Aqueous Solutions Of Polyacrylamide Research Articles

Study of aqueous polyacrylamide solutions with concentrations

Study of aqueous polyacrylamide solutions with concentrations

Heterogeneous electro-Fenton removal of polyacrylamide in aqueous solution over CoFe2O4 catalyst.

Polyacrylamide (PAM) in environmental water has become a major problem in water pollution management due to its high molecular mass, high viscosity and non-absorption by soil. CoFe2O4 with strong magnetic properties was prepared by solvent-thermal synthesis method and used as the catalyst for the removal on PAM in heterogeneous Electro-Fenton (EF) system. It showed that the removal efficiency of PAM by the heterogeneous EF system using CoFe2O4 catalyst was 92.01% at pH 3 after 120 min. Further studies indicated that ·OH was the most significant active species for the removal of PAM, and the contribution of ·O2- and SO4·- for the removal of PAM was less than 15%. The reusability test and XRD, XPS, FTIR analyses proved that the catalyst had good stability. After a repeated use for five times, the catalyst still had a high PAM removal rate and stable structure. The valence distribution and functional groups of the phase components of the catalyst did not change significantly before and after the reaction. The possible mechanism of catalyst activation of H2O2 was deduced by mechanism investigation. The CoFe2O4 is an efficient and promising catalyst for the removal of PAM wastewater.

Study of technological properties of aqueous solutions of polyacrylamide and fcl-1 with different concentrations

The quality and preparation methods of cotton seeds play a crucial role in increasing crop yield. Seed swelling capacity, germination energy, and laboratory germination are essential characteristics for precision sowing. The excessive fibrous covering on cotton seeds necessitates linting and delinting processes to ensure uniform distribution during sowing. However, existing methods have drawbacks, and none can be considered perfect. The results of a study on the structures, compositions, and physicochemical properties of polyacrylamide and other ingredients are presented. The potential utilization of these substances in the development of composite chemical preparations for cotton seed treatment is demonstrated. Based on the research findings, it is evident that the concentration of PAA significantly affects the viscosity, density, and water retention of the solutions. Choosing the right PAA concentration allows for the targeted regulation of the technological parameters of the solutions.

Numerical Study of the Time-Periodic Electroosmotic Flow of Viscoelastic Fluid through a Short Constriction Microchannel.

Electroosmotic flow (EOF) is of utmost significance due to its numerous practical uses in controlling flow at micro/nanoscales. In the present study, the time-periodic EOF of a viscoelastic fluid is statistically analyzed using a short 10:1 constriction microfluidic channel joining two reservoirs on either side. The flow is modeled using the Oldroyd-B (OB) model and the Poisson-Boltzmann model. The EOF of a highly concentrated polyacrylamide (PAA) aqueous solution is investigated under the combined effects of an alternating current (AC) electric field and a direct current (DC) electric field. Power-law degradation is visible in the energy spectra of the velocity fluctuations over a wide frequency range, pointing to the presence of elastic instabilities in the EOF. The energy-spectra curves of the velocity fluctuations under a DC electric field exhibit peaks primarily beneath 20 Hz, with the greatest peak being observed close to 6 Hz. When under both DC and AC electric fields, the energy spectra of the velocity fluctuations exhibit a peak at the same frequency as the AC electric field, and the highest peak is obtained when the frequency of the AC electric field is near 6 Hz. Additionally, the frequency of the AC electric field affects how quickly the viscoelastic EOF flows. Higher flow rates are obtained at relatively low frequencies compared to under the DC electric field, and the greatest flow rate is found close to 6 Hz. But as the frequency rises further, the flow rate falls. The flow rate falls to a level below the DC electric field when the frequency is sufficiently high.

Polymer gel amended sandy soil with enhanced water storage and extended release capabilities for sustainable desert agriculture

Herein, we report a facile preparation of super-hydrophilic sand by coating the sand particles with cross-linked polyacrylamide (PAM) hydrogels for enhanced water absorption and controlled water release aimed at desert agriculture. To prepare the sample, 4 wt% of aqueous PAM solution is mixed with organic cross-linkers of hydroquinone (HQ) and hexamethylenetetramine (HMT) in a 1:1 weight ratio and aqueous potassium chloride (KCl) solution. A specific amount of the above solution is added to the sand, well mixed, and subsequently cured at 150 °C for 8 h. The prepared super-hydrophilic sands were characterized by Fourier-transform infrared spectroscopy (FT-IR) for chemical composition and X-ray diffraction (XRD) for successful polymer coating onto the sand. The water storage for the samples was studied by absorption kinetics at various temperature conditions, and extended water release was studied by water desorption kinetics. The water swelling ratio for the super-hydrophilic sand has reached a maximum of 900% (9 times its weight) at 80 °C within 1 h. The desorption kinetics of the samples showed that the water can be stored for up to a maximum of 3 days. Therefore, super-hydrophilic sand particles were successfully prepared by coating them with PAM hydrogels, which have great potential to be used in sustainable desert agriculture.

Preparation of CuO loaded cation exchange resin composites and its degradation of polyacrylamide aqueous solution

Macroporous cation exchange resins (CER) were used as carriers, and CuO loaded cation exchange resin composites was successfully prepared under thermostatic oscillation and hydrothermal conditions. The results showed that the as-prepared composites exhibited obvious shell-core structure. The different amounts of NaOH affected the micro morphology of CuO on the surface and in the internal pores of the resin, and also affected the percentage content of Cu element. XRD characterization clearly revealed that the products were monoclinic crystal system CuO species with a grain size of about 16 nm. The highest degradation rate of polyacrylamide (PAM) by CuO@IER-1g reached 81.94%, after 6 cycles CuO@CER-1g has still good photocatalytic activity, and the decrease in degradation rate was the combined effect from the adsorption of ion exchange resins and the electron-hole pairs formed by CuO and a series of free radical transfer reactions under ultraviolet light. This study has important theoretical basis and practical significance for enriching ion exchange theory, developing the photocatalytic industry, and purifying the environment.

Non-Newtonian Flow of Hydrolyzed Polyacrylamide Solution

Structural rheological model is used to describe the rheological behavior of hydrolyzed polyacrylamide aqueous solutions. The change in viscosity during stationary flow is explained by structure change of the polymer solution associated with contacts between macromolecules. Flow curves are well approximated by the generalized flow equation, except for the region of high shear rates, where the phenomenon of shear thickening is observed. The behavior of the rheological equation coefficients with a change in the polymer concentration is consistent with the conclusions of the structural rheological model.

Efficiency of oil separation and demulsification following sonication gel degradation: Influence of Cr(III) ions, NaCl concentrations, and sodium-based retarders

This study investigates the impact of chromium (III) ions, salinity, and retarders on demulsification efficiency and oil separation in oil–water emulsions stabilized by hydrolyzed polyacrylamide (HPAM) aqueous solutions. Two different concentrations of HPAM (1000 and 2000 ppm) and NaCl (0–200,000 ppm), along with two distinct retarders (sodium lactate and sodium malonate), were employed to prepare the emulsion samples. A comprehensive analysis of emulsion stability and demulsification duration was conducted under varying treatment conditions, such as the presence or absence of chromium (III) ions and resin application for chromium removal. Results demonstrate that the presence of chromium (III) ions significantly increases emulsion stability, while their removal leads to a marked reduction in demulsification duration. Notably, the impact of salinity was found to depend on the specific retarder used, with sodium lactate and sodium malonate exhibiting differing demulsification durations. As the HPAM concentration was raised from 1000 to 2000 ppm, the demulsification duration also, regardless of the presence or absence of chromium (III) ions. Additionally, the oil separation rates were higher in samples treated with a resin for chromium removal and are notably influenced by the choice of retarder. In particular, using sodium malonate as a retarder resulted in a significant improvement in the oil separation rate compared to sodium lactate under various salinity conditions. The findings of this study provide valuable insights into the optimization of oil–water separation processes, offering the potential for improved oil recovery and environmental sustainability. This study is particularly novel in its comprehensive investigation of the interplay between different factors (chromium, salinity, and retarders) in oil–water separation processes.

Performance improvement of a pump running as turbine for energy recovery considering the effects of polymer additives: An experimental study

Employing pumps as turbines (PAT) has proven to be a cost-effective and efficient method for producing clean electricity in various engineering applications. PATs are now being considered for use in pumped hydro storage plants (PHS) instead of using a series of separate pumps and turbines and also in oil, petrochemical, and refinery industries as pressure energy recovery. Therefore, it is highly desirable to improve the hydraulic and mechanical characteristics of PATs in such applications. In this study, the effects of polymer additives as drag reducing agents on the performance of a centrifugal pump running as turbine mode is experimentally investigated. Reducing the friction drag within a turbulent flow using additives such as long-chain flexible polymers has attracted considerable attention from an energy-saving perspective. For this purpose, a test rig including the feed pump and the main pump has been set up where aqueous solutions of polyacrylamide with concentrations of 150, 300, and 450 ppm are used as working fluid. In order to compare the turbine mode with the pump mode, the pump performance in direct operation is also evaluated. The findings reveal that compared to tap water, using polymer solutions increases the efficiency and output power of the PAT, which even further improves with increasing polymer concentration. In the turbine mode, the highest increase in efficiency occurred at 450 ppm, which represented an increase of 7.61%. On the other hand, in the pump mode, the maximum improvement in pump efficiency (8.30%) has been recorded when the 150 ppm solution is used instead of tap water. By increasing the flow rate of polymeric solutions, the percentage of increase in the pump’s efficiency, compared to tap water, is ascending. Conversely, the percentage of increase in the PAT’s efficiency declines as the flow rate of polymeric working fluid passing the turbine is increased. The degradation of the utilized polymer in solutions leads to a decrease in output power and efficiency of the PAT compared to its fresh state. Nevertheless, the PAT efficiency and generated power in the degraded condition of the solution are still higher than what can be achieved in presence of tap water as the working fluid. The results of this study generally show that the use of working fluids with viscoelastic properties, which contain additive polymers, significantly improves the performance of reverse and direct pumps. As such, it can be used as an alternative working fluid in the industries mentioned above.

ZIF-8 Assisted Polyacrylamide Functionalized Silica Core-Shell Stationary Phase for Hydrophilic Interaction Liquid Chromatography

A novel ZIF-8 assisted polyacrylamide functionalized silica polar stationary phase was prepared by a facile method of adding ZIF-8 nanoparticles and silica into polyacrylamide (PAM) aqueous solution, and then stirring the mixture until the solution was evaporated absolutely with the help of mechanical agitator. Interestingly, the prepared stationary phase (PAM-Sil@ZIF-8/PAM) showed favorable hydrophilicity, as demonstrated by good separation performance and strong retention ability toward several types of polar compounds, such as amino acids, saccharides, and alkaloids. In addition, PAM-Sil@ZIF-8(50 mg)/PAM showed better separation performance compared with amino-modified silica and Sil/PAM stationary phase due to the addition of ZIF-8. Furthermore, it was demonstrated that the addition of ZIF-8 improved the specific surface area and provided extra interaction sites for the stationary phase and analytes, which is beneficial for the separation of samples. In addition, the column efficiency can reach 7861.9 plates/m for colchicine. Moreover, it exhibited good stability and reproducibility under our operation conditions. In short, a novel stationary phase, which can be used for hydrophilic interaction liquid chromatography, was obtained and proved that the separation performance of polymer modifying silica stationary phase can be greatly improved by the addition of MOF nanoparticles.

Effects of drag-reducing polymers on the flow patterns, pressure gradients, and drag-reducing rates of horizontal oil–water flows

The effects of drag-reducing polymers on the flow patterns, pressure gradients, and drag-reducing rates of oil–water two-phase flows were investigated using a horizontal acrylic pipe with an inner diameter of 25.4 mm and No. 7 white oil with a viscosity of 10.6 mPa∙s and a density of 888.9 kg/m3 at 25 °C. An aqueous solution of polyacrylamide (PAM), with a molecular weight of 19 million Daltons and a concentration of 100 ppm, was used. In the experiment, the oil and water velocities were 0.1-1.5 m/s and 0.1-1.6 m/s, respectively. The DRPs were found to extend the transition boundaries of stratified flow (ST), ST with mixing at the interface (ST&MI), dispersion of oil in water and water (Do/w&w), and oil and dispersion of oil in water (o&Do/w) but did not change the transition boundaries of dispersion of water in oil (Dw/o). The maximum drag reduction rate could be obtained by adding the DRPs to the dispersion of oil in water (Do/w). The drag reduction effect was closely related to the oil and water velocities. An empirical model for the friction factor was established.

Particle image velocimetry for investigating the effect of liquid rheology on flow field of liquid–solid hydrocyclone

ABSTRACT Liquid rheology affects the separation performance of hydrocyclones. Sewage entering a de-foulant hydrocyclone with a reflux ejector (DFHRE) exhibits different rheological properties based on the source. In this study, particle image velocimetry is used to investigate the effect of liquid rheology on the overflow–suck–underflow effect of the DFHRE. Results show that the effects of the rheological properties, liquid concentration, and inlet velocity on the flow field are primarily reflected inside the locus of the zero vertical velocity at the cone section of the DFHRE. In addition, the overflow–suck–underflow effect becomes less prominent as the apparent viscosity increases. An increase in glycerin (Newtonian) concentration increases the total pressure drop, unlike an increase in polyacrylamide aqueous solution (PAM, non-Newtonian). Increasing the inlet velocity can enhance the overflow–suck–underflow effect in PAM owing to the lower drag force. This implies that the DFHRE can achieve an overflow–suck–underflow effect on fluids with a lower drag force and enhance the separation performance.

Application of polymeric drilling fluids for reducing wearing of drill bit

The drill bit or cutting tool is a very important part of the rock drilling operation, it is directly associated with the rate of penetration. Bit wearing has significant involvement of time, labor, and wealth. By identifying the effect of various machine and rock parameters on bit wearing, the optimum working condition can be adopted to achieve high drilling efficiency. In this experimental work, the rate of penetration and parameters of drilling fluids (i.e. type, additives, and concentration, etc.) were optimized to identify their respective impact on the bit wearing of impregnated core diamond bit. The study has been conducted on a laboratory rotary drilling setup. The role of aqueous solutions of carboxymethyl cellulose (CMC), guar gum (GG), and polyacrylamide (PAM) has been examined as polymeric drilling fluid additives on sandstone rock samples and compared with the results of tap water alone as drilling fluid. A significant decrement in bit wearing has been noticed with all additives and the maximum reduction of 70.02% was achieved with CMC fluid additive.

Selection of effective methods of increasing oil recovery in dealed fields based on retrospective analysis

The object of research is methods of increasing oil recovery in «old», depleted oilfields. One of the main tasks of the oil-extracting industry in any country in the world was and still is ensuring the project level of oil production at the maximum possible coefficient of its extraction from the subsoil. In this case it is extremely important to study and use technological methods and means of acquired experience in oilfield development. The paper considers the historical aspects of the development of stabilization and oil recovery methods from 1770s to the present day on the example of Ukrainian oilfields. In parallel with the history of the implementation of methods, their physical and technological content and conditions of application are discussed. Of all the methods used to increase the level of oil production, the most effective ones, which have found application at certain stages of the Ukrainian oilfields’ development, are considered. This is, first of all, a vacuum process, areal flooding, cyclic flooding, gas and water-gas repression, injection of surfactants, surfactant polymer-containing systems, polymer flooding, horizontal branched drilling. The methods development analysis is considered against the background of their geological and industrial acceptability and obtaining technical and economic effects. Based on the results of the study, a group of methods has been identified. These methods are advised to apply in geological and industrial conditions, similar to those described, which should ensure the expected efficiency. Undoubtedly, along with this, it is advisable to use the methods of mathematical modeling of oilfield development processes. Proposals are formulated on the conditions and principles of applying the methods under consideration in order to improve the systems for the development of oilfields. It has been established that the most acceptable methods of increasing oil recovery in depleted oilfields are the injection of surfactant solutions both independently and together with an aqueous solution of polyacrylamide, creation of gas-water repression and polymer flooding, in which preference is given to AN132SH and AN125SH reagents of FLOPAAM S series from SNF FlOERGEL.

Statistical interpretation of LDA measurements in naturally developing turbulent drag-reducing flow using invariant theory

Turbulent drag reduction by an extremely diluted aqueous solution of polyacrylamide was studied in a fully developed plane channel flow under non-tripped flow conditions allowing the natural development of turbulence presumably from the initially laminar like a flow state. Using laser-Doppler anemometry, all components of the Reynolds stress tensor were measured. This permitted the determination of the turbulence anisotropy and independent invariants of the anisotropy tensor. Introducing a measure for the departure of the Reynolds stress tensor from the statistically axisymmetric state that ensures laminarity, fundamental insights relating the origin of turbulence and turbulent drag reduction were analyzed in light of the measured results and existing databases of direct numerical simulations. The chief mechanism relevant to the onset of turbulence and turbulent drag reduction deduced from analytic considerations involving only kinematic constraints was confirmed by the experimental data. Parametrization of the drag reduction effect in terms of the Deborah number based on turbulence quantities evaluated at the wall supports the deduction of the polymer-turbulence interaction in terms of the elastic properties of the polymer and the near-wall turbulence structure.

Experimental study on the flow and heat transfer behavior of polymer solutions in the closed liquid ring vacuum pump system

The closed liquid ring vacuum pump system, which mainly includes the liquid ring vacuum pump and the heat exchanger, is widely used for gas pumping in various industries. In this paper, the energy saving effect in the liquid ring vacuum pump and the flow and heat transfer behavior in the shell-and-tube heat exchanger are investigated for aqueous solutions of rigid xanthan gum (XG) and flexible Polyacrylamide (PAM), and the effects of the concentration, Reynolds number, polymer conformation and flow geometry on the flow behavior of polymer solutions are studied. Results show that, despite the significant differences in molecular conformation and rheological properties between XG and PAM, the similar energy saving rate, about 1.5 ∼ 17.5%, is obtained in the liquid ring vacuum pump. However, in the shell-and-tube heat exchanger, XG solutions exhibit the more obvious pressure drop enhancement and heat transfer reduction than that of PAM solutions for the same concentration. Furthermore, due to the polymer shear degradation, the shaft power in the liquid ring vacuum pump decreases first and then stabilizes, conversely, the flow resistance decreases and the flow rate increases in the heat exchanger. The great difference in the flow condition between the intense rotating gas–liquid two-phase flow field and the gentle liquid pipe flow causes the different flow behavior for XG and PAM solutions.

Sliding Behavior of Silica Ball–Shale Rock Contact Under Polyacrylamide Aqueous Solutions

Abstract The tribological properties of proppant particle sliding on shale rock determine the shale gas production. This work focuses on investigating the impacts of sliding speed on the coefficient of friction (COF) and wear of the silica ball–shale rock contact, which was lubricated by water or different types of polyacrylamide (PAM) aqueous or brine solution. The experimental results show that both boundary and mixed lubrication occur under specific speed and normal load. COF and wear depth of shale rock under water are higher than those under PAM solution due to superior lubrication of PAM. COF of shale rock under PAM brine solution increases and the wear of the rock is more serious, attributed to the corrosion of shale rock and adverse effect on lubrication of PAM by brine.

Experimental investigation of viscoelastic turbulent fluid hammer in helical tubes, considering column-separation

The fluid hammer phenomenon is a devastating incident that can cause substantial damages to the hydraulic systems. If the fluid reaches the vapor pressure due to high pressure gradients, the phenomenon is called column separation. In this study, the overpressures and the column separation induced by the sudden closure of the valve are studied experimentally. To this end, an experimental apparatus consisting of copper and polyethylene tubes is built, and polyacrylamide (PAA) aqueous solution is used as the viscoelastic fluid. Experiments are carried out with water, fresh, and degraded PAA solutions at different concentrations of 100, 200, 300, and 400 ppm. Results indicated that the occurrence of the column separation in the copper tube is considerably impeded by implementing polymer additives. However, the influence is weakened significantly after degradation. On the other hand, this phenomenon in PE tubes is not as significant, because of the viscoelastic behavior of the pipe wall, which eliminates the abnormal pressure peaks, leading to a smoother pattern for the pressure wave. The overpressures are more remarkable in fresh polymer solutions at higher concentrations, and decreasing the concentration, as well as the degradation, mitigates them. Furthermore, the pressure wave rate of attenuation in the copper tube became 9.82% less substantial when the Deborah number increased from 6.59 to 9.21 (roughly 40%). Besides, this attenuation was 35.71, 62.00, 37.00, and 21.78% more severe in the degraded 100, 200, 300, and 400 ppm solutions than the corresponding fresh solutions, respectively. The pressure-time history in PE tubes with viscoelastic fluids followed a different trend. Also, the viscoelasticity has resulted in a decrease in acoustic wave speed as the wave speed in the 400 ppm solution is roughly 15.04% lower than water.

Dripping and jetting of semi-dilute polymer solutions co-flowing in co-axial capillaries

This work is focused on the mechanisms of the dripping and jetting flow modes of viscoelastic semi-dilute polyacrylamide aqueous solutions co-flowing with silicone oil in co-axial capillaries. A phase diagram of the dripping, jetting, and intermediate flow modes is established. It was found that in the dripping mode, the elongation velocity of the filament between the terminal droplet and the inner capillary is controlled solely by the continuous phase rate. At the same time, the decrease in the filament diameter is due to both stretching and outflow of the polymer solution into the terminal droplet. In the jetting mode, the thread diameter was found to evolve in three stages. In the first stage, the average jet velocity increases, whereas in the second and third stages, it becomes constant and corresponds to the velocity of the continuous phase. The transition from the second to the third stage is defined by the appearance of capillary waves resulting in the formation of the beads-on-string structure. In the third stage, the filament diameter between the neighbor beads decreases exponentially and is governed by the relaxation time, which strongly depends on polymer concentration, but does not depend on the continuous phase flow rate. A simple physical model was proposed for describing the evolution of dimensions of filaments and beads during development of jet capillary instability. The universal character of the evolution of filaments and beads sizes, which is independent of concentration of semi-diluted polymer solutions and flow rates of the continuous phase, is revealed.

Particle coating with composite shell in a pan granulator

In this study, the coating of urea granules with a composite shell was performed in a laboratory-scale pan granulator. The composite shell of coated particles consisted of a filler and a binder. Aqueous solutions of sodium silicate, methylcellulose, and polyacrylamide were used as the binders. Powdery calcium carbonate was used as the filler. The influence of the pan rotation speed, the pan-tilt angle, and the binder type on coating performance and the product properties was investigated. The pan rotation speed varied in the range from 30–70 rpm and the pan-tilt was changed from 30° to 75°. The relative shell mass, crushing strength, moisture content of the coated particles, and particle size distribution (PSD) were determined. A mathematical model was developed based on the population balance equation with the main purpose of predicting PSD. Particles’ weight gain was assumed to be proportional to the ratio of the surface area of the given size particles and the surface area of all particles in the coater. A comparison of calculated and experimental cumulative distributions of particle size was performed. Good agreement was observed between the modeling and the measurements.