Amorphous Aluminum Phosphate Research Articles

Surface engineering of P2-type cathode material targeting long-cycling and high-rate sodium-ion batteries

The widespread interest in layered P2-type Mn-based cathode materials for sodium-ion batteries (SIBs) stems from their cost-effectiveness and abundant resources. However, the inferior cycle stability and mediocre rate performance impede their further development in practical applications. Herein, we devised a wet chemical precipitation method to deposit an amorphous aluminum phosphate (AlPO4, denoted as AP) protective layer onto the surface of P2-type Na0.55Ni0.1Co0.1Mn0.8O2 (NCM@AP). The resulting NCM@5AP electrode, with a 5 wt% coating, exhibits extended cycle life (capacity retention of 78.4% after 200 cycles at 100 mA g−1) and superior rate performance (98 mA h g−1 at 500 mA g−1) compared to pristine NCM. Moreover, our investigation provides comprehensive insights into the phase stability and active Na+ ion kinetics in the NCM@5AP composite electrode, shedding light on the underlying mechanisms responsible for the enhanced performance observed in the coated electrode.

Selective oxidation of methanol to green oxygenates on vanadium-aluminum phosphate based catalysts

The methanol transformation reaction in the presence of oxygen was carried out in the temperature range of 210–310 ºC, over vanadium catalysts based on vanadium oxide (V2O5) and on vanadium-phosphorus oxide (VPO) calcined at 450 ºC in air. Specifically, the vanadium oxide systems with V2O5 loadings below, above or corresponding to the theoretical monolayer (1–34 wt% of V2O5) were obtained by the impregnation of a mesoporous amorphous aluminum phosphate, AlPO4, calcined at different temperatures (from 350 ºC to 650 ºC) with vanadyl oxalate. Additionally, mechanical mixtures of either VPO or V2O5 with AlPO4 were also employed. Under the experimental conditions employed, with a methanol enriched feed (O2/methanol molar ratio=0.6), formaldehyde and dimethoxymethane were the main products obtained with all the catalysts studied. Vanadyl phosphate (VPO) exhibited slightly lower activity than vanadium oxide, formaldehyde being the main product (SFA ≥ 95%). The conversion of both vanadium oxide and vanadyl phosphate appreciably increased when mixed with the AlPO4, also promoting the formation of dimethoxymethane. The interaction of the vanadium species with the aluminum phosphate surface took place preferentially through the surface Al-OH groups, the vanadium species with less development being the most active in the formation of formaldehyde and dimethoxymethane, per at-g of vanadium.

Impact of aluminum adjuvants on the stability of pneumococcal polysaccharide-protein conjugate vaccines

Development of a vaccine drug product requires formulation optimization to ensure that the vaccine’s effectiveness is preserved upon storage throughout the shelf-life of the product. Although aluminum adjuvants have been widely used in vaccine formulations to safely and effectively potentiate an immune response, careful attention must be directed towards ensuring that the type of aluminum adjuvant does not impact the stability of the antigenic composition. PCV15 is a polysaccharide-protein conjugate vaccine comprising the pneumococcal polysaccharide (PnPs) serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F and 33F), each individually conjugated to the protein carrier CRM197. PCV15 was formulated with either amorphous aluminum hydroxyphosphate sulfate adjuvant (AAHS) or aluminum phosphate adjuvant (AP) and examined for both stability and immunogenicity. Using a collection of methods to evaluate vaccine stability, it was discovered that certain PCV15 serotypes (e.g., 6A, 19A, 19F) formulated with AAHS resulted in a reduction of immunogenicity in vivo and a reduction in recoverable dose as tested by an in vitro potency assay. The same polysaccharide-protein conjugates formulated with AP were stable regarding all measures tested. Moreover, the reduction in potency of certain serotypes correlated with chemical degradation of the polysaccharide antigen caused by the aluminum adjuvant as measured by reducing polyacrylamide gel electrophoresis (SDS-PAGE), High-Pressure Size Exclusion Chromatography coupled with UV detection (HPSEC-UV) and ELISA immunoassay. This study suggests a formulation, which includes AAHS, may negatively impact the stability of a pneumococcal polysaccharide-protein conjugate vaccine that contains phosphodiester groups. This decrease in stability would likely result in a decrease in the “active” concentration of antigen dose, and herein, it is shown that such instability directly compromised vaccine immunogenicity in an animal model. The results presented in this study help to explain critical degradation mechanisms of pneumococcal polysaccharide-protein conjugate vaccines.

Preclinical evaluation of the degradation kinetics of third-generation resorbable magnesium scaffolds.

The novel sirolimus-eluting resorbable scaffold DREAMS 3G was designed as a third-generation development of its predecessor, the Magmaris scaffold. This preclinical study aimed to examine the qualitative and temporal course of the degradation of the DREAMS 3G relative to the Magmaris scaffold. Forty-nine DREAMS 3G and 24 Magmaris scaffolds were implanted into 48 mini swine for degradation kinetics analysis. Another DREAMS 3G was implanted into one mini swine for crystallinity analysis of the degradation end product after 730 days. Degradation kinetics were determined at 28, 90, 120, 180, and 365 days. Discontinuity density in DREAMS 3G was significantly lower than that in Magmaris scaffolds for the follow-up timepoints of 90 and 120 days. Planimetric analysis indicated 99.6% backbone degradation for DREAMS 3G at 12 months. Compared to the Magmaris scaffold, individual strut degradation in DREAMS 3G showed less variability and the remaining backbone core was more homogeneous. The degradation end product of DREAMS 3G manifested as calcium phosphate with a minor share of aluminium phosphate. DREAMS 3G showed almost complete degradation after one year, with amorphous calcium and aluminium phosphate as the end products of degradation. Despite its thinner struts, scaffold discontinuity was significantly lower in the DREAMS 3G than in the Magmaris scaffold, likely providing a longer scaffolding time.

Corrosion resistance of amorphous AlPO4 coating in salty atmospheres

AbstractThe objective of the present study was to introduce a cost‐effective and environmentally friendly coating to improve the corrosion resistance of the structures located in salt water. The coating solution, based on amorphous aluminum phosphate composition, was synthesized by sol–gel process and applied to AISI 304 stainless steel by dip coating technique. X‐ray diffraction, scanning electron microscopy, and energy dispersive X‐ray spectroscopy analyses were employed to investigate the phase composition and morphology of the coating. Corrosion behavior of the uncoated and coated samples was investigated using standard salt spray test, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. Salt spray test results for the bare substrate revealed a corrosion rate of six‐time greater than that of the coated surface after 168 hr exposure time. Electrochemical test results declared that the amorphous AlPO4 coating decreased the corrosion current density of the AISI 304 stainless steel by 10 orders of magnitude. Furthermore, according to the corresponding EIS measurements, the coated surface exhibited a superior anti‐corrosion performance than uncoated sample. Overall, the results declared that the amorphous AlPO4 coating could be a good choice for surface protection of stainless steel against electrochemical corrosion in salty environments.

The preparation and property analysis of B4C modified inorganic amorphous aluminum phosphates-based intumescent flame retardant coating

In response to high environmental requirements, an incombustible inorganic intumescent flame retardant coating was prepared from amorphous aluminum phosphate emulsion as the matrix, with boron carbide as the modifier. The influence of boron carbide (B4C)on the fire resistance performance and physic-chemical properties of coatings were studied by means of large panel combustion method, smoke density test, Fourier transformed infra-red analysis (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET method) and pore size analysis. With the addition of 0.75 wt% B4C, the backside temperature of APB3 coating (aluminum phosphate-based coating modified with 0.75 wt% B4C) after an hour was only 140 ℃, 33.4 % lower than that of blank APB0 coating. And the smoke density (Ds) of APB3 was only 64.73 %, 36.3 % lower than that of blank APB0. The foaming expansion caused by decomposition reactions, the structural improvement caused by boron carbide oxidation, and the formation of ablative resistant ceramics and glass were the main reasons for excellent flame retardant and thermal insulation performance. Remarkably, the melting B2O3 generated from the oxidation of B4C could repair cracks, modify pore structure, improve the integrity of closed pores, increase the specific surface area of porous structure, and promote the formation of borosilicate glass. Due to the structural integrity of the outermost coating surface caused by the oxidation of B4C and the construction of borosilicate glass, much gas was shielded inside the coating, making the coating more eco-friendly. Besides, APB3 coating has good water resistance. After immersion in water for 360 h, the reduction rate of fire resistance performance of the coating was only 17.1 %. This work provides theoretical guidance for broadening the types of intumescent coatings and promotes the development of inorganic green coatings.

Influence of aluminum sulfate on properties and hydration of magnesium potassium phosphate cements

Aluminum sulfate shows a positive effect on preventing efflorescence of magnesium potassium phosphate (MKP) cements. Its influence on the MKP cement properties and hydration is explored in this study. Compared to a reference cement (Mg/PO4 molar ratio = 4, w/c ratio = 0.25), aluminum sulfate retards setting, increases compressive strength, and has little influence on the short-term volume stability. Aluminum sulfate slows down the hydration kinetics, decreases the pH values, accelerates the depletion of KH2PO4, and thus mitigates the formation of efflorescence. It also modifies the hydrate assemblage. In addition to K-struvite, aluminum sulfate leads to the formations of arcanite and aluminum-containing hydrates such as amorphous aluminum phosphate, possibly phosphate containing LDH (layered double hydroxide) and minyulite-like phases. The formation of amorphous MgHPO4 and minor amounts of bobierrite and brucite as observed in the reference paste, are suppressed in the presence of aluminum.

Aluminum phosphate as active matrix of fluid catalytic cracking catalysts: Y zeolite stabilization

The development of new matrices can improve the hydrothermal stability of fluid catalytic cracking catalysts and provide better selectivity to cracking products. Amorphous, mesoporous and stoichiometric aluminum phosphate (AlPO4) was investigated as active matrix to achieve these purposes. In its gel form, the material was initially added to ultra-stabilized Y zeolite to generate composites with mass ratio of about 1:1. The interaction between AlPO4 and Y zeolite avoided AlPO4 crystallization during steaming and increased framework aluminum retention, preserving more Brönsted acid sites. A spray-dried catalyst containing AlPO4 was steam deactivated and tested by vacuum gas oil cracking, being compared with an alumina-containing catalyst and a reference without active matrix. AlPO4-containing catalyst presented tolerance to contaminant metals, higher selectivity to naphtha yields and exhibited a higher hydrogen transfer reaction rate, leading to the increase in isoparaffins and aromatics yields and the increase in the motor octane number in the cracked naphtha.

Investigation of Phosphate based geopolymers formation mechanism

In the present research, phosphate-based geopolymers were prepared from metakaolin and commercial phosphoric acid H3PO4. The paper aims to observe and identify the different chemical early steps of the material formation mechanism, as well as the kinetics of each step. To achieve this goal, an investigation upon the reaction with respect to time has been fulfilled, using different techniques such as atomic absorption measurements, in situ quasi-isothermal Differential Scanning Calorimetry (DSC), pH-metry measurements, Scanning Electron Microscope (SEM) with Energy-dispersive X-ray (EDX) analysis, X-ray diffraction, magic angle spinning Nuclear Magnetic Resonance (MAS-NMR) and Fourier Transform Infrared spectroscopy (FTIR). As a result, a composite structure composed of amorphous aluminum phosphate phases and amorphous silica phases dispersed in a geopolymeric amorphous structure of (-Si-O-Al-O-P-) units with the presence of some terminal-Si-O-P units, was observed. Furthermore, the techniques combination suggested a geopolymeric mechanism composed principally of three great processes: the first one stands for the dealumination process. It was proved that this process is divided into two elementary overlapping steps. The second one corresponds to the condensation process. It was proved that this process is divided into four types of condensation, according to the chemical nature of the reactant units as well as that of the obtained ones. Eventually, the last one represents the polycondensation step, resulting in the finally polymerized 3D structure. In addition, this work monitored the duration and the kinetics of each geopolymeric step.

On structure and oxidation behaviour of non-stoichiometric amorphous aluminium phosphate coating

ABSTRACTThe purpose of this study was to investigate the structure and oxidation behaviour of non-stoichiometric aluminium phosphate coating. Phase composition analysis was performed by X-ray diffractometer (XRD). Fourier transform infrared (FTIR) was used for molecular spectroscopy. The micro-structural studies were investigated by TEM. AISI 304 stainless steel substrates were dip coated in the aluminium phosphate solution to evaluate the cyclic oxidation behaviour. The oxidised samples were characterised by SEM/EDS and XRD techniques. The XRD patterns and TEM images confirmed the amorphous structure of as-synthesised aluminium phosphate. Based on the FTIR result, the non-stoichiometric amorphous aluminium phosphate owned Al−O−Al bonding besides Al−O−P. Weight change measurements after 100 h oxidation at 1100°C revealed that the range of the weight gain of the bare substrate was 30 times higher than that of the coated one.

Layered double hydroxides for phosphorus recovery from acidified and non-acidified dewatered sludge

Phosphate, which contains the essential element phosphorous (P), is a necessary fertilizer for agriculture, but the current phosphate deposits are running out and alternative sources are needed. Sludge obtained from wastewater treatment plants contains high concentrations of phosphorus and represents an alternative, sustainable source. In this study, sludge obtained from a wastewater treatment plant with biological and chemical phosphorus removal was acidified (pH = 3, 4, 5 and 6) to release orthophosphate followed by sequestration of the orthophosphate by a zinc aluminum layered double hydroxide (Zn2Al-LDH). Sulfuric acid (H2SO4), nitric acid (HNO3), and hydrochloric acid (HCl) was tested, which showed that only sulfate anions compete with phosphate and results in reduced phosphate recovery (25–35%). The orthophosphate concentration in the liquid phase increased from 20% (raw sludge) to 75% of the total phosphorus concentration at a pH of 3, which enhanced the phosphate uptake by the ZnAl-LDH from 1.7 ± 0.2% to 60.3 ± 0.6%. During acidification, the competing anion carbonate is degassed as CO2, which further improved the phosphate uptake. PXRD showed the intercalation of carbonate in the LDH in the raw sludge at pH = 8, whereas orthophosphate was intercalated at lower pH values. 27Al MAS NMR spectroscopy and powder X-ray diffraction (PXRD) proved preservation of the LDH at all pH values. Furthermore, about a fourth of the Al is present as an amorphous aluminum phosphate (AlPO4) upon exposure to phosphate at low pH (pH = 3 and 5) based on 27Al MAS NMR spectroscopy. At a pH of 6 about a third of the P is present as brushite (CaHPO4·2H2O).

Evaluating oxidation behavior of amorphous aluminum phosphate coating

The aim of this study was to investigate the oxidation properties of amorphous aluminum phosphate coating. Aluminum phosphate precursor solution was prepared by a sol–gel process and then applied on AISI 304 stainless steel using dip coating technique. To evaluate the oxidation behavior, samples were placed in an electrical furnace upto 1100 °C for 100 h in air with weight measurements performed at regular ten-hour intervals. Phase composition analysis of the coatings before and after cyclic oxidation process were performed by X-ray diffractometer (XRD). The surface and cross-sectional morphology of the coatings were observed using scanning electron microscopy (SEM) analysis equipped with energy dispersive spectroscopy of characteristic X-rays (EDS). The amorphous-nanocrystalline structure and distribution of nanocrystals in the amorphous matrix were studied by transition electron microscopy (TEM). According to SEM images a uniform, continuous and crack-free coating was achieved. XRD analysis as well as TEM observations showed that the amorphous structure of coating remained unchanged after annealing at 500 °C for 15 min however; an amorphous-nanocrystalline structure was obtained after annealing at 1100 °C for 1 h. Weight change measurements after 100 h oxidation test revealed that the trace of weight gain against oxidation time for both coated and un-coated substrates were parabola in nature and the range of the weight change of the bare substrate was about 30 times greater than that of observed for the aluminum phosphate coating. In general, the results showed that the synthesized amorphous aluminum phosphate is capable of surface protecting of metals/alloys against degradation at harsh environments.

Sustainable reclamation of phosphorus from incinerated sewage sludge ash as value-added struvite by chemical extraction, purification and crystallization

Abstract A novel procedure for phosphorus (P) recovery as struvite from incinerated sewage sludge ash (ISSA) was proposed and investigated. The procedure is divided into three steps: transform P in the ISSA to amorphous iron phosphate (Fe P) and aluminum phosphate (Al P) by acid washing followed by alkali precipitation, re-dissolve Fe P and Al P via acid washing and adsorption of Fe and Al ions by a cation exchange resin (CER), and struvite crystallization. Results showed that about 80.4% P in the ISSA was successfully transformed to Fe P and Al P accompanied by achieving the removal of most undesirable metals. Subsequently, Fe and Al ions in the leachate of completely re-dissolution of Fe P and Al P in 2 N HCl were absorbed by CER to obtain a purified P solution. Over 99.0% of P in the purified P solution was recovered as struvite with a high purity (76.0%) and low heavy metal contents (Zn, Cu, As and Pb＜50 mg/kg) at a 1:1:1 M ratio of Mg: N: P and pH of 9.5. Overall, 79.7% P in the ISSA could be recovered as struvite with negligible environmental risk.

Polyesterification synthesis of amorphous aluminum phosphate thermal radiation material with high infrared emissivity

In this paper, a new kind of high infrared emissivity material, amorphous aluminum phosphate (AlPO4) was fabricated by polyesterification reaction between P2O5 and Al(NO3)3·9H2O in ethyl alcohol (EtOH) solvent, followed by being calcined at certain temperatures. And the influence of calcination temperatures on crystallization behavior, solid 27Al and 31P chemical shift changes and infrared radiation performance were studied. DSC-TG curves demonstrate that no significant crystallization and crystal transformation occurred below 900 °C. XRD patterns and 27Al and 31P NMR spectra reveal P and Al chemical coordination transformation from octahedral to tetrahedral, these characterizations all prove that AlPO4 in amorphous state possesses higher emissivity than that of crystalline AlPO4. Amorphous AlPO4 with the highest infrared emissivity of 0.913 was prepared at 900 °C.

Speciation and fractionation of phosphorus in biosolids-amended soils: effects of water treatment residual nanoparticles

Phosphorus (P) speciation and fractionation are useful tools for assessing P mobility and potential transfer to water bodies. The current study aims to evaluate drinking water treatment residual nanoparticles (nWTRs) effects on P species in biosolids-amended soils using sequential chemical fractionation and mineral equilibrium model. Three different soil types were selected (El-Bostan, Kafr El-Dawar, Borg Al-Arab), amended with biosolids (3%), and different rates of nWTRs were applied. The P fractionation results revealed that addition of nWTRs to biosolids-amended El-Bostan soil increased the immobile aluminum phosphates from 27.30 to 88.90, 92.20, and 94.93% at 0.10, 0.20, and 0.30% application rate, respectively. Similar trend was noticed in Kafr El-Dawar soil. In Borg Al-Arab soil, nWTRs significantly (p < 0.05) increased aluminum phosphate to only 71.73% at the highest application rate (0.30%) due to its high content of calcium carbonate (35.70%). Similarly, phosphorous speciation analysis revealed that application of nWTRs significantly increased the proportions of immobile phosphate form (P sorbed to Al hydroxide) and amorphous sodium aluminum phosphate. Thus, water degradation via eutrophication can be minimized by applying nWTRs to biosolids-amended soils.

Mobilization of X‐ray amorphous and crystalline aluminum and iron phosphates by common soil extraction procedures

Soil extraction with 0.1 M NaOH completely dissolves X-ray amorphous as well as crystalline AlPO4 and FePO4. Extraction with acidic NH4 oxalate completely mobilizes X-ray amorphous AlPO4 and FePO4 in addition to phosphate adsorbed to poorly-crystallized Al and Fe minerals, but only a minor portion of crystalline AlPO4 and FePO4. Extraction with dithionite-citrate-bicarbonate mobilizes X-ray amorphous AlPO4 and FePO4 as well as crystalline FePO4, but only a minor portion of crystalline AlPO4.

Vanadium oxides supported on amorphous aluminum phosphate: Structural and chemical characterization and catalytic performance in the 2-propanol reaction

The synthesis of vanadium oxide systems with V2O5 loadings below, above or corresponding to the theoretical monolayer (1–34wt.% of V2O5) obtained by impregnation with vanadyl oxalate or vanadyl acetylacetonate of a mesoporous amorphous aluminum phosphate, AlPO4, calcined at different temperatures (from 350°C to 650°C), has been carried out. Materials were characterized by XRD, Raman, DR UV–vis, 51V, 27Al and 31P MAS NMR and nitrogen adsorption. Their acidity and reducibility were evaluated through pyridine TPD and hydrogen TPR, respectively, and their catalytic behavior in the 2-propanol reaction. The vanadium salt promoted the crystallization and loss of porosity of AlPO4, to a greater degree when acetylacetonate of vanadyl was the vanadium source and the vanadium loading increased. Similarly, the highest vanadia dispersion was obtained on AlPO4 calcined at 350°C and impregnated with vanadyl oxalate. The vanadium systems were more active than their respective supports in the 2-propanol reaction. Furthermore, the weak-medium acid sites that predominate in AlPO4 and vanadia species are the active sites for the propene formation. The formation of propanone required redox sites, the most active being those of the vanadia species in close contact with AlPO4, which were also more easily reducible. Both parallel reactions would proceed though concerted mechanisms.

Production of acrolein from glycerol in liquid phase on heterogeneous catalysts

Research has been carried out on the liquid phase dehydration of glycerol to acrolein on mesoporous amorphous aluminum phosphates obtained by a simple ammonia sol–gel method and calcined at 450°C and 650°C as well as on commercial zeolites with different SiO2/Al2O3 ratio and structures (H-ZSM-5 and HY). The acidity of the solids was evaluated by pyridine adsorption (TPD and DRIFT) and also by the 2-propanol reaction test. The AlPO4-650 exhibited the highest yield to acrolein 23% (3.1mmolACR/gcath) at 270°C and 1bar pressure. The activity of the solids in the dehydration of glycerol to acrolein was not only affected by their acidity (nature and strength of the acid sites) but also by the volume and diameter of pore.

Amorphous AlPO4 coating formed on titanium alloy for high temperature oxidation protection: Oxidation kinetics and microstructure

Amorphous AlPO4 based ceramic coatings with 13μm thick were prepared on Ti–6Al–2Zr–1Mo–1V titanium alloy surface using amorphous aluminum phosphate as a binder and Al2O3/Cr2O3 based mixing particles as the fillers. The phase composition and microstructure of the coated samples before and after exposing oxidation test were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). After exposing oxidation at 600°C for 100h, no oxide scales were found either at coating/substrate interface or on coating surface, exhibiting a significantly lower weight gain (0.07mg/cm2) compared with the bare titanium (0.54mg/cm2). After exposing oxidation at 800°C, the TiO2 dominated oxide scales began to form on coating surface after oxidation for 5h and at coating/substrate interface after oxidation for 60h, finally got weight gain of 1.4mg/cm2 after oxidation for 100h. The coating had a higher infrared emissivity value (>0.8) than titanium substrate (0.15–0.3) in the wide wavelength range of 3–20μm, which was attributed to the uniform dispersion of high emissivity Al2O3 and Cr2O3 particles in the amorphous AlPO4 binder matrix.

Organic–inorganic hybrid hierarchical aluminum phenylphosphonate microspheres

Organic–inorganic hybrid phenylphosphonates with hierarchical morphologies have attracted much attention due to their structural versatility for various applications including catalysis, adsorption, and biomedicals, however, so far there have been no reports of the synthesis and application of aluminum phenylphosphonate microspheres. Here, we report a hydrothermal method for the synthesis of the flower-like porous aluminum phenylphosphonate microspheres by using phenylphosphinic acid and aluminum nitrate as the precursors. The nano-flakes formed in the initial growing stage are believed to play a key role in the formation of aluminum phenylphosphonate micro-flowers. The self-assembly of the flower-like microspheres has been identified to involve a two-stage growth process: a synergistic Ostwald ripening and oriented nanosheets attachment. The resultant aluminum phenylphosphonate micro-flowers can be easily converted to mesoporous amorphous aluminum phosphates by high temperature treatment without causing any morphology deterioration. The hierarchical aluminum phenylphosphonate microspheres have been applied to enrich peptide. This versatile synthesis method would enable to synthesize other metal phosphonates/phosphates spheres with interesting architecture for the potential application in catalysis, energy storage and nanomedicine.