Effect Of Cationic Polymer Research Articles

Thixotropy of fresh cement pastes in presence of cationic polymer

Cationic polymer can effectively improve the clay tolerance of polycarboxylate superplasticizer in cement pastes, but the thixotropy of fresh cement pastes in presence of cationic polymer has not received sufficient attention. In this paper, the effect of cationic polymer on the thixotropy of fresh cement pastes containing Na-bentonite was studied. The hydration heat was considered and measured. Besides hysteresis loop areas, the destruction and reconstruction of flocs in thixotropic behaviors of cement pastes were also investigated. The results showed that the cationic polymer delayed the release of cement hydration and decreased the total hydration heat. Cement hydration improved the thixotropy of cement pastes. An obvious decrease of hysteresis loop areas of cement pastes was observed with the addition of cationic polymer, which indicated the decrease of the thixotropy. The equilibrium shear stress, characteristic time of destruction of flocs and incipient structural parameter in thixotropic behaviors were also decreased with the addition of cationic polymer. On the other hand, cationic polymer increased the reconstruction rate of flocculated structure in cement pastes.

Effects of cationic polymers on the viability of microbial biofilms.

The number of published biofilm studies and novel ways for studying them has risen dramatically in recent years, ow-ing to the broad application of biofilms in medicine. Some bacteria develop biofilms that are highly resistant to antimicrobial agents, resulting in persistent infections. This necessitates the development of alternative methods for combating biofilms. In this regard, the application of cationic polymers is a good candidate for realization of this strategy. The aim of our study was to investigate the potential of a newly synthesized covalently attached star copolymer of N,N'-dimeth-ylaminoethyl methacrylate and hydroxyl-bearing oligo(ethylene glycol) methacrylate [P(DMAEMA-co-HOEGMA)] to silica surfaces and its quaternized version [P(QDMAEMA-co-HOEGMA)] for destruction of biofilms formed by Bacillus subtilis or Pseudomonas aeruginosa. Model strains representing different genera and taxonomic groups were selected for the study. The anti-biofilm activities of two different newly synthesized cationic polymers were investigated by observation (live/dead staining) of the viability of bacterial cells within the biofilm. The results obtained by the live/dead labeling of bacterial biofilms show a substantial decrease in the viability of population in the presence of cationic polymers, better expressed at B. subtilis. The studied two immobilized on silica wafers newly synthesized star copolymers exhibited potential for anti-biofilm effects. The results demonstrated combined potential for reducing the viability of bacterial cells within the biofilms and probably for loosening the biofilm matrix. The effect was better expressed in B. subtilis.

A novel bioreactor design for enhanced aerobic granular sludge formation: effects of cationic polymer and boric acid addition

AbstractCompared to the conventional activated sludge, granular sludge has many advantages like good settling ability, high biomass retention and ability to withstand a high organic loading rate. In this study, the effects of boric acid and chitosan addition on granule formation was investigated in a novel Custom‐made upflow aerobic granular sludge reactor for 22 days. According to the microscopic results, granulation in all reactors started at 5–7 days. The polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) results indicate the evolution of the bacterial community during the granulation process. In addition, high pressure liquid chromatography (HPLC) analysis showed that 100 mg/L of terephthalic acid (TA) was totally degraded in all reactors during 24 hours period. To date, chitosan was generally used in anaerobic granulation studies. Thus, there is little known about the role of chitosan in aerobic granulation. The findings in this study constitute important information about the process of granule formation and the factors that are essential to aerobic granulation.

Synergetic Effect of Cationic Polymers on Water Repellency of Cellulosic Fiber Network Paper Filled with Waste Lime Sludge

Lime sludge is commonly generated from the pulping waste liquor in alkali recovery of paper industry. It would cause a significant decrease in the alkyl ketene dimer (AKD) sizing efficiency as used to be the filler for cellulosic fiber networks paper. In the present work, Polyamide-Polyamine-Epichlorohydrin (PAE), Polyetherimide (PEI) and chitosan were used as sizing promoters for addressing the above issue. Results showed that the sizing degree of paper filled with 26% lime sludge could be increased by 83.4%, 68.9% and 49.7%, respectively, at the optimal dosage of PAE, PEI and chitosan. Curing time and curing temperature also had significant impacts on the efficiency of the three sizing promoters. All the three sizing promoters could remove the anionic trash in the wet end. Moreover, PAE could promote the reaction between AKD particles and cellulosic fibers.

Flocculation of wheat straw soda lignin by hemoglobin and chicken blood: effects of cationic polymer or calcium chloride

AbstractBACKGROUNDLignin is the largest byproduct of biomass processing. Flocculation could replace strong acid used in lignin recovery and be useful for the cleanup of lignin from residual processing waters. Commercial nonrenewable flocculants are known to be effective with lignin, but the investigation of renewable lignin flocculants has received little attention.RESULTSMethods were developed to economize on the use of biobased flocculant for wheat straw lignin flocculation. Thus, 43% less hemoglobin (HEM) and 39% less chicken blood (CB) were needed when the Zeta potential was increased by the co‐addition of poly (diallydimethylammonium chloride) (pDADMAC). Supernatant chemical oxygen demand (COD) was reduced by 78% with optimal pDADMAC and CB. Up to 94% less HEM was needed for lignin flocculation with the co‐addition of CaCl2.CONCLUSIONCharge neutralization promoted lignin flocculation with coflocculants pDADMAC/HEM or pDADMAC/CB. Some lignin flocculation was noted at higher levels of CaCl2 due to reduced lignin solubility. Charge neutralization contributed to lignin flocculation at lower CaCl2 levels and high HEM. A novel finding was that divalent cation bridging promoted lignin flocculation in the presence of CaCl2 at lower levels of HEM. Lignin flocculated with HEM‐CaCl2 is possibly useful as a protein‐enriched animal feed. © 2016 Society of Chemical Industry

Role of polymer–surfactant interactions in foams: Effects of pH and surfactant head group for cationic polyvinylamine and anionic surfactants

In a previous study (Langmuir, 28 (2012) 4996) we showed that the foamability of mixed solutions of the cationic polymer polyvinylamine (PVAm) and the anionic surfactant sodium dodecyl sulphate (SDS) is strongly reduced, whereas the stability of the formed foams is strongly enhanced, as compared to the solutions of SDS alone. Here we study in more detail the foaming properties of mixed solutions of PVAm with anionic surfactants. The effect of surfactant head group is studied by comparing SDS with another anionic surfactant (sodium dodecyl oxyethylene sulphate, SDP1S) which contains an additional ethoxy fragment in the charged head-group. For changing the electrostatic polymer–surfactant interactions, we varied pH between 6 and 10, thus crossing the polymer pKa ≈ 8.6. The foam tests showed that the foamability of all mixed solutions is strongly reduced in the entire range of pH values studied. The negative effect of PVAm on solution foamability is highest at low pH, where the polymer charge density is the highest. Model experiments revealed that the reduced foamability is due to prolonged lag-time for formation of mixed adsorption layer on bubble surfaces. Surprisingly, we found that the stability of SDP1S foams is also reduced strongly by PVAm at pH 6 (contrary to SDS and to conventional understanding). The obtained results indicate that the ethoxy group in SDP1S enhances the surfactant association with the polymer molecules, thus decreasing the concentration of free surfactant monomers, necessary to adsorb on the solution surface for foam stabilization during foaming and immediately after it. These results clearly demonstrate that excessively strong polymer–surfactant interactions could be a problem in the formation and stabilization of foams from mixed solutions. Moreover, the effect of cationic polymers on the foaming properties of anionic surfactants could depend significantly on the specific head group of the surfactant.

Effect of Cationic Polymers on Foam Rheological Properties

We study the effect of two cationic polymers, with trade names Jaguar C13s and Merquat 100, on the rheological properties of foams stabilized with a mixture of anionic and zwitterionic surfactants (sodium lauryloxyethylene sulfate and cocoamidopropyl betaine). A series of five cosurfactants are used to compare the effect of these polymers on foaming systems with high and low surface dilatational moduli. The experiments revealed that the addition of Jaguar to the foaming solutions leads to (1) a significant increase of the foam yield stress for all systems studied, (2) the presence of consecutive maximum and minimum in the stress vs shear rate rheological curve for foams stabilized by cosurfactants with a high surface modulus (these systems cannot be described by the Herschel-Bulkley model anymore), and (3) the presence of significant foam-wall yield stress for all foaming solutions. These effects are explained with the formation of polymer bridges between the neighboring bubbles in slowly sheared foams (for inside foam friction) and between the bubbles and the confining solid wall (for foam-wall friction). Upon addition of 150 mM NaCl, the effect of Jaguar disappears. The addition of Merquat does not noticeably affect any of the foam rheological properties studied. Optical observations of foam films, formed from all these systems, show a very good correlation between the polymer bridging of the foam film surfaces and the strong polymer effect on the foam rheological properties. The obtained results demonstrate that the bubble-bubble attraction can be used for efficient control of the foam yield stress and foam-wall yield stress, without significantly affecting the viscous friction in sheared foams.

Study on Granulation of Anaerobic Sludge in UASB Reactor Adding Cationic Polymer Treating Low Strength Wastewater at Room Temperature

Effect of cationic polymer on granulation and COD removal efficiency in lab scale UASB reactors was examined, treating low-strength wastewater (COD 300-500mg l-1) at room temperature. It was shown that cationic polymer was more effective for enhancing sludge granulation and COD removal efficiency as compared to the control experiment (without additives). After day 166 of operation, the amount of granules size above 0.5mm accounted for 32.1% of total sludge, higher than that of control experiment (19.3%). At 1.03 kg COD m-3 d-1 of OLR and 9.8 h of HRT, the effluent VFA had a maximum value of 168mg l-1 and 240mg l-1 in Reactor A and B respectively. The polymer-amended reactor took 36days to receive 1.44 kg COD m-3 d-1 of OLR at the 7.8 h of HRT, shorter than the control reactor (54days). The two reactors obtained above 80% in COD removal efficiency. It is shown that UASB reactor can also achieve higher COD removal treating low strength wastewater at room temperature.

Transfection efficiency and intracellular fate of polycation liposomes combined with protamine

Endosomal escape and nuclear entry are the two main barriers for successful non-viral gene delivery. To overcome these barriers, polyethylenimine (PEI) with a molecular weight of 800, conjugated to cholesterol (PEI 800-Chol) was synthesized to prepare polycation liposomes (PCLs). The effect of cationic polymers on transfection was investigated by pre-condensing DNA with these before using PCLs. The complexes of PCLs and protamine/DNA nanoparticles (PLPD) were introduced as efficient gene transfer vectors, and displayed obviously higher transfection efficiency (approximately 39-fold) than PCLs/DNA complexes. Kinetics of transgene expression indicated PLPD complexes could be maintained at a relatively high level over 72 h. The order of protamine addition affected the transfection of PLPD complexes. Pre-mixed and post-mixed PLPD complexes improved transfection, although the former was preferred. Distribution of FAM-labeled oligonucleotides (FAM-ODN) in cells mediated by PCLs were throughout the whole cell, while most FAM-ODN were nuclear when transfected with PLPD. These results suggest that the protonation of PEI and membrane destabilization of 1, 2-Dioleoyl- sn-glycero-3-phosphoethanolamine (DOPE) increases the endosomal escape ability of vectors. The addition of protamine, containing nuclear localization signals, improved nuclear entry of DNA. The internalization pathways for PCLs involved multiple processes and were possibly dependent on cell lines.

Effects of cationic polymer on start‐up and granulation in upflow anaerobic sludge blanket reactors

AbstractThe upflow anaerobic sludge blanket (UASB) has been used successfully to treat a variety of industrial wastewaters. It offers a high degree of organics removal, low sludge production and low energy consumption, along with energy production in the form of biogas. However, two major drawbacks are its long start‐up period and deficiency of active biogranules for proper functioning of the process. In this study, the influence of a coagulant polymer on start‐up, sludge granulation and the associated reactor performance was evaluated in four laboratory‐scale UASB reactors. A control reactor (R1) was operated without added polymer, while the other three reactors, designated R2, R3 and R4, were operated with polymer concentrations of 5 mg dm−3, 10 mg dm−3 and 20 mg dm−3, respectively. Adding the polymer at a concentration of 20 mg dm−3 markedly reduced the start‐up time. The time required to reach stable treatment at an organic loading rate (OLR) of 4.8 g COD dm−3 d−1 was reduced by more than 36% (R4) as compared with both R1 and R3, and by 46% as compared with R2. R4 was able to handle an OLR of 16 g COD dm−3 d−1 after 93 days of operation, while R1, R2 and R3 achieved the same loading rate only after 116, 116 and 109 days respectively. Compared with the control reactor, the start‐up time of R4 was shortened by about 20% at this OLR. Granule characterization indicated that the granules developed in R4 with 20 mg dm−3 polymer exhibited the best settleability and methanogenic activity at all OLRs. The organic loading capacities of the reactors were also increased by the addition of polymer. The maximum organic loading of the control reactor (R1) without added polymer was 19.2 g COD dm−3 d−1, while the three polymer‐assisted reactors attained a marked increase in organic loading of 25.6 g COD dm−3 d−1. Adding the cationic polymer could result in shortening of start‐up time and enhancement of granulation, which may in turn lead to improvement in the efficiency of organics removal and loading capacity of the UASB system. Copyright © 2004 Society of Chemical Industry

The effects of cationic polymers on flocculation of a coal thickener feed in washery water as a function of pH

The effects of cationic polymers on flocculation of a coal thickener feed in washery water as a function of pH

The effects of cationic polymers on flocculation of a coal thickener feed in washery water as a function of pH

The flocculation of a thickener feed using three cationic polyacrylamide copolymers of high molar mass and different charge densities was studied at three pHs in washery water. The binding capacities were very dependent on pH but only slightly dependent on the polymeric charge density. The reverse was true for the settling rates. At pH 7, all three polymers were equally effective at clarifying the suspensions, but there were marked differences at pH 4 and 9. For the polymers of highest charge density, reducing the pH increased their effectiveness; for the polymer of lower charge density, changing the pH had little effect on the residual turbidity. © l997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 783–789, 1997

Effect of cationic polymer on the separation of phenols by capillary electrophoresis

The capillary electrophoretic separation of substituted phenols was examined using high-molecular-mass polyethyleneimine (PEI) as a buffer additive. The added PEI to the running buffer showed a strong interaction with the phenols and affected the electrophoretic mobilities and migration order of phenols. The influence of pH, organic solvent and concentration of polyelectrolyte on the electrophoretic mobilities of analytes was investigated.

The effect of cationic polymers on the water retention value of various pulps

The effect of cationic polymers (cationic corn and potato starches, polyacrylamide and fractionated modified polyethylene imine) on the water retention value (WRV) of different pulps (bleached chem ...

Diatomaceous Earth Filtration of Cysts and Other Particulates Using Chemical Additives

Diatomaceous earth filtration was evaluated for removal of Giardia muris, Cryptosporidium, turbidity, and coliform bacteria from a surface water. The effect of cationic polymers and alum on this removal was also investigated. Essentially all of the Giardia cysts and >99.9 percent of Cryptosporidium oocysts were removed from waters containing approximately 2,000 cysts/L. The removal of Cryptosporidium was further improved by using alum. Greater removals of coliforms and turbidity, especially small particles (3 μm or less), were also achieved when chemical coagulants were added. Use of these chemicals reduced the length of filter runs, even for low‐turbidity waters, because of higher head losses.

The effect of cationic polymer on the settling characteristics of activated sludge

The physical properties of activated sludge flocculated by cationic polymer (polyethyleneimine) were investigated. It was found that the hindered settling rate, the typical settling rate of a typical aggregate and the sediment volume increased with the amount of cationic flocculant due to an increase in aggregate size. But the surplus addition of flocculant caused the deflocculation of aggregates and decreased the hindered settling rate and the sediment volume. It was confirmed by measuring the buoyant density of the individual flocculated aggregate that the flocculant made the aggregate more compact than a natural aggregate of activated sludge. The mean buoyant density of the flocculated aggregates was calculated from a hydrodynamic volume coefficient which was obtained in the hindered settling experiments. The relationship between the calculated mean buoyant density and the size of a typical aggregate which had the typical settling rate at the various concentrations of flocculant was roughly similar to the relationship between the buoyant density of an individual aggregate and the aggregate size when the concentration of flocculant was 3 p.p.m. In spite of an increase in buoyant density in comparison with a natural aggregate which had the same size as the flocculated one, the settling rate of a flocculated aggregate did not increase so much as was expected by applying the settling rate equation for a rigid body. This result was explained by the effect of permeability on the settling rate.

The effect of cationic polymers on the colloidal stability of latex particles

Using a simple turbidimetric procedure, relative flocculation rates of a polystyrene latex suspension with three cationic polymers and a cationic surfactant have been determined. All four materials showed about the same optimum flocculation concentration when expressed in equivalent amounts, indicating the predominance of charge effects. In agreement with previous findings, a considerable enhancement of flocculation rate was observed with cationic polymers of moderately high molecular weight, which is consistent with the “electrostatic patch” model of polyelectrolyte adsorption. At optimum polymer concentration, it was found that the rate of flocculation after a two-stage addition of suspension was just the same as that after the conventional one-stage addition. This, at first sight, surprising result also can be explained in terms of a simple patchwise adsorption model. However, the rate enhancement is considerably underestimated by this simple model, probably because the mutual orientation of colliding particles is not taken into account.

On the Mechanism by which Cell Contact Induces the Release Reaction of Blood Platelets; the Effect of Cationic Polymers

SummaryHuman blood platelets are aggregated by the basic polymers polylysine and DEAE- dextran. Under certain conditions a second phase of aggregation, concomitant with the release reaction, is elicited. The presence of ADP, calcium ions and a plasmatic cofactor within the primary aggregates are necessary for the induction of the release reaction. These experiments demonstrate that cell contact per se does not lead to a release reaction ; in order to become effective it must take place in the presence of ADP.