Phosphate Pellets Research Articles

U(Ⅵ) sorption by porous sodium zirconium phosphate pellets from aqueous solution

Zirconium phosphate is the first artificially produced layered phosphate that can sorb a variety of nuclides from solutions. Sodium zirconium phosphate (NZP) was a type of α-zirconium phosphate (α-ZrP). The porous sodium zirconium phosphate pellets (p-NZP-P) with a diameter of more than ∼3 mm were prepared and used for uranium sorption. The p-NZP-P could be immersed in solutions for more than 5 days without dissolving and structurally collapsing. The sorption properties of U(Ⅵ) on p-NZP-P in solutions were investigated by both static and dynamic sorption tests. Synthetic p-NZP-P was analyzed in detail using various characterizations to investigate their character and structural changes. In the static sorption experiment, the equilibrium sorption capacity reached the 77.5 ± 1.5 mg·g−1 when the initial concentration of U(Ⅵ) was 100 mg/L, pHinitial = 4.5, T = 25 ℃. Uranium sorption increased by ∼69 % and ∼215 %, respectively, when the initial uranium concentration was increased from 100 to 300 mg·L−1 and the temperature was increased from 15 to 55 °C. Furthermore, uranium sorption increased by ∼541 % when the initial pH increased from 2.5 to 4.5, while it decreased by ∼39 % when the initial pH increased from 4.5 to 7.0. The sorption data corresponded to the pseudo-second-order kinetic model and the Langmuir isotherm model, as well as the theoretically predicted value of sorption capacity (∼199.9 mg·g−1). The results of the dynamic sorption experiment showed that decreasing the quality, increasing the flow rate and the initial U(Ⅵ) concentration would shorten the breakthrough time. The dynamic sorption data agreed well with the Thomas model. The characterization confirmed the porous properties, while the U(Ⅵ) sorption mechanisms relate to –OH coordination and ion exchange. A radioactive rare earth wastewater treatment test suggested that p-NZP-P could be the potential uranium sorbent due to its good stability and efficiency. This paper opened opportunities for the development of practical materials for treating radioactive wastewater in the application of actual scenarios.

Recovery of Lithium from Industrial Li-Containing Wastewater Using Fluidized-Bed Homogeneous Granulation Technology

In this study, a novel fluidized-bed homogeneous granulation (FBHo-G) process was developed to recover lithium (Li) from industrial Li-impacted wastewater. Five important operational variables (i.e., temperatures, pH, [P]0/[Li]0 molar ratios, surface loadings, and up-flow velocities (Umf)) were selected to optimize the Li recovery (TR%) and granulation ratio (GR%) efficiencies of the process. The optimal operational conditions were determined as the following: a temperature of 75 °C, pH of 11.5, [P]0/[Li]0 of 0.5, surface loading of 2.5 kg/m2·h, and Umf of 35.7 m/h). The TR% and GR% at optimal condition could be as much as 90%. The material characterization of the recovery pellet products showed that they were highly crystallized Li3PO4 (purity ~88.2%). The pellets had a round shape and smooth surface with an average size of 0.65 mm, so could easily be stored and transported. The high purity enables them to be further directly reused as raw materials for a wide range of industrial applications (e.g., in the synthesis of cathode materials). Our calculation shows that the FBHo-G process could recover up to 0.1845 kg of lithium per cubic meter of Li-containing wastewater, at a recovery rate of ~90%. A brief technoeconomic analysis shows that FBHG process had economic viability, with an estimate production cost of USD 26/kg Li removed, while the potential gained profit for selling lithium phosphate pellets could be up to USD 48 per the same volume of wastewater and the net profit up to USD 22/m3 Li treated. In all, fluidized-bed homogeneous granulation, a seedless one-step recovery process, opens a promising pathway toward a green and sustainable recycling industry for the recovery and application of the resource-limited lithium element from nonconventional water sources.

Fabrication and Model-Guided Design of Thick-Format Lithium Ion Electrodes

To enable the use of renewable energy in place of fossil fuels for grid-scale electricity generation, low-cost, long-duration (3 hr charge, 12 hr discharge) energy storage systems must be developed to bridge the intermittency of these resources. This present work explores the adoption of thick-format lithium-ion electrodes to minimize inactive material cost and achieve <$100/kWh of storage. Thick lithium iron phosphate (LFP) pellets were fabricated using a dry pressing process, and the effects of composition, thickness/porosity balance, and electrolyte choice on the performance of the LFP half cells were explored. LFP electrodes with thicknesses up to 1 mm and capacities up to ~15 mAh/cm2 exhibited good rate performance (~90% utilization at a C/10 rate) and stable cycling over 100 cycles. A physics-based model was used to study transport within these thick electrodes. As thickness increases, large concentration gradients form across the electrode, with salt depletion at the current collector and salt accumulation at the separator exceeding the solubility limit of conventional electrolytes. Unlike fast-charging thin electrodes where kinetic overpotentials dominate inefficiencies, thick electrode performance is diffusion-limited, suggesting that methods for minimizing tortuosity and increasing ionic conductivity will be key in enabling low-cost thick electrodes. Figure 1

Biomineralization of calcium phosphates functionalized with hydroxyapatite-binding peptide

Functionalization of calcium phosphates with biomimetic peptides is a promising strategy to increase cellular response for bone tissue repair. In this work, biphasic calcium phosphate pellets were functionalized with the hydroxyapatite-binding peptide pVTK by dropping a suspension of the peptide on the pellet surface. The bioactivity tests were performed in vitro by using McCoy culture medium. Cytotoxicity tests were also performed to assess cell viability. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with field emission gun (FEG-SEM). The results showed that functionalization with the biomimetic peptide was most effective in inducing precipitation of bone-like apatite on the pellets surface, when compared to the control groups (two positive control groups and one negative control group). Cytotoxicity tests showed that all samples are biocompatible but the pellets with peptide showed the highest values of cell viability.

Assessing geochemical and natural radioactivity impacts of Hamadat phosphatic mine through radiological indices.

The utilization of phosphorite deposits as an industrial resource is of paramount importance, and its sustainability largely depends on ensuring safe and responsible practices. This study aims to evaluate the suitability of phosphorite deposits for industrial applications such as the production of phosphoric acid and phosphatic fertilizers. To achieve this goal, the study meticulously examines the geochemical characteristics of the deposits, investigates the distribution of natural Radioactivity within them, and assesses the potential radiological risk associated with their use. The phosphorites are massive and collected from different beds within the Duwi Formation at the Hamadat mining area. They are grain-supported and composed of phosphatic pellets, bioclasts (bones), non-phosphatic minerals, and cement. Geochemically, phosphorites contain high concentrations of P2O5 (23.59-28.36 wt.%) and CaO (40.85-44.35 wt.%), with low amounts of Al2O3 (0.23-0.51 wt.%), TiO2 (0.01-0.03 wt.%), Fe2O3 (1.14-2.28 wt.%), Na2O (0.37-1.19 wt.%), K2O (0.03-0.12 wt.%), and MnO (0.08-0.18 wt.%), suggesting the low contribution of the detrital material during their deposition. Moreover, they belong to contain enhanced U concentration (55-128 ppm). They are also enriched with Sr, Ba, Cr, V, and Zn and depleted in Th, Zr, and Rb, which strongly supports the low detrital input during the formation of the Hamadat phosphorites. The high Radioactivity of the studied phosphorites is probably due to the widespread occurrence of phosphatic components (e.g., apatite) that accommodate U in high concentrations. Gamma spectrometry based on NaI (Tl) crystal 3×3 has been used to measure occurring radionuclides in the phosphorite samples. The results indicate that the radioactive concentrations' average values of 226Ra, 232Th, and 40K are 184.18±9.19, 125.82±6.29, and 63.82±3.19 Bq Kg-1, respectively. Additionally, evaluations have been made of the radiological hazards. The calculated risk indicators exceeded the recommended national and world averages. The data obtained will serve as a reference for follow-up studies to evaluate the effectiveness of the Radioactivity of phosphatic materials collected from the Hamdat mine area.

РАЗРАБОТКА ЦЕНТРОБЕЖНОГО РАБОЧЕГО ОРГАНА РАЗБРАСЫВАТЕЛЯ МИНЕРАЛЬНЫХ УДОБРЕНИЙ

In variable-rate application of solid mineral fertilizers (SMF), working units of centrifugal fertilizer distributors can regulate precisely the application rate and evenly distribute pellets over the fi eld. To determine the most rational parameters and modes of a solid fertilizer distributor, infl uencing the fl ight path of pellets and the uniformity of their distribution over the fi eld, the authors carried out theoretical and experimental research of a centrifugal disc of a solid fertilizer distributor equipped with a rotary acceleration chamber and a set of exchangeable U-shaped blades. The authors describe the infl uence of the blade length on the trajectory and the fl ight distance of the fertilizer pellets as well as the infl uence of the rotation of the dispersal chamber outlet window on the fertilizer distribution pattern. The experiment on determining aerodynamic properties of the nitroammonium phosphate pellets (60:60:60) was carried out using the developed laboratory bench of the solid fertilizer distributor. The experiment allowed determining the physical parameters of pellets infl uencing the range and trajectory of their fl ight - the winglet ratio and the critical speed. It was found that the rotation displacement of the dispersal chamber outlet window of the spreading disc leads to the displacement of the intensive coverage zone in the direction of the window rotation. This makes it possible to regulate the intensity and has a direct impact on the distribution zone of solid mineral fertilizers. The paper justifi es the most rational design of the spreading disc. The research proved that the greatest uniformity of solid mineral fertilizer spreading is observed when using a disk with eight paired coaxially located blades with a length of 300, 250, 200, and 100 mm.

Energy and exergy efficiency analysis of solar still incorporated with copper plate and phosphate pellets as energy storage material.

In this work, a new attempt was made to study the behavior of the conventional solar still (CSS) by adding a black-painted copper plate and phosphate pellets. Therefore, the performance of the three solar stills has been studied and compared. The first is the CSS, and the second is the modified solar still (MSS). The MSS performance was tested using black-coated copper plate (measuring 49 × 49 cm and 0.2 cm thick) with and without phosphate pellets and compared to the CSS in the similar climatic conditions. The results showed that the combination of black coated copper plate and the inclusion of phosphate pellets improved the evaporation rate and daily productivity. During the experiments, yields using black coated copper plate without and with phosphate pellets were 14.96% and 29.53% greater than the CSS. The effectiveness of the CSS, MSS with copper metal plate (MSS-CP), and MSS with copper metal plate with phosphate pellets (MSS-CP and PP) are around 30.23, 35.3, and 41.44%, respectively.

Influence of lithium phosphate on the structural and lithium-ion conducting properties of lithium aluminum titanium phosphate pellets

Lithium aluminum titanium phosphate (LATP) with a formula of Li1.3Al0.3Ti1.7(PO4)3 has been regarded as one of the most promising inorganic solid-state electrolytes in all-solid-state lithium-ion batteries, and presently, to optimize the structural and electrochemical properties of its ceramic pellets is of crucial importance for potential application purposes. In this paper, chemical lithium phosphate Li3PO4 with a melting point of 837 °C is used as an agglutinant in the ceramics of as-prepared LATP crystallites, aiming to assay its functions in possible performance enhancement. At the sintering temperature of 900 °C, the self-fluxing agglutinant (10.0 wt%) in Li3PO4-LATP composite pellet is expected to fill gaps among close packed particles, and this actually induces an apparent shrinkage in the pellet diameter/thickness, a great decrease in grain-boundary resistance and an obvious increase in total Li+-ion conductivity (e.g., LATP-900 ~ 3.0 × 10−4 S cm−1; Li3PO4-LATP-900 ~ 1.2 × 10−3 S cm−1; at 60 oC). Especially, a polymorphic change of the agglutinant occurring during pellet-sintering process and the in situ formation of ion-conducting interphases may cooperatively explain the improvement of ionic conductivity.

Enhancement of the performance of hemispherical distiller via phosphate pellets as energy storage medium.

In this experimental work, the performance of hemispherical distiller has been enhanced via phosphate pellets. To investigate the best approach to the phosphate pellet utilization in a basin of hemispherical distiller to achieve the highest performance, the present study was carried out in two stages. In the first stage, 250 g of phosphate pellets was arranged in a layer of 5 mm thickness placed at the bottom of the basin. In the second stage, the phosphate pellets were distributed in a homogeneous manner in basin salt water with two concentrations 1% (10 g/L) and 2% (20 g/L) without aggregation on the basin. To achieve this idea, in the first test stage, two distillers were compared, the first is the conventional hemispherical distiller which represents the reference distiller (CHSS) and the second is the modified hemispherical distiller with a phosphate layer (MHSS-PL). In the second test stage, three distillers were compared, the first is the CHSS which represents the reference distiller, the second is the modified hemispherical distiller which contained 1% phosphate (MHSS-1), and the third is the modified hemispherical distiller which contained 2% phosphates (MHSS-2). The experimental results show that the cumulative yield was 4.6, 6.32, 6.15, and 6.85 L/m2·day for CHSS, MHSS-PL, MHSS-1, and MHSS-2, respectively. The results showed that the utilization of the phosphate pellets as a storage medium enhanced the performance of the hemispherical distiller. The enhancement in the distiller productivity was 37.4, 33.7, and 47.9% for MHSS-PL, MHSS-1, and MHSS-2, respectively, compared to conventional hemispherical solar still (CHSS). The peak enhancement in the productivity was achieved in the case of modified hemispherical solar still with 2% (20 g/L) phosphate pellets (MHSS-2).

Fast High-Resolution Multi-Elemental Mapping of Phosphate Pellets Using Laser Induced Breakdown Spectroscopy

Recent years have seen a growing trend towards analytical techniques capable of conducting spatially resolved analyses of surfaces for industrial, nanotechnology, geological and biomedical applications. Depending on the application, spatially resolved measurements are required to provide a better understanding of the sample surface composition with significant advantages over conventional bulk analyses. The recent developments of the LIBS technique and its simplicity of use have allowed the development of systems capable of performing multi-element imaging analyses of major and trace elements with ~50 μm (or lower) spatial resolution at fast acquisition speeds up to kHz per pixel. LIBS technology enables systematic and selective ways based on the physics of atomic emission spectroscopy (AES). Complex structures are revealed by LIBS imaging at ultrafast speed. This paper presents results on laser-induced breakdown spectroscopy (LIBS) performing fast high-resolution multi-elemental mappings of Phosphate samples. Phosphate Pellets samples were laser scanned at a repetition rate of 1 kHz with a spatial resolution of 50 μm, using the Mission: Coriosity platform from ELEMISSION Inc. The elemental mappings of the 10 mm2 surfaces for 6 elements were obtained, revealing high levels of detail and complexity in the elements distributions. Advanced graphical algorithms allow direct visualization of the distribution of several elements on the same image. In particular, LIBS imaging has been used for multi-elements surface mapping of Phosphate Pellets, and show specific clustering composition, indicating that line intensity of a given analyte element is not only related to that analyte, but also to other elements present in the samples. This last statement has been verified using multivariate approach for calibration and prediction of elemental concentration in Phosphate Pellets.

Hybrid fuzzy kinetic model of phosphorite pellets drying process

The chemical-technological process of phosphate pellets drying is investigated in the paper. The hybrid fuzzy kinetic model of phosphorite pellets drying process is proposed. The features of the proposed model are as follows: firstly, differential equations with fuzzy thermal-physical characteristics of pellets are used to estimate the thermal conductivity of pellets; secondly, a fuzzy rule-based model is used to determine the most difficult parameters to calculate. The method based on the developed hybrid model is proposed for analyzing the drying process of phosphorite pellets. The proposed method uses an original approach that allows solving the problem of increasing uncertainty of results in iterative calculations based on the modal interaction of fuzzy thermal characteristics represented by fuzzy numbers.

Geochemistry and stable isotopes of the upper Campanian–lower Maastrichtian phosphorite‐bearing sequence, Central Jordan: Implications for their age, origin, and diagenesis

Three major lithofacies have been described in Lajjun area, central Jordan, including the phosphorite and intercalated limestone of the Al‐Hisa Phosphorite Formation, as well as the Muwaqqar Chalk Marl Formation. 87Sr/86Sr isotopic data indicate a late Campanian age for the Al‐Hisa Phosphorite Formation, whereas the overlying chalk of the Muwaqqar Formation contains the lowest Maastrichtian planktic foraminiferal zone of Rugoglobigerina hexacamerata (CF8b).The phosphorites are of reworked origin as inferred from the homogeneous texture with lack of any concentric structure in the phosphatic pellets and the presence of bone fragments inside the phosphatic pellets, which are filled with phosphatic mud similar to the matrix of phosphatic pellet. They still reflect the original seawater rare‐earth pattern, as indicated from the similarity in their rare‐earth element (REE) concentration and patterns with seawater. Positive correlations between P2O5 and Fe2O3, TiO2 and K2O, relatively high rare‐earth contents, and similarity in (Nd/Yb)SN ratio to the modern shallow seawater suggest a continental marginal depositional environment for the limestone and chalk facies. δ13C values are lower and more variable compared with the estimated global range of upper Campanian–lower Maastrichtian δ13C values in shelf and oceanic basins. This indicates a diagenetic effect on the δ13C isotopes and suggests that a significant proportion of carbonate ions could have been resulted from the organic carbon oxidation. Three third‐order depositional sequences matching with the global and regional sea‐level patterns are identified in the studied section based on vertical facies changes. The basal transgressive surface of each sequence is constantly characterized by a phosphatic horizon.

Pengaruh Bahan Organik dan Suhu Pengeringan terhadap Ketahanan Hidup Aspergillus niger dalam Pupuk Pelet Bio-fosfat

This research was aimed to investigate the effect of organic matter and drying temperature on Aspergillus niger survivability in the rock phosphate pellet fertilizer namely bio-phosphate. The research was arranged by a completely randomized design 3x3x6. Addition of the mixing of tapioca waste, rice bran, and starch (BOC) and the humic substance (BH) in the bio-phosphate, and its drying temperature (SP) were the treatments. Aspergillus niger inoculums survivability in the bio-phosphate was determined using plating methods. The result showed that the addition of BOC decreased amount of A. niger in the bio-phosphate up to 28.0%, while the BH increased the amount of A. niger up to 24.4%. The ideal drying temperature of bio-phosphate pellet fertilizer was 600C.

Optimization of Energy and Resource Efficiency in a Multistage Drying Process of Phosphate Pellets

The roasting of phosphate pellets is an energy-intensive process the optimization of which can give rise to considerable efficiency improvements. To this purpose, the mathematical modeling and the computer-aided simulation of a multi-stage process of phosphate pellets roasting have been developed. This process includes drying, dissociation reaction of carbonates and a sintering process in a moving, dense, multilayer mass of phosphate pellets in a special horizontal grate apparatus. A theoretical model for the physical-chemical processes of a mass of phosphate pellets moving in a multistage process and subject to external operation variables (i.e., temperatures and flowrates of the drying gas at different positions of the conveyor length) has been developed. By letting these control variables vary over suitable ranges limited by technical constraints, it is possible to construct an algorithm that minimizes the overall energy consumption subject to the attainment of the required quality indicators of the pellets. Therefore, the set of constraints includes bounds on both the operational variables and quality indicators of the final product. A dynamic programming algorithm subject to suitable penalty functions for avoiding constraints violation has been used. The results obtained show that the scientifically based operation described in this paper achieves the goal of attaining considerable energy savings while assuring the quality of the finished pellets. Furthermore, the results highlight the convenience of extending the general strategy developed in this article to other chemical energy engineering processes.

Testing LA-ICP-MS analysis of archaeological bones with different diagenetic histories for paleodiet prospect

LA-ICP-MS is a powerful technique requiring minimal sample preparation and providing high spatial resolution which may offer the possibility of analysing trace elements in targeted pristine areas of archaeological bone sections. This would provide invaluable information about an individual's life if combined with the geochemical composition of the teeth from the same individual. However, there is no consensus regarding the calibration to be used for LA-ICP-MS analysis of bone, which is a highly complex organo-mineral tissue. In this study, we tested different calibration approaches (NIST and USGS glass series, synthetic phosphate glass and synthetic phosphate pellet from USGS) on a modern bone. The best method was applied to three Precolumbian skeletons (Lerma Valley, Mexico). These individuals show different degrees of preservation (crystallinity, calcite, F and organic matter content) which have been previously explored at the intra-skeletal level. A bone sample with exceptional preservation from the Dogon Country (Mali) was analysed for comparison.Based on BSE SEM images and element distribution of the bone sections obtained via LA-ICP-MS mapping, quantification of Ca, P, Li, Zn, V, U, Na, Mg, Sr and Ba was performed using LA-ICP-MS spot analysis on areas displaying varying concentration profiles and histological preservation. Although avoiding sampling at the external margin of the bone sections may minimize diagenetic Li, Zn, V, U, Sr and Ba, it was not possible to discriminate biological from diagenetic Sr adsorbed onto the bone crystallites of the best preserved Precolumbian skeleton, whose low crystallinity favored adsorption efficiency. In contrast, the well preserved Dogon sample, as well as the most altered Precolumbian skeletons provided Sr and Ba content roughly similar to concentrations obtained using bulk analysis. LA-ICP-MS can therefore not substitute solution analysis for paleodiet prospect, especially for bones in relatively early state of diagenetic transformations.

Модель комплексного управления рисками при обеспечении ресурсо- и энергосбережения процессов на примере сложных теплотехнологических систем

Under the conditions of constantly growing complexity of the processes used in technological systems, the main risk management tasks cannot be solved by using the traditional methods implying exact representation of problem situations. This is because such tasks are characterized by a large number of parameters, uncertainty and data ambiguity. The external environmental conditions for such systems are characterized by instability and uncertainty, which are caused, on the one hand, by high variability of the external environment and, on the other hand, by uniqueness of the emerging problem situations. The problem is formulated, and a cascade-composition integrated risk management model in setting up resource and energy saving processes is proposed taking complex thermal processing systems (CTPS) as an example. The proposed model is based on a fuzzy approach and on fuzzy model hybridization and integration methods. The need for comprehensively managing the risks in setting up resource and energy saving processes in a CTPS is primarily stemming from the requirement of keeping the violation risks within the acceptable level. It should be noted that the acceptable level of risk can be established not only for violation of technological processes in a CTPS as a whole, but also for all stages and for individual technological processes. The proposed cascade-composition model includes fuzzy models for carrying out a component-wise analysis of the technological processes in the CTPS, for estimating the resource and energy efficiency of technological processes, and for assessing the risks in setting up resource and energy savings. The article describes an approach to solving the problem of integrated risk management in setting up resource and energy saving processes in the CTPS using the proposed model. The approach implies specification of different combinations of control parameters at each stage for all technological processes with taking into account all constraints imposed on these processes, and modeling and determining the combinations of control parameters that will make it possible to improve the resource and energy efficiency of technological processes in the CTPS while keeping the violation risks within the acceptable level. The article presents the experimental results of integrated risk management in setting up resource and energy savings using the proposed model and approach taking as an example the process of drying phosphate pellets in the calcining conveyor machine. The obtained results are supposed to be used for integrated risk management in setting up resource and energy saving for various processes in CTPSs.

Chemical and Technological Thermally Activated Process Research of Roasting Pellets in Dense Bed of Conveyor Indurating Machine

The work focuses on an important scientific problem of modeling thermal processes of thermal technology, which are complicated with non-isothermal chemical reactions during the thermal preparation of raw materials in a dense layer. A mathematical model is presented for heat and mass transfer in a dense layer. The firing phosphate pellets parameters analysis calculated according to the model and performed on a kiln machinery in the scheduled mode was conducted. The features of the course of processes of drying, agglomeration and dissociation of carbonates in the pellets are revealed at their heat treatment. The received results, allow defining the temperature and gas dynamic condition of roasting the pellets for achievement of the required moisture content, necessary extent of dissociation of carbonates and the acceptable durability.

ANALYSIS OF FORMULATION EFFECTS IN THE DISSOLUTION OF KETOPROFEN PELLETS

In this work the effects of citric acid and two common fillers, lactose (soluble) and tricalcium phosphate (insoluble) are examined on the release profiles from pellets, using ketoprofen as a model drug with pHdependent solubility. Also studies were conducted on dependence of these profiles on the specific surface area, bulk density, apparent density, porosity and porosity parameters (pore size distribution, total pore surface area, mean pore diameter and pore shape), as determined by mercury intrusion porosimetry. Pellets were prepared by the extrusion-spheronization method. Four different formulations were considered: two ternary mixtures of ketoprofen (I), lactose (L) or tricalcium phosphate (P) and microcel (M) in the relative proportions 2:3:5 (ILM or IPM) and two four-component mixtures of the same components plus 5% citric acid (C) in the relative proportions 2:2.5:0.5:5 (CILM or CIPM). Pellets with high porosity and total pore sur face area but small median pore diameter ( t r icalcium phosphate pellets IPM) are found to produce similar dissolution results to those of low porosity and low total pore surface area, but having a high median pore diameter ( lactose pellets I LM) , ir respect ive of the solubility of excipients. Addition of citric acid causes a delay in the initial dissolution for both formulations. During dissolution, however, citric acid reduces the median pore diameter of lactose-based pellets. In contrast, in tricalcium phosphate/ cit r ic acid pellet s (CIPM) , this parameter increases considerably dur ing dissolut ion, when compared to the IPM formulat ion. These findings may just ify the cont rast ing dissolut ion behaviors of CIPM and CILM (lactose/citric acid) pellets, after their common behavior in the initial stages, and show that porosity and its related parameters, along with physical properties of excipients such as solubility, density and specific surface area, are helpful to predict pellet behavior in drug release profiles.

Reclamation of phosphorus from aqueous solutions as alkaline earth metal phosphate in a fluidized-bed homogeneous crystallization (FBHC) process

This investigation studies the crystallization of alkaline earth metal phosphates (Me-PO4, Me=Mg, Ca, Sr, Ba) to recover phosphorus (1000 ppm-P) in a fluidized-bed reactor without the addition of seeds. Experimental results showed that the effluent pHe critically determined the phosphorus removal rate (PR%) and crystallization ratio (CR%). The PR%s that were achieved by the generation of Mg, Ca, Sr and Ba-phosphates with an inlet molar ratio [Me]in/[P]in of 2 were 77.8%, 99.4%, 97% and 98.9% at the pHe values exceeded 7.5, 6.6, 7.2 and 6.4, respectively. However, the CR% was strictly optimized by a pHe that transformed the crystalline phases of granular pellets (0.5–2mm in diameter) from metal hydrogen phosphate (MeHPO4) to hydroxyapatite (Me5(PO4)3(OH)), and maximum CR%s of 54.5%, 78.8%, 79.0% and 89.0% were obtained by the generation of Mg, Ca, Sr and Ba-phosphates. According to estimates of aquatic chemistries and supersolubility behaviors in the effluent, a successful FBHC process operated under a supersaturation that was close to the metastable zone. Finally, a reasonable mechanism of the removal of phosphorus by converting the aqueous phosphorus into highly pure metal phosphate pellets was inferred.

Petro-Mineralogical Analysis of Sedimentary Phosphate of Marine Origin, Case of the Locality of El Kouif (Algerian-Tunisian Confines)

The sedimentary phosphate of marine origin mark the Paleo-Eocene period in the region of Tebessa, as elsewhere in northern Africa. The study sector of El Kouif is considered as a part of the eastern Saharan Atlas. The lithological description of the studied Cups has allowed showing a bundle of phosphate take by carbonate formations sprinkle of flint. The grain size analysis of sandyphosphorites revealed phospharenite deposits which were generally heterometric and misclassified. Moreover, the mineralogical and magnetic analysis of some samples of phosphatic sands showed a predominance of light minerals. As well as the sorting and morphoscopic observation led the isolation of coprolites, of fossil teeth of fish and lithoclasts but mainly ovoid phosphatic pellets. The XRD analysis confirmed the presence of apatitic minerals (Hydroxyapatite, Fluroapatite, francolite and Dahlias), of carbonates (Calcite, Magnesium calcite, Ankerite, dolomite), the quartz, opal-CT and even sulphides and gypsum. The petrographic analysis of phosphate samples has permit to surround primordially, a phosphatic pellets rich in organic matter, devoid of nucleus and others nucleated. The phases of connections are clay, carbonate or silica. The notable amounts of allochems have an impact on textures of typewackstone, packstone, and sometimes grainstone for bio-pel-microspars.