Alkaline Decomposition Research Articles

Extraction of rare earth Eu from waste blue phosphor strengthened by microwave alkali roasting

Spent phosphor is an important secondary resource for extracting rare earth elements. Microwave absorption properties and enhanced extraction of Eu from blue phosphor by microwave alkali roasting were studied. Dielectric properties of alkali roasting system were measured by resonator perturbation method. Dielectric constant increases linearly from 250 °C until it reaches a peak at 400 °C. The dielectric loss reaches a higher value at 400–550 °C, due to the strong microwave absorption properties of molten alkali and roasted products. Effects of roasting temperature, roasting time and alkali addition amount on Eu leaching were investigated. The phosphor was completely decomposed into Eu2O3, BaCO3 and MgO at 400 °C. The alkaline decomposition process of phosphor is more consistent with diffusion control model with Eα being 28.9 kJ/mol. Effects of the main leaching conditions on Eu leaching were investigated. The leaching kinetic of Eu was in line with diffusion control model with Eα being 5.74 kJ/mol. The leaching rules of rare earths in the mixed phosphor were studied. The results showed that the presence of red and green phosphor affected the recovery of blue phosphor. The optimum process parameters of rare earth recovery in single blue phosphor and mixed phosphor were obtained, and the recovery of Eu were 97.81% and 94.80%, respectively. Microwave alkali roasting promoted the dissociation of phosphor and leaching of rare earths. The results can provide reference for the efficient and selective recovery of rare earths in phosphors.

DEGRADATION DETERMINATION OF TINOSORB-S IN SUNSCREEN PREPARATIONS

Objectives: The main objective was to determine the Tinosorb-S degradation in the sunscreen preparations with a simple economic linear and specific analytical method. Methods: The RP-HPLC was achieved with 100% methyl alcohol as the mobile phase, a flow rate of 2.5 mL/min., and an octadecylsilane column (300 × 3.9 cm, 10 µ) at 254 nm. Results: The developed analytical method of Tinosorb-S was statistically validated for accuracy and linearity of 70–130 µg/mL. The correlation coefficient was 0.996, and the % RSD of precision was 0.957. The recovery percentage was 100.01–105.04, and the excellent thermal and photolytic stability of Tinosorb-S was confirmed by the thermal, dry, and wet chromatograms compared with the standard; no such degradation was developed, and the recovery was 99.52%, 99.44%, and 99.45%, respectively. Acid, oxidative, and alkaline decomposition of Tinosorb-S were established by screening the decomposition peaks, and the percentage recovery was 41.31%, 40.38%, and 40.44%, respectively. Conclusions: The stress degradation study of Tinosorb-S is important in stability to evaluate the maximum protecting power of skin from harmful UV rays. Conditions like photolytic degradation, exposure to thermal conditions, acid hydrolysis, oxidation, and alkali hydrolysis were studied with a cost-effective, specific, linear, high-performance liquid chromatographic method with a photodiode array detector.

FIXATION OF THE OPTICAL FIBER IN THE CONNECTOR USING HYDROGEL

A method of fastening optical fiber in a quartz connector with a sodium polysilicate hydrogel obtained in a cylindrical gap between the connector and the fiber due to the alkaline decomposition of quartz surfaces of parts was developed. The conditions of thermal decomposition of the hydrogel are determined and it is shown that the decomposition of the hydrogel with the formation of a cellular structure is possible at temperatures below the temperature of thermal decomposition of the polymer coating of the fiber. The conditions for obtaining and thermal properties of the hydrogel are determined. Conclusions are drawn about the suitability of the proposed method for fixing optical fiber in a quartz connector.

Quantification of the Monomer Compositions of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly(3-hydroxyvalerate) by Alkaline Hydrolysis and Using High-Performance Liquid Chromatography.

With the growing interest in bioplastics, there is an urgent need to develop rapid analysis methods linked to production technology development. This study focused on the production of a commercially non-available homopolymer, poly(3-hydroxyvalerate) (P(3HV)), and a commercially available copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), through fermentation using two different bacterial strains. The bacteria Chromobacterium violaceum and Bacillus sp. CYR1 were used to produce P(3HV) and P(3HB-co-3HV), respectively. The bacterium Bacillus sp. CYR1 produced 415 mg/L of P(3HB-co-3HV) when incubated with acetic acid and valeric acid as the carbon sources, whereas the bacterium C. violaceum produced 0.198 g of P(3HV)/g dry biomass when incubated with sodium valerate as the carbon source. Additionally, we developed a fast, simple, and inexpensive method to quantify P(3HV) and P(3HB-co-3HV) using high-performance liquid chromatography (HPLC). As the alkaline decomposition of P(3HB-co-3HV) releases 2-butenoic acid (2BE) and 2-pentenoic acid (2PE), we were able to determine the concentration using HPLC. Moreover, calibration curves were prepared using standard 2BE and 2PE, along with sample 2BE and 2PE produced by the alkaline decomposition of poly(3-hydroxybutyrate) and P(3HV), respectively. Finally, the HPLC results obtained by our new method were compared using gas chromatography (GC) analysis.

Methods of Extracting TiO2 and Other Related Compounds from Ilmenite

Although ilmenite and rutile are extensively used to extract TiO2 at the industrial level, through the sulphate and chloride processes, they can also be recognized to possess the potential to be employed as the raw material to synthesize other titanium compounds as well. The Pulmoddai mineral sand deposit in Sri Lanka is considered as a valuable resource containing pure ilmenite and can be used as a very good source of both titanium and iron. Because of the lower TiO2 content compared to rutile, processes, such as the Becher process, Laporte process and Kataoka process, have been developed to upgrade ilmenite into higher grade synthetic rutile. Additionally, research studies have been carried out to develop methods, such as the hydrochloride process, H3PO4/NH3 process, alkaline roasting process, aluminothermic reduction method, alkaline decomposition method, molten salt electroreduction method and magnesiothermic reduction method, to synthesize TiO2 and other related titanium compounds, such as titanium and iron oxides, composites and alloys, from naturally occurring ilmenite where these methods possess both rewards as well as drawbacks over the others.

Synthesis, Characterization and Decomposition of Potassium Jarosite for Adsorptive As(V) Removal in Contaminated Water: Preliminary Study

Jarosite-type compounds precipitated in the zinc industry for iron control can also incorporate arsenic and can be used for wastewater treatment for As elimination. According with the last, this work is related to arsenic incorporation at room temperature in decomposed potassium jarosite. The work began with the synthesis of the compound at 75 °C for 9 h using Fe2(SO4)3 and K2SO4 at a pH of 1.1. Once jarosite was obtained, solids were subjected to an alkaline decomposition using NaOH at pH 10 for 30 min, and then As was added to the solution as HAsNaO4 and the pH modified by adding HNO3 until it reached a value of 1.1. The initial, intermediate, and final products were wholly characterized by scanning electron microscopy (SEM) in conjunction with energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS), and X-ray photoelectron spectrometry (XPS). The obtained results show that As(V) can be adsorbed by ionic exchange in the amorphous FeOH structure of decomposed jarosite and when pH decreased to 1.1, the compound recrystallized, incorporating up to 6% As on average, which is indicative that this process can be used to reduce As in contaminated waters.

Efficient Method for α-TiP Synthesis using Alkaline Decomposition Pretreatment of Ilmenite Natural Beach Sand

The layered, acidic compound; α-TiP is widely popularized as a sorbent material for heavy metal removal from wastewater, as catalysts for biomass conversion and as an intermediate to produce high purity titanium dioxide particles. One of the conventional route for its synthesis is to react ilmenite with orthophosphoric acid under reflux conditions. However, the major drawback of this method is that the titanium recovery is only 35 wt. % and about 10 wt. % of the initial ilmenite remain unreacted as the residue. The conversion of ilmenite into an easily acid digestible compound could be attained via alkaline roasting. The objective of this research was to increase the yield of α-TiP from ilmenite using an additional alkaline roasting pre-treatment step to the acid leaching. Potassium hydroxide was selected for the alkaline roasting step since it is regarded to be an environmentally benign chemical. The pre-treatment of ilmenite with a 1:4 molar ratio of KOH to ilmenite at 700 C generated potassium iron oxides and potassium titanium oxides as intermediate compounds which were then washed with distilled water, filtered and dried at 100 C for 24 hours. The solid compound was reacted with orthophosphoric acid with a solid to liquid ratio of 1/8 under reflux conditions for 4 hours. Then the remaining acid leachate was decanted and the white precipitate from the leach liquor was filtered, washed and dried at 100 C for 24 hours. The obtained powder was characterized using X-Ray Diffraction (XRD) analysis, X-Ray Fluorescence (XRF) spectroscopy, FTIR spectroscopy and Raman spectrophotometry and was confirmed to be α-TiP. The parameters; the effect of KOH/ilmenite ore molar ratio, calcination temperature, solid to liquid ratio in the acid leaching step, acid leaching reflux time on the titanium recovery were fine tuned. This research concluded the possibility of increasing the titanium extraction. Therefore the research concludes the increment of α-TiP yield after the pre-treatment step using KOH.
 Keywords: Ilmenite, Titanium phosphate, Alkaline roasting, Alkaline pretreatment

Recovery and Preparation of Potassium Fluorotantalate from High-Tantalum-Bearing Waste Slag by Pressure Alkaline Decomposition

Tantalum slag is a type of high-grade tantalum resource with great recovery value. In this paper, a low fluorine process, including alkali pressure decomposition, low-acid transformation, solvent extraction, and crystallization, is proposed to recover tantalum and prepare potassium fluotantalate. First, some tantalum slag underwent alkali pressure decomposition, and the optimal decomposition conditions were obtained under a reaction time of 2 h, oxygen partial pressure 2.5 MPa, liquid–solid ratio 4:1, basicity 40 wt.%, and temperature 200 °C. Under these conditions, the decomposition efficiencies of Ta and Nb were 93.62% and 95.42%, respectively. X-Ray diffraction (XRD) and scanning electron microscope (SEM) were used to detect the main phase of the decomposition residue and showed that it was mainly sodium tantalate. With the increase in oxygen partial pressure, the particle size of decomposition slag gradually decreases and becomes loose. Second, the alkali decomposition residue was subjected to low-acid leaching to obtain fluorine tantalate and fluorine niobate, and the leaching efficiencies of tantalum and niobium were more than 99%. Last, the low-acid leaching solution was subjected to solvent extraction and evaporative crystallization to prepare potassium fluotantalate. The results showed that the tantalum extraction rate and tantalum and niobium separation factors were above 94% and 200, respectively, and the purity of potassium fluotantalate met the requirements of commercial products. Compared with current industrial practice, the consumption of hydrofluoric acid was greatly reduced, and the recovery rate of tantalum was increased.

Alkaline Decomposition of Solid Solution of Ammonium-Sodium Jarosite with Arsenic

In this study, a solid solution of arsenical ammonium-sodium jarosite, with the approximate formula [(NH4)0.72 Na0.06(H3O)0.21]Fe3(2.52)(SO4)1.85 (AsO4)0.15 [(OH)4.41 (H2O)1.59], was synthesized. The precipitate particle main size was 38 µm, with spherical morphology. A decomposition reaction in alkaline media was carried out; this decomposition comprised three stages: an induction period, a progressive conversion and a stabilization period. The process was controlled by the chemical reaction, and the progressive conversion period was consistent with the shrinking core model. The dissolution reactions of the compound in NaOH media were characterized by an ash layer formed by solid residues made of Fe(OH)3 with adsorbed arsenate surrounding an unreacted core through which Na+, NH4+ and SO42− ions diffused into the solution. At the same time, OH− ions diffused from the solution into the reaction front until the core disappeared, indicating the end of the reaction.

An Organogermanium Compound Enhances the Initial Reaction Rate of Alkaline Isomerization of an Aldose into a Ketose through Enediol Complex Formation.

We previously demonstrated that the organogermanium compound 3-(trihydroxygermyl)propanoic acid (THGP) enhances the enzymatic and alkaline isomerization of an aldose to a ketose through cis-diol complex formation by multiple mechanisms. Its higher affinity for the ketose than the aldose protects the ketose complex from alkaline decomposition. Furthermore, it has been reported that the aldose-ketose alkaline isomerization pathway includes 1,2-enediol. Therefore, we speculated that the complex-forming ability of THGP could also be applied to enediol, a transient intermediate of alkaline isomerization. To test this prediction, we analyzed the initial rates of glucose or lactose isomerization in a region where there was no substantial difference in pH with and without THGP addition. The results showed that THGP enhanced the rate of fructose or lactulose formation per unit time by approximately 2-fold compared to the control. This finding indicated that THGP could form a complex with the transition state of aldose-ketose alkaline isomerization.

Fading of nanocurcumin-based configured biosensor array for differentiation of carrier proteins in biological fluids

Herein, a simple, novel, and cost-effective biosensor array is developed for the differentiation of carrier proteins (i.e. human serum albumin (HSA), bovine serum albumin (BSA), transferrin (TRF), immunoglobulin G (IgG), fibrinogen (Fb) and casein (Cas) based on fading nanocurcumin in alkaline solutions. We found that the carrier proteins show different inhibitory effects with diverse extents on the alkaline decomposition of nanocurcumin. In the other words, in the presence of carrier proteins, the biosensor array produces fingerprint-like absorbance patterns to identify each carrier protein. The absorbance patterns of this biosensor array can be analyzed by linear discrimination analysis (LDA) and hierarchical cluster analysis (HCA). The six carrier proteins have been well discriminated in different concentrations levels. Furthermore, complex mixtures of HSA and TRF with a total concentration of 25 µM and different mole ratios are also discriminated without errors. Also, the HSA as an example of carrier proteins has been well determined in the range of 5–75 µM. The results revealed that the biosensor array shows high selectivity to the carrier proteins in the presence of other interfering substances. The analytical performance of the biosensor array is examined by the differentiation of carrier proteins in human urine and serum biofluids. It should be noted that the biosensor array is very simple, label-free, and selective, and only restricted sensor elements are required for attaining a high differentiation capability of carrier proteins.

Synthesis, characterization, and some metal complexes of bis(isocyanide)disiloxane, showing catalytic activity

AbstractIsocyanides (isonitriles) are unique organic compounds that contain a formally divalent carbon. Herein, the synthesis of 1,3‐bis(isocyanopropyl)tetramethyldisiloxane was performed by a modified carbylamine method, using a phase transfer agent. Spectral methods (nuclear magnetic resonance [NMR], Fourier transform infrared spectroscopy [FT‐IR], and electrospray ionization mass spectrometry [ESI‐MS]) were used to confirm the structure. Energy gap of 1.86 eV (measured by diffuse reflectance spectroscopy [DRS]), high dielectric permittivity (15 at 10 kHz), and conductivity value in the order of 10−7 S·cm−1 place this compound in the range of wide‐bandgap semiconductors. The synthesis of Pt, Ag, and Fe metal complexes without organic co‐ligands and their catalytic activity were also investigated. The Pt complex was active in hydrosilylation reaction and in reduction of p‐nitrophenol, whereas the Ag complex was found effective in alkaline decomposition of hydrogen peroxide. The Fe complex is a new and cheap heterogeneous hydrosilylation catalyst and also showed very good catalytic behavior in heterogeneous Fenton‐like photodecomposition of Congo Red in various photo‐irradiation conditions, with 100% color removal efficiency after 60 min under sunlight. Thus, a simple path for siloxane‐containing materials with promising applications is open.

Acidic decomposition of scheelite by organic sodium phytate at atmospheric pressure

The alkali residue formed during the alkaline decomposition of scheelite produces serious environmental pollution. A new acidic decomposition method for scheelite using sulfur-phosphorus mixed acid process has been industrialized, but it requires a high concentration of phosphoric acid. In this paper, sodium phytate, a green and natural organic phytic acid salt, was used as a chelating agent to decompose scheelite under acidic conditions. In the leaching process, calcium was precipitated by H2SO4 to generate insoluble CaSO4 in the residue, while tungsten was chelated by sodium phytate to form stable macromolecular multinuclear organic chelates in the solution. A satisfactory tungsten leaching extent of 99.39% was achieved using 10 g/L sodium phytate, 1 mol/L H2SO4, and a liquid/solid ratio of 8:1 at 353 K for 3.5 h. As such, the phosphorus consumption was significantly reduced in the sodium phytate leaching system without high temperature and pressure. This innovative process provides a new method for extracting tungsten from scheelite, which reduces the consumption of phosphorus and is environmentally friendly.

HPLC method for simultaneous determination of impurities and degradation products in Cardiazol

Aim. The aim of study was to develop a simple and accurate procedure that could be applied for the determination of impurities and degradation products in cardiazol. Materials and methods. Separation in samples was carried out with Acquity H-class UPLC system (Waters, Milford, USA) equipped with Acquity UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm) (Waters, Milford, USA). Xevo TQD triple quadrupole mass spectrometer detector (Waters Millford, USA) was used to obtain MS/MS data. Mobile phase A: 0.1% solution of trifluoroacetic acid R in water R; Mobile phase B: acetonitrile R. Samples were chromatographed in gradient mode (Table 1). Flow rate of the mobile phase: 1 ml / min. Column temperature: 30 °С. Detection: at 240 nm wavelength. Injection volume: 10 μl. Results. The retention time of the main substance is about 18.5 minutes. The order of the peak, the retention times and relative retention times: impurity B (12.04, 0.65); impurity А (18.5; 0.98); Cardiazol (18.87; 1.00). The LOD and LOQ values obtained were in the range of 30 ng/mL to 100 ng/mL and 80 ng/mL to 310 ng/mL respectively (with respect to sample concentration of 2 mg/ml). Linearity was established in the range of LOQ level to 0.2% having regression coefficients in the range of 0.9996 to 0.9999. The change in the temperature of the column affects the degree of separation of cardiazol and the impurity A, and thus, with a decrease of 5 ° C, the degree of separation is (1.06), while with increasing this index (3.43). When changing the flow rate of the mobile phase, the degree of separation changes in the following order, with a decrease to 0.9 ml / min separation (1.90), with an increase in speed to 1.1 ml / min (2.45). When the number of mobile phase B decreases by 5%, the degree of separation varies by (2.65), with an increase of 5% (1.82). In comparison with the chromatogram of the tested solution, the substance is not resistant to the action of peroxide, alkaline and acid decomposition. Conclusion. 1) HPLC method was developed and validated for the simultaneous detection and quantitation of impurities formed during the synthesis of cardiazol. 2) The method proved to be sensitive, selective, precise, linear, accurate and stability-indicating.

Nanobiocomposites of Pharmacophoric Iron and Bismuth Oxides with Arabinogalactan Matrix

Water-soluble nanocomposites with narrow distribution of nanoparticles of pharmacophore bismuth and iron oxides have been obtained. The biopolymer matrix of the arabinogalactan polysaccharide has exhibited strong stabilizing properties with respect to transition metal oxides. The size of the spherical metal oxide nanoparticles has been found of 5–7 nm as per transmission electron microscopy. The exclusion liquid chromatography data have revealed that the change in the molecular mass parameters of arabinogalactan is due to the combined processes of self-assembly of nanocomposites and alkaline decomposition.

PH-dependent cell\u2013cell interactions in the green alga Chara

Characean internodal cells develop alternating patterns of acid and alkaline zones along their surface in order to facilitate uptake of carbon required for photosynthesis. In this study, we used a pH-indicating membrane dye, 4-heptadecylumbiliferone, to study the kinetics of alkaline band formation and decomposition. The differences in growth/decay kinetics suggested that growth occurred as an active, autocatalytic process, whereas decomposition was due to diffusion. We further investigated mutual interactions between internodal cells and found that their alignment parallel to each other induced matching of the pH banding patterns, which was mirrored by chloroplast activity. In non-aligned cells, the lowered photosynthetic activity was noted upon a rise of the external pH, suggesting that the matching of pH bands was due to a local elevation of membrane conductance by the high pH of the alkaline zones of neighboured cells. Finally, we show that the altered pH banding pattern caused the reorganization of the cortical cytoplasm. Complex plasma membrane elaborations (charasomes) were degraded via endocytosis, and mitochondria were moved away from the cortex when a previously acid region became alkaline and vice versa. Our data show that characean internodal cells react flexibly to environmental cues, including those originating from neighboured cells.

Analysis of yellow sugar coloring substances from sugar beet production

Coloring substances (colorants) adsorbing on the surface of growing sugar crystals or incorporating into the crystal lattice, reduce the speed of sucrose crystallization, increase the color and hygroscopicity of sugar, tend to clod during storage. Most of the colored nonsugars are found on the surface of yellow sugar crystals so it is possible to reduce the color of yellow sugar by 50-80% with the help of affinity. The distribution of coloring substances in the crystals of yellow sugar and their composition have not been studied sufficiently. The purpose of this research was to study the coloring substances of yellow sugar obtained during the sugar beet processing. As a result of the research it was found that up to 90% of yellow sugar coloring substances is in the film located on the crystals surface and can be easily removed by affinity. It was experimentally learnt that the main products in the coloring matter are the products of alkaline decomposition of reducing substances: their content is 10 times higher than that of caramel and melanoidins, which is in good agreement with the conditions for carrying out the technological processes of sugar beet production. The content of all groups of coloring substances correlates well with the crystals size: the least fraction of the colorants contains a fraction of 0.5 mm in size; in crystals of a larger and smaller size, the content of all groups of coloring substances increases. Yellow sugar coloring substances are extracted with acetic acid most effectively, because it is a weakly polar proton solvent. The noted absorption maxima for aqueous, acetate and ethyl acetate extracts do not coincide, which indicates the presence of various coloring agents in them..

Development of Alkaline Decomposition of Lepidolite Concentrate by Melting with Calcined Soda and Melt Comprehensive Sulfuric Acid Treatment

Experimental research is conducted for recovery of lithium from lepidolite. A method is developed for alkaline decomposition of lepidolite based on melting with calcined soda and subsequent melt granulation with water. Lepidolite activated in this way is thoroughly and comprehensively broken down by sulfuric acid. In addition, kinetics are studied for reaction of the granulate obtained with sulfuric acid. It is established that the granulate sulfatization reaction with sulfuric acid proceeds in a diffusion region that makes it possible fundamentally to select equipment formulation for sulfatization.

Thermodynamic estimation of the probability of chemical reactions during alkaline decomposition of eudialyte concentrate

Thermodynamic estimation of the probability of chemical reactions during alkaline decomposition of eudialyte concentrate

Study of Products of the Alkaline Decomposition of Hydrolysis Lignin by Atmospheric Pressure Photoionization High-Resolution Mass Spectrometry

A method of high resolution-mass spectrometry with acetone doped atmospheric pressure photoionization was used to study products of the alkaline solvolysis of hydrolysis lignin. It was found that the mass spectrum of the depolymerization products of hydrolysis lignin consists of about seven thousand peaks of oligomers, containing up to 10 aromatic units with an average molecular weight of 150 Da. Calculations of the elemental compositions of all detectable oligomers and their visualization on the van Krevelen coordinates allowed us to show that the studied sample differs from native (virgin released) lignin by the presence of fractions with high oxygen contents and highly unsaturated condensed structures, including polynuclear aromatic hydrocarbons. The structural units of lignin oligomers were characterized using an approach based on the collision induced dissociation of precursor ions in a broad m/z range.