Addition Of Polyvinylpyrrolidone Research Articles

Influence of surfactant-assisted synthesis and different operational parameters on photocatalytic performance of Cu2FeSnS4 particles

In this work, a facile polyvinylpyrrolidone (PVP) assisted solvothermal route using mixed solvents was reported to synthesize uniform quaternary chalcogenide Cu2FeSnS4 (CFTS) particles. PVP played a crucial role in tuning the shape and size of the resulted CFTS particles. Without PVP irregular shaped CFTS particles were obtained, however, quasi-spherical CFTS particles were produced by addition of PVP. The average particle sizes of particles were in the range of ~ 360 to ~ 230 nm. Moreover, the photodegradation of Rhodamine-B (RhB) with CFTS particles under visible light was investigated and optimized in terms of PVP concentration, catalyst dosage, dye concentration and pH of the solution. The quenching experiments for reactive species indicates that both hydroxyl and superoxide radicals play roles in the photodegradation. The stability of the as-prepared CFTS particles was demonstrated by reusing it in five consecutive degradation cycles.

Polyether Sulfone-Graphene Oxide- Polyvinyl Pyrrolidone Nanocomposite Adsorptive Membrane for Arsenic Removal from Wastewater

Arsenic contamination poses a major public health concern and harms the environment with its toxicity. Long term exposure to a high concentration of arsenic is harmful to human health as well as the environmental biodiversity. This study is aimed to fabricate and investigate the possibility of polyethersulfone-graphene oxide-polyvinyl pyrrolidone (PES-GO-PVP) nanocomposite adsorptive membrane and use it to enhance the removal of arsenic from wastewater. The nanocomposite membrane in this study was fabricated via the non-solvent induced phase separation (NIPS) method with the addition of polyvinylpyrrolidone (PVP) as a pore-forming agent. Based on the characterization results of GO through Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy, the existence of high quantity of oxygen based functional groups with high degree of oxidation was observed, which indicated that the GO were well-synthesized. The characterization of the membrane indicated that the addition of GO and PVP could impact the membrane hydrophilicity and mechanical stability. Three adsorption parameters (initial concentration of arsenic, pH and contact time) were then optimized using a face-centred central composite design (FCCCD). The arsenic removal efficiency of 88.6 % was obtained with 55 mg/L of initial arsenic concentration, at pH 8 and 75 minutes of contact time between PES-GO-PVP membrane and the arsenic ion. The Langmuir isotherm model fitted the equilibrium data, describing the monolayer adsorption mechanism occurred on the surface of the membrane. Therefore, the results obtained in this study prove the suitability and promising potential of the nanocomposite membrane for effective removal of arsenic through adsorption.

Palladium Nanoparticles Functionalized with PVP-Quercetin Inhibits Cell Proliferation and Activates Apoptosis in Colorectal Cancer Cells

Nanotechnology is focused on the development and application of novel nanomaterials with particular physicochemical properties. Palladium nanoparticles (PdNPs) have been used as antimicrobials, antifungals, and photochemicals and for catalytic activity in dye reduction. In the present investigation, we developed and characterized PdNPs as a carrier of quercetin and initiated a study of its effects in colorectal cancer cells. PdNPs were first functionalized with polyvinylpyrrolidone (PVP) and then coupled to quercetin (PdNPs-PVP-Q). Our results showed that quercetin was efficiently incorporated to PdNPs-PVP, as demonstrated using UV/Vis and FT-IR spectroscopy. Using transmission electron microscopy, we demonstrated a reduction in size from 3–14.47 nm of PdNPs alone to 1.8–7.4 nm of PdNPs-PVP and to 2.12–3.14 of PdNPs-PVP-Q, indicating an increase in superficial area in functionalized PdNPs-Q. Moreover, hydrodynamic size studies using dynamic light scattering showed a reduction in size from 2120.33 nm ± 112.53 with PdNPs alone to 129.96 nm ± 6.23 for PdNPs-PVP-Q, suggesting a major reactivity when quercetin is coupled to nanoparticles. X-ray diffraction assays show that the addition of PVP or quercetin to PdNPs does not influence the crystallinity state. Catalytic activity assays of PdNPs-PVP-Q evidenced the chemical reduction of 4-nitrophenol, methyl orange, and methyl blue, thus confirming an electron acceptor capacity of nanoparticles. Finally, biological activity studies using MTT assays showed a significant inhibition (p < 0.05) of cell proliferation of HCT-15 colorectal cancer cells exposed to PdNPs-PVP-Q in comparison to untreated cells. Moreover, treatment with PdNPs-PVP-Q resulted in the apoptosis activation of HCT-15 cells. In conclusion, here we show for the first time the development of PdNPs-PVP-Q and evidence its biological activities through the inhibition of cell proliferation and apoptosis activation in colorectal cancer cells in vitro.

Origin of anomalous high-rate Na-ion electrochemistry in layered bismuth telluride anodes

Summary van der Waals layered metal chalcogenide Bi2Te3 has shown exceptional capacity and rate capability in alkali-ion batteries but the underlying reaction mechanism with Li+, Na+, and K+ remains undiscovered. It is unexpected that Na+ electrochemistry outperforms Li+ and K+ at high current densities. Here, in situ transmission electron microscopy is used to uncover nanoscale transformations during lithiation, sodiation, and potassiation, which follows two-step conversion and alloying reactions with Li+ and Na+, and three-step intercalation-conversion-alloying reactions with K+. Counterintuitively, sodiation exhibits the highest reaction kinetics, and its origin can be elucidated by first-principles and finite-element simulations in two aspects. The lower interfacial strain accommodation energy between Bi2Te3 and its Na-conversion products allows more facile sodiation phase transformation than Li- and K-ion reactions. The higher electrochemo-mechanical stress concentration at the concave-shaped sodiation reaction front facilitates continued Na-ion diffusion and reaction propagation. These fundamental insights are essential for fast-charging alkali-ion batteries.

Polyvinylidene Fluoride Membrane Via Vapour Induced Phase Separation for Oil/Water Emulsion Filtration.

Membrane-based technology is an attractive option for the treatment of oily wastewater because of its high oil removal efficiency, small footprint and operational simplicity. However, filtration performance is highly restricted by membrane fouling, especially when treating oil/water emulsion as a result of strong interaction between oil droplets and the hydrophobic property of the membrane. This study explores the fabrication of polyvinylidene fluoride (PVDF)-based membrane via the vapour induced phase separation (VIPS) method while incorporating polyvinyl pyrrolidone (PVP) as a hydrophilic additive to encounter membrane fouling issues and improve membrane filterability. The resulting membranes were characterized and tested for oil/water emulsion filtration to evaluate their hydraulic, rejection and anti-fouling properties. Results show that the changes in membrane morphology and structure from typical macrovoids with finger-like substructure to cellular structure and larger membrane pore size were observed by the prolonged exposure time from 0 to 30 min through the VIPS method. The enhanced clean water permeability is attributed to the addition of PVP–LiCl in the dope solution that enlarges the mean flow pore size from 0.210 ± 0.1 to 7.709 ± 3.5 µm. The best performing membrane was the VIPS membrane with an exposure time of 5 min (M-5), showing oil/water emulsion permeability of 187 Lm−2 h−1 bar−1 and oil rejection of 91.3% as well as an elevation of 84% of clean water permeability compared to pristine PVDF developed using a typical non-solvent induced phase separation (NIPS) method. Despite the relatively high total fouling, M-5 was able to maintain its high permeability by water flushing as a simple operation for membrane fouling control. The performance was achieved thanks to combination of the large mean flow pore size and hydrophilic property from residual PVP in the membarne matrix. Overall, the results demonstrate the potential of the optimum VIPS method in the presence of PVP and LiCl additives for oil/water emulsion treatment.

Polysulfone-Polyvinyl Pyrrolidone Blend Polymer Composite Membranes for Batik Industrial Wastewater Treatment.

Batik wastewater, in general, is colored and has high concentrations of BOD (biological oxygen demand), COD (chemical oxygen demand), and dissolved and suspended solids. Polysulfone (PSf)-based membranes with the addition of polyvinyl pyrrolidone (PVP) were prepared to treat batik industrial wastewater. PSf/PVP membranes were prepared using the phase inversion method with N-methyl-2 pyrrolidone (NMP) as the solvent. Based on the membrane characterization through FESEM, water contact angle, porosity, and mechanical tests showed a phenomenon where the addition of PVP provided thermodynamic and kinetic effects on membrane formation, thereby affecting porosity, thickness, and hydrophilicity of the membranes. The study aims to observe the effect of adding PVP on polysulfone membrane permeability and antifouling performance on a laboratory scale through the ultrafiltration (UF) process. With the addition of PVP, the operational pressure of the polysulfone membrane was reduced compared to that without PVP. Based on the membrane filtration results, the highest removal efficiencies of COD, TDS (total dissolved solid), and conductivity achieved in the study were 80.4, 84.6, and 83.6%, respectively, on the PSf/PVP 0.35 membrane operated at 4 bar. Moreover, the highest color removal efficiency was 85.73% on the PSf/PVP 0.25 operated at 5 bar. The antifouling performance was identified by calculating the value of total, reversible, and irreversible membrane fouling, wherein in this study, the membrane with the best antifouling performance was PSf/PVP 0.25.

Size Refinement of Copper Nanoparticles: A Perspective from Electrochemical Nucleation and Growth Mechanism

AbstractIn this paper, isotropic copper nanoparticles (CuNPs) were successfully sythesized by using Cu(CH3COO)2 and ascorbic acid in absolute ethanol solution. With the addition of polyvinylpyrrolidone (PVP) protective additive, the size distribution range of the synthesized CuNPs was significantly reduced from 650±415 nm to 51±12 nm. Electrodeposition analysis revealed that PVP could greatly suppress the reduction of Cu but had no prominent effects on the deposition mechanism. Based on the potentiostatic deposition results, a growth model was proposed to improve the applicability of the Scharifker‐Hills model by considering both the surface inhibition effect and the mass diffusion during the growth process of Cu nuclei. The experimental data fitted well with the prediction results from the proposed model, indicating that the electrodeposition of Cu followed the progressive nucleation process. The PVP additive could inhibit the deposition and growth of Cu by increasing the surface inhibition for cation incorporation on the nuclei, which was probably the main reason for the refinement of the sythesized CuNPs. Our findings can provide insights for the preparation of metallic nanoparticles and the understanding of their deposition mechanism.

Zinc sulfide quantum dots coated with PVP: applications on commercial solar cells

In this study, we report the synthesis and characterization of zinc sulfide quantum dots (ZnS QDs) coated with different concentrations of polyvinylpyrrolidone (PVP), as well as their deployment as luminescent films on the window side of previously characterized commercial silicon solar cells to quantify their influence on the power conversion efficiency (PCE). The synthesis of the semiconductor nanoparticles was carried out by the reaction of zinc nitrate with sodium sulfide in an aqueous solution at room temperature. XRD measurements indicated a cubic sphalerite phase of the QDs crystal structure, which was not modified by the addition of PVP in the synthesis process. However, the PVP concentration was a key parameter to modulate the size distribution and the luminescent intensity of the QDs, suggesting that an increase in the PVP concentration produced a slight decrease in the QDs size and improved their luminescent properties desired for the photovoltaic applications. The obtained nanoparticles presented great absorption of photons with energies above 3.72 eV and a broad intense blue photoluminescent emission centered at around 450 nm, under excitation of ultraviolet light of 325 nm. The implementation of the synthesized ZnS QDs as spectral response enhancer produced improvements on the performance of solar cells, leading to increases of 0.7%, 1.9%, and 6.1% on the efficiencies of commercial polycrystalline solar cells after the deposition of ZnS QDs synthesized without PVP, with 0.05 mM PVP and with 0.10 mM PVP, respectively.

Application of flying jet plasma for amelioration of polyvinylidene fluoride membrane properties towards enhanced membrane distillation

AbstractThis study explored the feasibility of applying sequential argon‐CF4 plasmas treatment as a featured approach towards enhancement of polyvinylidene fluoride (PVDF) membrane structure and surface topography for application in membrane distillation (MD). Systematic procedures were conducted to synthesize membranes of different combinations composed mainly from PVDF and assisted by addition of polyvinylpyrrolidone (PVP) at different percentages. Upon casting four classes of the membranes, the analysis results via Scanning Electron Microscopy (SEM), Energy Dispersive X‐Ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), as well as the contact angle measurements have shown that the membrane surface topography was mediated in terms of appearance of clear bumps on the surface. Upon implementing the sequential treatment cycles for several durations, the surface topography has considerably changed at the end of argon treatment cycle in terms of appearance of pores at small size. Further changes on the surface topography were detected at the end of CF4 treatment cycle elucidated by increase in the pore size and uniform distribution of the pores along the examined membranes. The function of the sequential plasma treatment was become certain upon implementing MD experiments for dilute solution of ethanol/water, in which higher permeation water flux and permeate separation index were observed for membranes of higher PVP content and sequentially treated for 6 min.

Porous Film Coating Enabled by Polyvinyl Pyrrolidone (PVP) for Enhanced Air Permeability of Fabrics: The Effect of PVP Molecule Weight and Dosage.

This study developed a versatile and facile method for creating pores and tuning the porous structure in the polymer latex films by selectively etching the added functional polyvinyl pyrrolidone (PVP) molecules. The pore formed in the latex films had a similar morphology to that of PVP aggregation before etching. This observation promotes us to regulate the pore morphology that determines the film’s property, such as air permeability through varying the PVP molecule weight and dosage. To this end, the effects of PVP molecule weight and dosage on the pore formation were systematically studied. The results showed that the average pore size of porous film decreased from >10 μm to sub-micron (about 0.4 μm) as the molecular weight or the dosage of PVP increased. This was ascribed to the strong adsorption affinity of PVP molecule onto the latex particle surface, which further hindered the diffusion and self-assembly of PVP molecule. In addition, this interaction became much stronger when the higher molecule weight of PVP or the higher dosage of PVP was employed, leading to the decreased size of PVP aggregation, as well as the formed pores in the latex films. Furthermore, the addition of PVP had little effect on the color of coated fabric based on the results of CIE L*a*b* measurement. The proposed facile method can be used to improve the air permeability of coated fabrics.

Effects of Polyvinylpyrrolidone and Ethyl Cellulose in Polyurethane Electrospun Nanofibers on Morphology and Drug Release Characteristics.

Polyurethanes (PUs) are a popular choice for composing nanofibers due to their spinnability, biocompatibility, high chemical stability, and good mechanical and elasticity properties. The desired release behaviors are also achieved by using combinations of PUs and various polymers. In this study, we investigated effects of polyvinylpyrrolidone (PVP) and ethyl cellulose (EC) on PU electrospun nanofibers in terms of morphological structures and drug release characteristics. Nanofibers were prepared using blends of PU with either EC or PVP in different ratios by electrospinning. The effects of PVP or EC on the morphology and diameter of the prepared nanofibers were examined with scanning electron microscope (SEM). The compatibility of the components used in the formulations of nanofibers was determined by attenuated total reflection (ATR)-fourier-transform infrared (FTIR). Donepezil hydrochloride (DNP), a water soluble compound, was selected as a model drug to examine its release characteristics from both PU/PVP and PU/EC electrospun nanofibers. In vitro drug release studies from electrospun nanofibers were performed according to the method defined in the monograph as the "paddle over disk method" of United States Pharmacopeia 38. The SEM images showed that addition of EC or PVP to PU solutions did not affect the generation of nanofibers, and those formed had a smooth surface without beads in nanoscale. The ATR-FTIR spectra disclosed that EC and PVP were separately incorporated into the PU matrix. The in vitro release data indicated that the presence of EC or PVP in PU nanofibers dramatically changed the release behavior of DNP. PU/EC nanofibers (F4) provided sustained drug release with the Korsmeyer-Peppas drug release kinetic mechanism, in which the release rate was controlled by diffusion of the drug, while all of the PU/PVP nanofibers exhibited fast drug release. Overall, these characteristics of PU/EC (10/8) electrospun nanofibers has suggested their potential use as a drug carrier from which water-soluble drug release may occur in a sustained fashion.

Antifouling properties of poly(vinylidene fluoride)-incorporated cellulose acetate composite ultrafiltration membranes

Poly(vinylidene fluoride) (PVDF) was incorporated in Cellulose acetate (CA) to prepare polymeric blend membrane to enhance the antifouling properties and rejection. Blend membranes consist of different concentrations (0, 2.5 and 5.0 wt%) of polyvinylpyrrolidone (PVP), which was the hydrophilic polymer additive and pore forming agent. The existence of membrane functional groups was analyzed by ATR-FTIR spectroscopy. AFM and SEM were conducted to explain the surface morphology of the synthesized blend membranes. Membrane properties were examined by contact angle, porosity and equilibrium water content (EWC). The membranes thermal and mechanical properties were determined by performing TGA and tensile test. Membrane performance was assessed by pure water flux (PWF), rejection, antifouling properties using bovine serum albumin (BSA) and Sodium alginate (SA) solution. In this study, CPA-2 membrane showed high PWF of 269.82 L m−2 h−1, flux recovery ratio (FRR) against BSA and SA was 94% and 92%, respectively. Rejection of BSA and SA was found to be 83% and 86%, respectively. From the results, it was significant that the hydrophilic additive PVP blended membrane ameliorated and showed better results in surface roughness, hydrophilicity, thermal and mechanical stability. Hence, CPA-2 membrane would exhibit less susceptibility to fouling with enhanced PWF, permeability and selectivity.

Self-assembled porous LiNi0.8Co0.1Mn0.1O2 cathode materials with micro/nano-layered hollow morphologies for high-power lithium-ion batteries

The Ni2+/Li+ disorder has become one of the core problems limiting the application of LiNi0.8Co0.1Mn0.1O2 cathode material. Herein, an ammonium bicarbonate (NH4HCO3)-assisted solvo/hydrothermal method has been effectively applied to synthesize a novel hollow porous LiNi0.8Co0.1Mn0.1O2 material through adding ethylene glycol (EG) and surfactant polyvinylpyrrolidone (PVP) for the first time in this paper. The obtained cathode materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The as-prepared material with unique spherical-like hollow structure is self-assembled from nanoblock primary particles into secondary micro-architectures. The results indicate that the addition of EG and PVP not only expands the electrochemical active region of LiNi0.8Co0.1Mn0.1O2 material, but also inhibits the Ni2+/Li+ disorder and the pulverization of the as-prepared sample. The practical application indicates that the material after adding EG and PVP delivers the highest discharge capacity of 220.18 mAh g−1 for the initial circle, and the capacity retention rate of the spherical-like cathode material is 82.36% at 20 mA g−1 after 100 cycles. In particular, this unique micro/nano-layered architecture effectively withstands high-rate charging and discharging process and maintains the integrity of the original structure after fast Li+ extraction and diffusion.

High-Performance Hemodialysis Membrane: Influence of Polyethylene Glycol and Polyvinylpyrrolidone in the Polyethersulfone Membrane

the preparation of high-performance hemodialysis membrane, the effect of polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and also the simultaneous effect of both additives in the polyethersulfone (PES) membrane were investigated. Viscosity measurements demonstrated that PVP has better compatibility with PES, owing to the amorphous nature, closer glassy transition temperature (Tg), and solubility parameters rather than PEG (semi-crystalline and low Tg). This could lead to enhancement in the solution viscosity. SEM results revealed that membranes morphology was dependent upon casting solution viscosity and with increasing viscosity; the formation of macro-voids suppressed and achieving to a membrane with a smaller mean pore size would be possible. The results of the AFM study demonstrated that, with the addition of PVP, membranes with smooth surface were achieved. In contrast, the PEG addition led to a rougher membrane surface. The results verified that PEG had a tangible effect on the permeability of membrane rather than PVP or blend of PVP and PEG, which is owing to its impressive pore-forming role. The maximum pure water permeability (PWP) was achieved for MV4 (24.9 L/m2.h.bar), MG2 (44.8 L/m2.h.bar), MVG2 (25.2 L/m2.h.bar), and MVG3 (25.1 L/m2.h.bar). Rejection test showed that MV3, MV4, MG3, MG4, MVG2, and MVG3 had the best performance in terms of urea removal and maintaining other components, especially bovine serum albumin (BSA). In-vitro cytotoxicity demonstrated the biocompatibility of MV2, MG3, and MVG3 as representative of all membranes. The lactate dehydrogenase (LDH) test confirmed that PVP has a tangible effect on the reduction of platelet adhesion on the membrane surface.

Enhanced photocatalytic activity of Bi2WO6 with PVP addition for CO2 reduction into ethanol under visible light.

The conversion of CO2 into new carbon-based products, such as fuels and chemicals, is an attractive and promising means of mitigating global energy needs and minimizing environmental damage. Although bismuth tungstate (Bi2WO6) as a photocatalyst can promote CO2 photoreduction, a systematic study for the development of a low-cost and efficient catalyst is needed. Thus, Bi2WO6 with different morphologies was successfully synthesized using the hydrothermal method. An experimental design was applied to investigate the effect of synthesis time and PVP (polyvinylpyrrolidone) concentration on catalyst photocatalytic activity. Crystal structures, morphologies, optical absorption, and surface charges of the catalysts were characterized by X-ray diffraction, scanning electron microscope, UV-vis diffuse-reflection spectroscopy, nitrogen adsorption, and zeta potential. All samples exhibited good performance for the photoreduction of CO2 into ethanol, and both time and PVP concentration were significant in the ethanol yield. Changes in synthesis conditions induced differences in catalyst characteristics, such as morphology, crystallinity, and, predominantly, surface area. Furthermore, PVP addition improved photocatalytic efficiency by up to 258% compared with results without the surfactant. The best sample, W-8h-10%, presented a flower-like morphology and ethanol yield of 68.9 μmol g-1 h-1.

An innovative strategy for improving the performance of forward osmosis membrane: stripe-like Turing structure constructed by introducing hydrophilic polyvinylpyrrolidone

Improving the performance of forward osmosis (FO) membranes has always been moving forward. Here we fabricate the novel Turing structures in the active layer (AL) of thin film composite (TFC) membrane through effectively introducing the polyvinylpyrrolidone (PVP) macromolecule with hydrophilicity both in the support layer (SL) and AL. The addition of PVP facilitates the formation of sponge-like pores in the SL and stripe-like Turing structures in the AL. The influence of PVP on the morphology and performance of the membranes was investigated by SEM, AFM, XPS, NMR, FTIR. Compared with the water flux (Jw) of the original composite membrane (approximately 25 L m−2 h−1), TFC-PVP (3:1) membrane with Turing structure achieved better performance (approximately 75 L m−2 h−1), and the reverse solute flux/water flux (Js/Jw) value was as low as 0.02 g/L. This study demonstrated that the Turing structures have a favorable effect on the performance of FO membrane and a promisingly practical application in water treatment.

EFFECT OF POLYVINYLPYRROLIDONE ON THE SYNTHESIS AND CATALYTIC PROPERTIES OF PLATINUM-CONTAINING OXYGEN ELECTROREDUCTION CATALYSTS

Results of the work on the synthesis of highly effective nanocomposite platinum-containing oxygen reduction electrocatalysts for hydrogen-oxygen fuel cells are presented and ways of increasing their activity are considered. Fuel cells (FCs) represent the most promising renewable and environmentally friendly energy sources that can operate at low temperatures with high efficiency and with low or zero levels of hazardous waste. The main problem of fuel cells is that the oxygen reduction reaction is slowed down in relation to the hydrogen oxidation reaction, which leads to an increase in the overvoltage at the cathode and, as a result, to a decrease in the productivity of FCs. To solve this problem, the new methods are being developed for the synthesis of highly efficient platinum electrocatalysts, which currently have the best performance, since platinum has the highest specific catalytic activity among other materials used in low temperature FCs. The purpose of this work is to determine the optimal composition of reaction mixture and conditions for the preparation of a platinum based catalyst for oxygen electroreduction where Vulcan XC-72 nanodispersed carbon black is used as a carrier. We have worked out 6 methods for preparing Pt (40 %)/XC-72 catalysts. To evaluate the activity of the prepared catalysts and to determine the kinetic parameters of the oxygen reduction on them, cathodic stationary polarization curves were recorded in a 0.5 M H2SO4 solution on a floating gas diffusion electrode superficially modified by the catalysts. For preparation of all electrocatalysts we are used 3.6 ml of a hexachloroplatinic acid (H2PtCl6) solution, containing 18.8 mg Pt/ml, 100 ml of ethylene glycol or its mixture with deionized water (3 : 1) and 100 mg of Vulcan XC-72 carbon black, previously oxidized in HNO3 solution. 1 M NaOH or KOH solutions were used to create the necessary medium (pH = 11). Some Pt(40 %)/XC-72 electrocatalysts were prepared when additions of polyvinylpyrrolidone (PVP) (100 mg or 300 mg) and/or 60 ml of formaldehyde were introduced into reaction mixture. Temperature during syntheses was in the range 75 - 160 °C. It was shown that reducing the synthesis temperature from 160 to 75 °C and introduction of PVP together with formaldehyde into reaction mixture had a positive effect on the activity of obtained nanocomposite platinum-containing catalysts Pt(40 %)/XC-72 for oxygen electroreduction.The sizes of the obtained platinum clusters on the surface of carbon black nanoparticles were in the range of 1.7 - 5.7 nm, and under optimal synthesis conditions they were evenly and densely distributed on the surface of the carbon carrier. The obtained kinetic characteristics of oxygen electroreduction on the studied catalysts indicate that the mechanism of this process depended on both the current density and the method of catalyst synthesis.

Investigation of polyvinylpyrrolidone as an inhibitor for trench super-filling of cobalt electrodeposition

Polyvinylpyrrolidone (PVP) is studied in this paper as an inhibitor of cobalt electrodeposition. The suppression effect of PVP was analyzed through electrochemical methods, including cyclic voltammetry (CV) and galvanostatic measurements (GM) tests. It is indicated that PVP effectively suppresses the electrodeposition of cobalt and chloride ion accelerates this suppression. Further experiments verify that PVP inhibits the deposition of cobalt through the adsorption on the electrode surface. Quantum chemical calculations were employed to calculate the molecular orbitals of PVP and the electrostatic potential (ESP) energy of the involved molecules. The simulation results imply that the amide group acts as the main electrophilic attack region and facilitates nucleophilic reactions to bond with cobalt. High aspect ratio trench filling on silicon wafer was achieved with the addition of PVP, which confirms that PVP is an applicable inhibitor for the practical electrodeposition of cobalt filling. The mechanism of cobalt trench filling was proposed to explain the role of PVP in the electroplating filling. Besides, crystalline and morphological characterizations reveal that PVP is able to inhibit the specific crystal growth of cobalt, especially the growth of 220 crystal plane, affect the crystal morphology of cobalt and improve surface compactness.

Mempelajari Pengaruh Konsentrasi Maltodekstrin dan Polivinil Pirolidon (PVP) terhadap Karakteristik Sifat Fisik Tablet Effervescent Kopi Robusta (Coffea robusta Lindl)

Effervescent tablets are soft drink products that contain organic acids such as citric acid and sodium bicarbonate, which react quickly in water by releasing carbon dioxide. The purpose of this research is to increase the empowerment of coffee plants, namely Robusta coffee as a popular commodity, with Robusta coffee diversification into functional food products in the form of effervescent tablets. This study aims to determine whether there are variations in the concentration of maltodextrin and polyvinyl pyrrolidone (PVP) on the physical characteristics of robusta coffee effervescent tablets. The method / design used in this study is a Randomized Group Design pattern with each factor of three levels with three replications with variations in the addition of maltodextrin (10%, 15%, 20%) and PVP (2%, 3 %, 4%). The results showed that the concentration of maltodextrin as a filler had an effect on the physical response, namely hardness, dissolution time and weight uniformity of effervescent tablets of robusta coffee. Concentration of polyvinyl pyrrolidone (PVP) as a binder gives effect to the physical response, namely hardness and soluble time of effervescent tablets of robusta coffee. The interaction between maltodextrin concentration and polyvinyl pyrrolidone (PVP) concentration influences the physical response, namely hardness and soluble time of effervescent tablets of Robusta coffee. Based on the results of the study, the best treatment was obtained at 15% maltodextrin concentration and 4% PVP concentration.

Effect of Polyvinyl Pyrolidone Additive on the Characteristics and Performance of Polyether Sulfone Membrane for Reducement of Fe in Water

Decreasing the iron (Fe) content in raw water until it reaches the permitted threshold value can be done with filtration using membranes. In this study, the fabrication of membrane for Fe removal was done by using polyethersulfone (PES) as polymer and Polyvinyl Pyrrolidone (PVP) as additive. The addition of PVP aims to increase membrane swelling degree. The asymmetric membrane was prepared by phase inversion method with composition 18 wt% of PES and PVP with a concentration variation of 1; 1.5, and 2 wt%. Variations in the concentration of PVP added to the membrane influence the resulting membrane. Increasing the concentration of PVP shows an increase in the value of permeability, SEM results from modification membranes also show the different morphological structures. The results of the FTIR analysis show that the fabricated membranes have different functional groups. The swelling degree of PES, PES/PVP1, PES/PVP1.5, and PES/PVP2 membranes are increased with a value of 153 to 323%, while the overall porosity value is 62 to 142%. Membrane performance on iron content with 30 ppm feed concentration gives an optimum rejection value of 98.5%.