Aqueous Phosphate Solutions Research Articles

Oxidized Black Phosphorus Nanosheets as an Inorganic Antiresorptive Agent

Black phosphorus (BP) is a newly discovered two-dimensional material that has promising applications from bioelectronics to biomedicine. However, facile oxidation of BP leads to changes in surface ...

Removal of phosphate at low concentration from water by porous PVA/Al2O3 composites

ABSTRACT The porous polyvinyl alcohol (PVA)/Al2O3 composite by supporting activated alumina on the cross-linked network of PVA has been successfully prepared and its property for the removal of phosphate in aqueous solution was also evaluated. The structure of the PVA/Al2O3 was examined by scanning electron microscopy. It showed that the activated alumina particles with an average size of 1 μm were evenly dispersed and fixed in the cross-linked network structure of PVA. The effects of adsorption time, solution temperature, pH, initial concentration of phosphate, Al2O3 loading rate, dosage and coexisting ions on the phosphate removal were further studied. The results showed that the highest removal phosphate efficiency of 95% can be obtained with the Al2O3 loading rate of PVA/Al2O3 being 60 wt.% at pH of 4 at 30 °C. The maximum adsorption capacities of by PVA/Al2O3 suggested by the Langmuir isothermal model was 10.12 mg/g. The adsorption process of phosphate can be fit well with a pseudo-second-order model (R 2 = 0.9900). The PVA/Al2O3 composite exhibited a high selective adsorption of phosphate in the presence of commonly coexisting anions except the obvious effect of in water. Meanwhile, the PVA/Al2O3 composite can be easily separated and recovered due to the granulation of adsorbent. PVA/Al2O3 composite also shows the excellent properties of regeneration and recycling use with the removal efficiency of phosphate was 88.93%, 88.38% and 94.34% after three cycles, respectively. It can be proposed that the PVA/Al2O3 composite is a promising recyclable adsorbent for removing phosphate at low concentration from aqueous solution.

Curing of inorganic composition coating of aluminum – phosphate system

Known methods for applying an inorganic composite coating are accompanied by its heat treatment at a temperature of at least 300 °C, which requires the use of furnaces. Recent developments have allowed to reduce the temperature of heat treatment to 90 °C for at least 3 hours or to 105 °C for at least 1 h, which allows the use of portable heating equipment. However, the use of any equipment with such prolonged heat treatment is not acceptable when applying corrosion protection to large structures, especially when their dismantling is impossible. The results of studies on the chemical curing of an inorganic composite coating that does not require heat treatment are presented. It is proposed to spray a hardener solution onto a composite coating having a more alkaline pH instead of heat treatment. When a hardener reacts with acidic residues of an inorganic binder on the surface of a dried coating, monosubstituted phosphates undergo a transition to poorly soluble two-and practically insoluble tri-substituted phosphates not only on the coating surface, but also on the inner surface of the pores, which leads to almost complete insolubility of the coating. Treatment of the coating with an aqueous solution of monosubstituted potassium phosphate, two-substituted potassium phosphate or potassium pyrophosphate gives the coating water resistance. The inorganic composite coating acquires a high protective ability (more than 1300 hours in a salt fog chamber) on steel parts after treatment with only aqueous solutions of mono-substituted or two-substituted potassium phosphate.

Field-amplified sample injection combined with CE for the enantiodetermination of cathinones in urine samples.

This work presents a capillary electrophoresis methodology for the enantiodetermination of cathinones in urine employing a liquid-liquid extraction sample pretreatment. The cathinones were enantioseparated by adding a mixture of 8mM 2-hydroxypropyl β-cyclodextrin and 5mM β-cyclodextrin to the background electrolyte, which consists of 70mM of monosodium phosphate aqueous solution at pH 2.5. Field-amplified sample injection was used as preconcentration strategy to improve the sensitivity. We studied various parameters that affect this stacking strategy, in particular, the sample solvent and its pH, the presence or absence of a low conductivity solvent plug introduced before the sample injection, the nature and volume of this plug, and the voltage and time of the electrokinetic injection of the sample. The optimum conditions were achieved by injecting a plug of isopropanol:H2 O 50/50 at 50mbar for 5s prior to the electrokinetic injection of the sample prepared in an aqueous solution of HCl 10-6 M. The sensitivity enhancement factors were from 562 to 601 in terms of peak area and from 444 to 472 in terms of peak height. The method was validated by analyzing spiked urine samples, obtaining a linear range of 25 to 1000ng/mL and limits of detection ranging from 15 to 45ng/mL.

Optimal Anode Potential Range for Electrochemical Synthesis of Struvite from Wastewater

Electrochemical recovery of phosphorous and nitrogen from wastewater as struvite (NH4MgPO4.6H2O) is progressively gaining importance as one of the innumerable pathways of sustainable development. However, the optimal range of anode potential that maximizes struvite purity under varied parametric conditions of pH and ion concentrations other than NH4 +and PO4 -3 has not been methodically explored so far. Additionally, corrosion behavior of a sacrificial magnesium anode under an anode potential range needs to be investigated because according to techno-economic feasibility criterion, it is advantageous to produce struvite with minimal consumption of magnesium. In this study, we will report on the effects of pH (4 and 8) and chloride ion concentration (0.1 M to 1 M) on struvite production and magnesium dissolution rates through performing a systematic investigation using Linear Sweep Voltammetry (LSV) and Potentiodynamic Polarization (PDP) techniques. Aqueous solutions of dihydrogen ammonium phosphate with varied chloride ion concentration are used as simulated wastewater. Electrochemical experiments are conducted in batch mode with a sacrificial magnesium anode and a stainless-steel cathode. Furthermore, bulk and electrode surface (both anode and cathode) precipitates are analyzed for elemental composition, crystallinity,and morphological features. The present research outcomes are expected to serve as a baseline protocol to select an optimal anode potential window in electrochemical struvite production from wastewater.

Formation of Anisotropic Hydroxyapatite Particles under Hydrothermal Conditions

Using X-ray diffraction analysis, transmission electron microscopy, and complex thermal analysis, it was shown that brushite crystals are formed from aqueous solutions of ammonium hydrogen phosphate and calcium nitrate. The hydrothermal treatment of brushite results in the formation of quasi-one-dimensional hydroxyapatite nanoparticles, the longitudinal size of which is about 400 nm, and the transverse size is 40 nm. It was demonstrated that hydroxyapatite nanoparticles can be used as fillers of composite matrices for tissue engineering, in particular, in bone grafting.

Phosphorus recovery by core-shell γ-Al2O3/Fe3O4 biochar composite from aqueous phosphate solutions

Biochar can act as an adsorbent for phosphate removal from water sources, which can be highly beneficial in limiting eutrophication and recycling elemental phosphorus (P). However, it is difficult to use a single biochar material to overcome problems such as low adsorption efficiency, difficulty in reuse, and secondary pollution. This study addresses these challenges using a novel core-shell structure γ-Al2O3/Fe3O4 biochar adsorbent (AFBC) with significant P uptake capabilities in terms of its high adsorption capacity (205.7 mg g−1), magnetic properties (saturation magnetization 24.70 emu g−1), and high reuse stability (91.0% removal efficiency after five adsorption-desorption cycles). The highest partition coefficient 1.04 mg g−1 μM−1, was obtained at a concentration of 322.89 μM. Furthermore, AFBC exhibited strong regeneration ability in multiple cycle trials, making it extremely viable for sustainable resource management. P removal mechanisms, i.e., electrostatic attraction and inner-sphere complexation, were explained using Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) measurements. A surface complexation model was established by considering the formation of monodentate mononuclear and bidentate binuclear surface complexes of P to illustrate the adsorption process. Owing to its high adsorption efficiency, easy separation from water, and environmental friendliness, AFBC is a potential adsorbent for P recovery from polluted waters.

Use of a spectrophotometric assay to evaluate amino acid activation and tRNA charging

Conventional assays that investigate amino acid activation and tRNA‐charging rely on using radiolabeled amino acids (14C) and tRNAs (32P) to detect the presence of activated amino acid adenylate(s) and acylated tRNAs. There are also several assays that monitor activation and acylation products by using (32P) radiolabeled ATP and inorganic pyrophosphate. The radioisotope based assays offer unmatched sensitivity. However, the experiments require the use of hazardous reagents and often laborious protocols. More recently a colorimetric based assay has been developed to detect the level of inorganic free phosphate in aqueous solution. The assay is based on the complexation of malachite green molybdate and inorganic phosphate – the complex absorbs at 620 nm. The assay, referred to as the malachite green assay, has been modified to measure amino acid activation and tRNA charging. Our short‐term goal is to use the malachite green assay to measure the ability of aminoacyl‐tRNA syntheses (aaRSs) to activate and charge analog amino acids (AAs). Analog or “unnatural” AAs are non‐proteinogenic residues beyond the set of natural 20 L‐AAs. Bacteria and fungi use large multi‐subunit enzyme complexes, nonribosomal peptide synthetases (NRPs), to generate peptides composed of analog AAs. The resulting analog peptides typically possess enhanced bioactivity. Analog peptide bioactivity is generally linked with enhanced: i)membrane permeability, ii)protease stability and iii)chemical complexity. These advantages make analog peptide ideal for biological therapeutics. Our long‐term goal is to use the cell free expression system – the PURE system ( Protein synthesis Using Recombinant Elements) to synthesize analog peptides. The resulting peptides will be directed against protein‐protein interactions known to exacerbate disease. Our initial studies focus on using the malachite green assay to screen analog amino acids for activation and tRNA charging using purified aaRS and tRNA (total tRNA and single isoacceptors). Analogs identified via screening will be assembled into a library that will be used to generate analog peptides.Support or Funding InformationUniversity of San Diego

Synthesis of magnetite/lanthanum hydroxide composite and magnetite/aluminum hydroxide composite for removal of phosphate

Two magnetic adsorbents, magnetite/aluminum hydroxide composite (MAC) and magnetite/lanthanum hydroxide composite (MLC), were successfully synthesized by a simple one-pot method and their phosphate adsorption process was investigated. The properties of synthesized adsorbents were studied using Fourier transform infrared spectroscopy (FTIR), zeta potential, vibrating sample magnetometry (VSM) and X-ray photoelectron spectroscopy (XPS). The adsorption isotherms, adsorption kinetics and the effects of solution pH and dissolved organic carbon (DOC) on the adsorption of phosphate in aqueous solution by MAC, MLC-2, MLC-10 and LMB were investigated to evaluate the difference in phosphate removal efficiency of the magnetic adsorbents and non-magnetic adsorbent. According to the results of this study, MLC-10 had a higher phosphate adsorption capacity (19.34 mg P g−1) than LMB (11.55 mg P g−1), MAC (10.48 mg P g−1) and MLC-2 (8.89 mg P g−1). MLC-10 showed a relative higher partition coefficient (PC) (1.74 mg g−1 μM−1) than other three adsorbents at initial P concentration of 15 mg L−1. Also, MLC-10 was less pH dependent than MAC and had higher phosphate adsorption capacities under different DOC concentrations (0–72 mg L−1) than LMB, MAC and MLC-2. Further, MLC-10 had excellent recyclability due to high magnetism. Electrostatic interaction and the inner-sphere surface complexation were the potential phosphate adsorption mechanisms employed by MLC-10. In summary, MLC-10 is a promising adsorbent for phosphate removal from eutrophication water.

Separation and characterization of unknown impurities in rutin tablets using trap-free two-dimensional liquid chromatography coupled with ion trap/time-of-flight mass spectrometry.

A new high-performance liquid chromatography method was developed for the determination of impurities in rutin tablets to improve on the method of the official monograph in national drug standards. Five impurities in rutin tablets were characterized using trap-free two-dimensional liquid chromatography coupled with ion trap/time-of-flight mass spectrometry (2D-LC/IT-TOFMS) in both positive and negative ion modes of electrospray ionization. In the first dimension, the LC column was a Thermo Acclaim 120™ C18 (4.6 mm × 250 mm, 5 μm), and the mobile phase was composed of 0.1 M sodium dihydrogen phosphate aqueous solution (pH adjusted to 4.4 with phosphoric acid) and acetonitrile (80:20, v/v). In the second dimension, the column was a Shimadzu Shim-pack GISS C18 (50 mm × 2.1 mm, 1.9 μm), and the mobile phase was composed of 10 mM ammonium formate solution and methanol. The structures of five impurities in rutin tablets were deduced based on the MS n data in both positive and negative ion modes, in which two impurities were unknown. Impurity 1, impurity 2 and impurity 3 were proposed as flavonol 3,7-di-O-glycoside, flavonol mono-O-triglycoside and quercetin 3-O-glycoside, respectively, and impurity 4 and impurity 5 were proposed as kaempferol 3-O-rhamnosylglucoside and isorhamnetin 3-O-rhamnosylglucoside, respectively. The method established in this study was simple and reliable for the routine quality control of rutin tablets. The contradiction between non-volatile salt mobile phase and mass spectrometry was solved by means of a multiple heart-cutting 2D-LC approach and on-line desalination technology. Five impurities were separated and characterized. These results provide a scientific basis for further improving the national drug standard of rutin tablets.

Preparation of mesoporous zirconia ceramic fibers modified by dual surfactants and their phosphate adsorption characteristics

Phosphate removal is an essential measure in controlling the eutrophication of water. In this work, the electrospinning mesoporous zirconia fibers with high surface area were prepared and used as adsorbents to remove phosphate in aqueous solutions for the first time. The electrospinning mesoporous zirconia fibers which had large surface area and uniform pore size were prepared by the use of ammonium lauryl sulfate (ALS) and triblock co-polymer Pluronic (P-123) as dual surfactants. The morphology and composite were represented by XRD, TGA/DTA, FT-IR, SEM, and TEM. The specific surface area and pore properties of fibers were investigated by nitrogen adsorption-desorption method. These mesoporous zirconia fibers performed an outstanding phosphate adsorption ability whose maximum adsorption capacity could reach 222.79 mg/g, meanwhile, a nice cycle performance was also observed as the removal rate could remain 92.5% after 5 cycles on the initial concentration of 30 mg/L. The Freundlich model and the pseudo-second-order kinetic model were both fitted with the adsorption data properly. Besides, the fibers also performed a nice ability in anti-interference against the changes of solution pH value and co-existing ions. Thus, the prepared mesoporous zirconia fibers would be a potential adsorbent of phosphate removal process under the conditions of actual wastewater treatment, with the advantages of the excellent adsorption efficiency, low in production cost, high repeatable utilization and environment friendly.

Effect of Fe(III) Impurity on the Antisolvent Crystallization of Aqueous Ammonium Dihydrogen Phosphate Solutions

AbstractExperimental results of a study of the effect of FeCl3 impurity on the antisolvent crystallization of ammonium dihydrogen phosphate, involving processes of formation of 3D nuclei and growth of these nuclei, from its aqueous solutions saturated at 30 °C and containing different impurity concentrations ci from in situ measurements of temperatures of saturated solutions and pure water as functions of feeding time t of antisolvent ethanol at predefined rates RA are described and discussed. The processes of formation of 3D nuclei and growth of these nuclei are studied in terms of the maximum antisolvent content ΔxmaxN and ΔxmaxG, determined from intervals of temperature difference (Ts−Tw) = ΔT < 0 and ΔT > 0, respectively, obtained from measurements of temperature Ts and Tw of saturated solution, without and with impurity, and pure water. It is found that: 1) the processes of 3D nucleation in antisolvent crystallization from solutions containing impurities can be explained in the framework of theoretical expressions such as a Nývlt‐like relation and an approach based on 3D‐nucleation theory, and 2) adsorption of impurity particles accounts for the increase in the values of antisolvent contents ΔxmaxN and ΔxmaxG of solutions during 3D nucleation and growth of crystallites.

Direct Electrochemical Sensing of Phosphate in Aqueous Solutions Based on Phase Transition of Calcium Phosphate.

Electrochemical determination of phosphate in aqueous solutions attracts considerable interests in both biological and environmental fields. Because of the electrochemically inactive nature of phosphate, direct electrochemical detection of phosphate is still a highly challenging task. Herein, we reported a direct electrochemical approach for the determination of phosphate based on the oxidation of coordinated OH during the phase transition of calcium phosphates (CaPs). The mixture of amorphous CaPs and octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O), which acts as the starting material for hydroxyapatite (Ca10(PO4)6(OH)2), was self-assembled on a Nafion-modified glassy carbon electrode. The as-prepared electrode (CaPs/Nafion) showed a distinct oxidation peak at 1.0 V versus Ag/AgCl in phosphate solution. The peak heights were directly proportional to the concentration of phosphate from 0.1 to 10 μM in the presence of 1 mM Ca2+. After comprehensive characterization of the CaPs/Nafion electrode, it was understood that phosphate ions as a proton acceptor could stimulate the generation of coordinated OH from coordinated water (H2O) in CaP. The addition of Ca2+ could magnify the coordinated H2O source because of its hydration to H2O. The CaPs/Nafion electrode also displayed good selectivity as the electrochemical oxidization response was not affected by up to 10 μM of potentially competitive species like CO32-, NO3-, CH3COO-, SO42-, and Cl-. The results obtained in this work not only provided a new method for direct detection of phosphate in aqueous solution but also suggested that Ca2+ could be a promoter for electrochemical oxygen generation.

An Integrated Optofluidic Platform Enabling Total Phosphorus On-Chip Digestion and Online Real-Time Detection.

This paper presents a total phosphorus online real-time monitoring system integrated with on-chip digestion based on the merits of optofluidic technology. The integrated optofluidic device contains a hollow optical fiber employed for pretreatment and digestion of phosphorus solution samples, a polydimethylsiloxane (PDMS)-based micromixer with convergent–divergent walls designed to enable sufficient mixing and chromogenic reaction, and a couple of optical fiber collimators attached with a Z-shaped flow cell for optical detection. Details of system design and fabrication are introduced in this paper. In the experiment, on-chip digestion of four typical phosphates in aqueous solution including organophosphorus and inorganic phosphorus is investigated under different reaction conditions, such as digestion temperature, concentration of oxidant and pH value, and the optimal reaction parameters are explored under different conditions. Meanwhile, we demonstrate the online real-time monitoring function of the optofluidic device, and the digestion mechanisms of four different phosphates are analyzed and discussed. Compared with the national standard method, we find that the measurement accuracy and sensitivity are acceptable when the concentration of total phosphorus is between 0.005–0.9 mg/L (by weight of P) in aqueous solution, which covers the range defined in the national standard. The traditional digestion time of several hours is greatly reduced to less than 10 s, and the content of total phosphorus can be obtained in a few minutes. The integrated optofluidic device can significantly shorten the test time and reduce the sample amount, and also provides a versatile platform for the real-time detection and analysis of many biochemical samples.

High-Resolution AlGaN/GaN HEMT-Based Electrochemical Sensor for Biomedical Applications

We have investigated the characteristics of pH and salinity sensor derived from the gated AlGaN/GaN high-electron mobility transistor (HEMT) structures in phosphate buffer saline (PBS) and aqueous salt solutions (NaCl + DI). In deionized (DI) water, the HEMT device showed good drain ${I}$ – ${V}$ characteristics, which is very close to the output characteristics of the typical HEMT structures subjected to the air. We observed a significant change in the output drain characteristics curves concerning to the variation in the pH values of PBS solutions, signifying the subsequent potential variation at the AlGaN surface. The output drain current recorded at ${V}_{\text {ds}}= +1$ V was linearly decremented with the pH value. A high sensitivity of $4.32~{\mu }\text{A}$ /mm-pH was obtained. These GaN HEMT structures demonstrated a quick response to the pH changes. It was also investigated that the devices were susceptible toward the aqueous salt solution (NaCl + DI). The percentage change in drain current linearly decreased with decreasing NaCl molar concentration in DI water. We have reported on the change in current with the smaller range of molar concentration of NaCl present in water. Evaluating the sensitivity and response time, we obtained a high sensitivity of 6.48 mA/mm-molar and a response time of 250–350 ms at ${V}_{\text {ds}}= +1$ V. We have also reported on the change in current with the molar concentration of NaCl present in PBS with a high sensitivity of 2.02 mA/mm-molar at ${V}_{\text {ds}}= +5$ V. These outcomes show that the AlGaN/GaN HEMTs are exceptionally promising as a high-sensitivity pH sensor and salinity sensor for biological experiments.

Fabrication of calcium phosphate composite polymer/SLS-stabilized emulsion-based bioactive gels and their application for dentine tubule occlusion

ObjectivesCalcium phosphate/SLS/P123 composite bioactive gels were prepared to achieve dentine tubule occlusion. MethodsGels containing calcium phosphate particles were prepared in a water-in-oil microemulsion system with a mixture of triblock copolymer pluronic (P123) as a co-surfactant and sodium lauryl sulfate (SLS) as a surfactant in cyclohexane. Subsequently, calcium chloride dihydrate and sodium hydrogen phosphate aqueous solutions were added in a water phase. Finally, slow evaporation of the oil phase at room temperature was performed to produce a hybrid gel. The obtained gels were investigated for their toxicity by the sulforhodamine B (SRB) assay and applied on human dentine specimens to examine their ability to occlude dentine tubules. ResultsThe size and morphology of the calcium phosphate particles embedded in the gel depended on the concentration of P123 and SLS, which were used as a template for mineral precipitation. The prepared calcium phosphate particles (200–500 nm in diameter) with the maximum polymer and surfactant content exhibited spherical shapes. Further, on reducing their content twice and tenfold yields micro-particles with flower-like shapes. These bioactive gels were able to occlude into dentine tubules after 3 days of application with a plugging rate of 79.22% when using the smallest particles. In addition, calcium phosphate nanorods were transformed into dentine tubules with a maximum depth of 6 μm on increasing the amount of gel. ConclusionsThe bioactive gels were effectively used as bioactive fillers to occlude exposed human dentine tubules.

Preparation of polyaminated Fe3O4@chitosan core-shell magnetic nanoparticles for efficient adsorption of phosphate in aqueous solutions

In this study, novel polyethylenimine (PEI)-grafted chitosan (CS) core-shell (called as Fe3O4/CS/PEI) magnetic nanoparticles were synthesized and applied for adsorbing phosphate in water. The magnetic and physicochemical properties of as-synthesized nanoparticles were first analyzed by means of a superconducting quantum interference device, X-ray diffractometer, X-ray photoelectron spectroscope, Fourier-transform infrared spectroscope, transmission electron microscope, zeta potential analyzer, and nitrogen sorptiometer. The followed experiments indicated that the amount of phosphate adsorbed increased with increasing equilibrium pH to near 4.0 and then decreased when the pH was further increased. The adsorption isotherms of phosphate on Fe3O4/CS/PEI particles were well fit by the Langmuir equation, and its maximum adsorption was 48.2mgg−1 at an equilibrium pH of 3.0 and 25°C. The primary mechanism for phosphate adsorption on Fe3O4/CS/PEI particles was electrostatic attraction. The preferential adsorption of phosphate in the presence of other excess anions including chloride, nitrate, carbonate, and sulfate was presented. Under the conditions studied, more than 90% of phosphate was desorbed from the laden Fe3O4/CS/PEI particles by 0.05mol L−1 of NaOH solution. The remained adsorption efficiency obtained in the five-cycle reusability tests has demonstrated the promising application potential of Fe3O4/CS/PEI particles.

Exploring the potential of N-acylated chitosan for the removal of toxic pollutants from wastewater

Modified chitosan was prepared by chemical derivatisation using caproyl and palmitoyl fatty acid chains. The performance of the materials on the removal of phosphates in aqueous solutions was evaluated through a series of batch adsorption experiments. The phosphate adsorption studies showed enhanced adsorption efficiencies for caproyl chitosan (63%) and for palmitoyl chitosan (71%) in aqueous solutions containing phosphate at a pH of 6.2. The pristine and modified chitosans showed increases in the removal efficiency at an optimal solution pH of 4. The adsorption kinetics studies performed on palmitoyl-chitosan indicated that a contact time of approximately 30 minutes is required to reach equilibrium at solution concentrations ranging from 10-20 mg/l. Co-existing anions such as nitrates and sulphates do affect the phosphate removal efficiency of modified chitosans in aqueous solutions. This study demonstrates that modified chitosans has the potential of being used as a rigid and degradable material for water treatment.

ОСОБЕННОСТИ ПРОЦЕССА ГРАНУЛИРОВАНИЯ ОРГАНОМИНЕРАЛЬНЫХ УДОБРЕНИЙ МЕТОДОМ ОКАТЫВАНИЯ

Актуальность. Использование органоминеральных удобрений позволяет существенно повысить плодородие почвы и восстановить ее агрохимические и физические свойства. Исследование позволит решить некоторые проблемы, связанные с применением удобрения в необработанном виде, а полученный продукт в виде сферических гранул размером от 2,0 до 5,5 мм будет иметь высокую статическую прочность и может быть легко использован в сельском хозяйстве в условиях сплошного внесения удобрений в почву с использованием агротехники. Цель: изучение процесса гранулирования органоминерального удобрения методом окатывания с предварительной подформовкой и определение оптимальных технологических параметров; исследование вероятности образования труднорастворимых соединений при взаимодействии растворов связующих с компонентами, входящими в состав органоминеральных удобрений. Объект: органоминеральное удобрение биогумус с влажностью 55–60 %. Методы: электронная сканирующая микроскопия (Hitachi «S-3400N»), позволяющая определить элементный состав биогумуса и оценить поверхность частиц удобрения и готового гранулированного продукта; рентгеноспектральный анализ, используемый для установления элементного состава; термодинамический анализ, необходимый для оценки вероятности протекания реакций и возможности образования труднорастворимых соединений в гранулированном удобрении, способствующих увеличению прочности гранул; ситовой анализ, используемый для определения гранулометрического состава, и метод определения статической прочности гранул на приборе ИПГ-1М. Результаты. С помощью электронно-сканирующего микроскопа была изучена и описана поверхность частиц органоминерального удобрения – биогумус. Установлен элементный состав органоминерального удобрения: C, N, P, K, O, Fe, Al, Ca, Mg, Na, Cl, S, Ti. Определены оптимальные параметры технологии гранулирования органоминерального удобрения с предварительным формованием через ячейки диаметром 4,0 мм: продолжительность 180 с, температура окатывания 25 °С, сушка при 110 °С в течение 60 мин и величина ретура 3 %. Определен вид связующего раствора и его содержание в тукосмеси, благодаря которому можно получить продукт с наилучшими товарными характеристиками (статическая прочность, выход товарной фракции от 2,0 до 5,5 мм). На основании термодинамического анализа установлена возможность протекания химических реакций между связующим раствором и компонентами биогумуса, в результате которых образуются труднорастворимые соединения (Mg3(PO4)2, Ca3(PO4)2, Fe3(PO4)2), способствующие увеличению прочности гранул. Применяемый в качестве связующего вещества водный раствор фосфата натрия позволяет получить гранулы, обладающие высокой статической прочностью (51,1 Н/гранула). С помощью электронно-сканирующей микроскопии изучена и описана структура получаемого гранулированного удобрения.

Synthesis of calcium phosphate composite organogels by using castor oil and sorbitan monopalmitate based for dentine occlusion material

Calcium phosphate composite organogel was synthesized from a mixture of sorbitan monopalmitate as emulsifier and castor oil as oil phase at 60 °C to establish emulsion system with calcium chloride and di-sodium hydrogen phosphate aqueous solution as water phase. The heated mixture was cooled at room temperature to form organogel. The prepared organogels were investigated by thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM) and cytotoxicity test. The prepared organogels of 4:3 and 1:1 in oil/water content ratio were white and gritty in nature, which resulted in calcium phosphate nanoparticles with spherical shape of 1.3 to 1.9 μm and 1.2 to 2.3 μm, respectively. They were able to successfully occlude into dentine tubules within 1 day. In addition, the prepared organogels were found to have acceptable toxicity level for daily human use with high concentration up to 1600 μg/ml. Hence, these organogels showed the promising results to be developed as an effective dentine occlusion material in relieving of dentin hypersensitivity.