 98 in the second crop, and from 13 to 111 for the total of both crops. Correlation coefficients for the relationships between superphosphate equivalent and water‐soluble and Netherlands alkaline ammonium citrate‐“available” P (NAAC‐“available” P) were highly significant for crop I, crop II, and the total of both crops. The correlation coefficients relating superphosphate equivalent to AOAC‐“available” P were barely significant at the 5% level. It is concluded from these results that both water‐soluble and NAAC‐“available” P are good criteria to use in judging phosphate fertilizer quality for crops and it is obvious that AOAC‐“available” P is poorly related to plant available P.

An Improved Alkaline Citrate Method for Evaluation of Phosphorus in Fertilizers

Abstract The Netherlands alkaline ammonium citrate extraction method for the determination of available P2O5 was modified for routine use. The water-insoluble portion of the sample is extracted with the alkaline citrate solution for 2 hours in a shaking apparatus at 65°C. Dicalcium phosphate dissolves, but apatite, whether formed in processing (as in the ammoniation of superphosphate) or present as unreacted phosphate rock, does not dissolve. The results of the extraction method correlate well with those of field tests of the fertilizers.

How Available Is Available?

Abstract Results of field tests of ammoniated superphosphate fertilizers correlated well with availabilities determined by an alkaline ammonium citrate extraction, but showed no relation to availabilities determined by the official neutral ammonium citrate extraction procedure. It is recommended that water solubility of phosphate fertilizers be guaranteed and that the alkaline ammonium citrate extraction be considered for determination of the availability of phosphate fertilizers.

Phosphate Effectiveness, Quality of Phosphorus in Mixed Fertilizers as Revealed by Solubility in Water, Neutral Ammonium Citrate, and Alkaline Ammonium Citrate Solutions

Phosphate Effectiveness, Quality of Phosphorus in Mixed Fertilizers as Revealed by Solubility in Water, Neutral Ammonium Citrate, and Alkaline Ammonium Citrate Solutions

Interference of silicon in the determination of phosphorus by the vanadomolybdate method

Silicon interferes with the determination of phosphorus by the vanadomolybdate method because it forms a yellow complex that shows strong absorbance at 400 mμ. Alkaline ammonium persulphate oxidation in polypropylene test tubes, instead of glass, eliminates the interference of silicon in the determination of organophosphorus compounds.

Phosphate Solubility, Evaluation of Water-Insoluble Phosphorus in Fertilizers by Extraction with Alkaline Ammonium Citrate Solutions

Phosphate Solubility, Evaluation of Water-Insoluble Phosphorus in Fertilizers by Extraction with Alkaline Ammonium Citrate Solutions