Adsorption Of Polyvinyl Alcohol Research Articles

Restraining the shuttle effect of polyiodides and modulating the deposition of zinc ions to enhance the cycle lifespan of aqueous Zn-I2 batteries.

The boom of aqueous Zn-based energy storage devices, such as zinc-iodine (Zn-I2) batteries, is quite suitable for safe and sustainable energy storage technologies. However, in rechargeable aqueous Zn-I2 batteries, the shuttle phenomenon of polyiodide ions usually leads to irreversible capacity loss resulting from both the iodine cathode and the zinc anode, and thus impinges on the cycle lifespan of the battery. Herein, a nontoxic, biocompatible, and economical polymer of polyvinyl alcohol (PVA) is exploited as an electrolyte additive. Based on comprehensive analysis and computational results, it is evident that the PVA additive, owing to its specific interaction with polyiodide ions and lower binding energy, can effectively suppress the migration of polyiodide ions towards the zinc anode surface, thereby mitigating adverse reactions between polyiodide ions and zinc. Simultaneously, the hydrogen bond network of water molecules is disrupted due to the abundant hydroxyl groups within the PVA additive, leading to a decrease in water activity and mitigating zinc corrosion. Further, because of the preferential adsorption of PVA on the zinc anode surface, the deposition environment for zinc ions is adjusted and its nucleation overpotential increases, which is favorable for the dense and uniform deposition of zinc ions, thus ensuring the improvement of the performance of the Zn-I2 battery. This investigation has inspired the development of a user-friendly and high-performance Zn-I2 battery.

The adsorption of HEC and PVA as surfactants on SrTiO3 surface: A theoretical, experimental and applied investigation

Surfactants at solid/liquid interface could effectively improve the wettability of the liquid to the solid. Both the atomic force microscope (AFM) and theoretical calculations were applied to illustrate the mechanisms of behaviors of nonionic polymer surfactants represented by hydroxyethyl cellulose (HEC) and polyvinyl alcohol (PVA) at the solid/liquid interface of surfactant-assisted Pechini sol-gel method. The results clarified that the contact angles of surfactant-added sol reduced from64.92° ± 0.42° to 44.04° ± 0.37° and 48.53° ± 0.52° and the surfactants adsorbed on the solid in the form of disk shape, of diameter d = 500 nm and 100 nm for HEC and PVA, respectively. In addition, the adsorption energies between the oxygen atoms of the hydrophilic groups and the metal ion sites of the solid surface are -0.13 eV atom−1 for HEC and -0.04 eV atom−1 for PVA, respectively, indicating that the ion paring played a crucial role in improving the wettability of the sol to the solid. Furthermore, Bi-based superconductors with various morphologies could be prepared using surfactant-assisted Pechini sol-gel method with excellent crystallinity and transition temperatures of ∼70 K, exhibiting potential prospect in the preparation of functional oxide materials with different morphologies by wet-chemical technique.

Infrared imaging of modified chitosan hydrogel film morphology study of polyvinyl alcohol adsorption

The hydrogel film of chitosan with pore structure can be produced by using glutaraldehyde as reaction crosslinking agent to crosslink polyvinyl alcohol and chitosan, which has higher adsorption efficiency. The structure of film is characterized by infrared image, and its morphology is characterized by SEM. The adsorption of acid red 73 under different conditions is primarily studied. The results show that the hydrogel film has a three-dimensional porous microstructure, and the material kinetics is found to effectively absorb acid red 73, with a maximum adsorption amount of 6.5639 mg/g. It is proven as an ideal adsorption material. After studying the thermodynamics of adsorption of the material, △H < 0 was obtained, ∣△H∣ = −81.59861kJ/mol, which belongs to exothermic reaction, primarily reflected as chemical adsorption.

Structural and Optical Properties of polyvinyl alcohol doped silver ( PVA :Ag) film

The present paper investigates a detailed study on the optical properties of PVA/Ag nanocomposite films. In this interest , PVA/Ag nanocomposites with different ways of study ,the first prepared film by reduction 0.2M of Ag+ ions in 2 gm of PVA and study the transmission , absorption coefficient, refractive index, extinction coefficient, reflection, real & imaginary part of the dielectric constant and the energy gap he results proved that the best values of the absorbency was within the range(350-500 )nm, as well as to both we noticed an increase of the refractive index , the extinction coefficient and reflectivity with increasing energy, the second step of research was by using Density Functional Theory (DFT) ,It was calculate spectrum absorption , intensity and energy gap for the same compound PVA/Ag, The cooperation of polyvinylalcohol (PVA) nanofibers with silver (Ag) nanoparticles (mean width 8nm) has been displayed utilizing thickness useful hypothesis (DFT) computations. The physical adsorption of PVA through the hydroxyl gathering, to the Ag,

Understanding Cationic Polymer Adsorption on Mineral Surfaces: Kaolinite in Cement Aggregates

We present a joint experimental and theoretical investigation into the adsorption of polycationic quaternary ammonium polymers on the clay mineral kaolinite. Within the cement and concrete manufacturing industries such polymers are used to improve the final product by inerting the adsorption capacity of the clay minerals for more expensive additives. The adsorption of the presently used polymer (FL22) was compared with both a similar variant, but without a hydroxyl group (Fl22mod) and uncharged polyvinyl alcohol (PVA). Experimental results show that adsorption of FL22 is higher than that of FL22mod at both pH 6 and at pH &gt; 10 and that the adsorption of PVA is the highest. Theoretical density functional theory (DFT) results and simplified models consisting of the basal surfaces of kaolinite, with monomers of FL22, FL22mod and PVA gave monomer coverage per unit surface area of kaolinite, a comparison of the configurations of the relaxed models, formation energies and Mulliken charges. These results show that the polycationic polymers interact with the basal surfaces of kaolinite electrostatically, explaining the high affinity of these polymers for kaolinite surfaces in the experimental results. The hydroxyl groups of FL22 and PVA form hydrogen bonds with the basal surfaces of kaolinite in conditions of pH 6. The joint experimental and theoretical results suggest that, due to the presence of the hydroxyl group, the conformation of FL22 changes under pH, where at neutral pH it lies relatively flat to the kaolinite surfaces, but at higher pH, conformational changes of the polymer occur, thereby increasing the adsorbed quantity of FL22.

Effect of Polyvinyl Alcohol on Ice Formation in the Presence of a Liquid/Solid Interface.

Tuning ice formation is of great importance in biological systems and some technological applications. Many synthetic polymers have been shown to affect ice formation, in particular, polyvinyl alcohol (PVA). However, the experimental observations of the effect of PVA on ice formation are still conflicting. Here, we introduced colloidal silica (CS) as the model liquid/solid interface and studied the effect of PVA on ice formation in detail. The results showed that either PVA or CS promoted ice formation, whereas the mixture of these two (CS-PVA) prevented ice formation (antifreezing). Using quantitative analysis based on classical nucleation theory, we revealed that the main contribution came from the kinetic factor J0 rather than the energy barrier factor Γ. Combined with the PVA adsorption behavior on CS particles, it is strongly suggested that the adsorption of PVA at the interface has significantly reduced ice nucleation, which thus may provide new ideas for developing antifreezing agents.

Influence of PVA and CMC on the Properties of Pigment Coating Colors and their Effects on Curtain Stability

The influence of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) on the properties of ground calcium carbonate (GCC) and clay coating colors, as well as its effect on curtain stability during the coating process was investigated. Based on the experimental results of the zeta potential, sediment porosity, rheological measurements, the floc formation mechanisms of the cobinders were proposed. The zeta potential decreased with an increase in the amount of added PVA, while it barely changed when CMC was added. This was attributed to the adsorption of PVA onto the pigment surface, while the adsorption of CMC was hindered by electrostatic repulsion. CMC cobinder increased the low-shear viscosity, but it resulted in relatively low viscosity under high-shear conditions, indicating the disruption of the formed flocs under high shear. The destabilization mechanism of the curtain coating differed depending on the type of cobinder. The PVA cobinder flocculates the coating color via a gelling mechanism, while the CMC cobinder flocculates the colors via a depletion flocculation mechanism.

Removal of Cd(II) and Pb(II) from aqueous solutions by modified polyvinyl alcohol

In this study, modified polyvinyl alcohol (PVA) was prepared and characterized by element analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and surface area and proximity analysis. The isotherms and thermodynamic parameters of the modified PVA adsorption process were estimated. The data indicate that the adsorption process is exothermic, feasible, spontaneous, and fit to the Langmuir isotherm model. The maximum adsorption capacities for Cd(II) and Pb(II) were calculated to be 1.19 and 1.48 mmol/g, respectively. Sorption was rapid, with the removal percentage higher than 98% after 10 min. Adsorption behavior mechanisms were analyzed using pseudo-first-order and pseudo-second-order models, which were highly fitted to pseudo-second-order model. This suggests the main adsorption mechanism is a chemical adsorption, involving ion exchange and valence forces through sharing or exchange of electrons between metal ions and modified PVA. The modified PVA is a good reusable sorbent, enhancing the economics of practical application for the removal of Cd(II) and Pb(II) from water and wastewater.

Effect of polyvinyl alcohol adsorption on the mixed alumina–silica–titania suspension stability

The adsorption and electrokinetic properties as well as the stability of the AST71 suspension in the absence and presence of polyvinyl alcohol (PVA) were examined. AST71 is a mixed oxide of alumina, silica and titania. All measurements were carried out as a function of solution pH and the polymer molecular weight. The pooled result analysis showed that the PVA adsorption amount strongly depends on the solution pH. The higher solution pH value is, the more polymer macromolecules are adsorbed on the solid surface. This dependence is mainly associated with the PVA chain conformation. The adsorption of polyvinyl alcohol changes the stability of the AST71 suspension, but only in the solution of pH 9. Under these conditions the system without PVA is unstable, which is connected with the isoelectric point of the solid particles. In the presence of the polymer the electrosteric stabilization occurs.

Interactions between silver nanoparticles and polyvinyl alcohol nanofibers

The interaction of polyvinylalcohol (PVA) nanofibers with silver (Ag) nanoparticles (mean diameter 8nm) has been modeled using density functional theory (DFT) calculations. The physical adsorption of PVA through the hydroxyl group, to the Ag, and its corresponding molecular orientation was compared with experimental results obtained from surface-enhanced Raman scattering (SERS) studies of the same material. A good agreement was found between the computational model of the vibrational spectrum of the adsorbate and the experimentally observed SERS. In general, aliphatic capping molecules are used to passivate the surface of Ag55 nanocrystals (55 = atomic number of Ag). In this study, a DFT simulation was employed to show binding energies and electron contour map analyses of Ag55 with PVA. Here we show that the PVA interacts with the Ag nanoparticle's surface, through the OH group, thereby contributing significantly to the increase in SERS activity.

INHIBITION OF CORROSION OF ALUMINIUM IN ALKALINE MEDIUM BY POLY(VINYL ALCOHOL) (PVA)

The inhibition efficiency of polyvinylalcohol (PVA) in controlling corrosion of aluminium in well water in the absence and presence of Zn 2+ has beenevaluated by weight loss method. The formulation consisting of 250 ppm of PVA and 25 ppm of Zn 2+ offers 85 % inhibition efficiency. It is found that the inhibition efficiency of PVA increases by addition of Zn 2+ ion. A synergistic effect exists between PVA and Zn 2+. The mechanistic aspects of corrosion inhibition have been studied using polarization study. Also FTIR spectra reveal that the protective film consists of PVA - Zn 2+ complex and Zn(OH) 2 . The scanning electron microscopy confirms the protection of aluminium surface by strong adsorption of PVA. A suitable mechanism for corrosion inhibition is proposed based on the results from the above studies.

Influence of Polyvinyl Alcohol on Corrosion Resistance of Mild Steel Simulated Concrete Pore Solution Prepared in Well Water

Corrosion resistance of mild steel in simulated concrete pore solution (SCPS) prepared in well water in the absence and presence of polyvinyl alcohol (PVA) and Zn 2+ has been evaluated by weight loss method. It was observed that when PVA is added the corrosion inhibition efficiency (IE) increases. As the concentration of PVA increases, inhibition efficiency also increases. Addition of Zn 2+ improves of IE further. 50 ppm of PVA has 50% IE. 100 ppm of PVA shows 90% IE. When 50 ppm of Zn 2+ was added to the above system, both system shows 94% IE. The mechanistic aspects of corrosion inhibition have been studied using AC impedance spectra. The scanning electron microscopy (SEM) study confirms the protection of mild steel surface by strong adsorption of PVA.

SYNERGISTIC INFLUENCE OF POLYVINYL ALCOHOL AND SURFACTANTS ON THE CORROSION INHIBITION OF MILD STEEL IN 0.1 M H2SO4

The corrosion inhibition behavior of mild steel in 0.1 M H2SO4 in the presence of polyvinyl alcohol (PVA) was investigated using weight loss and potentiodynamic polarization measurements in the temperature range of 30°–60°C. The inhibition efficiency (IE) increased with increasing PVA concentration, showing a maximum IE of 81.41% at 30°C at 100 mg/L and decreased with increasing temperature. The inhibiting action of PVA is synergistically enhanced on addition of very small amounts of surfactants sodium dodecyl sulfate (SDS) and cetyl pyridinium chloride (CPC). The adsorption of PVA alone or in combination with surfactants on the metal surface is found to obey the Langmuir adsorption isotherm from the fit of the experimental data of all concentrations and temperatures studied. The synergism parameter evaluated is found to be greater than unity, indicating that the enhanced IE of PVA caused by addition of surfactants is due only to synergism. The phenomenon of physical adsorption is proposed from the trend of the IE with temperature as well as the values of Ea, ΔHads, and ΔGads obtained. Thermodynamic parameters reveal that the adsorption process is spontaneous. The results obtained by weight loss measurements are consistent with the results of the potentiodynamic polarization measurements. The surface morphology of the corroded steel samples in the presence and absence of inhibitors was also evaluated using scanning electron microscopy (SEM).

Flow behaviour of polyvinyl alcohol (PVOH) modified blends of polyvinyl acetate (PVAc)/natural rubber (NR) latexes

During compounding processes, polymer latexes are mixed with various colloidal systems (in particular, PVOH) or surface-active agents to modify the flow behaviour in order to suit the manufacturing process. In this study, the flow behaviour of aqueous dispersed PVAc, NR and different mixed dispersions were investigated both in the absence and presence of PVOH as flow modifier, using an Ostwald glass capillary viscometer. The results show an almost linear decrease in the relative viscosity of the NR/PVAc dispersion mixtures in the absence of a modifier, but the presence of different amounts of PVOH gave rise to significant deviations from this behaviour. It was found that these changes in the relative viscosities are governed by a balance between the following four effects: (i) the higher mobility of the NR chains compared to those of PVAc, which generally caused a decrease in the viscosities of the dispersion mixtures; (ii) the physical adsorption of PVOH on the NR chains that slowed down the movement of these chains and caused an increase in relative viscosity; (iii) the chemical interaction between the functional groups on PVAc and PVOH that gave rise to latex thickening and increased the relative viscosity; (iv) a dilution effect which reduced the viscosity, unless counterbalanced by one or more of the other effects. Key words: Dispersion flow behaviour, viscosity, rubber latex, polyvinyl alcohol, polyvinyl acetate.

Effect of Polyvinyl Alcohol on Stability and Rheology of Nano Kaolinite Suspensions

A sedimentation study of suspensions of nano kaolinite in aqueous solutions of polyvinyl alcohol (PVA) as well as in water has been conducted. The results demonstrate that PVA can be used to control the stability of nano clay suspension with respect to sedimentation. The adsorption of PVA lowers the viscosity of system resulting in an increase of solid loading for the same viscosity level. The results indicate that solid volume fraction, polymer concentration, and polymer molecular weight can be adjusted to get desired rheological behaviour and sedimentation stability.

Adsorption of polyvinyl alcohol from wastewater by sintered porous red mud

Several types of red mud-based porous materials (RMPM) and other raw minerals via different processes were prepared and characterized using X-ray diffraction (XRD) analyses and scanning electron microscope (SEM) observations. Using the polymer sponge method, a 72% apparent porosity could be reached compared with 64% by adding a pore-forming agent. These materials were tested for their adsorption of polyvinyl alcohol (PVA) from simulated textile wastewater. The best mass ratio of RMPM to PVA solution was 50:100 with a removal maximum of 25.8% after they were in contact for 50 min. The adsorption rate and kinetics could be better described by Lagergren's pseudo-second-order model in comparison with the pseudo-first-order model.

Temperature effects on the adsorption of polyvinyl alcohol on silica

Abstract The influence of temperature on the adsorption of polyvinyl alcohol (PVA) on a silica surface was studied from 15–35°C. The structure of the polymer adsorption layer was determined from spectrophotometric, viscosity and thermogravimetric measurements. The amount of PVA adsorbed, macromolecules’ conformation in solution, thickness of the polymer adsorption layer, and changes in the heating curve of SiO2 with adsorbed polymer were determined. Temperature influences the PVA chain conformation in solution and the structure of the polymer adsorption layer. A temperature rise causes relaxation of polymer coils which results in an increase in the linear dimensions of PVA chains in the solution, the creation of a thicker adsorption layer, and an increase in polymer adsorbed. Polymer adsorption on the silica surface also causes changes in the heating curve of these systems. The mass losses due to heating are smallest for the systems obtained at 15°C because the least polymer is adsorbed at this temperature.

The Spectrophotometric Investigation of Nonionic Polymer Adsorption (Polyethylene Glycol (PEG), Polyethylene Oxide (PEO) and Polyvinyl Alcohol (PVA)) Influence on the Alumina Suspension Stability – Effects of Polymer Type, its Molecular Weight and Solution pH

The effect of nonionic polymer adsorption on the stability of alumina (Al2O3) in the pH range 3–9 was examined. The influences of polymer type and its molecular weight, as well as solution pH, were studied. The following macromolecular substances were used: polyethylene glycol (PEG), polyethylene oxide (PEO) and polyvinyl alcohol (PVA). The spectrophotometry method was applied to obtain the stability curves (dependence of suspension absorbance vs. time). The obtained results indicate that the addition of the polymer influences alumina suspension stability. The addition of the polymer at pH 3 improves the stability conditions of investigated systems. At pH = 6 the decrease of Al2O3 suspension stability (except PEG 2 000) was obtained. On the other hand, at pH 9 the presence of polymer improves the stability properties of the alumina. The higher the molecular weight of the polymer, the more pronounced effects were observed. Moreover, adsorption of polyvinyl alcohol whose macromolecules contain ionizable acetate groups causes greater changes in alumina suspension stability in comparison to the systems containing polyethylene glycol and polyethylene oxide.

Investigation of the alumina properties with adsorbed polyvinyl alcohol

The influence of solution pH on the structure of polyvinyl alcohol adsorption layer on the alumina surface was investigated. The spectrophotometry, viscosimetry, thermogravimetry, potentiometric titration and microelec- trophoresis were applied in experiments. These methods enable determination of the following parameters: adsor- bed amount of PVA, stability of suspension without and with polymer, thickness of its adsorption layers, changes in thermal characteristics of Al2O3 surface with the adsorbed polymer, surface charge density and zeta potential of solid particles in the presence and absence of PVA, respectively. All measurements were carried out in the pH range 3-9. The obtained results indicate that pH has a great influence on the conformation of PVA chains adsorbed on the alu- mina surface. It is due to incomplete hydrolysis of acetate groups of polyvinyl alcohol macromolecules (degree of hydrolysis 97.5%), which dissociate with the increasing pH. Moreover, the polymer adsorption on the alumina surface causes changes in the course of thermogravimetric curves. The effect of weight loss for Al2O3-PVA systems is smaller than that of Al2O3 without polymer. It is due to elimination of water molecules from the solid surface by adsorbed polymer.

Studies of temperature influence on adsorption behaviour of nonionic polymers at the zirconia–solution interface

The temperature influence (15–35 °C) on the adsorption mechanism and conformation of nonionic polymers (polyethylene glycol (PEG), polyethylene oxide (PEO) and polyvinyl alcohol (PVA)) on the zirconium dioxide surface was examined. The applied techniques (spectrophotometry, viscosimetry, potentiometric titration and microelectrophoresis) allowed characterization of the changes in structure and thickness of polymer adsorption layers with the increasing temperature. The rise of temperature favours more stretched conformation of polymer chains on the ZrO2 surface, which results in higher adsorption and thicker adsorption layer. Moreover, these conformational changes of adsorbed macromolecules affect the electric (solid surface charge density) and electrokinetic (zeta potential) properties of the zirconia–polymer interface. The obtained data indicate that the polyvinyl alcohol adsorption has a greater influence on zirconia properties in comparison to that of PEG and PEO. It is due to the presence of acetate groups in the PVA macromolecules (degree of hydrolysis 97.5%), which undergo dissociation.