Adsorption Of Polyethylene Glycol Research Articles

Benzotriazole as inhibitor for copper with and without corrosion products in aqueous polyethylene glycol

Electrochemical methods, including polarization experiments and impedance spectroscopy, were used to evaluate the eAectiveness of benzotriazole (BTA) in an aqueous solution of polyethylene glycol (PEG) in protecting polished archaeological copper or archaeological copper covered with corrosion products. The adsorption of PEG on the polished copper significantly limited the corrosion current. The presence of benzotriazole enhanced the protection of the polished copper, giving maximum protection at a concentration of 10 ˇ2 mol l ˇ1 of BTA in 20 vol % PEG 400 solution. On the other hand, PEG solutions caused degradation of the corrosion products of the copper. This degradation increased with time. When BTA was added, the corrosion products were preserved and, the higher the BTA concentration, the more the corrosion current decreased. In PEG 400 solution protection of the corrosion products of the copper by BTA improved over time.

Hexadecylpyridinium Chloride + Trimethyltetradecylammonium Bromide Mixed Micelles in Polyethylene Glycol + Water Mixtures

Abstract The conductances of hexadecylpyridinium chloride (HPyCl) + trimethyltetradecylammonium bromide (TTAB) mixtures over the entire mole fraction range of HPyCl (αHPyCl) were measured in aqueous binary mixtures of polyethylene glycol (PEG) 200, 400, 600, and 4000 containing different amounts of each PEG in their respective binary mixtures at 30 °C. Each conductivity curve showed a single break, except in the presence of PEG 4000 where two breaks were observed. From the conductivity (κ) data, the critical micellar concentration (cmc), degree of counter ion association (χ), the equivalent conductivities (Λ) from the slope of κ versus C plots, and the standard Gibb’s free energy of transfer of the surfactant hydrocarbon chain from the medium to the interior of the micelle (ΔGHP°) were computed. It was observed that micelle–PEG interactions in the case of HPyCl and TTAB were quite similar to mixed micelle–PEG interactions especially in the presence of PEG 200, 400, and 600. The results were explained on the basis of medium structure-breaking effects of PEG and adsorption of PEG on the micelle–solution interface. In the presence of PEG 4000, the micelle formation corresponding to the first break was found to be similar to that in the presence of PEG 200, 400, and 600. The second break was designated to the polymer bound micellar aggregates, which became more stable as the amount of PEG 4000 was increased.

Influence of the Adsorption of Polyethylene Glycol at the A12O3 Surface on the Electrochemical Properties of the Al2 O3/Solution Interface

The kinetic/adsorption properties of polyethylene glycol (PEG) on an alumina surface were examined. The influence of the molecular weight of PEG and of changes in the pH of the solution on the electrical properties at the solid/polymer solution interface were considered. The data obtained allowed the main factors responsible for the observed zeta potential and the surface charge changes on the A12O3 surface to be determined. The calculated differences in the values of the surface charge (Δσd) and in the charge on the diffuse layer (Δσd) for the A12O3/NaCl and A12O3/PEG-NaCl systems enabled a mechanism to be proposed for the zeta potential changes. It was confirmed that the molecular weight of the polymer has an influence on the calculated thickness of the PEG adsorption layer on the alumina surface and thus on the conformation of the polymer chain in the near-surface region. The pH of the solution also affects the thickness of the adsorbed layers on the A12O3 surface by influencing the interaction between the surface groups of the oxide and the conformational structures of the adsorbed macromolecule at the alumina/polymer solution interface.

Evaluation of methods for detecting alloantibodies underlying warm autoantibodies.

In pretransfusion testing of patients whose sera contain autoantibodies reacting optimally at 37 degrees C, it must be determined whether alloantibodies are also present. Two approaches, testing a 1-in-5 dilution of patients' sera and the adsorption of sera in the presence of polyethylene glycol (PEG), have been proposed as alternatives to the time-consuming approach of adsorbing sera with ficin- or ZZAP-treated red cells (RBCs). The three approaches were compared. Patients' sera containing warm autoantibodies, with and without alloantibodies, were retested 1) after dilution (1-in-5) and 2) after adsorption with allogeneic RBCs in the presence of PEG. Results were compared to those after adsorption with ZZAP-treated allogeneic RBCs. Dilution (1-in-5): Twenty-seven of 119 sera (7/26 [27%] with and 20/93 [22%] without alloantibodies) did not react; one example each of alloanti-D, -E, -e, -Fy(a), and -Jk(a), and two examples of anti-Jk(b) were not detected at a dilution of 1 in 5. Alloantibodies were identified in 5 (19%) of 26 1-in-5 diluted sera containing alloantibodies; 87 (73%) of 119 sera still reacted with all cells and would have required further workup. PEG adsorption: Thirty-nine sera were tested after parallel PEG and ZZAP adsorptions. The PEG adsorptions required a total of 55 aliquots of adsorbing cells and 13.75 hours, whereas ZZAP adsorptions required 61 aliquots and 30.5 hours. All alloantibodies (anti-D [3], -C [2], -c [1], -E [4], -K [2], -Fy(a) [1], -Jk(a) [2], -Jk(b) [1]) reacted in the adsorbed serum-PEG mixtures at a strength equal to or greater than that in the ZZAP-adsorbed sera. Although the 1-in-5 dilution approach is convenient, only 22 percent of warm autoantibodies without alloantibodies were nonreactive, and 27 percent of alloantibodies of potential clinical significance were not detected. PEG adsorption appears to give similar results to those of ZZAP adsorption, but it has the advantages of eliminating the cost and time of prior treatment of the allogeneic adsorbing cells and of a reduction of at least a 50 percent in adsorption time.

Copper Deposition in the Presence of Polyethylene Glycol: I. Quartz Crystal Microbalance Study

The addition of polyethylene glycol (PEG) and to an acid copper electrolyte inhibits the deposition reaction for cathodic overpotentials of up to about 150 mV. Adding only promotes the deposition reaction, while adding PEG alone has a relatively small effect on electrode kinetics. Frequency shifts of an electrochemical quartz crystal microbalance suggest the adsorption of a monolayer of PEG molecules that are collapsed into spheres provided chloride ions are present, with little adsorption occurring when is absent. This behavior is the same for gold and copper surfaces. Transient current measurements suggest that chloride ions affect the PEG adsorption equilibrium rather than adsorption kinetics alone.

Changes of the effective surface area and pore volume of precalcined aluminas induced by pre-adsorption of low molecular weight polymers

The adsorption of low molecular weight polymethacrylic acid- n-butyl ester (PBMA) and polyethylene glycol (PEG) on aluminas precalcined at 673–1473 K was carried out. The changes brought about by the adsorption of these polymers in the total surface area and pore volume distribution were determined. Adsorption of PBMA and PEG resulted in a decrease in the total surface area as determined by nitrogen adsorption. A fraction of the surface located in the micropores is covered by the polymer. Adsorption of polymers on precalcined aluminas reduces the water adsorption capacity as a result of decreasing the number of surface OH groups. Blocking of a fraction of micropores by the adsorbed polymer makes the contribution of mesopores more prominent. In the course of preparation of alumina, the stage at which the polymer is added determines the changes in surface area and porosity.

The use of polyethylene glycol (PEG) to enhance the adsorption of autoantibodies

The use of polyethylene glycol (PEG) to enhance the adsorption of warm autoantibodies on red blood cells (RBCs) was evaluated in our laboratory in an effort to reduce the time and cost associated with routine differential adsorptions. Sera from 19 patients with warm autoantibodies were tested. Fourteen of these sera contained alloantibodies or additional autoantibody specificities underlying the dominant autoantibody. The sera were differentially adsorbed using equal volumes of serum, reagent RBCs, and PEG for 15 minutes at 37 degrees C. The PEG/serum mixture was harvested and used for testing. Six drops of the PEG/serum mixture were tested against reagent RBCs for 15 minutes at 37 degrees C. An antiglobulin test was then performed using anti-IgG. The PEG adsorption technique took a total of 10 hours to completely eliminate autoantibody reactivity in all 19 samples. The reference method required a total of 59.5 hours to adsorb the autoantibodies in all 19 samples. Two weak alloantibody specificities (anti-K, anti-Jkb), known to be present in the serum, were not detected in the PEG tests. Four specificities were weaker with the PEG adsorbed serum. All other alloantibody specificities (13) were detected with equal or greater strength in the PEG adsorbed serum. The use of PEG to enhance the adsorption of autoantibodies should be considered as an option to reduce the time and cost of labor-intensive differential adsorptions. Laboratories should be cautioned that weak alloantibodies may not be detected using this method.

The chemistry of the additives in an acid copper electroplating bath: Part I. Polyethylene glycol and chloride ion

The mechanisms by which chloride ion and polyethylene glycol, two of the common additives in commercial acid copper electroplating baths, influence the cathodic deposition of copper have been investigated using potential sweep and potential step techniques as well as laser Raman spectroscopy. It is confirmed that adsorption of polyethylene glycol onto the copper surface decreases strongly the rate of copper deposition. In fact, it is suggested that the polymer can adsorb in two different forms. One predominates close to the open circuit potential and may well be a copper chloride complex with the polyethylene glycol as a ligand. The other prevails at the more negative potentials where copper plating is carried out; this species is likely to be the simple, neutral polymer molecule.

Characterization of polyethylene glycol modified proteins using charge-reversed capillary electrophoresis

A capillary electrophoretic method employing a charge reversal technique [J. E. Wiktorowicz and J. C. Colburn, Electrophoresis, 11 (1990) 769] has been developed to characterize polyethylene glycol (PEG)—proteins. A removable coating is applied to a standard fused-silica capillary in order to change the negative charge of the capillary surface to a positive charge. This prevents the adsorption of basic and PEG—proteins. The positive electrode is positioned at the detector end of the capillary, orienting electroosmotic flow towards the detector. Automated reconditioning procedures prior to each analysis give relative standard deviations in migration time and area of less than 2%, with most analysis times under 20 min. As the number of PEGs conjugated to a protein increases, the net positive charge and migration time of the copolymer decrease. Resulting peak widths are broad, reflecting the broad molecular mass distribution of PEGs and the heterogeneous nature of the PEG conjugates. This method can be used to monitor process steps, optimize reaction conditions, determine extent of modification, or assess product quality and consistency. Examples of PEG derivatized molecules characterized in our laboratory by charge-reversed capillary electrophoresis are tryptophan, Lys-Trp-Lys, lysozyme, myoglobin, RNase and immunoglobulin G; the size of the attached monomethoxy-PEG molecules varied from 0.15 kDa to 10 kDa (10 3 dalton).

Effect of organic matter and allophane on adsorption of polyethylene glycols onto some soils

Polyethylene glycols were adsorbed onto some soils that had been previously leached with hot water to remove water-soluble organic substances and then either oven-dried or kept moist. The amount of glycol adsorbed onto the dried soils decreased as organic matter content increased. The amount adsorbed onto the moist soils showed a different trend. The parameters for an adsorption equilibrium model based on statistical thermodynamic considerations, namely the equilibrium constant, Ka, and the total volume of the adsorbed phase, w1(0), were estimated in order to interpret this adsorption behaviour. The change in Ka (indicating the change in nature of the soil surface due to drying) significantly depended on allophane content, while the value of w1(0) (representing the amount of surface exposed) was more affected by organic matter content. In addition, the relationship of w1(0) to the liquid limit confirms the validity of w1(0) in modelling soil-water systems.

Adsorption of polyethylene glycol from aqueous solution on montmorillonite clays

Adsorption rates and capacities of polyethylene glycol (PEG) were investigated for five montmorillonite clays. The adsorption of PEG for all the montmorillonite clays was rapid, and equilibrium was attained within 30 min. The adsorption isotherms of PEG for all the montmorillonites conformed to the Freundlich equation. The adsorption heats were 7.3 and 11.6 kJ · mol−1(mw.:2000), and 8.7 and 14.2 kJ · mol−1(mw.:20000) for the montmorillonite and the bentonite II-Ca, respectively. Adsorption capacities for all the clay samples approached constants for the molecular weight of PEG over 2000, though they increased with the increase of molecular weight under 2000. The adsorption capacities were slightly influenced by a nearly neutral pH. The montmorillonite clays which had different interlayer cations showed quite different adsorption capacities. The bentonite II-Ca, the acid clay, and the activated clay showed large adsorption capacities that were 30–50 % of that of an activated carbon.

Polyethyleneglycol adsorption at the TiO 2H 2O interface: Distortion of ionic structure and shear plane position

Polyethyleneglycol (PEG) adsorption at the surface of titanium dioxide does not hinder the potential-determining ions H + and OH − from ionizing the TiOH sites and creating a surface charge σ o. It also does not modify the PZC and the IEP of titanium dioxide, which remain identical at pH 6.1 in the presence of indifferent electrolytes. The zeta potential decrease observed for increasing PEG concentrations at constant pH values is not related to the surface charge, but results from the fact that increasing quantities of adsorbed polymer shift the shear plane. The adsorption of polymer and shift of the shear plane increase with higher molecular weights. The presence of polymer at the interface distorts the ionic atmosphere, thereby increasing and then decreasing the zeta potential as the shear plane shifts due to increasing adsorption of polymer.

Der Einfluß von pH, Elektrolytkonzentration und Mischverfahren auf die Flockung von gefällten und pyrogenen Silikahydrosolen durch Polyethylenglykol

AbstractWith a laser photosedimentometer one obtaines parameters which enable characterization of the turbidity and of the sedimentation in the Silica suspension flocculated by the adsorption of Polyethyleneglycols. By continuous addition of the polymer solution to the silica suspension the influences of the time of addition, stirring time, stirring intensity, polymer coverage, concentration of silica, pH and ionic strength on the flocculation state can be quantified. In contrast to pyrogenic silica precipitated silica is only flocculable by decreasing the pH below pH 3.5 or by addition of salt above 10−2 mol/l. The flocculation of pyrogenic silica is markedly dependent on the mixing conditions at high pH and without salt. At high salt concentrations and pH <3.5 the flocculation of precipitated and pyrogenic silicas becomes independent of mixing conditions.

A study on lower fatty acids and polyethylene glycols adsorption on activated carbon

AbstractThe dependence of the Freundlich constants on molecular weight of members of a homologous series was studied using lower fatty acids and polyethylene glycols. The adsorption was conducted on powdered activated carbon Carboraffin at 18±1°C. The obtained results may be summarized as follows:The adsorption of both fatty acids and polyethylene glycols may be satisfactorily described by the Freundlich adsorption isotherm.The constant K from the Freundlich equation increases with increasing molecular weight of both fatty acids and polyethylene glycols.The exponent n was found to be practically constant for fatty acids but to decrease with increasing molecular weight of polyethylene glycols.The pH of solution exerts an influence upon the adsorption of fatty acids and has no influence upon the adsorption of polyethylene glycols. The amenability of fatty acids to the adsorption decreases with increasing pH. No adsorption may be expected above pH of 8.2.

Some remarks on the adsorption of polyethyleneglycols at the mercury-solution interface

Some remarks on the adsorption of polyethyleneglycols at the mercury-solution interface

Adsorption of Organic Polymers on Platinum Electrode

Abstract The adsorption behavior of polyvinylpyrrolidone (PVP), polyethyleneglycol (PEG), and alkylphenoxy polyethoxy ethanols (Triton X) on a smooth platinum electrode was investigated by observation of the inhibition effect on the electrosorption of hydrogen and oxygen in the potential range between hydrogen and oxygen evolution. The adsorption of PVP, PEG, and Triton X on platinum always took place within the potential range from −0.20 to 1.25 V vs. SCE, the inhibition effect on the electrosorption of hydrogen and oxygen being distinctly shown. The order of inhibition of these adsorbates was Triton X>PVP>PEG. The inhibition effect became larger in most cases with decreasing mean molecular weight of adsorbate. In contrast to the case with a mercury, the adsorbates were oxidized or reduced on the platinum electrode in the adsorption range, the anodic peak due to oxidation being distinctly revealed in the case of PEG.

Adsorption of Polyethyleneglycol at the Mercury/Solution Interface

Abstract The adsorption of polyethyleneglycol (PEG) was investigated at the mercury/solution interface by the observation of the differential capacity and the inhibitive action on the deposition of cadmium or copper. From the differential capacity measurements, the adsorption of PEG was found to be controlled by the diffusion of the adsorbate to the dropping mercury electrode under the present experimental conditions. The relation between the time required to attain the saturated adsorption and the bulk concentration (a) was explained approximately by the Koryta equation, though its deviation from the Koryta equation was somewhat larger than that for polyvinylpyrrolidone. When the maximum surface concentration and the mean molecular weight of PEG were expressed by Γm and \barM respectively, the plot of logΓm-log\barM revealed two linear parts crossing each other at \barM=ca. 600. The slope for \barM≥600 was ca. −1, which implied the relation of “\barM·Γm=const.”, i.e., the segment numbers of PEG molecules adsorbed per unit area were constant, independently of \barM, in the region of \barM≥600. The configuration of PEG of \barM<600 at the interface was considered to be different from that of PEG of \barM≥600 because the slope for \barM<600 was different from that for \barM≥600. From the polarographic current measurements i.e., the inhibitive effect on the reduction of Cd2+ or Cu2+), the time (tmi) needed to achieve the maximum inhibition was obtained; it was then compared with that obtained from the capacity data. The relation of “loga=(−1⁄2)logtmi+const.” based on the Koryta equation was approximately applicable to the cases with a relatively large \barM value.

The adsorption of polyethylene glycols (PEG) from aqueous solutions on channel black treated at 3000°C

The adsorption of polyethylene glycols (PEG) from aqueous solutions on channel black treated at 3000°C

The Adsorption of Polyethylene Glycol on the Suspended Silver Iodide

The Adsorption of Polyethylene Glycol on the Suspended Silver Iodide

The Adsorption of Polyethylene Glycols to a Dropping-Mercury Electrode and their Effect on Surface Potential

AbstractThe adsorption of two polyethylene glycols to a dropping-mercury electrode has been studied. Like cationic surfactants, they were more strongly adsorbed on a negative surface than a positive one and like cationic surfactants therefore, they must shift the potential of an isolated surface to more positive values. This effect was also observed in alkaline solution and was therefore unlikely to be due to the formation of oxonium ions. Rather it was due to the adsorption of a number of oriented dipoles.