Magnesium Hydrogen Phosphate Trihydrate Research Articles

Calcium silicate cements endowing bioactivity and sustaining mechanical strength of low-heat-releasing and fast-curing magnesium phosphate cements.

It is known that magnesium phosphate cements (MPCs) show appreciable mechanical strength and biocompatibility, but the hydration reaction processes often lead to intense heat release while the hydration products present weak resistance to mechanical decay and low bioactivity. Herein we developed an MPC-based system, which was low-heat-releasing and fast-curing in this study, by compounding with self-curing calcium silicate cements (CSCs). The MPC composed of magnesium oxide (MgO), potassium dihydrogen phosphate (KH2PO4), disodium hydrogen phosphate (Na2HPO4), magnesium hydrogen phosphate trihydrate (MgHPO4·3H2O) and chitosan were weakly basic, which would be more stable in vivo. The physicochemical properties indicated that the addition of CSCs could increase the final setting time while decrease the heat release. Meanwhile, the CSCs could endow MPC substrate with apatite re-mineralization reactivity, especially, which add 25 wt.% CSCs showed the most significant apatite deposition. What's more, the mechanical evolution in buffer demonstrated CSCs could enhance and sustain the mechanical strength during degradation, and the internal constructs of cement implants could still be reconstructed by μCT analysis in rabbit femoral bone defect model in vivo. Particularly, appropriate CSCs adjusted the biodegradation and promoted new bone tissue regeneration in vivo. Totally, the MPC/CSCs composite system endows bioactivity and sustains mechanical strength of the MPC, which may be promising for expending the clinical applications of MPC-based bone cements.

Changes in the mechanism of the reaction between phosphate and magnesium ions: Effect of initial concentration and contact time on removal of phosphate ions from aqueous media

In this study, the mechanism of the reaction between phosphate and magnesium hydroxide ions was assessed. In particular, the effect of initial concentration and contact time on the removal of phosphate ions from aqueous media using magnesium hydroxide was demonstrated. The evaluations were conducted after analyses entailing scanning electron microscopy, powder X-ray diffraction, and elemental distribution. The rate of removal of phosphate ions using magnesium hydroxide increased with increase in the initial phosphate ion concentration. Under our experimental conditions, the products after the removal of phosphate ions were magnesium hydroxide, magnesium potassium phosphate hexahydrate, and magnesium hydrogen phosphate trihydrate when the initial concentration was low (5 to 2000 mg/L), medium (from 4000 to 8000 mg/L), and high (15,000 mg/L), respectively. When the initial concentration was 15,000 mg/L, the product changed with elapsed time. Our findings indicated that the crystalline structure changed from that of magnesium potassium phosphate hexahydrate to that of magnesium hydrogen phosphate trihydrate (after 6 h). These results serve as useful information regarding the interaction between phosphate and magnesium ions at high concentrations of phosphate ions in aqueous media.

Calcium phosphate coating on biomedical WE43 magnesium alloy pretreated with a magnesium phosphate layer for corrosion protection

Rapid degradation of biomedical magnesium alloys under physiological conditions has hindered clinical applications such as bone fixation devices. Herein, in order to mitigate corrosion, a calcium phosphate (CP) coating is prepared on the WE43 magnesium alloy (MA) pretreated with a magnesium phosphate (MP) layer to provide relatively stable deposition conditions for the CP coating and achieve smooth transition from the MA substrate to the CP coating. The MP coating is composed of magnesium ammonium phosphate hexahydrate and magnesium hydrogen phosphate trihydrate and the CP coating with improved homogeneity, compactness, and interface continuity consists of hydroxyapatite, tricalcium phosphate, and dicalcium phosphate anhydrous. The corrosion current density of MA with the composite coating decreases from (1.756 ± 0.678) × 10−4 to (9.096 ± 1.618) × 10−7 A cm−2 and the charge transfer resistance of the modified MA in the simulated body fluid (SBF) increases by 2685 times. Long-term immersion tests in SBF reveal that the composite coating suppresses leaching of magnesium ions and propagation of corrosion along the surface. The corrosion rate after soaking in SBF for 30 days drops to 0.56 mm y−1 which decreases by 77% compared to MA. The formation mechanism of the composite coating and relationship between the surface characteristics and corrosion protection are proposed and discussed.

Composite Microstructure and Formation Mechanism of Calcium Phosphate Conversion Coating on Magnesium Alloy

In order to improve the biodegradability and surface biocompatibility of magnesium (Mg) alloys, a calcium phosphate conversion coating (CPCC) was deposited onto an AZ60 Mg alloy. The coating's components and composite microstructure and its formation mechanism were studied using electrochemical measurements, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy and by developing a thermodynamic stability diagram. The results revealed that the presence of Mg2+ originating from the electrochemical reaction of the Mg alloy could affect the precipitation of different coating components. Because the concentration of Mg2+ at the solution/coating interface continuously changed, three layers of the conversion coating were progressively produced. The inner layer was composed of magnesium hydrogen phosphate trihydrate (MHPT, MgHPO4·3H2O) and had a thickness of ∼1.1 μm. The middle layer was ∼1.6 μm thick and consisted of dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O), magnesium whitlockite (MWH, Ca9Mg(HPO4)(PO4)6), and MHPT. The top layer was ∼2.3 μm thick and was composed of a combination of DCPD and MWH.

Formation Mechanism of Magnesium Ammonium Phosphate Stones: A Component Analysis of Urinary Nanocrystallites

The components of urinary nanocrystallites in patients with magnesium ammonium phosphate (MAP) stones were analyzed by X‐ray diffraction (XRD), Fourier‐transform infrared (FT‐IR) spectrometer, high‐resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), fast Fourier transformation (FFT), and energy‐dispersive X‐ray spectroscopy (EDS). The main components of the stones were MAP hexahydrate (MAP·6H2O), magnesium hydrogen phosphate trihydrate (MgHPO4·3H2O), and a small amount of calcium phosphate (CaP), while the main components of urinary nanocrystallites were MgHPO4·3H2O, CaP, and MAP monohydrate (MAP·H2O). MAP·H2O induced the formation of MAP stones as seed crystals. MgHPO4·3H2O was accompanied by the appearance of MAP·6H2O. The formation mechanism of MAP stones and influencing factors were discussed on the basis of the components of urine nanocrystallites. A model diagram of MAP stone formation was also put forward based on the results. Formation of MAP stones was closely related to the presence of high amounts of MAP crystallites in urine. Urinary crystallite condition and changes in urine components could indicate the activity of stone diseases.

Kinetic and thermodynamic studies of MgHPO4 · 3H2O by non-isothermal decomposition data

Abstract The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO4 · 3H2O was investigated in air atmosphere using TG-DTG-DTA. MgHPO4 · 3H2O decomposes in a single step and its final decomposition product (Mg2P2O7) was obtained. The activation energies of the decomposition step of MgHPO4 · 3H2O were calculated through the isoconversional methods of the Ozawa, Kissinger–Akahira–Sunose (KAS) and Iterative equation, and the possible conversion function has been estimated through the Coats and Redfern integral equation. The activation energies calculated for the decomposition reaction by different techniques and methods were found to be consistent. The better kinetic model of the decomposition reaction for MgHPO4 · 3H2O is the F 1/3 model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”. The thermodynamic functions (ΔH*, ΔG* and ΔS*) of the decomposition reaction are calculated by the activated complex theory and indicate that the process is non-spontaneo...

Synthesis of Poly(butylene succinate) and Poly(ethylene succinate) Including Diglycollate Moiety

Poly(butylene succinate) (PBS) copolymers were prepared from succinic acid, diglycollic acid, and 1,4-butanediol, in the presence of titanium tetraisopropoxide and magnesium hydrogen phosphate trihydrate. All the polymers produced exhibited a higher number-average molecular weight than 65,000. The composition of the copolymers was found to be almost the same as the feed composition. The copolymers exhibited a higher break strain compared to the homopolymer. The biodegradability of copolymers showed a maximum when 2% diglycollic acid was added. However, the addition of more diglycollic acid decreased biodegradability. Poly(ethylene succinate) (PES) copolymers, including diglycollate moiety, were also prepared from succinic acid, diglycollic acid, and ethylene glycol, using the same reaction conditions as the PBS copolymers. Unlike the PBS copolymers, the molecular weights of the PES copolymers decreased for an increasing amount of diglycollate while the biodegradability rose with an increase of the diglycollate ratio in the copolymers, in the range 0–20%.

Calcium Phosphates as Fillers in Struvite Cements

Struvite or magnesium ammonium phosphate MgNH4PO4 has been proposed as active component in setting surgical cements. The usual formulation is one in which the magnesium component in the powder is either magnesium hydrogen phosphate trihydrate or trimagnesium phosphate or a mixture of these two compounds. As the cement liquid a concentrated solution of diammonium phosphate is taken. To make the cement attractive as a bone substitute material a calcium phosphate filler is generally incorporated. Thus such materials are a type of pseudo calcium phosphate cements. This study was intended to find out which calcium phosphate and which magnesium compound are the most suitable. In the first series of experiments a mixture of 12 g Mg3(PO4)2 and 4 g MgHPO4.3H2O was used as the magnesium component in the powder. To that powder 30 g of either precipitated hydroxyapatite PHA or CaHPO4 or CaHPO4.H2O or b-TCP or a-TCP was added. The cement liquid was a 3.5 M solution of (NH4)2HPO4. At specific liquid/powder ratios L/P suitable setting times were obtained for the different formulations. However, the compressive strengths after immersion of the cements in 0.9% saline solution at 37°C varied over a large range. The best formulation was that with a-TCP which reached a compressive strength of 57 MPa after 18 h of immersion. In the second series of experiments 20 g of Mg3(PO4)2 was used as the magnesium component in the powder. Again 30 g of either of the above mentioned calcium phosphates was used as filler and again a 3.5 M solution of (NH4)2HPO4 was used as the cement liquid. At the appropriate L/P ratios the respective setting times were longer than in the first series of experiments but all five formulations appeared to result in good compressive strengths varying from 41 MPa for the formulation with b-TCP to 67 MPa for the formulation with PHA. In the third series of experiments 30 g a-TCP was taken as the calcium phosphate in the powder. As magnesium components mixtures of Mg3(PO4)2.8H2O and MgHPO4.3H2O and Mg3(PO4)2 were used. Again the cement liquid consisted of a 3.5 M solution of (NH4)2HPO4. The formulations with Mg3(PO4)2.8H2O had the shortest setting times and the lowest compressive strengths, whereas those with Mg3(PO4)2 had the longest setting times and the highest compressive strengths. Therefore, it is advantageous to use Mg3(PO4)2 as the magnesium component.

Vibrational Spectra of Magnesium Hydrogenphosphate Trihydrate and of its Manganese Analogue

Abstract The infrared (IR) and Raman spectra of MgHPO4. 3H2O and of a series of partially deuterated analogues as well as the IR spectra of MnHPO4. 3H2O have been recorded and interpreted. The analysis of the IR spectra in the HOD bending region rules out the possibility of existence of H3OC+ ions in the structure.

Preparation of Trimagnesium Phosphate by Mechanochemical Reaction

Trimagnesium phosphate hydrate was synthesized by mechanochemical reaction of a slurry of magnesium hydrogen phosphate trihydrate and magnesium oxide with the molar ratio of 2:1 in a pot mill for a few hours. Mg3(PO4)2⋅8H2O was obtained by using a slurry with more than 60wt% water; Mg3(PO4)2⋅22H2O, with 40wt% water. The anhydrate of trimagnesium phosphate was obtained by heating Mg3(PO4)2⋅8H2O or Mg3(PO4)2⋅22H2O above 700°C.

The Solubility of Calcium Hydrogen Phosphate Dihydrate and Magnesium Hydrogen Phosphate Trihydrate and Ion Pair Formation in the System M(OH)2‐H3Po4‐H2O (M = Ca or Mg) at 37°C

AbstractThe solubility of CaHPO4·2H2O and MgHPO4·3H2O is determined in the system M(OH)2‐H3PO4‐H2O at 37°C with M = Ca or Mg and in the range 4.1 < pH < 6.3 and 4.9 < pH < 7.2 respectively. The solubility behaviour of both solids can be described consistently only by taking into account the formation of the ion pairs MH2PO4+ and MHPO4. The thermodynamic solubility product of CaHPO4·2H2O and the thermodynamic association constants for CaH2PO4 + and CaHPO4 with their standard error are determined as (2.06 ± 0.05)×10−7 mol2/L2, 8.4 ± 1.7 L/mol and 542 ± 46 L/mol. The corresponding constants for MgHPO4·3H2O, MgH2PO4 + and MgHPO4 are (1.15 ± 0.07)×106 mol2/L2, 43.0 ± 6.7 L/mol and 1004 ± 89 L/mol.

Solubility of magnesium hydrogen phosphate trihydrate and ion-pair formation in the system magnesium hydroxide-phosphoric acid-water at 25.degree.C

Solubility of magnesium hydrogen phosphate trihydrate and ion-pair formation in the system magnesium hydroxide-phosphoric acid-water at 25.degree.C

The mineral composition of some India and Indonesian bladder stones.

Abstract Examination of 70 bladder stones from India and Indonesia seems to show that a large number of them arise with a primary formation of a small ammonium hydrogen urate stone. This is particularly pronounced in the bladder stones from boys, 14 of 17 “nuclei+Zone 1” being of this composition. Further research on the etiology of these stones should thus be directed toward the uric acid metabolism and excretion in children in the areas where the stones are endemic.It has been shown that magnesium hydrogen phosphate trihydrate is of relatively frequent occurrence in these bladder stones, and that this mineral has a characteristic location in relation to magnesium ammonium phosphate hexahydrate.There is a marked excess of calcium oxalate monohydrate in relation to the dihydrate, and apatite is found more rarely than in European stones.

Phase changes during heating of magnesium ammonium phosphate hexahydrate and magnesium hydrogen phosphate trihydrate to high temperatures

Magnesium ammonium phosphate hexahydrate MgNH4PO4,6H2O and magnesium hydrogen phosphate trihydrate MgHPO4,3H2O have been heated to temperatures up to 1220° and X-ray powder photographs taken of the products. Both substances decompose during the process and gradually change first into an amorphous phase and then into crystalline magnesium pyrophosphate. The incandescence which appears on the ignition of these substances may be associated with the dimerisation of the ion HPO42–.