Water‐soluble acrylamide copolymers. X. Flocculation efficiencies of poly[acrylamide‐co‐N,N‐dimethylacrylamide], poly[acrylamide‐co‐methacrylamide], poly[acrylamide‐co‐N‐t‐butylacrylamide], and their cationic derivatives

A hydrated, 1% by weight Na‐kaolinite suspension in deionized water was prepared, completely characterized, and reproducible measures of flocculation efficiency were validated. Flocculation tests of copolymers of acrylamide (AM) with dimethylacrylamide (DMA), methacrylamide (MeAM), or N‐t‐butylacrylamide (NTBAM) with 1% Na‐kaolinite suspensions gave average settling rate rates which decreased as the proportion of DMA, MeAM, or NTBAM in the copolymer increased. However, for a similar weight‐average molecular weight and slightly lower 〈r_g〉, the copolymer from DMA‐co‐AM‐3 gave settling rates and supernatant turbidities comparable to similar types of commercial polymers. This new copolymer was also more resistant to changes in pH or the presence of an electrolyte than were the tested commercial polymers. Cationic derivatives of the new copolymers gave lower average settling rates and higher supernatant turbidities than those of Percol 721 (cationic PAM), probably because of their lower charge densities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2090–2108, 2002; DOI 10.1002/app.10562     

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     

Flocculation and sedimentation of cane sugar juice particles with cationic homo‐ and copolymers

Rapid flocculation and sedimentation of suspended particles in primary cane sugar juice is achieved using a high molecular weight anionic polymer flocculant. This work reports on efforts to enhance the performance of an anionic flocculant by the addition of cationic polymers. Homopolymers of poly(trimethylammonium ethyl methacrylate chloride) (TMAEMAC) and cationic copolymers of poly(trimethylammonium ethyl acrylate chloride) (TMAEAC) and acrylamide were synthesized and their performance, to enhance the flocculation and sedimentation of cane sugar juice particles, was evaluated by turbidity and settling rate measurements. The charge–patch mechanism best explains the performance of the homopolymers, whereas the action of the copolymers is attributed to the bridging mechanism. The results of this work indicate that the copolymers are more effective than the homopolymers to aid flocculation and sedimentation of the cane sugar juice particles, and that the best‐performing polymers are those that act by the bridging mechanism. Addition of increased amounts of anionic flocculant did not confer an improvement, suggesting that the cationic bridging flocculant targets a different population of particles that is largely responsible for the residual turbidity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 316–325, 2003     

Parameters affecting the performance of polyelectrolytes as aids to water clarification

An investigation of the flocculation of silica and alumina suspensions by a series of synthetic flocculants of a wide range of charge density both anionic and cationic in nature has been carried out. The extent of flocculation was determined by measurements of settling rate, sediment volume and supernatant clarity. The effect of the pH of the suspension on the performance of a number of selected polymers has been investigated. In the systems examined, flocculation was largely controlled by the charge carried by the suspended particles and polymer molecules. The dosage/settling rate characteristics of kaolin suspensions flocculated with non-ionic polymers of varying molecular weight are reported. The dosages of non-ionic polymers required for optimum flocculation of kaolin suspensions of varying solids content have been measured. At low particle concentrations bridging is less effective, and is probably reduced due to the adsorption of polymer molecules on to single particles.     

Investigation of Emulsified Oil Wastewater Treatment with Polymers

Abstract

Wastewater from metal industry hot milling operations contains oil primarily from coolant sprayed on metal strips to dissipate heat during the rolling of metals. The emulsified oil wastewater for this study was withdrawn from two holding ponds where free oil would rise to the surface and was removed periodically, and used as influent for the chemical addition (CA)-gravity separation (GS) process. The principal objective of this research was to evaluate the effectiveness of different polymer addition systems through a CA-GS process for oil/grease (O/G) and total suspended solids (TSS) removal. Polymers from two corporations were investigated. A dual polymer system was recommended and supplied by Calgon Corporation—a cationic polymer (W-2923) to break the emulsion and an anionic polymer (POL-Z-E 2706) to enhance coagulation. A single polymer system was recommended and supplied by Grace Dearborn (GD) Corporation—a cationic polymer (KLAR-AID 2400) as a coagulant. Two types of experiments were performed: jar tests and larger scale batch-mixing tank (BMT) experiments. O/G and TSS removal efficiencies were 99% for both the Calgon and GD polymer systems. The range of optimum dosage was broader for the Calgon polymers, but both systems were susceptible to overdosing. A longer settling time was required for the GD polymer, but the Calgon polymers were more sensitive to pH. Average residual production rates were 89 and 148 gallons per 1000 gallons of wastewater treated for Calgon and GD polymers, respectively.     

Effects of cationic and anionic clays on the hydrolytic degradation of polylactides

Polylactide (PLA)/montmorillonite (MMT) cationic clay and PLA/hydrotalcite (HT) anionic clay composites at 5wt% clay were melt compounded and characterized for morphology before and after hydrolytic degradation. Semicrystalline and amorphous polymers were used as well as noncalcined and calcined clays. The addition of cationic clays led to the formation of microcomposites, whereas the addition of anionic clays produced a much finer dispersion and enhanced polymer intercalation corresponding to that found in nanocomposites. Hydrolytic degradation rate constants of cationic microcomposites and, particularly, of anionic nanocomposites are lower than those of the unfilled polymers, possibly due to the reduction of the carboxylic group catalytic effect through neutralization with the hydrophilic alkaline filler. Comparison of calcined MMT and HT clays vs. their noncalcined counterparts suggest that calcination can further reduce hydrolytic degradation rates, particularly for semicrystalline PLA. Based on the calculated activation energies, the degradation kinetics did not differ significantly above and below the assumed T_g of 58–60°C. The results of this work would be applicable to controlled release pharmaceutical formulations containing clay/drug combinations produced by melt compounding with a biodegradable polymer matrix. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Ionic graft copolymerization. VI. Graft copolymerization of β-propiolactone and N-vinylcarbazole onto trunk polymer containing carboxylic acid,sulfonic acid,and their salts

It was pointed out in previous papers that both cationic and anionic polymerization might be involved simultaneously in grafting onto trunk polymers containing ? COOH or ? SO₃Na. The graft copolymerization of β-Propiolactone (βPL)–N-vinylcarbazole (NVCZ) onto styrene-divinylbenzene copolymers containing carboxylic acid, sulfonic acid, and their salts was carried out in order to distinguish between the polymers produced by anionic and cationic mechanisms. The polymer obtained by the polymerization of βPL–NVCZ with BF₃·OEt₂, a typical cationic catalyst, consisted mainly of NVCZ units, but the polymer obtained with BuLi, a typical anionic catalyst, consisted mainly of βPL units. In the graft copolymerization of NVCZ–βPL onto trunk polymer containing ? COOH, the NVCZ contents of the branch polymer and the tolueneinsoluble fraction were estimated to be ca. 50 mole-%; therefore these polymers were produced by both cationic and anionic mechanisms. In the case of graft copolymerization onto the trunk polymer containing SO₃Na, it was found that both cationic and anionic polymerization also occurred simultaneously.     

Interaction mechanism of flocculants with coal waste slurry

Coal tailings are the inevitable by-product of coal mining and preparation plants, and often are problematic in terms of dewatering and solid-liquid separation. The interaction of multi-component fine coal tailings with various coagulants and flocculants are important in dewatering processes. Tunçbilek coal preparation plant wastes are composed of 81% inorganic solids with negative surface charges dominating at all pHs. The highest settling rate and turbidity values without flocculant are obtained at natural pH of 8.3 due to the presence of inorganic ions in the suspension particularly Mg²⁺and Ca²⁺that act as natural coagulants. Additon of medium and low charge density anionic flocculants with high molecular weight at natural pH produced higher settling rates at lower dosages than nonionic and cationic flocculants. It shown that the charge density of anionic flocculants has a significant effect on both settling rate and supernatant turbidity, also the settling rate increases with increasing the degree of anionicity. Anionic flocculants having high molecular weight and high anione charge density produced flocs at sufficient size necessary for settling conditions, yet anionic flocculants having low charge density were more effective in the clarification of suspensions containing clay minerals of high stability. The multivalent ions act as a bridge between negatively charged coal, quartz and clay minerals with anionic groups (-CH₂-(CH-CO)-COO groups) of the polymer. Non-ionic flocculants required higher dosages than other flocculants to achieve equivalent settling rates; though excellent turbidity values were obtained in most common pH values. Cationic flocculants of higher charge densities (%70) achieved good settling rates and low supernatant turbidities (9.9 NTU) at natural pH for a dosage of 119.7 g/t-solids flocculant. An interaction mechanism of each polymer type with different components of the tailings is proposed.     

造纸用粉煤灰纤维的表面阳离子化改性

将粉煤灰纤维通过盐酸预处理后,采用低取代度季铵型阳离子淀粉对其进行表面阳离子化改性,研究了粉煤灰纤维的酸化条件筛选、阳离子化改性的工艺条件及纤维表面Zeta电位对其在水中分散的影响. 结果表明,经0.3 mol/L HCl预处理30 min后,常温下加入粉煤灰纤维质量3%的阳离子淀粉(水相浓度0.06%),作用40 min,所得阳离子化粉煤灰纤维的Zeta电位达最高值19.00 mV;由SEM观测到其包覆状况较好,水中分散和沉降实验证实了其表面Zeta电位越高,沉降时间越长,分散性越好,当Zeta电位增至17.20 mV以上时,纤维的抗絮凝性明显改善.     

Preparation of breathable polyurethane membranes with quaternary ammonium salt diols providing durable antibacterial property

Aim of this study was to produce hydrophilic breathable polyurethane membranes providing antibacterial property permanently by incorporation of a quaternary ammonium salt diol (QAS). The study was carried out by synthesis of nine different polyurethanes by solution polymerization through variations of their QAS and isocyanate contents. Fully amorphous membranes at a thickness of ~30 μm were produced from the synthesized polymers and their thermal and morphological characteristics were determined. The effect of morphological structures on the membrane water vapor transmission rates (WVTR) and antibacterial properties were correlated. The WVTR increased with the increased temperature in all membranes over 10–40 °C, all produced membranes showed water resistance up to a pressure of 2100 cmH2O and WVTR values above 60 g/m² h at 30 °C. The WVTR increased by increasing amount of QAS including cationic groups and decreased by increasing isocyanate amount reducing the molecular chain flexibility. In addition, while the unmodified membranes did not show any antibacterial activity, the QAS-added membranes provided significant inactivation against Staphylococcus aureus and Escherichia coli of about 104 CFU within 5 h of contact time. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47133.     

Radiation-induced polymerization of styrene at high dose rates

A kinetic equation was derived for the radiation-induced polymerization of styrene under the assumption that both radical and cationic polymerizations take place concurrently throughout the whole range of the dose rate of radiation and the water content of the styrene. The equation enables one to calculate rates of the total, radical, and cationic polymerization at a given dose rate and water content and agrees satisfactorily with experimental results, which cover dose rates from 4.2 × 10 to 2.1 × 10⁵ rad/sec and water contents from 3.2 × 10^?3 to 3.5 × 10^?2 mol/l. Experimental estimation of the contribution of radical and cationic mechanisms was done by GPC curves of polymers obtained under various conditions. When the contribution of ionic mechanism is expressed in weight percent, it changes from 0% to 100% in the range of the experiment; on the other hand, if it is expressed in mole percent, it is independent of the dose rate and remains constant throughout the whole range of the experiment.     

Impact of Polymer Flocculants on Treated Water Quality in Surface Water Treatment by Coagulation-Microfiltration

The effects of polymer flocculants on coagulation/flocculation-microfiltration of two surface waters were investigated in terms of turbidity, dissolved organic matter concentration and molecular characteristics. The results showed that all polymers studied improved the dissolved organic carbon removal by polyaluminum chloride coagulation, but only cationic polymers improved UV ₂₅₄ removal. High performance size exclusion chromatography analyses showed that cationic polymers slightly increased removal of small UV absorbing matters in the molecular weight range of 1100 to 4000 Da compared to 4000–9000 Da by polyaluminum chloride only. These impacts have significant implications in the membrane fouling potential and permeate water quality of the pretreated water.     

The pH‐responsive cycloterpolymers of diallyldimethylammonium chloride, 3‐(N,N‐diallylammonio)propanesulfonate,and sulfur dioxide

The cycloterpolymerizations of diallyldimethylammonium chloride, 3‐(N,N‐diallylammonio)propanesulfonate, and sulfur dioxide afforded a series of pH‐responsive cycloterpolymers in excellent yields. The solution properties of these ionic polymers were controlled by the composition of the monomeric units; exhibiting dominance either in polyzwitterionic or cationic character. The unquenched valency of nitrogen in the monomeric units of the sulfobetaine zwitterions has permitted these cationic/zwitterionic polymers to be converted into a series of polyampholytes with a charge asymmetry arising out of excess of either the cationic or anionic centers. The water‐solubility of these polymers, upon low‐ and high‐salt (NaCl) additions has been investigated to provide critical solution concentrations to promote water‐insolubility and ‐solubility. A series of associating polymers of the above two monomers and SO₂ with a hydrophobic incorporation of 3–7 mol % of diallyloctadecylammonium chloride has also been synthesized. The solubility and viscosity of the hydrophobically modified polymers in the polyampholytic form were increased considerably in the presence of anionic surfactant sodium dodecyl sulfate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Composition and properties of complexes between anionic liposomes and diblock copolymers with cationic and poly(ethylene oxide) blocks

A series of cationic diblock copolymers were synthesized via sequential anionic polymerization of 2‐vinylpyridine and ethylene oxide and further quaternization of the resulting diblock copolymers with dimethyl sulfate. Diblock copolymers with a degree of polymerization (DP) of the cationic block equal to 40 and DP of the poly(ethylene oxide) (PEO) block equal to 45, 210 and 450, as well as a cationic homopolymer with DP = 40 (control), were adsorbed on the surface of anionic liposomes of 40–60 nm in diameter. The liposomes were constructed with egg lecithin admixed with 0.1 mole fraction of a doubly anionic lipid, cardiolipin. The liposome–polymer complexes were characterized using electrophoretic mobility measurements, dynamic light scattering, conductivity, fluorescence and UV spectroscopy, and differential scanning calorimetry. Adsorption of the polymers causes the liposomes to aggregate; the only exception is the diblock copolymer with DP of the PEO block of 450, which shows an aggregation‐preventing effect. In all cases, the integrity of liposomes is retained upon their complexation with polymers. The diblock copolymer with a short PEO block induces clustering of anionic lipid in the outer leaflet of the membrane; this effect becomes less pronounced with increasing DP of the PEO block. The differences in behaviour of the diblock copolymers are explained in terms of copolymer cluster formation via hydrogen bonding between neighbouring PEO blocks. These observations are important for interpretation of biological effects produced by cationic polymers and selection of cationic polymers for biomedical applications. © 2017 Society of Chemical Industry     

Settling characteristics of microparticles modified by hydrophilic semi-interpenetrating polymer networks

Microparticles of 2-hydroxyethyl methacrylate cross-linked with ethylene glycol dimethacrylate were produced by suspension polymerization. Semi-interpenetrating polymer networks were prepared by diffusion of poly(ethylene oxide) (PEO) solution into the particles. The PEO was allowed to diffuse into the dried particles and the resulting swollen particles were treated with an excess of acetone to collapse them. The ensuing networks consisted of the collapsed particles and the trapped PEO. The modified particles were allowed to settle in water, and characteristic settling times were measured as a function of swelling time. The settling times were compared to those of the unmodified particles. It was found that the settling time changes with volume fraction, particle size, degree of functionality, and amount of swelling. An increased volume fraction in both unmodified and modified particles causes a slower settling rate. The smaller particle sizes fall more slowly, and size difference plays a more significant role in hindering the settling for lower amounts of trapped PEO. As the amount of PEO increases, the settling rate decreases dramatically. Swelling also slows the settling rate, until the particles reach equilibrium. Equilibrium swelling occurs near 10 min for both unmodified and modified particles. Optical photo-microscopy verified the amount of swelling and demonstrated the process of PEO penetration. © 1995 John Wiley & Sons, Inc.     

低渗油田压裂控水用聚电解质复合溶液性能研究

将阴离子聚丙烯酰胺(HPAM)与阳离子聚合物(DP-1)应用溶液共混法,制备了低渗油田压裂控水用聚电解质复合溶液。研究了阴阳离子聚合物稳定共存的条件,评价了复合溶液的耐温抗盐性能、抗剪切耐冲刷性能以及控水性能。结果表明,在一定量外加盐(KCl)的作用下,阴阳离子聚合物可形成稳定的低粘度聚电解质复合溶液,且具有良好的耐温性和抗盐性;随剪切速率的增加,复合溶液粘度先降低后又有增加;在60℃下岩心流动实验中,盐水驱替100 PV时残余阻力系数为2.66,具有良好的耐冲刷性;水相渗透率降低90.53%,油相渗透率降低14.60%,具有明显的不等比例降低油水相渗透率特征,可用于近水或高含水低渗油层控水压裂改造,降低现场施工风险。     

Poly(ethylene oxide)‐block‐poly[2‐(dimethylamino)ethyl methacrylate] as Strengthening Agent in Paper: Dynamic Mechanical Characterization

To enhance adhesion properties of PEO on wood fibers, block polymers of PEO and 2‐(dimethylamino)ethyl methacrylate were synthesized. The polymers were further modified to obtain strongly cationic species. The resulting polymers were used as additives in paper sheets. Papers were studied by DMA in a controlled‐humidity chamber. Addition of the PEO block co‐polymers enhanced paper strength. The strength of the paper sheets was highest when polymer with molecular weight of 400 kg · mol^?1 was used as an additive. Highly cationic block co‐polymers increased moduli of paper sheets more than their weakly cationic analogs, which indicated strong interaction with fiber surfaces. Strength of the paper sheets decreased both with increased temperature and humidity.

     

Water-soluble polymers as retention aids in a model papermaking system. III. Modified polyacrylamides

The pigment retention efficiency, in a model papermaking system, of anionically and cationically modified polyacrylamides was compared to that of the unmodified homopolymer. The anionic polyacrylamide is a much less efficient retention aid, especially at high pH's; the nonionic and cationic polymers perform similarly and without any marked pH dependence. However, it is the nonionic and anionic polyacrylamides which are similarly poor at fiber flocculation, at pH's between 4.5 and 7.5, whereas the cationic polymer is a good fiber flocculant. All three polymers stabilize pigment suspensions. The anionic polymer is not effective in heteroflocculation of mixed dispersions of fibers and pigment, whereas both the nonionic and cationic are good flocculants, the latter being less susceptible to overdosing. Equilibrium adsorption isotherms were determined; the cationic polymers is, unlike the other modified polyacrylamide, very well adsorbed by cellulose fibers. Onto titanium dioxide, polymers adsorbed in the order anionic < nonionic < cationic. A further differentiation of the cationic polymer is that it gives high pigment retention in sheet formation without markedly increasing the resistance to fluid flow through the forming sheet. Although a process of heteroflocculation is postulated for both nonionic and cationic polymers, in the former case it is thought that the primary adsorption is onto titanium dioxide, whereas with the latter it is onto cellulose.     

Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

Water-soluble polymer flocculants have been used to efficiently release entrapped water in oil sands tailings by bridging fine particles to create large heavier flocs which can then settle faster and release water more efficiently. Due to their initial interaction with the fine particles suspended in tailings, polymer nanofibres may perform better than their parent polymers because of the entire surface of the nanofibres being fully accessible to the fine particles. In this work, commercially available poly(acrylamide-co-diallyl dimethylammonium chloride) was chosen as a basis for this study. Initial settling rate, supernatant turbidity, water recovery, capillary suction time, and solids content were measured to determine the effect of polymer nanofibres on solid-liquid separation. The solid forms of the polymer (either as nanofibre or powder) perform better than the polymer solution in each test, with optimum dosages of 5 wt% mature fine tailings (MFT) loading. Nanofibres could achieve settling rates of 60 m/h, while the other forms were only able to achieve 42 m/h. Additionally, the turbidity of the supernatant obtained after flocculation with nanofibres was 15 nephelometric turbidity units (NTU), while the polymer solution and powder produced turbidites of 162 NTU and 70 NTU, respectively. In addition, polymer nanofibres and powders generated larger flocs compared to the polymer solution, which produced small, homogenized flocs.     

Effect of molecular weight of poly(N‐isopropyl acrylamide) temperature‐sensitive flocculants on dewatering

The influence of molecular weight (MW) and dose of Poly(N‐isopropyl acrylamide) (PNIPAM) (temperature‐sensitive flocculant) on sedimentation rate, sediment density, and supernatant clarity of silica suspensions was investigated. The addition of PNIPAM resulted in rapid sedimentation (T > critical solution temperature, CST) and low sediment moisture (T < CST). Higher MW polymers resulted in more effective flocculation and sediment consolidation. At 10 ppm, PNIPAM (3.6 million Da) produced 20 m/h settling rate and 48 vol % solids sediment density, whereas 0.23 million Da polymer produced 0.1 m/h settling rate. PNIPAM produces effective flocculation and consolidation by cycling the interparticle interactions between repulsion and attraction as temperature is cycled around the CST. The change in temperature produces a hydrophilic/hydrophobic transition of the polymer, influencing adsorption onto the surface and the inter‐particle forces. Conventional polyacrylamide flocculants (not influenced by temperature), cannot be used to produce both rapid sedimentation and dense sediments. © 2009 American Institute of Chemical Engineers AIChE J, 2009