Amount Of Impurities Research Articles

Measurement of helium diffusion in Lotsberg Salt cores: A proxy to evaluate hydrogen diffusion

Hydrogen can be a critical part of the energy transition and salt caverns have been considered for underground hydrogen storage. Although there have been some successful experiences of hydrogen storage in salt caverns in Europe and the United States, it is essential to exercise caution when selecting caverns for storage to ensure safe operations. This study investigates the relationship between rock heterogeneity and helium diffusion by testing salt-rock cores from the Lotsberg Formation, Alberta, Canada. We characterized salt rock heterogeneity by analyzing the results of X-ray diffraction (XRD) analysis, thin-section microscopy, scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS), and high-resolution CT scans. Then, diffusion tests were conducted using a custom-designed HPHT visualization cell on core samples with different compositions and crystal sizes. The samples in this study were categorized as Lotsberg Salt and Lotsberg Marlstone. Lotsberg Salt mainly consisted of halite with trace amounts of carbonate impurities, while Lotsberg Marlstone comprised halite with a carbonate matrix containing carbonates, clays, quartz, and muscovite. Helium diffusion through pure and intact halite crystals was negligible, and the micro-scale halite crystal boundaries are non-open or poorly unconnected for helium diffusion. Halite samples with macro-scale grain boundaries and carbonate impurities exhibited more interconnected pore networks, resulting in increased rates of helium diffusion. However, the formation of secondary halite veins between grain boundaries can lead to tightly sealed boundaries that have poor connectivity, limiting helium diffusion within the sample. Salt-rock cores with intergranular fractures and unsealed grain boundaries showed accelerated pressure declines, attributed to the preferential diffusion of helium through these fracture and crack pathways.

Effects of Marine Shellfish on Mechanical Properties and Microstructure of Coral Concrete

Using coral debris as coarse and fine aggregates and seawater as mixing water has been proposed to address transportation and material shortage issues in island and reef construction projects. However, the utilization of coral may result in impurities, such as shellfish and other marine organisms, which could impact the mechanical properties of the resulting concrete. The goal of this study is to find out how different amounts of shellfish and marine organism impurities affect the mechanical properties and microstructure of coral concrete. This study builds on the process of making full coral concrete. Substitution optimization is carried out using the response surface method (RSM), with the polynomial work expectation serving as a validation measure. The experimental findings indicate that impurities have an insignificant impact on the mechanical properties of coral concrete when their dosage is below 2%, causing a decrease of only around 6%. The mechanical properties of coral concrete containing shellfish and marine organism impurities exhibit a strong correlation at 28 days. SEM and XRD analysis revealed that the primary factor contributing to the decline of mechanical properties in coral concrete with shellfish and marine organism impurities is the weak strength of the impurity shell structure, in addition to the rehydration of internal biomass during the cement hydration process, leading to the formation of numerous small pores within the coral concrete. The results of an ANOVA test indicate that the model is statistically significant, with a p-value of less than 0.05.

Influence of Microstructure on the Sulfur Tolerance of Ceria-Based Anodes in Low Temperature SOFC

Hydrocarbon fuels such as natural gas, propane or biogas commonly contain small amounts of impurities like sulfur which result in a strong degradation of the cell performance in the intensively studied Ni/YSZ cermet anode [1-3]. The sulfur poisons the nickel catalyst and hinders the electrooxidation of hydrogen [2-3].At common SOFC operation temperatures of 700 to 900 °C the polarization resistance of a Ni/CGO fuel electrode is less influenced by sulfur [3-5]. With a modification of the surface by infiltration of Ni and / or ceria nanoparticles the impact can be even reduced [5-6]. The trend to a much lower operating temperature of SOFCs [7-8] even below 600 °C raises the question to what extend the sulfur tolerance of ceria-based fuel electrodes is maintained.In this study we analyze the impact of H2S on the polarization resistance of ceria-based fuel electrodes at operation temperatures around 600 °C. Ni/ceria anodes, differing in their microstructure, are investigated by electrochemical impedance spectroscopy (EIS). The distribution of relaxation times (DRT) analysis is applied to deconvolute the electrochemical processes followed by a complex nonlinear least square approximation to quantify the loss processes and the impact of sulfur amounts of 0.1-3 ppm. Compared to previous results [5] the polarization resistance increases more significantly at 600 °C than at 750 °C. The influence of the microstructure will be discussed in detail.

Adsorption/Desorption Behaviors of Sulfur Species at Pt Single Crystal Surfaces

Platinum is an excellent electrocatalyst for polymer electrolyte membrane (PEM) fuel cells because it drives hydrogen oxidation and oxygen reduction with very high efficiency. However, when sulfur species contained as a trace amount of impurity in hydrogen fuel and/or pollutant in air adsorb on platinum surfaces, power output significantly decrease because of reduced electrochemically active surface area. Such negative effect caused by the adsorption of sulfur species, so-called sulfur poisoning, is a serious problem because interaction between sulfur species and platinum surfaces is very strong. Thus, understanding and control of adsorption behavior of sulfur species at platinum surfaces are very important to maintain the cell performance of PEM fuel cells. In the present study, adsorption/desorption behaviors of sulfur species at well-defined platinum single crystal surfaces in acidic aqueous solutions are studied by electrochemical measurements, x-ray photoelectron spectroscopy (XPS), and surface x-ray diffraction (SXRD).Prior to each experiment, platinum single crystal surfaces were annealed by induction heating method [1, 2, 3] at 1600°C more than 1 h under the flowing of Ar and H2 mixed gas, followed by cooling under the Ar and H2 flow for 7 min. The surface was immersed in a 1 mM Na2S aqueous solution saturated with Ar and H2 mixed gas, for 1 h. After rinsing with ultrapure water, electrochemical measurements were carried out in an aqueous solution of 0.1 M HClO4 or H2SO4 deaerated with pure N2 gas.At the bare Pt(111) surface, characteristic current responses such as adsorption/desorption of hydrogen and hydroxyl group were observed. After immersing in the sulfur-containing solution, however, those characteristic current responses disappeared, confirming the adsorption of sulfur species and decrease of electrochemically active surface area. XPS in the S 2p region of the Pt(111) surface immersed in the sulfur-containing solution showed three major adsorbed species; adsorbed hydrosulfide ion (Pt-HS- ad) at 161.8 eV, adsorbed sulfur (Pt-Sad) at162.7 eV, and adsorbed polysulfide (Pt-Sn) at 164.3 eV. While Pt-HS- ad reductively desorbed from the surface by the potential sweeping up to -0.2 V vs. Ag/AgCl, Pt-Sad and Pt-Sn oxidatively desorbed by the potential sweeping up to the potential more positive than 0.7 V vs. Ag/AgCl. SXRD showed that the sulfur species adsorbed at the Pt(111) surface in the (√3×√3)R30° structure.At the Pt(100) surface, the oxidative desorption of sulfur species occurred at more positive potential than that at the Pt(111) surface. This indicates that the recovery from sulfur poisoning at the Pt(100) surface is more difficult than that at the Pt(111) surface. Unlike the Pt(111)-(√3×√3)R30° structure, SXRD showed that the sulfur species adsorbed at the Pt(100) surface in the (√2×√2)R45° structure. While the sulfur species occupies a three-fold hollow site of the Pt(111)-(√3×√3)R30° structure, it occupies a four-fold hollow site of the Pt(100)-(√2×√2)R45° structure. The different coordination number of adsorbed sulfur species is considered as the origin of different oxidative desorption behaviors.

The effect of temperature on the hydrothermal synthesis of carbonated apatite from calcium carbonate obtained from green mussels shells

Hydroxyapatite (HAp) refers to a bioceramic broadly employed in bone tissue engineering since it has bioactive and osteoconductive properties. The synthesis of HAp will be more economically viable using waste materials because it is cheap, easy to find, and available in large quantities. Therefore, this study aimed to synthesize and characterize HAp from green mussel shells by hydrothermal method at various temperatures. Precipitated calcium carbonate (PCC), made from green mussel shell powder, is employed in this study. Utilizing a hydrothermal reactor for 14 hours at 120℃, 140℃, as well as 160℃, a combination of PCC and (NH4)2HPO4 with a Ca/P molar ratio of 1.67 was synthesized to form HAp. Note that the synthesis findings were categorized using scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), as well as X-ray diffraction (XRD) tests. Apart from that, the FTIR test showed the formation of HAp in all test variations because the results of –OH, and –PO4 were found. XRD results that have been analyzed using HighScore Plus software show the percentage of weight (%) and crystal size of HAp increases with increasing hydrothermal temperature. Other than that, HAp produced at hydrothermal temperature variations of 160℃ has a hexagonal crystal system with a percentage of weight (%) as well as a crystal size of 46.43 nm and 99.3%, whilst the amount of impurity (%) produced is 0.7%. The higher the hydrothermal temperature, the weight percentage (%), and the crystallite size in HAp are getting bigger while the number of impurities gets smaller.

Investigation and characterization of dielectric, thermal, and chemical properties of recycledhigh‐density polyethyleneblended with virginpolyethylene

AbstractDielectric performance of post‐consumer recycled HDPE blended with virgin HDPE was investigated to evaluate the possibility of using these materials for the insulation of electrical wires and cables. The presence of organic and inorganic impurities was investigated using thermal and chemical methods (TGA, DSC, and EDX). The characterization of impurities revealed different amount of inorganic impurities in recycled material that was depending on the execution of melt filtration by the recycler to prepare the recycled material. Higher values of both dielectric losses and dielectric constant were observed for post‐consumer recycled PE, with the dielectric loss of recycled material almost 17 times higher than the one of virgin PE at power frequency (60 Hz). The short‐term breakdown strength of post‐consumer recycled HDPE was observed to be slightly lower than that of virgin PE. The experimental result showed that blending the recycled stream with virgin materials was effective in order to enhance dielectric properties of recycled material. In this regards, dielectric losses decreased by almost 50% when 50% of virgin HDPE was added to the recycled material. In addition, breakdown strength was improved when virgin HDPE was added.

Examining the molecular origins of anomalously high H2O generation at oxide-passivated metal surfaces for plasma applications

Elucidating the mechanisms responsible for sub-microsecond desorption of water and other impurities from electrode surfaces at high heating rates is crucial for understanding pulsed-power behavior and optimizing its efficiency. Ionization of desorbed impurities in the vacuum regions may create parallel loads and current loss. Devising methods to limit desorption during the short time duration of pulsed-power will significantly improve the power output. This problem also presents an exciting challenge to and paradigm for molecular length-scale modeling and theories. Previous molecular modeling studies have strongly suggested that, under high vacuum conditions, the amount of water impurity adsorbed on oxide surfaces on metal electrodes is at a sub-monolayer level, which appears insufficient to explain the observed pulsed-power losses at high current densities. Based on density functional theory (DFT) calculations, we propose that hydrogen trapped inside iron metal can diffuse into iron (III) oxide on the metal surface in sub-microsecond time scales, explaining the extra desorbed inventory. These hydrogen atoms react with the oxide to form Fe(II) and desorbed H2O at elevated temperatures. Cr2O3 is found to react more slowly to form Cr(II). H2 evolution is also predicted to require higher activation energies, so H2 may be evolved at later times than H2O. A one-dimensional diffusion model, based on DFT results, is devised to estimate the water outgassing rate under different conditions. This model explains outgassing above 1 ML for surface temperatures of 1 eV often assumed in pulsed-power systems. Finally, we apply a suite of characterization techniques to demonstrate that when iron metal is heated to 650 ∘C, the dominant surface oxide component becomes α-Fe2O3. We propose such specially-prepared samples will lead to convergence between atomic modeling and measurements like temperature-programmed desorption.

Sol-gel construction of honeycomb-like CuMn2O4 spinels with high infrared emissivity

Spinel materials are gradually becoming high infrared radiation materials with the most potential because of their special crystal structure. However, it is still difficult to design the microstructure reasonably and synthesize it at low temperature. In this paper, the honeycomb-like CuMn2O4 spinels were prepared via a facile sol-gel method with a subsequent low-temperature sintering treatment. Therefore, the CMO samples with numerous pores are conducive to improving absorptivity and emissivity. Moreover, the optimum experimental conditions for high infrared emissivity were acquired by detailed investigation of the synthesis parameters including the molar ratio of trimonium citrate to metal ions, the molar ratio of urea to metal ions and the sintering temperature. Under the synergistic effect of internal factors such as, a suitable amount of impurities, abundant oxygen vacancy, small band gap, and good crystallinity, the obtained sample CMO-800 achieved excellent infrared radiation performance. Its infrared emissivity values at the test temperature of 30 °C and 600 °C separately reached 0.801 and 0.965 in the wavelength range of 3–5 μm. More significantly, this work provides significant guidance for the design and preparation of spinel materials with excellent infrared emissivity.

Novel Synergistic Process of Impurities Extraction and Phophogypsum Crystallization Control in Wet-Process Phosphoric Acid.

Phosphogypsum, as a byproduct of wet-process phosphoric acid reaction, has caused many environmental pollution problems. To improve the property and purity of phosphogypsum in the wet-process phosphoric acid process, a liquid-solid-liquid three-phase acid hydrolysis synergistic extraction reaction system was established by adding a certain amount of extractant in the actual production process. In order to study the extraction effect and residue of impurities in the reaction system, the phase, morphology, and impurity occurrences of phosphogypsum were systematically analyzed. The results showed that when the reaction time was 7 h, the reaction temperature was 80 °C, the reaction speed was 200 r/min, the volume ratio of the extractant to diluent (dilution ratio) was 1:4 and the volume ratio of the oil phase/aqueous phase (O/A ratio) was 1:1, P2O5 conversion was the highest in phosphate rock, and the residual P2O5 content in phosphogypsum was as low as 0.36%. The morphology of the phosphogypsum crystal was uniform and coarse long strip. The main forms of residual impurities were silicate, aluminum fluoride with crystal water, aluminate, phosphate, and fluoride. Meanwhile, the residual amount of main impurities in phosphogypsum was significantly reduced. Through this novel method, the property of phosphogypsum can be improved through the generation process and is greatly beneficial for its utilization and the recycling development of the wet-process phosphoric acid industry.

Configuration of a Simple Method for Different Polyamides 6.9 Recognition by ATR-FTIR Analysis Coupled with Chemometrics.

This study proposes a simple approach for the recognition of polyamide 6.9 samples differing in impurity amounts and viscosities (modulated during the synthesis), which are parameters plausibly variable in polymers' manufacturing processes. Infrared spectroscopy (ATR-FTIR) was combined with chemometrics, applying statistical methods to experimental data. Both non-supervised and supervised methods have been used (PCA and PLS-DA), and a predictive model that could assess the polyamide type of unknown samples was created. Chemometric tools led to a satisfying degree of discrimination among samples, and the predictive model resulted in a great classification of unknown samples with an accuracy of 88.89%. Traditional physical-chemical characterizations (such as thermal and mechanical tests) showed their limits in the univocal identification of sample types, and additionally, they resulted in time-consuming procedures and specimen destruction. The spectral modifications have been investigated to understand the main signals that are more likely to affect the discrimination process. The proposed hybrid methodology represents a potential support for quality control activities within the production sector, especially when the spectra of compounds with the same nominal composition show almost identical signals.

Mild pyrolysis of cotton coated with graphene-like materials as a method to produce superhydrophobic and highly absorptive oil sorbents

In recent years, hydrophobized cellulose-based materials have been proposed as oil spill sorbents. We investigate the possibility of using cheap, industrialgrade, graphene-like materials (GM), such as graphite flakes (GrF), exfoliated graphene nanoplatelets (xGNP) and microwave-plasma turbostratic graphene nanoplatelets (mGNP) as hydrophobic agents for naturally hydrophilic cotton. From among investigated GM, mGNP showed the highest ability to form superhydrophobic coating due to small flake size and small amount of impurities. Furthermore, we showed that mild pyrolysis not only makes cotton more hydrophobic, but also increases its sorption capacity towards organic solvents and oils. Pyrolyzed and coated with mGNP and xGNP cotton showed exceptional superhydrophobic properties and water contact angle equal 148° and 142°, respectively, besides the sorption capacity towards motor oil of 46 g/g and 51 g/g, respectively. What is more important, the price of graphene oxide used in previous research is still very high (approx. 100 $/g), while the price of xGNP and mGNP is 0.45 $/g, 7.3 $/g, respectively. This difference may be crucial for the implementation of graphene-based sorbents in the remediation of massive oil spill remediation.

Health Benefits, Antioxidant Activity, and Sensory Attributes of Selected Cold-Pressed Oils.

The consumption of cold-pressed oils (CPOs) has continuously increased due to their health-promoting compounds, such as polyunsaturated fatty acid (PUFA), tocopherols, sterols, and polyphenols. This study focused on the estimation and comparison of the physicochemical properties and sensory quality of six CPOs: linseed oil (CPLO), pumpkin oil (CPPO), milk thistle oil (CPMTO), rapeseed oil (CPRO), camelina oil (CPCO), and sunflower oil (CPSO), which are the most popular in the Polish market. These oils were analysed for their fatty acid composition (FAC), their tocopherol, sterol, polycyclic aromatic hydrocarbon (PAHs), water, and volatile matter (WVM) contents, as well as their antioxidant activity (AA) and oxidative stability parameters. Moreover, quantitative descriptive analysis (QDA) was performed to obtain detailed information on the sensory profiles and quantitative data on the CPOs' attributes that affected consumer acceptability and purchase intent. All of the analysed CPOs were rich in PUFA (27.94-68.42%). They were characterised by the different total amounts of health-beneficial compounds, such as tocopherols (TTC = 44.04-76.98 mg/100 g), sterols (TSC = 300-684 mg/100 g), and polyphenols (TPC = 2.93-8.32 mg GA/100 g). Additionally, their AA was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) methods, with results ranging between 185.36-396.63, 958.59-1638.58, and 61.93-119.21 µmol TE/100 g, respectively. However, the deterioration parameters of CPOs, such as peroxide values (PV = 0.24-4.61 meq O2/kg), p-anisidine values (pAnV = 0.39-4.77), acid values (AV = 0.31-2.82 mg KOH/g), and impurity amounts (Σ4PAHs = 1.16-8.76 μg/kg and WVM = 0.020-0.090%), did not exceed the level recommended by the Codex Alimentarius Commission. The obtained results indicated that all of the investigated CPOs are valuable sources of health-promoting bioactive compounds.

Development and Comparison of Alternative Methods for the Purification of Adalimumab Directly from Harvested Cell Culture Fluid.

Protein A affinity chromatography is a well-established method currently used in the pharmaceutical industry. However, the high costs usually associated with chromatographic separation of protein A and the difficulties in continuous operation make the investigation of alternative purification methods very important. In this study, extraction/back-extraction and precipitation/dissolution methods were developed and optimised. They were compared with protein A and cation exchange chromatography separations in terms of yield of monoclonal antibody (mAb) and amount of residual impurities, such as DNA and host cell proteins, and amount of mAb aggregates. For a comprehensive comparison of the different methods, experiments were carried out with the same cell-free fermentation broth containing adalimumab. Protein A and cation exchange chromatographic separations resulted in high yield and purity of adalimumab. The precipitation-based process resulted in high yield but with lower purity. The extraction-based purification resulted in low yield and purity. Thus, the precipitation-based method proved to be more promising than the extraction-based method for direct purification of adalimumab from harvested cell culture fluid. Although alternative purification methods may offer the advantages of simplicity and low-cost operation, further significant improvements are required to compete with the performance of chromatographic separations of adalimumab from true fermentation broth.

Density-oriented deep eutectic solvent-based system for the selective separation of polysaccharides from Astragalus membranaceus var. Mongholicus under ultrasound-assisted conditions

The water extraction and ethanol precipitation method is an extraction method based on the solubility characteristics of polysaccharides that offers wide applicability in the extraction and separation of plant polysaccharides. However, this method leads to large amounts of proteins, nucleic acids, pigments, and other impurities in the polysaccharides products, which makes downstream purification complicated and time-consuming. In this study, a green, high-density natural deep eutectic solvents was used for the high-purity extraction and separation of polysaccharides from Astragalus membranaceus (Fisch) Bge. var. Mongholicus (Bge.) Hsiao roots under ultrasound-assisted conditions. In this study, 16 different natural deep eutectic solvents were designed to screen the best solvent for extracting Astragalus polysaccharides (APSs). Based on the yield and recovery of APSs, a natural deep eutectic solvents composed of choline chloride and oxalic acid with a molar ratio of 1:2 was selected. The related factors affecting polysaccharides extraction and solvent precipitation were investigated. To improve the operating methodology, single-factor trials, a Plackett-Burman design, and a Box-Behnken design were used. The optimal extraction process conditions were obtained as follows: water content of 55%, liquid–solid ratio of 24 mL/g, ultrasonic irradiation time of 54 min, ultrasonic irradiation temperature of 50 °C, ultrasonic irradiation power of 480 W, ethanol precipitation time of 24 h, and ethanol concentration of 75%. Under optimal extraction conditions, the recovery of APSs was 61.4 ± 0.6 mg/g. Considering the special matrix characteristics of A. membranaceus var. Mongholicus roots, physical-technology-based ultrasonic waves promote penetration, and the mass transfer function also solves the bottleneck of high-viscosity deep eutectic solvents in the extraction stage. In comparison with the conventional method, the proposed method based on deep eutectic solvents isolation can significantly increase APSs recovery, which is beneficial to simplifying the process of polysaccharides purification by using solvent properties to separate extracts and reduce impurities in APSs.

Nutrient recovery from anaerobic digester supernatant using a fluidized-bed reactor

This study investigated nutrient recovery by struvite precipitation from anaerobic digester supernatant containing nitrogen and phosphorus at high concentrations using a fluidized-bed reactor. In the first phase, hydraulic retention time (HRT) in the system was reduced from 15 min to 2.5 min at molar Mg2+/NH4+/PO43− ratio of 1.5/16.6/1. No significant differences were detected and struvite could be precipitated at high performances even at an HRT of 2.5 min. In the second stage, the impact of Mg/P molar ratio on struvite precipitation performance was evaluated at the molar ratios of 1/1, 1.5/1, 2/1 and 2.5 min HRT. The highest NH4-N and PO4-P precipitation performances were around 38 % and 99.7 %, respectively, at an Mg/P molar ratio of 2. In the last stage, the impact of volatile fatty acid presence on the system performance was investigated by adding 1000 mg/L acetate to the synthetic wastewater at an Mg/P molar ratio of 1.5/1. Observing above 99 % PO4-P removal efficiency both in the presence and absence of acetate confirmed that VFA may not have adverse impact on struvite precipitation performance. According to XRD results, struvite precipitates had a crystal structure with only a small amount of impurities.

Enhancing the separation of Fe/Al/Ca impurities from metallurgical silicon to purify by slagging-directional solidification

Metallurgical silicon (MG-Si) with low content of Fe, Al and Ca impurities is very important for the production of organosilicon. A novel approach of slagging-directional solidification was investigated to remove Fe, Al and Ca impurities. Firstly, the study analyzed the effect of cooling methods and solidification rates on removal of Fe, Al and Ca impurities during directional solidification without the slagging agent. Then, the crystal morphology and impurity micromorphology of silicon ingots obtained with optimal conditions were analyzed and found the shape of the impurity was related to the crystal morphology of the ingot, precipitating at grain boundaries. On this basis, the removal of Fe, Al and Ca impurities by the slagging-directional solidification was studied. The result showed Al and Ca impurities in silicon were few and a small amount of Fe impurity was in the form of Fe–Si. The mechanism of the slagging-directional solidification was analyzed and revealed that it not only effectively removed Al and Ca impurities from MG-Si, but also decreased the effective segregation coefficient of Fe and enhanced the separation of Fe impurity. The method of slagging-directional solidification provides a new idea for the separation of Fe, Al and Ca from MG-Si.

Fabrication of CZTS Films through a Combined Electrodeposition and Solution Process: An Experimental and First‐Principles Study

AbstractSulfurization has a critical role in preparation of CZTS films since the main drawback of CZTS is due to the presence of S‐based impurities. In general, sulfurization could be performed during or following annealing, or the entire CZTS structure could be prepared through sol‐gel. However, toxic gases are used for the former, and the latter takes prolonged times. Alternatively, a combined electrodeposition and solution process was proposed in the present work to prepare CZTS. Briefly, we electrodeposited CZT layers on a metal substrate, and then immersed the as‐prepared coating in a S containing solution for the sulfurization. The effects of electrodeposition time, electrodeposition order, current density, electrolyte compositions, sulfurization time, and annealing pressure were studied. Overall, the results show that S content of the films varied between 27 and 52 % depending on process parameters, thus, suggesting the effectiveness of the proposed approach regarding sulfurization. However, various secondary phases were also detected as well as considerable amount of oxygen impurity. Accordingly, we opted for a computational approach to elucidate the effect of oxygen impurities, and report that the band gap of the films varied between 0.59 and 0.05 eV depending on the presence and which sites oxygen atoms occupy.

Detection and Identification of an Unknown Impurity in Ephedrine HCl 5mg/mL Cyclic Olefin Syringes: Formulation Development.

An unknown impurity was detected in in-house prepared ephedrine hydrochloride (HCl) 5mg/mL prefilled sterilized syringes when applying a stability-indicating British Pharmacopoeia 2018 impurity method for ephedrine injection. Ultraviolet, chromatographic, mass spectral, and physicochemical methods were combined to identify the unknown impurity. The unknown impurity was identified as methcathinone, which is generated from ephedrine drug substance through an oxidation reaction. A formulation study, in which different process adjustments were tested, was carried out to reduce the amount of unknown impurity. Nitrogen gassing in combination with 0.05M citrate buffer addition proved to be the most potent process adjustment in reducing methcathinone formation in ephedrine HCl 5mg/mL prefilled sterilized syringes after 4months of storage in the dark at room temperature (20°C ± 5°C). More detailed research on the long-term stability of the reformulated ephedrine HCl drug product is currently underway, with promising results for up to 9months gathered already.

Indoor air quality assessment on polygons for solid municipal waste for microbial contamination and a method of its cleaning

Landfill biogas contains large amounts of toxic and harmful impurities and may be a source of microbiological contamination of both the complex municipal waste landfill itself and adjacent territories. This paper uses modern biotechnologies designed to protect the environment, to study the quantitative and qualitative composition of biogas for harmful factors, as well as for harmful substance removal from biogas. An assessment was made of air purification in the premises near landfills and adjacent territories using green plantations and a biological system based on an apparatus-biological complex for purification from microbiological contamination. The data obtained in our laboratory studies show that such apparatus-biological complexes can reduce the negative influence on the personnel and workers at operative points and the inhabitants of adjacent territories by air purification.

MODIFICATION OF BITUMENS WITH OIL INDUSTRY WASTE

A literature review on the topic of the study has shown that there is not much work with the use of oily waste in the modification of bitumen. Many methods of bitumen modification include the oxidation of a heavy oil residue to obtain the target product and its further compounding with the finished bitumen. Old oil sludge from oil sludge storage tanks has been used as the oil residue. Oil sludge is prepared by dehydration, the water content should not exceed no more than 5 wt. % and separation of mechanical impurities up to a content of not more than 16.4 wt. %. Purpose of the work. The main objective of the study is to develop a technology for modifying oil bitumen with industrial waste for the disposal of oil sludge, and to show the possibility of improving the physical-chemical, rheological characteristics of modified bitumen. Results. In the process of bitumen modification, the physical-chemical characteristics of the modified bitumen have been studied. It has been established that the composition of oil sludge from the Uzen and Zhetybai oilfield of the Mangistau region contains a significant amount of heavy oil residues and a small amount of mechanical impurities. From the conducted laboratory esearch, it has been found that oil sludge can be used as a filler in the modification of bitumen. Conclusion. Used oil sludge can be used as a bituminous base modifier without removing the mechanical impurities. Polymer-bitumen compositions have been prepared and the optimal parameters for the process of preparing polymer-bitumen binders have been determined.