Determination of seven plant nutritional elements in potassium dihydrogen phosphate fertilizer from northeastern China

Contents of seven plant nutritional elements in potassium dihydrogen phosphate fertilizer were determined by ICP-MS. Correlation coefficients of the detected elements changed between 0.9631 and 0.9999, the limits of detection range from 0.18 to 0.77 μg/L, and relative standard deviations range from 1.17% to 3.82% for all the elements, ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) is a good method to determine plant nutritional elements simultaneously. Data showed that brand 1 is a real KH₂PO₄ fertilizer, but P and K concentrations are obviously lower than the labeled value; another brand contained little KH₂PO₄, so this fertilizer is a false fertilizer. We can know that KH₂PO₄ fertilizers contain some other plant nutritional elements, such as B, Si and Zn, so KH₂PO₄ fertilizers not only provide K and P but also some trace elements.     

Study of the process for obtaining special-purity potassium dihydrophosphate

Method of radioactive tracers was used to study the coprecipitation of 3d-element impurities from KH₂PO₄ solutions on hydrated potassium-aluminum phosphate. The influence exerted by the mass of the collector, its contact duration with solution, pH value and concentration of KH₂PO₄ on the process efficiency was examined. The purification coefficients were calculated. The high efficiency of the process of KH₂PO₄ purification was demonstrated.     

An EPR investigation of room temperature radiation damage and molecular motion in the ferroelectric phosphates

Several types of paramagnetic centers have been detected in the room temperature irradiated KH₂PO₄, KD₂PO₄, KH₂PO₄KH₂AsO₄, KD₂PO₄KD₂AsO₄ and in the newly discovered ferroelectric NaTh₂(PO₄)₃. Comparative studies of temperature dependence in the EPR spectra show that as in KH₂PO₄-type crystals, the ferroelectric phase transition in NaTh₂(PO₄)₃ crystals also seems to be related to the motion of the PO₄ units. The results help to clarify some earlier observed anomalies on the effects of γ-irradiation on dielectric properties of KH₂PO₄ and in particular, show that the extent of the damage can be controlled by changing the impurity content of the unirradiated samples.     

Preparation and characterization of cellulose acetate‐coated compound fertilizer with controlled‐release and water‐retention

A novel cellulose acetate‐coated compound fertilizer with controlled‐release and water‐retention (CAFCW) was prepared, which possessed the three‐layer structure. Its core was water‐soluble compound fertilizer granular, the inner coating was cellulose acetate (CA), and the outer coating was poly(acrylic acid‐co‐acrylamide)/unexpanded vermiculite (P(AA‐co‐AM)/UVMT) superabsorbent composite. The effects of the amount of acrylamide, crosslinker, initiator, degree of neutralization of acrylic acid (AA), and unexpanded vermiculite concentration on water absorbency were investigated and optimized. The water absorbency of CAFCW was 72 times its own weight if it was allowed to swell in tap water at room temperature for 90 min. Element analysis and atomic absorption spectrophotometer results showed that the product contained 11% nitrogen, 6% phosphorus (shown by P₂O₅), 9% potassium (shown by K₂O), 1% calcium (shown by CaO), and 0.4% magnesium (shown by MgO). Swelling rate, slow‐release, and water‐retention properties of CAFCW were also investigated. This product with good controlled‐release and water‐retention capacity, being degradable in soil and environmentally friendly, could be especially useful in agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Protonic conduction in NH4H2PO4

The conductivity of ammonium dihydrogen phosphate has been measured as a function of temperature and dopant concentration. A previously disputed break in the log conductivity vs reciprocal temperature plots has been observed. The activation energy is in agreement with previous work on NH₄H₂PO₄. In addition, the conductivity vs concentration of NH₄HSO₄ plot is linear, permitting the calculation of the L defect mobility and indicating that the proton is the conducting species. It is concluded that the mechanism of conduction is the same as previously proposed for KH₂PO₄ and KH₂AsO₄.     

Structural and transport properties of compounds in the CsHSO4-KH2PO4 system with a high potassium dihydrophosphate content

The (1?x)CsHSO₄-xKH₂PO₄ system was studied in a wide range of compositions (x = 0.05?0.97). Mixed salts with different crystal structures and different transport, thermodynamic, and thermal properties were shown to form. In these mixed (1?x)CsHSO₄-xKH₂PO₄ compounds (x = 0.05?0.5), solid solutions formed on the basis of the compound with a crystal structure Cs₃(HSO₄)₂(H₂PO₄) (C2/c). As the content of KH₂PO₄ increased further, another compound with a crystal structure, CsH₅(PO₄)₂ (P2₁/c), formed and existed up to x = 0.95. At x ≥ 0.7, KH₂PO₄ existed as an individual phase along with CsH₅(PO₄)₂; its content increased considerably at x ≥ 0.9. The low conductivities and high activation energies of (1?x)CsHSO₄-xKH₂PO₄ at x = 0.6?0.95 were close to those for CsH₅(PO₄)₂. The compounds with x = 0.5–0.9 showed low thermal stability corresponding to the individual CsH₅(PO₄)₂ phase.     

Xylanase recovery effect of extraction conditions on the aqueous two-phase system using experimental design

The partitioning of xylanase produced byPenicillium janthinellum in aqueous two-phase systems (ATPS) using poly(ethylene glycol) (PEG) and phosphate (K₂HPO₄/KH₂PO₄) was studied employing a statistical experimental design. The aim was to identify the key factors governing xylanase partitioning. The interactions of five factors (PEG concentration molecular weight, concentration of buffer K₂HPO₄/KH₂PO₄, pH, and NaCl concentration) and their main effects on the partition coefficient (K) were evaluated by means of a 2⁵ full-factorial experimental design with four center points. The %PEG, %NaCl, and pH were the most important factors affecting the response variable (K). Response surface methodology (RSM) was adopted and an empirical second-order polynomial model was constructed on the basis of the results. The optimum partition conditions were pH 7.0, PEG = 8.83% and NaCl = 6.02%. Adequacy of the model for predicting optimum response value was tested under these conditions. The experimental xylanase partition coefficient (K) was 2.21, whereas its value predicted by the model was 2.33. These results indicate that the predicted model was adequate for the process. PEG molecular weight and phosphate concentration did not affect the xylanase partition coefficient.     

Extraction and isolation of lithospermic acid B from Salvia miltiorrhiza Bunge using aqueous two‐phase extraction followed by high‐performance liquid chromatography

A rapid and effective method integrating separation and purification of lithospermic acid B from Salvia miltiorrhiza Bunge was developed by combining an aqueous two‐phase system extraction with preparative chromatography. An aqueous two‐phase system of n‐butyl alcohol/KH₂PO₄ was chosen from seven systems. The influence of parameters including concentration of KH₂PO₄, n‐butyl alcohol concentration, pH, and the ratio of an aqueous two‐phase system to crude extract were investigated using a single factor design. Response surface methodology was subsequently used to find the optimal compositions of an aqueous two‐phase system. Keeping a solvent‐to‐solid ratio of 10, the final optimized composition of an aqueous two‐phase system was 39.1% w/w n‐butyl alcohol and 22.6% w/w KH₂PO₄. Under these conditions a recovery yield of 99.8% and a high partition coefficient of 310.4 were obtained. In a pilot‐scale experiment using optimized conditions, 18.79 g of lithospermic acid B with a purity of 70.5% and in a yield of 99.8% was separated from 0.5 kg of crude extract. Subsequently, 9.94 g lithospermic acid B with a purity of 99.3% and recovery yield of 70.3% was obtained with a preparative chromatographic process, and the two‐step total recovery was 70.1%.     

Electrical conduction in deuterated hydrogen bonded crystals

Alternating current conduction of pellets of KH₂PO₄, KD₂PO₄, KH₂AsO₄, and KD₂AsO₄ have been studied. In all these crystals protons are the main carrier of the current. It is observed that with all the deuterated crystals, the enthalpy for the conduction is higher than for the normally hydrogen bonded crystal. The results are explained on the basis of the synchronous rotation mechanism proposed by the author in his earlier publications.     

Transport and structural properties of compounds (1 − <Emphasis Type="Italic">x</Emphasis>)CsHSO<Subscript>4</Subscript>-<Emphasis Type="Italic">x</Emphasis>KH<Subscript>2</Subscript>PO<Subscript>4</Subscript>

The homogeneous substitution of cations (K⁺) and anions (H₂PO₄⁻) for CsHSO₄ is performed. The dependences of protonic conductivity and structure of (1 − x)CsHSO₄-xKH₂PO₄ (x = 0.05–0.9) compounds on the composition are studied. It is found that the introduction of KH₂PO₄ leads to the formation of a new highly conductive phase. At small amounts of introduced KH₂PO₄ (x = 0.05), a mixed salt forms; its low-temperature conductivity is by more than two orders of magnitude higher than that of the source salts. The thermal behavior of mixed salt (1 − x)CsHSO₄-xKH₂PO₄ of various compositions and the peculiarities of crystal structure are studied. The structural parameters of the salt at x = 0.05–0.5 are close to those of Cs₃(HSO₄)₂(H₂PO₄). At higher x, another phase forms, whose structure has yet to be determined. The thermal stability of the salt decreases with increasing fraction of KH₂PO₄ introduced. The conductivity of the composites based on the mixed salt and silicon dioxide (1 − y){xKH₂PO₄-(1 − x)CsHSO₄}-ySiO₂ (x = 0.05, 0.1; y = 0.1–0.7) is studied. It is shown that, in the low-temperature range, the conductivity of composite systems increases within an order of magnitude, passes through a maximum, and, then, decreases at y > 0.5 due to the percolation effect.     

One-step approach for nano-crystalline hydroxyapatite coating on titanium via micro-arc oxidation

Nano-crystalline hydroxyapatite (HAp) films were formed at the surface of Ti by a single-step micro-arc oxidation (MAO) using Ca²⁺ and P⁵⁺ ion-containing electrolytes. The HAp films were 10–25 μm thick, showing strong crystallinity dependence on the CaCl₂ concentration in the electrolytes. Also, the formation of an amorphous CaTiO₃ interlayer was identified to exist between the HAp and Ti substrates. In contrast to the previous researches using K₂HPO₄ for the electrolytes, KH₂PO₄ was used in this study, and this could allow the formation of the crystalline HAp layer. It is suggested as the most probable mechanism for the HAp formation that the high-density hydroxyl groups of TiO(OH)₂, formed by the reactions between the amorphous CaTiO₃ interlayer and the H⁺ ions from the dissolution of the KH₂PO₄, can play a key role in the nucleation and crystal growth of HAp by attracting Ca²⁺ and P⁵⁺ ions in the electrolytes.     

Stability of hydroxyapatite-TiO2-Ti structures in physiological solutions of KH2PO4-Na2HPO4 at varied pH

Thermally annealed structures of hydroxyapatite-TiO₂-Ti prepared by high-frequency magnetron spraying have been studied before and after incubation in the 0.02 mol/l buffer solutions of KH₂PO₄-Na₂HPO₄ at pH 6.0, 7.0, and 8.0. Atomic force microscopy has revealed that the surface relief and mean roughness are not changed in the course of incubation. No sharp changes in the calcium to phosphorus ratio have been observed according to local X-Ray spectral microanalysis. The stability of hydroxyapatite-TiO₂-Ti towards buffer solutions has been confirmed by X-Ray powder diffraction studies.     

Isotherme à 25°C du Système Quaternaire Réciproque H3PO4?K2SO4?H2SO4?K3PO4?H2O Etude des Nappes du Liquidus

25°C Isotherm of the Reciprocal Quaternary System H₃PO₄? K₂SO₄? H₂SO₄? K₃PO₄? H₂O Study of the Liquidus Curves The liquidus of the reciprocal system H₃PO₄? K₂SO₄? H₂SO₄? K₃PO₄–H₂O has been investigated as a last step in the determination of the equilibrium diagram at 25°C and 1 atm pressure. Solubility has been detected by conductometric measurements in isopletic sections selected in order to complete the data obtained from the limiting ternary systems and the previously found boundary curves. Four isopletic sections have been completely established: K₂SO₄? KH₂PO₄, K₂SO₄? K₂HPO₄, KHSO₄? K₂HPO₄ and KHSO₄? KH₂PO₄. The two first ones are quasi ternary systems. Nine portions have been studied and the curves of equal water content plotted. The liquidus of KHSO₄, K₈(H₂PO₄)_1+x(HSO₄)_7?x and KH₂PO₄ · KHSO₄, show a rotationel shape which reveals a retrosolubility depending on the water content.     

Evaluation of the impact of phosphate salts on the formation of ionic-liquid-based aqueous biphasic systems

The present study aims at evaluating the capability of phosphate-based salts, whose anions can coexist in water depending on the media pH, to promote aqueous biphasic systems (ABS) formation with 1-butyl-3-methylimidazolium-based ionic liquids, as well as to infer on the influence of the ionic liquid anion in the overall process of liquid–liquid demixing. In this context, novel phase diagrams of ABS composed of several imidazolium-based ionic liquids and three phosphate salts and a mixture of salts (K₃PO₄, K₂HPO₄, K₂HPO₄ + KH₂PO₄, and KH₂PO₄) were determined by the cloud point titration method at 298 K and atmospheric pressure. The corresponding tie-line compositions, tie-line lengths, and pH values of the coexisting phases were also determined. The ionic liquids ability to promote ABS is related with the hydrogen-bond basicity of the composing anion – the lower it is the higher the ability of the ionic fluid to undergo liquid–liquid demixing. Moreover, similar patterns on the ionic liquids sequence were observed with the different phosphate salts. The phosphate anion charge plays a determinant role in the formation of ABS. The two-phase formation aptitude (with a similar ionic liquid) decreases in the rank: K₃PO₄ > K₂HPO₄ > K₂HPO₄ + KH₂PO₄ > KH₂PO₄. Yet, besides the charge of the phosphate anion, the pH and ionic strength of the aqueous media also influence the phase separation ability.     

Optimization of keratinase production and enzyme activity using response surface methodology with streptomyces sp7

A two-step response surface methodology (RSM) study was conducted for the optimization of keratinase production and enzyme activity from poultry feather byStreptomyces sp7. Initially different combinations of salts were screened for maximal production of keratinase at a constant pH of 6.5 and feather meal concentration of 5 g/L. A combination of K₂HPO₄, KH₂PO₄, and NaCl gave a maximum yield of keratinase (70.9 U/mL) production. In the first step of the RSM study, the selected five variables (feather meal, K₂HPO₄, KH₂PO₄, NaCl, and pH) were optimized by a 2⁵ full-factorial rotatable central composite design (CCD) that resulted in 95 U/mL of keratinase production. The results of analysis of variance and regression of a second-order model showed that the linear effects of feather meal concentration (p<0.005) and NaCl (p<0.029) and the interactive effects of all variables were more significant and that values of the quadratic effects of feather meal (p<1.72e-5), K₂HPO₄ (p<4.731e-6), KH₂PO₄ (p<1.01e-10), and pH (p 7.63e-7) were more significant than the linear and interactive effects of the process variables. In the second step, a 2³ rotatable full-factorial CCD and response surface analysis were used for the selection of optimal process parameters (pH, temperature, and rpm) for keratinase enzyme activity. These optima were pH 11.0, 45°C, and 300 rpm.     

High-pressure phase relations of CsD2PO4

The high-pressure phase diagram of CsD₂PO₄ to 4.5 GPa and temperatures between 0 and 470°C is reported. Comparisons are made with CsH₂PO₄ and correlated with the isotope effect on the high-temperature high-pressure phase relations of KH₂PO₄.     

Synthesis and Properties of a Novel Diverting Agent Derived From the Copolymerization of Acrylamide with Sodium Acrylate

A novel diverting agent, which derived from the copolymer of poly(acrylamide-co-sodium acrylate) [P(AM-co-SA)], was synthesized by using aluminium nitrate [Al(NO₃)₃] as crosslinker, L-ascorbic acid/peroxide hydrogen [Vc/H₂O₂] as initiator, and methanol as temperature regulator. Thereafter, as key investigation points, the aging time and water absorbency of the resulting diverting agent were recruited, the amount of crosslinker and initiator, the ratios between acrylic acid and acrylamide, the neutralization of acrylic acid, the feeding ratios of methanol, the temperature and the reaction time were investigated. The dependency relationship between the water absorbency and aging time on each factor was also obtained.     

Synthesis,characterization and water absorbency properties of poly(acrylic acid)/sodium humate superabsorbent composite

A novel poly(acrylic acid)/sodium humate superabsorbent composite was synthesized by aqueous solution polymerization of acrylic acid using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator in the presence of sodium humate. The effects on water absorbency such as initial monomer concentration, degree of neutralization of acrylic acid, amount of crosslinker, initiator and sodium humate, etc. were investigated. The water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with a sodium humate content of 20% exhibited an absorption of 1268 g H₂O/g sample and 93 g H₂O/g sample in distilled water and in 0.9 wt% NaCl solution, respectively. Swelling rate and water retention tests were also carried out. The results show that sodium humate, as a kind of functional filler, can enhance comprehensive properties of superabsorbent composite and reduce the product cost significantly. Copyright © 2005 John Wiley & Sons, Ltd.     

Liesegang rings of copper chromate in gelatin gel

Summary DistinctLiesegang Rings of Copper chromate in gelatin gel are not formed as the salt forms a very stable colloid in this medium. As this sol is coagulated by KH₂PO₄, well defined rings of Copper chromate in gelatin gel are formed in the presence of this electrolyte.

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Zusammenfassung DeutlicheLiesegang-Ringe werden in Kupfer-Chromat und Gelatine-Gel nicht gebildet, da das Salz ein sehr stabiles Kolloid in diesem Medium darstellt. Wenn dieses Sol durch KH₂PO₄ koaguliert wird, entstehen definierte Ringe von Kupfer-Chromat im Gelatine-Gel bei Gegenwart dieses Elektrolyten.

     

Properties of nanocrystalline electrodeposited CoFeP alloy with low phosphorus content

CoFe and low phosphorus containing (<4 at.%) CoFeP alloy films were electrodeposited from NaH₂PO₂ containing solutions at pH 4 on copper substrates under galvanostatic conditions. At the low phosphorus composition, nanocrystalline CoFeP alloy films are formed. The structure, composition and morphology of the thin films were studied using X-ray diffraction, energy dispersive spectroscopy and atomic force microscopy. The magnetic properties of the film were studied using superconducting quantum interference device magnetometer. The thin film performance features were explained on the basis of microstructural features developed during deposition. Whereas the electrodeposited CoFe alloy thin film exhibited mixed hcp and fcc phase structure in the absence of phosphorus, the low phosphorus containing thin film exhibited an increasing mixed bcc and hcp phase structure as its phosphorus content increases, showing modification in the grain size morphology and magnetic properties. In addition to applied current, the amount of P co-deposited in CoFeP alloy depends on the concentration of NaH₂PO₂ source in the bath. Qualitative analysis of the Tafel slope of CoFe and CoFeP deposition suggests that the presence of P in the CoFe deposit does not affect the mechanism of anomalous deposition of Co and Fe, thereby suggesting that CoFeP deposition is anomalous.