Effect Of Cationic Polyelectrolytes Research Articles

Effect of cationic polyelectrolyte on the structure and antimicrobial activity of silver-containing nanocomposites based on interpolyelectrolyte complexes with a pectin anionic component

This paper investigates the structure, morphology and antimicrobial properties of silver-containing nanocomposites based on interpolyelectrolyte complexes (IPEC) of pectin with polyethylenimine, cationic starch or chitosan as a cationic polyelectrolyte. The reduction of silver ions was carried out by thermochemical technique by heating of the interpolyelectrolyte–metal complexes, which in turn prepared by adsorption of ions on IPEC. The chemical reduction was also performed using ascorbic acid as reductant. The temperature and time needed to produce the nanocomposites at which completely reduction of silver ions occurs are 150 °C and 30 min. It is revealed that during thermochemical reduction depending on the type of cationic polyelectrolyte (PEI, cationic starch, chitosan), silver nanoparticles with an average size of 4.1, 5.3 and 4.7 nm, respectively, are formed. Various mechanisms of thermochemical reduction for interpolyelectrolyte–metal complexes containing polymers with aminogroups or polymers with the glucopyranose units are considered. It is found that the silver-containing nanocomposites, formed by thermochemical reduction, exhibited higher antimicrobial activity against strains of S. aureus and E. coli than ones obtained using ascorbic acid.

Shifts in the pKa value of acid–base indicators caused by immobilization on solid substrates via water-soluble polycationic polymers: a case study of Congo Red

Objectives. Herein, the effects of cationic polyelectrolytes on the properties of solid substrate immobilized acid–base indicators are investigated to predict shifts in their spectral patterns and characteristics. Methods. The properties of the silica gel immobilized indicator dye in a solution of the cationic polyelectrolyte were studied using automatic photometric titration in the visible region and spectrophotometry using a specialized computerized setup. Results. The measured pKa value of the immobilized dye, which had shifted by three units to the acidic region, was very similar to the pKa value observed for the indicator in the modifying polymer solution. The observed change in pKa of the immobilized dye and the influence of the solution’s ionic strength were attributed to the local electric potential of the polymer globule. In contrast to the processes associated with covalent immobilization, the effect exerted by the solution’s ionic strength on the indicator reaction diminishes, which, in turn, affects the measured values obtained.Conclusions. The creation of a sensor for continuous visualization of pH levels based on Congo Red immobilized on silica gel was described. Here, a color transition was noted between pH 1 and 4. These materials can be used to monitor metal extraction processes from industrial effluents or to optimize the extraction of valuable actinides. The approach demonstrated in this work can be applied to immobilize other indicators for pH level monitoring purposes or the production of sensors for other analytes.

Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization

Abstract Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

Effect of cationic polyelectrolytes on the performance of paper diagnostics for blood typing

We investigated the effect that two common types of cationic polyelectrolytes used in papermaking might have on the performance of paper diagnostics using blood typing as an example. The results were analyzed in terms of red blood cells (RBC) retention and antibody–antigen specificity. Two questions were addressed: (1) can poly(amido-amine) epichlorohydrin (PAE) typically used for paper wet strength affect the diagnostic performance? (2) can high molecular weight cationic polyacrylamide (CPAM) employed as retention aid enhance or affect the selectivity and sensitivity of paper diagnostics?A series of paper varying in type of fibers and drying process were constructed with PAE and tested for blood typing performance. Residual PAE has no significant effect on blood typing paper diagnostics under normal conditions. Positives are unaffected with PAE, while negatives lose slight sharpness as some RBCs are unselectively retained.CPAM, the most common retention aid, can also be used to retain cells and biomolecules on paper. Paper towel was treated with CPAM solutions varying in polymer concentration and charge density and tested for blood typing. We found that CPAM dried on paper can retain RBC. CPAM affects the negative tests by retaining non-specifically individual RBC on fibers. RBC retention increases non-linearly with the CPAM charge density and concentration. As expected, wet CPAM retain RBCs at concentrations higher than 0.1wt%.As paper diagnostics are becoming a reality, more realistic papers than the Whatman filter paper will be engineered. This study provides guidance on how best use the required polymeric wet-strength and retention agents.

Removal of perchlorate from groundwater by the polyelectolyte-enhanced ultrafiltration process

The polyelectrolyte enhanced ultrafiltration (PEUF) process for perchlorate removal from groundwater containing common co-contaminants like nitrate and sulfate was investigated. Existing processes such as ion exchange can remove perchlorate but with greater complexity, especially when applied in the presence of high nitrate and sulfate concentration. The effect of cationic polyelectrolyte, poly(diallyldimethyl ammonium chloride) (PDADMAC) concentration and the effect of nitrate and sulfate in a broader concentration range were observed. In the absence of other anions, a lower amount of PDADMAC (0.5–1 mM) can remove more than 90% of perchlorate from the aqueous phase. However, in the presence of 5 mM nitrate, perchlorate removal decreases as the available binding sites of PDADMAC for perchlorate are reduced. In the presence of both 1 mM to 10 mM nitrate and sulfate, 60–80% perchlorate was removed with 30 mM PDADMAC. The removal of sulfate and nitrate in this case was nearly 75% and 65%, respectively. The effect of other parameters such as relative flux, membrane material and pore size were also observed to study the feasibility of PEUF for perchlorate removal. Consequently, PEUF proved to be an effective perchlorate removal process owing to the high removal efficiency and suitability in groundwater remediation containing other contaminants.

Effect of cationic polyelectrolyte and surfactant on cohesion and friction in contacts between cellulose fibers

The methodics and devices are presented for quantitative study of the characteristics of interaction in contact between individual fibers: friction force F in shear test, and cohesion force, i.e. contact strength p in rupture test. In experiments with cellulose fibers in various liquid media, the friction coefficient μ has been estimated, and the molecular component of friction force related only to attraction of fibers, in the absence of any external normal load has been found. The specific free energy of interaction U has been evaluated in measurements using model samples with the nature of surface similar to that of cellulose fibers. The effects of cationic polyelectrolyte and surfactant: polyethyleneimin and tetrabuthylammonium iodid on these parameters have been quantitatively determined. Complicated, non-monotonic (with several extrema) dependence have been estimated between values F, μ, p, U and surfactant concentration C. Comparison of these data with the ζ-potential measurements of cellulose fibers in the same surfactant solutions allows one to propose an explanation of the mechanisms of these polyelectrolyte and surfactant influence on fiber interactions.

Effect of cationic polyelectrolytes on the dissolution of magnetite in thioglycolic acid solutions

The influence of cationic polyelectrolytes, polyethyleneimine (PEI) and polyvinylbenzyltrimethylammonium chloride (PVBTA-Cl),on the kinetics of dissolution of an iron oxide (magnetite, Fe3O4) by thioglycolic acid (HTG), is presented. It was found that both polyelectrolytes accelerate the dissolution reaction at pH values below ca. 4, whereas an inhibition is observed at higher pH values. These findings are at variance with the results obtained in the case of anionic polyelectrolytes, in which the reaction is inhibited over the whole pH range. The effects of PEI concentration, of the addition of inert salt to the PEI–HTG–Fe3O4 system and of temperature on both systems were also studied. The main effects of PEI are the enhancement of the acidity of the oxide surface, and the decrease of the available surface sites for HTG complexation; the effect of PBVTA-Cl is more modest, due to the higher rigidity of the polyelectrolyte. Modeling of the experimental results in PEI media leads to a kinetic scheme similar to that describing the reaction in the absence of PEI, with a pKas shifted by -2; this shift alters the pH dependence of the surface speciation, thus modifying the rate–pH profiles. For PVBTA-Cl, the shift derived from the data is -1.

The effect of cationic polyelectrolytes, containing terminal hydrophobic anchors, on the stability of vesicles of dioctadecyldimethylammonium chloride in calcium chloride solutions

AbstractDioctadecyldimethylammonium chloride (DODMAC) dispersions containing high concentrations of CaCl2 were stabilised using cationic polyelectrolytes with terminal hydrophobic anchors. The cationic polyelectrolytes were based on quarternised poly(vinyl‐2‐pyridine). The stability of the dispersions was dependent on the molecular weight of the polymer and the length of the hydrocarbon anchor. The amount of polyelectrolyte required to stabilise the dispersions was dependent on the type of polymer used and the concentration of salt in the dispersion. Some of the polymers were also capable of stabilising dispersions that were heated above the Lβ‐Lα phase transition temperature of the DODMAC vesicles. The polyelectrolytes that stabilised the dispersions most successfully in this study had molecular weights of about 10000‐20000 and hydrocarbon anchors containing 16 carbon atoms.

Effects of Cationic Polyelectrolytes on the Removal of Suspended Particulates During Direct Filtration

This research investigated the important parameters influencing the degree of particulate removal from low turbidity water in a configuration that included rapid mixing followed by filtration. The varied parameters were rapid‐mixing velocity gradient, cationic polyelectrolyte type, and polyelectrolyte dosage. The cationic polyelectrolytes were characterized for molecular weight by membrane osmometry, light scattering, and high performance liquid chromatography. The filtration kinetics variables, including maximum depth‐averaged singlecollector efficiency and specific deposit, were used to characterize the efficiency of particulate removal for each of 72 filter runs. Statistical analyses demonstrated that the choice of polyelectrolyte was the only significant factor. Additionally, volume size distribution analyses of particle count data from in‐depth samples in the filter demonstrated that the polyelectrolyte configuration may be critical for adsorption of polyelectrolytes to particulates and media in filtration.

Errata

Journal AWWAVolume 78, Issue 12 p. 4-6 ErrataFree Access Errata This article corrects the following: Effects of Cationic Polyelectrolytes on the Removal of Suspended Particulates During Direct Filtration Theodore S. Tanaka, Massoud Pirbazari, Volume 78Issue 12Journal - American Water Works Association pages: 57-65 First Published online: December 1, 1986 First published: 01 December 1986 https://doi.org/10.1002/j.1551-8833.1986.tb02766.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume78, Issue12December 1986Pages 4-6 RelatedInformation