Water-soluble Polyelectrolyte Research Articles

The Seed Germination Test as a Valuable Tool for the Short-Term Phytotoxicity Screening of Water-Soluble Polyamidoamines

Six differently charged amphoteric polyamidoamines, synthesized by the polyaddition of N,N′-methylenebisacrylamide to alanine, leucine, serine, arginine (M-ARG), glutamic acid (M-GLU) and a glycine/cystine mixture, were screened for their short-term phytotoxicity using a seed germination test. Lepidium sativum L. seeds were incubated in polyamidoamine water solutions with concentrations ranging from 0.156 to 2.5 mg mL−1 at 25 ± 1 °C for 120 h. The seed germination percentage (SG%), an indicator of acute toxicity, and both root and shoot elongation, related to plant maturation, were the considered endpoints. The germination index (GI) was calculated as the product of relative seed germination times relative radical growth. The SG% values were in all cases comparable to those obtained in water, indicating no detectable acute phytotoxicity of the polyamidoamines. In the short term, the predominantly positively charged M-ARG proved to be phytotoxic at all concentrations (GI < 0.8), whereas the predominantly negatively charged M-GLU proved to be biostimulating at intermediate concentrations (GI > 1) and slightly inhibitory at 2.5 mg mL−1 (0.8 < GI < 1). Overall, polyamidoamine phytotoxicity could be correlated to charge distribution, demonstrating the potential of the test for predicting and interpreting the eco-toxicological behavior of water-soluble polyelectrolytes.

Three-Dimensional Cross-Linking Network Coating for the Flame Retardant of Bio-Based Polyamide 56 Fabric by Weak Bonds.

Weak bonds usually make macromolecules stronger; therefore, they are often used to enhance the mechanical strength of polymers. Not enough studies have been reported on the use of weak bonds in flame retardants. A water-soluble polyelectrolyte complex composed of polyethyleneimine (PEI), sodium tripolyphosphate (STPP) and melamine (MEL) was designed and utilized to treat bio-based polyamide 56 (PA56) by a simple three-step process. It was found that weak bonds cross-linked the three compounds to a 3D network structure with MEL on the surface of the coating under mild conditions. The thermal stability and flame retardancy of PA56 fabrics were improved by the controlled coating without losing their mechanical properties. After washing 50 times, PA56 still kept good flame retardancy. The cross-linking network structure of the flame retardant enhanced both the thermal stability and durability of the fabric. STPP acted as a catalyst for the breakage of the PA56 molecular chain, PEI facilitated the char formation and MEL released non-combustible gases. The synergistic effect of all compounds was exploited by using weak bonds. This simple method of developing structures with 3D cross-linking using weak bonds provides a new strategy for the preparation of low-cost and environmentally friendly flame retardants.

СУДА ЕРИТІН ПОЛИМЕРЛЕР МЕН ОЛАРДЫҢ ПОЛИКОМПЛЕКСТЕРІНІҢ СУЛЫ ЕРІТІНДІДЕГІ ҚАСИЕТТЕРІ

Abstract. The interaction of oppositely charged polyelectrolytes (sodium salt of carboxymethylcellulose (NaCMC), methylcellulose (MC), polyethylenimine (PEI) and polydimethyldiallylammonium chloride (PDMDAAС), and unifloc (UF)) in an aqueous environment was studied using the methods of viscometry, spectrophotometry and macroelectrophoresis. It has been established that the interaction of these polyelectrolytes is accompanied by a significant decrease in reduced viscosity (up to 0.1-0.15 dl/g, which is typical for compacted macromolecules of globular proteins), an increase in optical density and an inversion of the sign of the electrokinetic potential. All this indicates the formation of interpolymer complexes from interacting cationic and anionic polyelectrolytes. Experimental results of studying the properties of water soluble polymers and their polyelectrolyte complexes in aqueous solutions at the water/air interface are described and discussed. It has been shown that complex formation in relatively simple systems is accompanied by changes in the pH of the medium, optical, hydrodynamic, electrochemical and other properties of macromolecules. In the systems we studied, the interaction of the system components is not accompanied by variations in the pH of the medium, therefore, information about the interaction of water-soluble polyelectrolytes in the systems we studied was obtained based on viscometric and spectrophotometric titration data, as well as from changes in the electrokinetic potential of macromolecules. The study of the electrokinetic potential showed that the formation of interpolymer complexes in the systems under consideration is accompanied by significant changes in the electrokinetic potential of macromolecules. A study of the properties of mixtures of aqueous solutions of Na-CMC, MC, UF with polydimethyldiallylammonium chloride and polyethylenimine indicates the formation of interpolyelectrolyte complexes that have a more compact structure than the original macromolecules. Key words: polyelectrolytes; flocculation; cross-linking; stability; interpolymer complexes; optical density; polymer.

Ultra-High-Molecular-Weight, Narrow-Polydispersity Polyacrylamides Synthesized Using Photoiniferter Polymerization to Generate High-Performance Flocculants.

Ultra-high-molecular-weight, water-soluble polyelectrolytes are commonly employed as flocculants for solid-liquid separation via colloidal destabilization, enabling the rapid and efficient removal of particulate matter from wastewater streams. A drive toward more sustainable and less polluting industrial practices, coupled with the desire to reduce freshwater usage and improve closed-loop systems, demands the development of flocculants with ever-higher dewatering dose performance. Herein, the use of trithiocarbonate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization under either blue LED (λmax = 470 nm) or UV (λmax = 365 nm) irradiation, known as photoiniferter polymerization, was successfully utilized to generate ultra-high-molecular-weight (Mn > 1,000,000 g mol-1) polyelectrolyte copolymer flocculants with narrow molecular weight distributions (Mw/Mn < 1.2). Cationic and anionic polyelectrolyte flocculants were synthesized containing various monomer compositions of acrylamide (AM), dimethylacrylamide (DMA), 3-(acryloyloxyethyll)trimethylammonium chloride (DMAEAq), 3-(acrylamidopropyl)trimethylammonium chloride (APTAC), sodium acrylate (NaAA), and sodium 2-(acrylamido)-2-methylpropylsulfonate (NaATBS) with high monomer conversion using simple experimental apparatus. The narrow molecular weight distribution cationic polyelectrolytes showed improved flocculation efficiency in the clarification of kaolin suspensions of up to 50% in comparison to a broad polydispersity (Mw/Mn > 5.0) commercial benchmark with an equivalent number average molecular weight. The improved performance of the narrow-polydispersity copolymers is attributed to the reduction in the content of the lower-molecular-weight polymer chains, which impart lower flocculation performance.

Structure and Physico-Mechanical Properties of Polyelectrolyte Complexes Based on Sodium Carboxymethylcellulose Polysaccharide and Polyacrylamide

In this paper, the structure and physico-mechanical properties of films of polyelectrolyte complexes (PEC) based on sodium carboxymethylcellulose (Na-CMC) with linear polyacrylamide (PAA) have been studied. Polyelectrolyte complexes were obtained by mixing aqueous solutions of Na-CMC and PAA components in various ratios of components and pH of the medium. The structure of the obtained products was determined using IR spectroscopy and electron microscopy. IR spectra in the range 400–4000 cm-1 were recorded on NIKOLET Magna-560 IR and Specord-75IR spectrophotometers (Carl Zeiss, GDR). The mechanical properties of films of polyelectrolyte complexes were determined by stretching at a constant speed of movement of the lower clamp, 50 mm/min, on an Instron-1100 automatic dynamometer (England) at room temperature. IR spectroscopic data showed that polyelectrolyte complexes based on Na-CMC and PAA were stabilized due to the cooperative ionic bond between Na-CMC carboxylate anions (-COO-) and amine groups (-NH2) of polyacrylamide. It is shown that PEC films with an equimolar ratio of Na-CMC and PAA components have an increased value of mechanical strength (σр = 38 MPa), elastic modulus (Е = 73 MPa) and a minimum relative elongation (ε = 0.5%). And in excess of Na-CMC or PAA leads to a decrease in mechanical strength and elastic modulus, which is associated with a decrease in the frequency of intermolecular bonds. It has been ascertained that water-soluble polyelectrolyte complexes based on Na-CMC and PAA with increased strength properties can be obtained from solutions of components taken at an equimolar ratio of interacting components. By changing the ratio of components, properties such as mechanical strength, modulus of elasticity and elongation can be controlled. This can serve as one of the means of controlling the structure and properties of Na-CMC and PAA polyelectrolyte complexes. The regulation of the physico-mechanical properties of PEC films opens up wide opportunities for their use as a soil structure former in agriculture and water management and as the basis for soft drugs in pharmacy.

INVESTIGATION OF MODIFIED POLYACRYLAMIDE FOR OIL DISPLACEMENT

At present, the use of surfactants and water-soluble polyelectrolytes, which act as stabilizing and selective agents, is inextricably linked with the successful solution of the technological issues in the world of chemical, oil and other industries. The purpose of the work is to synthesize and study the physicochemical properties of modified polyacrylamide with gossypol resin and further crosslinking in the presence of potassium persulfate and sodium sulphate to displace oil. Methods. To establish the spectral characteristics of the modified PAA, IR spectra have been taken on an IR-Fourier spectrometer. For the structural-elemental composition (SEM), a Jeol JSM-6490l V electron microscope has been used. The viscosity of modified PAA solutions has been measured in a Ubellode capillary viscometer with a hanging level. Results and discussion. The studies, carried out by the authors of the study of the colloid-chemical properties of polymer composites, allow us to conclude that the reagents obtained during the hydrolysis of vat residues of fatty acids distillation with sodium hydroxide with further cross-linking in the presence of potassium persulfate and sodium sulphate have good surfaceactive and emulsifying properties, which is important when displacing oil from layers. The surface tension of polymer compositions has been studied. With an increase in the concentration of the solution, the surface tension decreases, i.e., the surface activity increases. Conclusion. The research results show that the injection of a polymer reagent solution can increase the oil displacement efficiency by 6-7%.

Impact of polyelectrolyte adsorption on the rheology of concentrated poly(N-isopropylacrylamide) microgel suspensions.

We explore the impact of three water-soluble polyelectrolytes (PEs) on the flow of concentrated suspensions of poly(N-isopropylacrylamide) (PNIPAm) microgels with thermoresponsive anionic charge density. By progressively adding the PEs to a jammed suspension of swollen microgels, we show that the rheology of the mixtures is remarkably influenced by the sign of the PE charge, PE concentration and hydrophobicity only when the temperature is increased above the microgel volume phase transition temperature Tc, namely when microgels collapse, they are partially hydrophobic and form a volume-spanning colloidal gel. We find that the original gel is strengthened close to the isoelectric point, attained when microgels are mixed with cationic PEs, while PE hydrophobicity rules the gel strengthening at very high PE concentrations. Surprisingly, we find that polyelectrolyte adsorption or partial embedding of PE chains inside the microgel periphery occurs also when anionic polymers of polystyrene sulfonate with a high degree of sulfonation are added. This gives rise to colloidal stabilization and to the melting of the original gel network above Tc. Contrastingly, the presence of polyelectrolytes in suspensions of swollen, jammed microgels results in a weak softening of the original repulsive glass, even when an apparent isoelectric condition is met. Our study puts forward the crucial role of electrostatics in thermosensitive microgels, unveiling an exciting new way to tailor the flow of these soft colloids and highlighting a largely unexplored path to engineer soft colloidal mixtures.

Strain-Induced Self-Rolling of Electrochemically Deposited Co(OH)2 Films into Organic–Inorganic Microscrolls

Strain-induced self-folding is a ubiquitous phenomenon in biology, but is rarely seen in brittle geological or synthetic inorganic materials. We here apply this concept for the preparation of three-dimensional free-standing microscrolls of cobalt hydroxide. Electrodeposition in the presence of structure-directing water-soluble polyelectrolytes interfering with solid precipitation is used to generate thin polymer/inorganic hybrid films, which undergo self-rolling upon drying. Mechanistically, we propose that heterogeneities with respect to the nanostructural motifs along the surface normal direction lead to substantial internal strain. A non-uniform response to the release of water then results in a bending motion of the two-dimensional Co(OH)2 layer accompanied by dewetting from the substrate. Pseudomorphic conversion into Co3O4 affords the possibility to generate hierarchically structured solids with inherent catalytic activity. Hence, we present an electrochemically controllable precipitation system, in which the biological concepts of organic matrix-directed mineralization and strain-induced self-rolling are combined and translated into a functional material.

Study on Hydrolysis Properties and Mechanism of Poly(3-Methacrylamido Propyl Trimethyl Ammonium Chloride) Solution.

Poly(3-methacrylamido propyl trimethyl ammonium chloride) (PMAPTAC) is a typical cationic water-soluble polyelectrolyte, which has been widely used in petroleum, papermaking, daily cosmetics and other fields in the form of an aqueous solution. However, the acid–base and thermal stability of PMAPTAC in aqueous solution have not been reported yet, which hinders its further application in high-temperature and acid–base environments. To address these deficiencies, the effects of temperature and pH of PMAPTAC with different intrinsic viscosities on its hydrolysis stability were investigated qualitatively and quantitatively, and the hydrolysis mechanism was studied. Firstly, the qualitative analysis showed that the apparent viscosity of the PMAPTAC solution decreased with hydrolysis time at different temperatures and pH. The higher the temperature and the lower the pH, the greater the viscosity loss of PMAPTAC. The quantitative analysis showed that the hydrolysis rate of the PMAPTAC sample solution increased with the increase in temperature and pH. In addition, the intrinsic viscosity of PMAPTAC samples had little effect on the hydrolytic stability of PMAPTAC. Secondly, by analyzing the viscosity curves at different pH and temperatures by Arrhenius analysis, the Arrhenius equations were found to be 1/τ = 200.34e^((−25.04)/RT), 1/τ = 9127.07e^((−38.90)/RT) and 1/τ = 4683.03e^((−39.89)/RT) for pH 3, pH 7 and pH 11, respectively. Thirdly, the hydrolysis rate of PDMC was the fastest under alkaline conditions. In addition, compared with PDMC, PMAPTAC had better hydrolysis stability under the same conditions. Finally, the mechanism of the hydrolyzed polymer was studied by FTIR and 13CNMR, which showed that the carbonyl group of PMAPTAC was hydrolyzed into a carboxyl group, and the small molecule (3-aminopropyl) trimethylammonium chloride was generated, while the ester group of PDMC was hydrolyzed into a carboxyl group, and choline chloride was released. The above results can provide a theoretical basis for the application of PMAPTAC in some high-temperature and acid–base environments.

Water-soluble polycarbodiimides and their cytotoxic and antifungal properties

We have successfully synthesized water-soluble neutral and polyelectrolyte helical polycarbodiimides and studied their biological properties. These polymers were prepared by decorating carbodiimide backbones with nonionic, hydrophilic functional groups such as dimethylamine, piperazine, and morpholine. Additionally, the 3° amines present in these functional groups were quaternized using methyl iodide as the alkylating agent to produce their ionic analogs. Polycarbodiimides were chosen as the base polymer used because of their facile chemical modification, pH tolerance in terms of both their helical conformations and degradation behaviors, and tunable helical inversion barriers. Hydrophilic side groups, such as morpholine, dimethylamine, and piperazine, can be used to balance the amphiphilic architecture of the polycarbodiimides along with lipophilic groups, such as alkyl side chains. A chiral R or S BINOL Ti(IV) isopropoxide catalyst was used to control the handedness of the polycarbodiimide helices in these studies. These ionic and neutral polycarbodiimides were subsequently studied for potential antimicrobial and cytotoxic properties. Poly[N-methyl-N’-2-morpholinoethylcarbodiimide], as an example, exhibited significant antifungal properties against Candida albicans. Also, Poly[N-methyl-N’-2-morpholinoethylcarbodiimide] showed significant inhibition of biofilm formation. This suggests that the polymer is a promising candidate for antifungal biomedical applications. Measuring cytotoxicity against urinary bladder cancer cells, poly[N-[3-(dimethylamino)propyl)]-N’-[3-(morpholino)propyl]carbodiimide] (S-cat) and poly[N-[3-(dimethylamino)propyl)]-N’-[3-(morpholino)propyl]carbodiimide]-MeI (S-cat) showed significantly low IC50 values. The IC50 values of poly[N-[3-(dimethylamino)propyl)]-N’-[3-(morpholino)propyl]carbodiimide] (S-cat) and Poly[N-[3-(dimethylamino)propyl)]-N’-[3-(morpholino)propyl]carbodiimide]-MeI (S-cat) are 3.50 μM and 1.27 μM, respectively. The significantly low cancer cell growth inhibition concentration implies the highest cytotoxicity of the polymers, suggesting potential applications as cancer therapeutics. These results also showed that the functionalization and chirality of polycarbodiimides modulate their anticancer and antifungal activity.

Reactive Fibrous Materials for Decontamination of Chemical and Biological Threats

Polyamines are water-soluble polyelectrolytes with the amino groups that can be used to attach the polymers onto functional surfaces of fibrous materials. In addition, polyamines can be readily modified by (super) nucleophilic groups such as (alkyl) aminopyridines that enhance the polymer’s ability to promote hydrolysis of organophosphorous chemical warfare agents. Furthermore, attachment of hydantoin moieties augments the number of the imide, amide, or amine groups on the polyamine’s chain, which provides oxidizing properties to the resulting modified polyamine after halogenation. We report on polyamines with side chains modified to contain both (4-aminopyridine, APy) and 5-(4-hydroxybenzylidene) hydantoin (HBH) functionalities with enhanced content of the active bromine. Virucidal activity of the APy-and HBH-modified polyallylamine against human coronavirus (type 229E) was tested both in solution and on nylon-cotton fabric. The polymers appeared to be effective in inactivation of the coronavirus, at both low concentrations and short exposure times.

Valorisation of invasive plant species in the production of polyelectrolytes

The purpose of this work was the valorization of wood/wastes of two invasive tree species, namely Acacia dealbata and Ailanthus altissima, in the production of polyelectrolytes as high value-added products for a range of applications. Kraft cooking of wood chips followed by the introduction of quaternary ammonium groups into the cellulose backbone using a typical sodium periodate oxidation/Girard’s reagent T cationization was performed. Water-soluble polyelectrolytes were obtained with a cationic group content of 3.0–3.6 mmol/g which were characterized, and, as a proof of concept, evaluated as flocculants in the treatment of an industrial effluent from olive oil mill, a harsh and difficult to treat effluent. Under optimized conditions of pH (4.5–7) and flocculant dosage (50−100 mg/L), an effluent turbidity removal of up to 65 % was achieved. The proposed approach enabled to obtain, for the first-time, valuable polyelectrolytes from very low value woods, with potential interest for application as flocculants in effluent treatment. Additionally, the experiments also proved that there is no need to completely remove lignin from wood before cationization, mild deconstruction procedures allowing to produce water-soluble polyelectrolytes and achieve a good performance in the flocculation process.

Lignin-containing adhesion enhancer for wood-plastic composites

A lignin-containing adhesion enhancer, a water-soluble polyelectrolyte complex (LPEC) composed of soda hardwood lignin (HASL) and polyethylenimine (PEI), and the effect of the treatment of hydrolyzed and ammoxidized aspen sawdust with the LPEC nanoparticles were studied relative to the properties of wood-plastic composites (WPCs) based on recycled polypropylene (rPP). The presence of the excess of free amine groups and salt bonds between PEI and soda lignin, forming hydrophobic sites in the LPEC structure, caused the enhanced surface activity of the LPEC. The treatment with the LPEC nanoparticles increased the content of the fixed nitrogen in the modified sawdust samples and was accompanied by decreasing their water sorption and increasing contact angles that favored the decrease in the polar part of their surface free energy. The decreasing wetting ability enhanced the mechanical and water sorption properties of the obtained WPC samples. The improvement of the interfacial adhesion between the nitrogen-containing groups of the treated sawdust and the oxygen-containing groups of rPP was explained by the formation of both covalent and physicochemical bonds.

Associative Phase Separation of Aqueous π-Conjugated Polyelectrolytes Couples Photophysical and Mechanical Properties

The associative phase separation of water-soluble polyelectrolytes is important across many different fields including food science, biomedicine, materials science, and prebiotic organization. Spec...

Effect of Low-Molecular-Weight Alcohols on Emulsion Stabilization with Lignosulfonates.

Lignosulfonates are biobased surfactants and specialty chemicals, which are described as water-soluble polyelectrolyte macromolecules that are generated during the sulfite pulping of lignocellulose biomass. Due to their amphiphilic nature, lignosulfonates have made their way into various applications, such as plasticizers, dispersants, and suspension or emulsion stabilizer. The stabilization efficiency for oil-in-water emulsions is affected, among other aspects, by the presence of alcohols. Low-molecular-weight alcohols can improve the performance of lignosulfonates; however, the effects of such additive have not yet been fully explored. In this article, we hence studied emulsion stability in dependence of alcohol concentration and other parameters, such as salinity. One or two regions of improved stability were found, which occurred at approximately 0.001–0.01 M alcohol in water, and in some cases additionally at 1–3 M. The four lignosulfonate samples responded distinctly to the alcohol additives. Little difference was found for varying lignosulfonate concentration or the alcohol type, that is, methanol, ethanol, or 2-propanol. Adding ethanol at high salinity (720 mM NaCl) showed a destabilizing effect. A decrease in interfacial tension was noted when adding 1 M ethanol or more, but the surface pressure of lignosulfonates decreased progressively at 0.3 M ethanol and above. These effects are counteracting, which could explain why increasing alcohol concentration would either enhance or impair stability. Overall, emulsion stability was affected by concentration effects and not cosurfactant action of the alcohols. Composition changes can influence the dielectric properties of the bulk solvent, further affecting the anionic functional groups, which was evidenced by alcohol addition affecting the lignosulfonates with lower hydrophobicity more strongly and by ethanol exhibiting the destabilizing effect at high salinity. In conclusion, adding low-molecular-weight alcohols may hence influence the behavior of lignosulfonates and render them more accessible for interactions with hydrophobic interfaces.

Formation and stabilization of CO2 bubbles with different sizes and the interaction with solid particles

Various applications of CO2 have received extensive attention, especially those realizing the reuse of the greenhouse gas and meeting the application requirements simultaneously, of which the CO2 enhanced oil recovery (EOR) and enhanced gas recovery (EGR) approaches is a paradigm. In recent years, the applications of CO2 foam as flooding or fracturing system are both of the research hotspots. Since conventional surfactants are generally poor in stabilizing CO2 foam, the exploration of CO2 foam stabilizer is of great significance, while it is also a difficult problem. In this work, a kind of hydrophobically modified water-soluble polyelectrolyte (HMPE) was used in the stabilization of CO2 foam containing millimeter-sized and micron-sized bubbles, which both exhibit high stability and perfect foam viscoelasticity, due to the enhancement of the mechanical strength of the foam films through HMPE absorbed at the gas/liquid interfaces. The interaction between the CO2 bubbles and ceramiste particles was investigated, the mechanism of the excellent sand-carrying performance of the CO2 foam system was discussed. Based on the comprehensive understanding of all aspects of the properties, the HMPE-CO2 foam system has bright potential being used in the CO2-foam fracturing.

Adsorption of cefotaxim sodium on activated carbons of various origin

The adsorption of the cephalosporin antibiotic sodium cefotaxime (CEFOT) on two activated carbons in the temperature range 288–313 K was under study. Experimental charcoal AC obtained from hydrolysis lignin was established to be mesoporous. It demonstrates greater CEFOT adsorption activity than the commercially available charcoal OU-A made from wood and characterized by both micro- and mesoporous structure. The surface modification of both activated carbons by a water-soluble polyelectrolyte cellulose acetate sulfate in the form of sodium salt (Na-CAS) leads to an increase in specific adsorption. The multilayer model with saturation (MMS) was used for data analysis. As a result, the number of molecules on the adsorption center, the density of adsorption centers, the total number of formed layers and the energy characteristics of adsorbate – adsorbent interactions at the interface and adsorbate – adsorbate ones within the adsorption layer were estimated.

Designing Microparticle-Impregnated Polyelectrolyte Composite: The Combination of ATRP, Fast Azidation, and Click Reaction Using a Single-Catalyst, Single-Pot Strategy.

Polystyrene microparticles were covalently impregnated into the networks of functional polyelectrolyte chains designed via a tandem run of three reactions: (i) synthesis of water-soluble polyelectrolyte, (ii) fast azidation and (iii) a ‘click’ reaction, using the single-catalyst, single-pot strategy at room temperature in mild aqueous media. The model polyelectrolyte sodium polystyrenesulfonate (NaPSS) was synthesized via the well-controlled atom transfer radical polymerization (ATRP) whose halogen living-end was transformed to azide and subsequently coupled with an alkyne carboxylic acid through a ‘click’ reaction using the same ATRP catalyst, throughout. Halogen to azide transformation was fast and followed the radical pathway, which was explained through a plausible mechanism. Finally, the success of microparticle impregnation into the NaPSS network was evaluated through Kaiser assay and imaging. This versatile synthetic procedure, having a reduced number of discrete reaction steps and eliminated intermediate work-ups, has established a fast and simple pathway to design functional polymers required to fabricate stable polymer-particle composites where the particles are impregnated covalently and controllably.

OPTIMIZATION OF THE REAGENT METHOD OF CLEANING OF COPPER (II) -STATER WATER

Sewage water of electrochemical manufactures that exist at almost every machine and instrument making enterprise are the main source of the heavy metals that flow into the reservoir. The greatest interest is the purification of sewage from ions of copper (II).From the variety of available methods for purifying water from heavy metal ions, the most potentially suitable are traditional reagent methods as they are versatile, easy to operate and cheap. But they do not always provide theadmissible concentrations. All this necessitates the development and implementation of new modern technologies that allow ensuring high efficiency of the processes of purification from heavy metal ions. This also gives possibility of creating integrated technologies with a closed cycle of water consumption on their basis.Recently, the interest in derivatives of iron-synthetic acid has increased considerably; ferrocyanides acquire a rapidly growing practical value. It is known that ferrocyanides of heavy metals have very low solubility, therefore it was suggested to use potassium ferocyanide as a precipitant in order to remove copper ions from the researched solutions.Since the copper (II) ferrocyanides can form stable colloidal systems, settling solutions will be a long-term and technologically not always justifiable solution, because of its inappropriate usage as an independent method of purification. Typically, this method is combined with the filtering method.In this work, the effectiveness of the flocculantZetag 7547 was investigated.The purpose of this work is to study the features of sewage purification from copper ions (II) applying precipitation method using potassium ferrocyanide and water soluble polyelectrolyte Zetag 7547.To achieve this goal, the following tasks need to be solved: increase the depth of the deposition reaction; intensify the processes of aggregation and sedimentation of particles of the dispersed phase.To reach the optimal conditions for reagent treatment of wastewater, preliminary studies of the pH solution influence on the solubility of the formed copper (II) ferrocyanates have been made. Studies have shown that optimal pH values of precipitation of Cu (II) are within the range of 6.5 to 7.5.In order to intensify the reagent water purification, it was suggested to make its processed flocculation. When used in low concentrations, Zetag-7547 flocculant decreases potassium ferrocyanide significantly from aqueous solutions. From obtained results list of ratios of concentrations of potassium ferrocyanide and flocculant, which should be used to purify water from ions copper (II) were selected. After settling in the solution, a part of coarse dispersed impuritiesremain. They were removed by filtration, which increased the degree of purification up to 99%.Thus, in current research the processes of formation of copper (II) ferrocyanides complexes depending on the pH environment are analyzed, the conditions of reagent treatment of water using Zetag 7547 flocculantare set. The most effective methods of controlling the process of flocculation are shown. The amount of solid waste is reduced.

Complexation and precipitation of scale-forming cations in oilfield produced water with polyelectrolytes

Divalent cations such as Ba2+, Sr2+, Ca2+, and Mg2+, commonly found in oil/gas produced water at high concentrations, adversely affect oil and gas production by forming scales in pipes, tanks, process equipment such as oil-water separators, and treatment equipment such as filters and reverse osmosis membranes. If the water is reinjected, e.g., for water flooding, scales may also form on the well screens and in the producing formation. Water soluble polyelectrolytes have been used to inhibit scale formation in oil and gas production and to eliminate cationic metals from water via membrane separation. However, the underlying interactions between scale-forming cations and various polyelectrolytes are not well understood. To this end, two commercially available anionic polyelectrolytes with different repeating functional groups, poly(acrylic acid) (PAA) and poly(sodium 4-styrenesulfonate) (PSS), were used to evaluate complexation and precipitation of Ba2+, Sr2+, Ca2+, and Mg2+ in binary systems, multi-ion mixtures, and produced water. The apparent dissociation constant (pKa) of PAA was determined by titration to be 6.7, indicating a high affinity of PAA for H+. The strength of the complexes formed between PAA and scale-forming cations (binding strength) decreased in the order Ba2+ > Ca2+ > Sr2+ > Mg2+ at pH 5. Higher pH values led to a higher affinity of PAA for divalent cations, which is attributable to the increase in binding sites for cations as the PAA more completely ionizes. By contrast, the affinity of PSS decreases in the order Ba2+ > Sr2+ > Ca2+ > Mg2+, with no significant pH effect. The formation and precipitation behavior of polyelectrolyte complexes (PECs) was investigated by reacting cations with the sodium salt of PAA (sodium polyacrylate) or with PSS. Only Ba2+ formed precipitates with PSS in single-cation solutions, although small amounts of Sr2+ were also removed by PSS from a mixed cation solution. However, all of the scale-forming cations formed PEC precipitates with PAA in both binary and mixed-ion solutions, depending on the cation concentration and molar ratio of PAA to divalent cations. The maximum amount of precipitation occurred at a molar ratio of PAA to M2+ of 1.5–1.7, while overdosing of PAA caused dispersion of the precipitates. High concentrations of monovalent cations inhibited precipitation of divalent cations with PAA. Up to 73% of scale-forming cations were removed from field-collected produced water samples through repeated (4 times) addition of PAA at a molar concentration ratio of 1. The release of scale-forming cations from PAA-M2+ precipitates, thereby regenerating PAA, was achieved by adding HCl.