Polyvinylpyrrolidone Concentration Research Articles

Comb-shaped Sb2S3 nanorod arrays on ZnO nanofibers for thin-film photovoltaics

A hierarchical composite of Sb2S3 nanorods grown on zinc oxide (ZnO) nanofiber was prepared, and the formation of comb-shaped Sb2S3 nanorod arrays on the ZnO nanofibers was confirmed. It was found that the size of the diameter and the density of the nanorods are regulatable by changing the concentration of polyvinyl pyrrolidone as an additive for the growth of Sb2S3 nanorod on ZnO nanofiber. The obtained Sb2S3 nanorod arrays were applied as a light absorber for thin-film solar cells composed of glass-fluorine-doped tin oxide/compact ZnO/ZnO nanofibers−ZnS/Sb2S3 nanorod arrays/poly(3-hexylthiophene-2,5-diyl)/MoOx/Ag. The rectification ratio and photocurrent generation efficiency of the comb-shaped Sb2S3 nanorod arrays were improved as compared with the heterojunction of randomly stacked Sb2S3 nanorods. Smaller series resistance (Rs) of 8.13 Ω cm−2 and an ideality factor (n) of 2.84 with the comb-shaped Sb2S3 nanorod arrays than those of the randomly stacked ones of Rs = 15.01 Ω cm−2 and n = 3.83 also indicated superior charge extraction property and suppressed recombination of the comb-shaped Sb2S3 nanorod arrays at the interface.

Formulasi Granul Effervescent Ekstrak Aseton Rimpang Kencur (Kaempferia Galanga L.) dengan Variasi Konsentrasi Polivinilpirolidon

Kencur is one of the plants that is useful as an anthelmintic drug. This study aims to formulate effervescent granules of acetone extract of Kencur rhizome (Kaempferia galanga L.) with various concentrations of polyvinylpyrrolidone. Kencur rhizome extraction was carried out by maceration method using acetone solvent for 3 days then filtered and concentrated with a rotary vacuum evaporator. The extract was granulated using the wet granulation method with a ratio of citric acid monohydrate and tartaric acid 1:2. Variations in PVP concentrations were 2%, 4%, and 6%. Physical evaluation of granules includes Density and Porosity, Compressibility Index (Carr Index), Flow Time, and Angle of Bed. The best porosity was in formula 3 with 30.47±1.471. The compressibility index (Carr Index) of the three formulas is in the range of 515%. The best dosage flow times were formulas 2 and 3 with 8.67±0.526 and 7.58±0.344. The Hausner Ratio of the three formulas is below 1.25. The angles of repose in formulas 1 and 2 are 24.94º and 29.74º with a recline angle <40. The foam stopping time is 23 seconds. From theresults abtained it can be concluded that the formula with good pharmaceutical properties is formula 3 with a variation of 6% pvp concentration.

Optimization of Graphene Nanoplatelets Dispersion and Its Performance in Cement Mortars.

As promising next-generation conducting materials, Graphene Nanoplatelets (GNPs) have been widely used to enhance the mechanical and pressure-sensitive properties of cement-based materials. However, this beneficial effect highly depended on its dispersion. In this study, polyvinyl pyrrolidone (PVP) surfactant, high-speed shear, and ultrasonication were used to disperse GNPs. To fully exert the mechanical and pressure-sensitive properties and enhance the dispersion effect of GNPs in cement-based materials, the dispersing method parameters, including PVP concentration, ultrasonication time, shear time, and rate, were optimized. The dispersion degree of GNPs was evaluated by absorbance. The results show that the optimal dispersion parameters were 10 mg/mL of PVP concentration, 15 min of ultrasonication time, 15 min of shear time, and 8000 revolutions per minute (rpm) of shear rate. In addition, the effect of GNPs dosage (0.05, 0.1, 0.3, 0.5, 0.7, and 1.0 wt%) on the setting time, flowability, and mechanical and pressure-sensitive properties of cement mortar were examined. Results reveal that the optimum dosage of GNPs was found at 1.0 wt%.

Tailoring of Narrow Pores, Pore Size Distribution and Structural Details in Asymmetric Nanofiltration Membranes via Polyvinyl-pyrrolidone Additive

The roles of polyvinyl-pyrrolidone (PVP) additive in the tailoring of pores, pore size distribution, morphologies and molecular weight cut-off (MWCO) in phase inversion asymmetric nanofiltration membranes was addressed. Using established solute transport method, scanning electron microscopy (SEM) and Minitab software, details analysis of the enhanced performance-properties of narrow pores nanofiltration membranes were verified. Experimental and analysis data revealed that the membranes prepared with 2 wt% of PVP demonstrated fine performance-properties. At this concentration, the fabricated nanofiltration membranes possessed narrow pore size and molecular weight cut-off of 1.14 nm and 2290 Da, respectively. In addition, the fabricated nanofiltration membranes displayed fine structural details of narrow pore size distribution, good morphology and critical key properties. With the combinations of thinner skin layer, fine structures and narrow pores, it can be concluded that the 2 wt% of PVP is the optimum PVP concentration to produce selective narrow pore nanofiltration membranes. Eventually, summary data on pores, pore size distributions (PSDs) and key properties proved that the PVP additive is effective for controlling performances-properties and structural details in asymmetrical based membranes.

Development of braid reinforced hollow fiber membranes as both ultrafiltration and nanofiltration membranes: Effect of pore forming additive on structure and performance

AbstractHollow fiber membranes have higher surface area and are easy to be applied in systems. Because of theirs self‐supporting construction, they have limited mechanical durability. By reinforcing these membranes with a braid, the mechanical strength can be improved. In this study, the impact of polyvinyl pyrrolidone (PVP) as a pore‐forming additive with different contents on the fabrication of polysulfone braid reinforced hollow fiber membranes was investigated both as a ultrafiltration membrane and as a support for the fabrication of thin film composite (TFC) nanofiltration membranes. Characterization and filtration studies of all membranes were performed to examine membrane performance. It was discovered that the porosity and hydrophilicity of the ultrafiltration membranes were enhanced by enhancing PVP concentration, thus increasing the pure water flux in the membranes. As regards to results of fabricated TFC membranes, salt rejections were increased with increasing PVP ratios. The rejection efficiency of magnesium sulfate and sodium chloride was found to be approximately 80% and 49%, respectively, when a PVP ratio of 8% was used.

Mechanical and thermal (Poly methyl methacrylate' / Poly Vinyl Pyrrolidone) blend use in denture material

In the main search, efforts are made to develop the properties of the PMMA resin that is used: To create a blend polymer for the upper and lower prosthesis of a complete denture, several weight ratios of poly vinyl pyrrolidone (pvp) (0,2%, 6%, 10%, 14%, 18%, 22%, 26%) were added to cold-cured poly methyl methacrylate (PMMA). The effects of external polyvinylpyrrolidone (PVP) concentrations on mechanical features such as hardness, impact resistance, wear resistance, and thermal conductivity are studied. The results indicate that as concentrations were elevated, hardness, strength, impact resistance, and wear resistance increased, along with a decrease in thermal conductivity. The positive findings seem to have been (22% PVP and 78% PMMA).

Acid-triggered polyether sulfone - Polyvinyl pyrrolidone blend anion exchange membranes for the recovery of titania waste acid via diffusion dialysis

Dense PES (polyether sulfone) - PVP (polyvinyl pyrrolidone) blend membranes are proposed to recover titania waste acid by diffusion dialysis. These dense membranes can simply be prepared by the solution casting method, and the spontaneous quaternization of the N and O atoms in pyrrolidone with H+ in sulfuric acid solution turns them into effective anion exchange membranes very suitable for the fractionation of sulfuric acid/sulfate. In this work, the influence of the PVP molecular weight (K30 and K90), the composition of the casting solution and the concentration of sulfuric acid in the post-treatment step on the physicochemical properties and mass transfer performance of the membranes are systematically investigated. It is found that the content of absorbed sulfuric acid in the dense membranes increases with the increasing PVP content (20–60 wt%) in the membranes, after the equilibration in 2.68 M H2SO4. The content of H+ in blend membranes with PVP K30 (K30 series) is 0–5.73 mmol/(g dry membrane), while that in the membranes with PVP K90 (K90 series) is 0–5.34 mmol/(g dry membrane). The permeability coefficients of H2SO4 and FeSO4 in the K30 and the K90 series membranes also increase gradually, ranging from 0–200 × 10−9 m2/h and 0–8.81 × 10−9 m2/h, respectively. The largest selectivity coefficient of H2SO4/FeSO4 can reach 1800. The permeability coefficients of H2SO4 and FeSO4 also increase gradually with the increase of the solution acid concentration, and the selectivity remains excellent. These PES-PVP dense membranes show very good chemical stability, the permeability coefficients of H2SO4 and FeSO4 for a blend membrane with 55 wt% PVP K30 remain unchanged in a 2.68 M H2SO4 solution for 337 days. This study would provide valuable guidance for the application of these PES-PVP blend anion exchange membranes in the recovery of titania waste acid by diffusion dialysis.

Antibacterial Studying of Silver Nanoparticles Synthesized by Chemical Reduction Method Using Different Stabilized Concentrations

Silver nanoparticles were prepared by the chemical reduction method. Silver nitrate was taken as a metal precursor and sodium borohydride as a reducing agent with polyvinyl alcohol (PVA) stabilizers of different concentrations, polyvinylpyrrolidone (PVP). X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM) techniques have been used, these measurement results showed that the prepared material is silver nanoparticles. The average size of silver nanoparticles using the Scherrer equation with values ranging from 8.49-12.15nm. TEM images showed that the silver nanoparticles are spherical in size between 5-47nm. Nanoscale distribution of silver nanoparticles (AgNPs) prepared at different concentrations was studied by AFM. Silver nanoparticles showed high antimicrobial and antibacterial activity against Gram-positive bacteria such as Escherichia Coli and Gram-negative Staphylococcus aureus, whose bacterial activity was dependent on the concentration of PVA and PVP and the degree of intramolecular accumulation. Low concentrations of PVP lead to increase the activity, while high concentrations of PVA give better activity.

Optimization of Oligomer Chitosan/Polyvinylpyrrolidone Coating for Enhancing Antibacterial, Hemostatic Effects and Biocompatibility of Nanofibrous Wound Dressing.

A synergistic multilayer membrane design is necessary to satisfy a multitude of requirements of an ideal wound dressing. In this study, trilayer dressings with asymmetric wettability, composed of electrospun polycaprolactone (PCL) base membranes coated with oligomer chitosan (COS) in various concentrations of polyvinylpyrrolidone (PVP), are fabricated for wound dressing application. The membranes are expected to synergize the hygroscopic, antibacterial, hemostatic, and biocompatible properties of PCL and COS. The wound dressing was coated by spraying the solution of 3% COS and 6% PVP on the PCL base membrane (PVP6–3) three times, which shows good interaction with biological subjects, including bacterial strains and blood components. PVP6–3 samples confirm the diameter of inhibition zones of 20.0 ± 2.5 and 17.9 ± 2.5 mm against Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The membrane induces hemostasis with a blood clotting index of 74% after 5 min of contact. In the mice model, wounds treated with PVP6–3 closed 95% of the area after 10 days. Histological study determines the progression of skin regeneration with the construction of granulation tissue, new vascular systems, and hair follicles. Furthermore, the newly-growth skin shares structural resemblances to that of native tissue. This study suggests a simple approach to a multi-purpose wound dressing for clinical treatment.

Apparent Diffusion Coefficient Reproducibility Across 3T Scanners in a Breast Diffusion Phantom.

To date, the accuracy and variability of diffusion-weighted MRI (DW-MRI) metrics have been reported in a limited number of scanner/protocol/coil combinations. To evaluate the reproducibility of DW-MRI estimates across multiple scanners and DW-MRI protocols and to assess the effects of using an 8-channel vs. 16-channel breast coil in a breast phantom. Prospective. Breast phantom containing tubes of water and differing polyvinylpyrrolidone (PVP) concentrations with apparent diffusion coefficients (ADCs) matching breast tissue. 3 T (three standard and one wide bore), three DW-MRI single-shot echo planar imaging protocols of varying acquired spatial resolution. Accuracy of estimated ADCs was assessed using percent differences (PD) relative to nuclear magnetic resonance spectroscopy-derived reference values. Coefficients of variation (CV) were calculated to determine variation across scanners. CVs based on the median standard deviation (CVM ) were used to evaluate tube-specific dispersion using 8- or 16-channel coils at a single scanner. ADCs of PVP-containing tubes were additionally normalized by the median water tube ADC to account for temperature effects. Two-way repeated measures analysis of variance and post hoc tests were used to evaluate differences in ADC, CV, and CVM across scanners and protocols (α=0.05). ADCs were within 11% (interquartile range [IQR] 7%) of reference values and significantly improved to 2% (IQR 7%) after normalization to an internal water reference. Normalization significantly reduced interscanner variability of ADC estimates from 7% to 4%. DW-MRI protocol did not affect ADC accuracy; however, the clinical and higher-resolution clinical protocols resulted in the greatest (9%) and least (6%) interscanner variability, respectively. The 8- and 16-channel receive coils yielded similar accuracy (PD: 12% vs. 16%) and precision (CVM : 2.7% vs. 2.9%). Normalization by an internal reference improved interscanner ADC reproducibility. High-resolution protocols yielded comparably accurate and significantly less variable ADCs compared to a clinical standard protocol. 2 TECHNICAL EFFICACY: Stage 1.

Modeling and optimization of the core-shell nanofibrous composite mat as a scaffold via hybrid models

It has been a challenging subject for researchers to manipulate the electrospinning key factors to achieve a composite nanofiber with proper properties. In this study, an experiment according to central composite design to investigate the effect of parameters including polyvinylpyrrolidone concentration, zeolite concentration, voltage, core flow rate and shell flow rate on diameter, maximum strength and porosity of polyethersulfone/polyvinylpyrrolidone/zeolite core-shell composite nanofiber has been designed. Later on, two sets of models consisting of response surface methodology and artificial neural network are trained. Then, their performance was evaluated based on the definition of a novel goodness function. In the next step, the genetic algorithm is used to find the optimal design for scaffold applications. The results demonstrated that the average goodness value of models based on an artificial neural network ([Formula: see text] 1.999) is higher than response surface methodology ones ([Formula: see text] 1.780). Additionally, the genetic algorithm was able to find an optimal design with lower cost value (0.006) than the optimum sample (0.113) among the produced ones. Finally, the scanning electron microscopy micrographs highlighted that there is a strong and good cell proliferation on the selected design of nanofiber composite mat as the optimum scaffold.

Dual functionality of ultralow levels of a model kinetic hydrate inhibitor on hydrate particle morphology and interparticle force

Gas hydrate plug formation is a major concern in oil and gas exploitation efforts, wherein line blockages can pose major safety, economic, and environmental risks. Kinetic hydrate inhibitors (KHIs) are a promising class of hydrate management chemicals, which are potentially cleaner, cheaper, and greener than traditional thermodynamic hydrate inhibitors (THIs). Therefore, understanding the effects that KHIs have on hydrate particles is vital to their application. In this study, polyvinylpyrrolidone (PVP), a model KHI, was investigated at ultralow concentrations to determine its effect on the properties of hydrates and elucidate when nucleation and growth inhibition begins. It was found that PVP can adsorb at the hydrate particle surface to reduce interparticle force by 40–54 %. Low concentration PVP continues to affect interparticle forces at prolonged contact times, reducing forces at 30-minutes to 1-hour of contact by 20–40 % and reducing sintering rate. PVP also reduces film growth rates by 30–50 % depending on the concentration of PVP in the water phase. The onset of major nucleation and growth effects was observed to occur at 0.01 wt% PVP in the water phase, two orders of magnitude below concentrations typically employed in hydrate management. It was discovered that low dosage PVP can cause major morphological changes to the hydrate particles in both the short and long term, which can influence interparticle forces and particle agglomeration, and may serve as a morphological screening tool for KHIs. A proposed mechanism for the observed morphology changes explains how the heterogenous adsorption of chemicals at the particle surface can lead directly to the newly observed particle morphology. The results presented in this paper show that ultralow concentrations of KHIs (0.0005 wt%) can have combined effects on the interfacial activity and crystal growth and morphology of hydrates, showing KHIs to be a dual function inhibitor of both interparticle interactions and hydrate growth. These results can inform KHI applications from industrial flow assurance to carbon dioxide transport for unimpeded carbon capture and sequestration.

Graphene oxide incorporated polyether sulfone nanocomposite antifouling ultrafiltration membranes with enhanced hydrophilicity

In this study, the polyether sulfone (PES) based membranes containing various concentrations of graphene oxide (GO), polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG) were synthesized via the phase immersion method. This study aims to evaluate the effect of GO addition on the structural properties and performance of the membranes. The membranes were analyzed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FTIR). The FTIR-ATR spectra indicated the presence of hydroxyl and carboxylic acid groups on the surface of GO-incorporated membranes, which improved their dispersion in the polymeric matrix and hydrophilicity. The SEM analysis of the GO-containing PES membranes confirmed the formation of a well-defined finger-like porous structure presenting adequate water flux (95 l.m–2.h–1) and salt rejection (72%) compared to the pristine PES membranes (46 l.m–2.h–1 and ∼35%, respectively). In addition, the significantly large wettability and considerably improved antibacterial characteristic (against S. aureus and E. coli strains) of the GO-PES membranes are considered impressive features.

Optimization of inhibition efficiencies process of polyvinylpyrrolidone using response surface methodology

Inhibition efficiencies (IE) process in polyvinylpyrrolidone (PVP) which is influenced by independent factors, concentration and size of PVP, temperature, time of immersion, and perchloric acid concentration was investigated in this paper. The relationship between factors and their responses is established by the concept of response surface methodology (RSM) explicitly through regression statistical analysis and probabilistic analysis is used in this work. The concept is a combination of mathematical and statistical techniques allowing the modeling and problems analysis by experimental design. In this study, the results based on statistical analysis showed that the quadratic models for the inhibition efficiencies (IE) were significant at the value of probability P < 0.0001 and the coefficient of multiple regressions R2=0.9997, for further validation of the model, R2Adj=0.9993 indicated a good model. The observed experimental values were in good agreement with predicted ones and the model washighly significant with Q2= 0.9884. The optimal conditions of inhibition efficiencies (IE) obtained are 104.301% for a concentration of 3.55×10−3 mol/L, temperature of 20.15°C, immersion time of 2h, size of PVP 58000 g/mol, and acid concentration of 0.5 mol/L.

Centrifugal Spinning Enables the Formation of Silver Microfibers with Nanostructures.

Silver nanowires (AgNWs) have received much attention and application in transparent electrodes, wearable electronic devices, and sensors. The hope is for these nanowires to eventually replace the most commonly used transparent electrode material—indium tin oxide (ITO). However, electrospinning used for the preparation of AgNWs on a large scale is limited by its low productivity and high electric field, while the alcohol-thermal method is limited to mixing by-product silver nanoparticles in silver nanowires. We demonstrate a novel and simple centrifugal spinning approach in order to successfully fabricate ultra-long silver microfibers based on AgNO3 and polyvinyl pyrrolidone (PVP). The centrifugal-spun precursor fiber and silver fiber can be prepared to as thin as 390 and 310 nm, respectively. Annealed fibers show typical nanostructures with grains down to a minimum size of 51 nm. Combinations of different parameters, including concentrations of PVP, needle size, and annealing temperature are also investigated, in order to optimize the spinning process of ultra-long silver microfibers. The feasibility of preparing silver microfibers by centrifugal spinning is preliminarily verified, examining prospects for mass production. Furthermore, numerous strategies related to assisting the creation of silver nanofibers using centrifugal spinning are presented as possibilities in future development.

Particle Agglomeration of Acid-Modified Tapioca Starches: Characterization and Use as Direct Compression Fillers in Tablets.

Acid-modified tapioca starches (AMTSs) possessed good compressibility but showed poor particle flowability for preparing tablets by the direct compression method. The aims of this work were to prepare and characterize AMTS agglomerates using polyvinylpyrrolidone (PVP) as an agglomerating agent. The dilution potential and stability studies of the AMTS agglomerates were investigated. The results showed that particle enlargement of TS and AMTS could be achieved via agglomeration using PVP. The thermal behavior and molecular interaction of the agglomerates were revealed using DSC and FTIR spectroscopy, respectively. An increase in PVP concentrations resulted in greater particle strength of the TS agglomerates and a higher acid concentration for modification enhanced the strength of the AMTS agglomerates. All agglomerates presented good particle flowability. Moreover, the AMTS agglomerates provided higher compressibility hardness than the TS agglomerates. The addition of PVP could extend the disintegration time and slow drug dissolution from the agglomerate tablets. The humidity of the storage conditions influenced the thickness and hardness of the AMTS agglomerate tablets, and good physical and chemical stability of the tablets was obtained under ambient conditions and in the refrigerator. Furthermore, the AMTS agglomerates displayed good carrying capacity and possessed desirable characteristics for use in direct compression tablets.

Enhanced Methylene Blue Adsorption by Cu-BTC Metal-Organic Frameworks with Engineered Particle Size Using Surfactant Modulators

Metal–organic frameworks (MOFs) featuring porous structures and large specific surface areas have shown great potential in removing organic pollutants from wastewater via adsorption processes. Although the particle size of MOFs determines the adsorption performance (something known as the size-dependent effect), engineering it into desirable dimensions for enhancing the adsorption performance is a great challenge. Here, we develop a practical and facile approach to regulate the particle size of copper benzene-1,3,5-tricarboxylate (Cu-BTC) adsorbents with high tunability by screening the functional modulator of various surfactants adding in hydrothermal synthesis procedure. The effect of surfactant type and concentration on the particle size of Cu-BTC was systematically investigated. The results show that the nonionic surfactant polyvinylpyrrolidone (PVP) demonstrated the greatest ability to control the particle size of Cu-BTC among other counterparts (e.g., N, N, N-trimethyl-1-dodecanaminium bromide (DTAB), polyethylene glycol (PEG1000), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS) and hexadecyl trimethyl ammonium bromide (CTAB)). By increasing the PVP concentration to 0.14 mmol L−1, the average particle size of Cu-BTC could be correspondingly reduced by more than ten times, reaching to a comparative smaller value of 2.4 μm as compared with the reported counterparts. In addition, the PVP allowed a large increase of the surface area of Cu-BTC according to porosity analysis, resulting in a great enhancement of methylene blue (MB) adsorption. The PVP-modulated Cu-BTC showed fast adsorption kinetics for MB removal accompanied with a maximum adsorption capacity of 169.2 mg g−1, which was considerably competitive with most of the analogs reported. Therefore, our study may inspire concepts for engineering the particle size of Cu-BTCs with improved properties for more practical applications.

Resistive switching behavior of the memristor based on WS2 nanosheets and polyvinylpyrrolidone nanocomposites

Ag/tungsten disulfide (WS2)–polyvinylpyrrolidone (PVP)/Cu memristors based on monolayer WS2 nanosheets and polyvinylpyrrolidone (PVP) nanocomposites were fabricated, and the influence of PVP content on the switching behaviors was investigated. The results indicate that the WS2–PVP based memristors show write-once read-many times (WORM) memory behavior. Remarkable resistive switching results such as a low operating voltage (VSET < 1 V), a high switching ratio (>103), good endurance (>100 cycles), and data retention time (>200 s) are obtained. With the increase in the PVP content, the device VSET gradually increases, and the switching ratio first slightly increases and then remarkably decreases. The double logarithm I–V curves verify that the switching mechanism of the devices is the trap-controlled space charge limited current mechanism, which is explained with the energy band diagram.

Efficient Separation of Ultrafine Coal Assisted by Selective Adsorption of Polyvinylpyrrolidone

The efficient separation of ultrafine coal is a challenging process due to the ultrafine particle size and gangue entrainment. In this study, a polymer, polyvinylpyrrolidone (PVP), was introduced as a regulator for ultrafine coal beneficiation. The addition of PVP improved the combustible recovery of clean coal and decreased the ash content. This effect was also presented by the selectivity index. The regulation mechanism of PVP was investigated using diverse methods. The adsorption tests performed demonstrated the adsorption amount of PVP on coal, kaolinite, and quartz, which were related to the increase in the separation efficiency. A zeta potential analyzer was employed to elucidate the effect of PVP on the electrical properties of ultrafine particles. The results revealed that the electrokinetic potential of mineral was sensitive to the varying PVP concentration. The particle size distribution was observed to value the influence of PVP on the particle behavior, which was tested by a laser particle size analyzer. X-ray photoelectron spectroscopy was used to investigate the surface elemental compositions of coal, kaolinite, and quartz, which were regulated by the adsorption of PVP. This research is beneficial to understanding the role of PVP as regulators and provides a basis for the efficient separation of ultrafine coal.

Research of complex of Сalendula officinalis extract–hydrogel for application in cosmeceuticals

The complexes Calendula officinalis extract–hydrogel were prepared and investigated, which are intended for the use in cosmeceuticals. The hydrogel matrix was fabricated based on the copolymers of polyvinylpyrrolidone (PVP) with 2-hydroxyethyl methacrylate (HEMA) with different content of monomeric blocks, namely at the weight ratio of HEMA:PVP=60:40, 70:30, 80:20, and 90:10. The physicochemical characteristics of the obtained hydrogels were determined as follows: water content 48–69%, the degree of swelling 1.19–1.35, conditional porosity 53–84%, elasticity 82–89%, and pure plasticity 11–18%. Ethanol extract of Calendula officinalis was obtained by infusion, and the content of flavonoids was determined. The sorption capacity was measured and the kinetics of hydrogel swelling and extracts desorption from the complex was studied. The effects of hydrogel composition and thickness on the complex sorption capacity were studied. It was stated that the degree of swelling increases with increasing the PVP content in the original composition, therefore the hydrogel with the composition HEMA:PVP=80:20 seems to be the most optimal sample with enhanced sorption and desorption properties. The rate of release also depends on the content of PVP in the original composition and the content of pores, which are remained after washing. It was established that the best sorption of the extract and faster desorption are observed at the hydrogel matrix thickness of 1 mm. The study of flavonoid content in the obtained complexes and sorption/desorption processes revealed rapid sorption and desorption within 24 h, which is sufficient for the development of cosmeceutical mask on the basis of the investigated complexes.