Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties, including the density, viscosity, and refractive index of aqueous solutions of sodium glycinate as a solvent for CO2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K. The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol·L?1. The coefficients of thermal expansion values were estimated from measured density data. It was found that, the densities, viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature, whereas with increasing sodium glycinate concentration in the solution, all three properties increase. Thermal expansion coefficients slightly increase with rising temperature and concentration. The measured values of density, viscosity and refractive index were correlated as a function of temperature by using the least squares method. The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.     

Micellization, Interaction and Microenvironment in the Mixed Solution of Pluronics and Surfynol 104 with Nuclear Magnetic Resonance

The micellization, intermolecular interaction and microenvironment of molecular segments in the mixed aqueous solution of PEO-PPO-PEO triblock copolymer (Pluronic? F88, P84 and P123) and Surfynol? 104 (S104) were studied by nuclear magnetic resonance method. The results showed that the addition of S104 decreased the critical micellization temperature of copolymer. When its concentration was 0.5 g/L, the most reduction was up to more than 10℃ for F88, which was most hydrophilic in the selected copolymers. This reduction was caused by the hydrophobic interaction between S104 molecules and PPO segments. The addition of S104 enhanced the hydration of PEO segments most obviously for P123. And S104 slightly increased the hydration of PPO segments before the micellization, but obviously decreased their hydration after micellization, which was attributed to the hydrophobic interaction mentioned above and temperature rising. This effect was most observable for F88.     

Thermosensitive Poly(N-isopropylacrylamide-co-acrylonitrile) Hydrogels with Rapid Response

Acrylonitrile （AN） was copolymerized with N-isopropylacrylamide （NIPA） to synthesize thermosensitive hydrogels, and the on-off switch behavior of poly（NIPA-co-AN） hydrogels with different fraction of hydrophobic component （AN） was investigated. It is found that the lower critical solution temperature （LCST）, the swelling ratio at certain temperature and the reswelling rate of poly（NIPA-co-AN） hydrogels decreased as AN unit fraction in copolymers increased. In order to improve the responsive rate of poly（NIPA-co-AN） hydrogels, they were further treated by surface crosslinking using N, N′-methylene bisacrylamide （BIS） as a crosslinking agent. The swelling and deswelling behaviors of these copolymers were compared with those of the untreated hydrogels. The results indicated that the responsive rate of poly（NIPA-co-AN） hydrogel was improved by surface crosslinking. The resulting hydrogels bearing cyano groups with fast response have potential applications in the field of drug-controlled release and immobilization of biomolecules.     

Absorption of Low Concentration Sulfur Dioxide Using Liquid-containing Microporous Membrane

The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated. The absorption efficiency of hydrophilic and hydrophobic membranes by using the concept of dynamic contact angle was mainly studied. The influences on absorption efficiency from absorption time, flowrate of gas phase, SO2 concentration of gas phase, air pressure, citrate concentration, pH value of solution as well as the generation of sulfate radical in absorption solution were examined. The results indicate that the hydrophobic hollow fiber membrane is better than hydrophilic membrane, the absorption efficiency decreases with increasing absorption time, gas phase flowrate, gas phase SO2 concentration and air pressure, the absorption rate and capacity of SO2 can be improved by increasing the citrate concentration, the absorption efficiency can be improved by increasing the pH value of citrate solution, the concentration of SO42- in absorption solution increases linearly with the absorption time at a rate around 0.192 g/(L×h).     

超临界CO2中异丁醇的相平衡研究

Vapor-liquid phase equilibrium data including composition, densities, molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2 K to 353.2 K were measured in a variable-volume visual cell. The properties of critical point were obtained by extrapolation. The results showed that critical temperature, critical pressure and critical compressibility factor of CO2-isobutanol system decreased with the increase of critical CO2 content. The phase equilibrium model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation, and model parameters were determined by optimization calculation of nonlinear least square method. The correlation between calculated values and the experimental data showed good agreement.     

采用纳米Al203和碳纳米管颗粒强化CO2吸收的理论及实验研究（英文）

The influence of nano-particles on CO2 absorption was studied experimentally in a stirred thermostatic reactor. Nano-A1203 and carbon nanotube （CNT） particles which showed different hydrophobic properties were chosen for the investigation. The experimental results were compared with that of micron-size activated carbon （AC） and Al2O3 particles. From the results, no enhancement by micron-size A1203 was found, and with the increase of A1203 concentration, the enhancement factor decreased. However, nano-Al203 showed a weak enlaancement tor me COz absorption. AC and CNT particles all intensified the gas-liquid mass transfer effectively, yet the trend of the enhancement factor with stirring speed for the two particles was different. With increasing stirring speed, the enhancement factor of AC particles was decreased, wl＇iereas in CNT suspensions it was increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nano-particles, besides the influence of adsorbability and hydrophobicity, the micro-convection caused by Brownian motion should be also taken into account. Considering the micro-convection effect, a theoretical model was developed to shed light on the absorption enhancement bv nano-oarticles.     

低浓度草酸水溶液的电导研究

Oxalic acid is a weak and unsymmetrical bi-basic acid. There exist dissociation and association equilibria among the species in aqueous solution. The molar conductivity of the solution is the sum of the ionic contributions.Based on this idea, a new prediction equation of ionic conductivity was proposed at low concentration. The molar conductivities of the solution and its relevant ions were calculated respectively. The results obtained were in good agreement with those from experiments and the Quint-Viallard equation.     

菲污染土壤的电修复过程

Removal of hydrophobic organic contaminants(HOCs) form soil of low permeability by electroremediation was investigated by using phenanthrene and kaolinite as a model system.Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene.The effects of pH on the adsorption of phenanthrene and Tween 80 on kaolinite and the magnitude of ζ-potential of kaolinite were examined,respectively.The effects of electric field strength indicated by electric current on the electroremediation behavior,including the pH of purging solution,the conductivity,phenanthrene concentration and flow rate of effluent,were experimentally investigated,repectively,In case of an electric field of 25mA applied for 72 hours,over 90% of phenanthrene was removed from 424g(dry mass)of kaolinite at an energy consumption of 0.148kW.h.The experimental results described in present study show that the addition of surfactant into purging solution greatly enhances the removel of HOCs by electroremediation.     

Concentration of mixed acid by electrodialysis for the intensification of absorption process in acrylic acid production

The absorption process in acrylic acid production was water-intensive. The concentration of acrylic acid before distillation process was low, which induced to large amount of wastewater and enormous energy consumption.In this work, a new method was proposed to concentrate the side stream of absorption column and thus increase the concentration in bottom product by electrodialysis. The influence of operating conditions on concentration rate and specific energy consumption were investigated by a laboratory-scale device. When the voltage drop was 1 V·cP~(-1)(1 cP=10~(-3) Pa·s), flow velocity was 3 cm·s~(-1) and the temperature was 35 °C, the concentration rates of acrylic acid and acetic acid could be 203.3% and 156.6% in the continual-ED process. Based on the experimental data, the absorption process combined with ED was simulated, in which the diluted solution from ED process was used as spray water and the concentrated solution was feed back to the absorption column. The results shown that the flow rate of spray water was decreased by 37.1%, and the acrylic acid concentration at the bottom of the tower was increased by 4.56%. The ions exchange membranes before and after use 1200 h were tested by membrane surface morphology(scanning electron microscope), membrane chemical groups(infrared spectra), ion exchange capacity, and membrane area resistance, which indicated the membrane were stable in the acid system. This method provides new method for energy conservation and emission reduction in the traditional chemical industry.     

用多粒模型模拟丁二烯气相聚合的颗粒增长

Gas phase polymerization of butadiene by neodymium catalyst was modeled. The effects of mass and heat transfer resistances in the external boundary layer and within particles, sorption of butadiene in polybutadiene,and deactivation of active sites on polymer particle growth and morphology were studied. Simulation results show that the effects of intraparticle mass and heat transfer resistances on the growth rate of polymer particles are insignificant, and that there is no significant effect of mass transfer resistance on the morphology of polymer particles.The simulation results were compared with the experimental results.     

Viscosity behavior and surface and interfacial activities of hydrophobically modified water‐soluble acrylamide/N‐phenyl acrylamide block copolymers

In this study, the viscosity behavior and surface and interfacial activities of associative water‐soluble polymers, which were prepared by an aqueous micellar copolymerization technique from acrylamide and small amounts of N‐phenyl acrylamide (1.5 and 5 mol %), were investigated under various conditions, including the polymer concentration, shear rate, temperature, and salinity. The copolymer solutions exhibited increased viscosity due to intermolecular hydrophobic associations, as the solution viscosity of the copolymers increased sharply with increasing polymer concentration, especially above a critical overlap concentration. An almost shear‐rate‐independent viscosity (Newtonian plateau) was also displayed at high shear rates, and typical non‐Newtonian shear‐thinning behavior was exhibited at low shear rates and high temperatures. Furthermore, the copolymers exhibited high air–water and oil–water interfacial activities, as the surface and interfacial tensions decreased with increasing polymer concentration and salinity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2290–2300, 2003     

Hydrophobically modified poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate): synthesis and viscosity of aqueous solution

BACKGROUND: Hydrophobically modified polyelectrolytes are widely used polymers due to their good water solubility, stretched configuration in water and strong hydrophobic association. The study reported here aimed at researching the double action of hydrophobic association and electrostatic effect of novel hydrophobically modified polyelectrolytes in solution. RESULTS: A series of novel hydrophobically modified polyelectrolytes were synthesized by micellar copolymerization with various feed ratios of sodium 2‐acrylamido‐2‐methylpropanesulfonate, N‐n‐dodecylamine and sodium dodecylsulfonate. Their structure was characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography, and the viscosities of their aqueous and salt solutions were studied. CONCLUSION: The results show that the addition of the hydrophobic comonomer results in a decrease in molecular weight (M_w). The smaller the initial number of hydrophobes in one micelle, the higher is M_w of the resulting copolymer. The viscosity of PAD‐1.73 polyelectrolyte is less sensitive to salt than those of the others. According to the zero shear viscosity and corresponding concentration, the critical cluster‐forming concentration, critical overlap concentration and critical entanglement concentration of these polymer solutions were determined. Moreover, in the dilute regime the viscosity decreases with increasing salinity, while in the semi‐dilute regime the viscosity decreases first and then increases. It is suggested that in dilute and semi‐dilute regimes, hydrophobic intramolecular association and intermolecular association dominate, respectively. Copyright © 2009 Society of Chemical Industry     

Self-association and microenvironment of random amphiphilic copolymers of sodium N-acryloyl-l-valinate and N-dodecylacrylamide in aqueous solution

The present paper reports on the syntheses and association behavior of two random copolymers of sodium N-acryloyl-l-valinate and N-dodecylacrylamide in buffered (pH 8.0) aqueous solution containing 0.1 M NaCl. Surface tension and viscosity results showed pronounced amphiphilic nature of the copolymers in aqueous solution at pH 8.0. Steady-state fluorescence studies using pyrene and N-phenyl-1-naphthylamine as probe molecules suggested microdomain formation through interpolymer association above a critical concentration called ‘critical aggregation concentration’ (CAC) as low as ca. 10⁻³ g L⁻¹. The local polarity of the hydrophobic domain formed in aqueous solution was estimated from steady-state fluorescence spectra of pyrene. The microviscosity of the domains was evaluated using 1,6-diphenyl-1,3,5-hexatriene as a fluorescent probe using steady-sate fluorescence depolarization and time-resolved fluorescence method. Dynamic light scattering technique was performed over a wide range of concentration to determine hydrodynamic size of the aggregates. It was observed that both copolymers retain rather open conformation in dilute solutions having polymer concentrations less than CAC. However, with increase in concentration the intermolecular association becomes favorable towards the formation of more compact aggregates. The transmission electron microscopic images of both copolymers at a concentration above CAC revealed spherical aggregates of uniform diameter (∼50 nm).     

Solution behavior of two novel anionic polyacrylamide copolymers hydrophobically modified with n‐benzyl‐n‐octylacrylamide

Two novel hydrophobically modified anionic polyacrylamides (HM‐PAMs), p(AM/NaA/NaAMC₁₂S/BOAM) and p(AM/NaA/OP‐10‐AC/BOAM) have been prepared by an aqueous micellar copolymerization technique from acrylamide, sodium acrylate (NaA), sodium 2‐(acrylamido)dodecane‐1‐sulfonate (NaAMC₁₂S), octylphenol polyoxyethylene acrylate (OP‐10‐AC), and small amounts of N‐benzyl‐N‐octylacrylamide, respectively, with the objective of investigating the copolymers' rheological behaviors and surface activities under various conditions such as polymer concentration, shear rate, temperature, and salinity. As expected, the copolymers exhibit improved thickening properties due to intermolecular hydrophobic associations as the solution viscosity of the copolymers increases sharply with increasing polymer concentration. A decrease in viscosity is observed with increasing temperature, and the solution viscosity of the copolymers decreases with increasing NaCl concentration. Furthermore, the block copolymers exhibit high air–liquid surface activities as the surface tensions (STs) decrease with increasing polymer concentration. This behavior is yet another evidence of polymolecular micelles formation of the copolymers in aqueous solution, and thus the high tendency to adsorb at an interface. The ST exhibited by the copolymers was found to be relatively insensitive to the concentration of salt (NaCl). Scanning electron micrographs showed large aggregates in solutions, which is formed by the association from the hydrophobic groups of the polymers. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Solubilization properties of N-substituted amphiphilic acrylamide copolymers

Amphiphilic copolymers of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) and dodecylmethacrylamide (DodMAAm) were synthesized. The ratio of the reduced viscosities of these copolymers in water and in 0.2 mol/L NaCl solution shows that these copolymers containing from 50 to 66 mol % of DodMAAm have a relatively small and constant hydrodynamic size. Viscometric and static light scattering measurements indicated that the copolymers shrinked and intermolecularly associated, forming interchain aggregates in water through hydrophobic interactions. These copolymers solubilize dl-α-tocopherol acetate, giving a transparent solution; but the solution became turbid in a month due to increasing intermolecular association. To suppress this excess intermolecular association, polymers with four different crosslinking ratios were synthesized. The polymer of a crosslinking ratio of 0.5 mol % showed a strong solubilization property, resulting in transparent solution with an improved stability. The fluorescence spectra of pyrene in the polymer solution proved that these copolymers could form strong hydrophobic domains, which solubilize a hydrophobic compound, in less than 30 w/w % ethanol solution. These copolymers could have an excellent function of sustained release of perfume as a novel function. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2447–2453, 1999     

Solution and interfacial behavior of hydrophobically modified water-soluble block copolymers of acrylamide and N-phenethylacrylamide

Hydrophobically modified water-soluble block copolymers were prepared by aqueous micellar copolymerization of acrylamide and small amounts (2 and 3 mol %) of a hydrophobe (N-phenethylacrylamide) that is characterized by a long spacer that places the aromatic ring far away from the backbone, with the objective of investigating the copolymers' rheological behavior and surface and interfacial activities under various conditions such as polymer concentration, shear rate, temperature, and salinity. As expected, the block copolymers exhibit improved thickening properties attributed to intermolecular hydrophobic associations as the solution viscosity of the copolymers increases sharply with increasing polymer concentration. Additional evidence for intermolecular association is provided by the effect of NaCl, the presence of which substantially enhances the viscosity. An almost shear rate–independent viscosity (Newtonian plateau) is also exhibited at high shear rate and a typical non-Newtonian shear thinning behavior appears at low shear rates and high temperatures. Furthermore, the block copolymers exhibit high air–liquid surface and liquid–liquid interfacial activities as the surface and interfacial tensions decrease with increasing polymer concentration, indicating strong adsorption of the copolymer at the interface. The surface and interfacial tensions exhibited by the copolymers were found to be relatively insensitive to the concentration of salt (NaCl). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 467–476, 2001     

Flourescent probe and ESEM morphologies of a acrylamide‐based terpolymer in aqueous solution

The terpolymer (PASA) of acrylamide with butyl styrene and sodium 2‐acrylamido‐2‐methylpropane sulfonate was synthesized. The composition and molecular structure were characterized by elemental analysis, UV, FTIR, and ¹H NMR. The aggregation behaviors of PASA were studied by means of the fluorescent probe analysis and environmental scanning electron microscope (ESEM). The flourescent probe analysis indicates that the PASA molecules form excellent hydrophobically associating structures in pure water and with the increase in PASA concentration at low concentrations, the nonpolarity of hydrophobic microdomains and the degree of intermolecular hydrophobic association increase in aqueous and brine solution. ESEM measurements show that gigantic aggregates have been formed in the PASA aqueous solution at the polymer concentration of 0.05 g dL^?1, which is the critical association concentration of the polymer, and excellent solution properties of PASA are attributed to integrated network‐structures formed by PASA in aqueous solution, which are collapsed by the addition of salt, resulting in the decrease in apparent viscosity of PASA in brine solution. However, with the increase in the NaCl concentration or the PASA concentration, the number and size of aggregates increase, leading to the remarkable increase in the apparent viscosity of PASA in brine solution. These results are consistent with the AFM and viscosity study results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:277–286, 2007     

疏水缔合水溶性聚合物的分子结构对疏水缔合的影响

疏水缔合水溶性聚合物是水溶性聚合物中含有少量疏水基团,在水溶液中疏水基团由于范德华力聚集在一起,使水溶液具有良好的增粘作用和抗盐耐温性。对该类聚合物的分子结构对疏水缔合的影响作了综述。     

Effect of microscopic aggregation behavior on polymer shear resistance

The study of polymer aggregation behavior effect on shear resistance shed light on the synthesis of antishear polymer for oil displacement and enhances the application effect of polymer flooding. The effects of mechanical degradation on the properties of polymer solutions were studied by using partially hydrolyzed polyacrylamide (HPAM), hydrophobically modified HPAM (HMPAM), and dendritic hydrophobic associative polymers (DHAP), which are characterized by “granular,” “chain,” and “cluster” aggregation behavior, respectively. The results show that mechanical shearing can dramatically reduce the performance of polymer solution. The shearing resistance can be effectively enhanced by improving the polymer aggregation behavior. After being strongly sheared, hydrophobically associating polymers can still partially restore its network through hydrophobic association, therefore rebuild the solution viscosity. For DHAP, the broken molecular chains distribute more evenly in solution after shearing. In addition, the strength of reconstructed network structure of DHAP is better than that of HMAPM, which implies a better shear resistance. Furthermore, the hydrophobic association of linear polymers will increase their static adsorption on quartz sand. Meanwhile, DHAP with stronger spatial structure has less static adsorption, which is beneficial to maintain a higher polymer concentration in solution. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48670.     

Solution microstructure of a micro-crosslinked acrylamide-based terpolymer

The hydrophobically associating copolymer poly (acrylamide/butyl styrene/sodium 2-acrylamido-2-methylpropane sulphonate) (PASA) is micro-crosslinked with a small amount of phenolic aldehyde (PL) to obtain the micro-crosslinked polymer PASA–PL with excellent liquidity and water solubility. After crosslinked, the critical association concentration of copolymer reduces in the brine solution with high NaCl concentration and PASA–PL displays much better thickening and anti-aging properties in brine solutions at low polymer concentrations. The contribution of micro-crosslink of PASA with PL to the associating structures is investigated by fluorescent probe and scanning electron microscope (SEM). The fluorescent probe results show that a large amount of hydrophobic microdomains with very strong non-polarity are formed because of greatly strengthened intermolecular hydrophobic association for the PASA–PL polymer in aqueous and brine solutions, and PASA and NaCl concentration greatly influence intermolecular hydrophobic association in PASA–PL brine solutions. SEM measurements show that continuous associative structures with huge sizes are formed in PASA–PL aqueous and brine solution.