Reuse of a waste adsorbent poly(AAc/AM/SH)‐Cu superabsorbent hydrogel,for the potential phosphate ion removal from waste water: Matrix effects,adsorption kinetics,and thermodynamic studies

The most commonly applied methods for the treatment of used adsorbents is to recover them in acid/alkaline medium or direct enflame them. This work dealt with a new potential and economic method to utilize a waste adsorbent. Poly(AAc/AM/SH) superabsorbent hydrogels have proved to be a good adsorbent for Cu²⁺ ions and after adsorption the hydrogels were recovered in acid medium. In this report, the Cu²⁺ ion adsorbed hydrogel has not undergone any regeneration process and applied directly to phosphate ion adsorption. The Cu²⁺ ions‐loaded poly(AAc/AM/SH) hydrogels, were stable within a wide pH range and suitable for phosphate ion adsorption. The factors affecting the phosphate adsorption, such as pH, ionic strength, contact time, temperature, initial concentration of the phosphate ion, and coexisting ions were systematically investigated. The phosphate adsorption was highly pH dependent; and the maximum adsorption of 87.62 mg/g was achieved at pH 6.1. The adsorption data fitted the Langmuir adsorption isotherm better than the Freundlich isotherm. The concomitant anions show profounder adverse influence on phosphate ion adsorption of poly(AAc/AM/SH)‐Cu hydrogel and the effect follows the order citrate > sulfate > bicarbonate > chloride > nitrate. The thermodynamic parameters including ΔH°, ΔG°, and ΔS° for the adsorption processes of phosphate ions on the gel were also evaluated, and the negative ΔG° and ΔH° confirmed that the adsorption process was spontaneous and exothermic. The adsorption kinetic results suggest that the adsorption process was well described by the pseudo second‐order kinetic model. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical properties of interpenetrating polymer network hydrogels based on hybrid ionically and covalently crosslinked networks

Hydrogels are polymer networks swollen in water. Because of their soft and wet nature, and their ability to show large volume changes, hydrogels can be useful in many biomedical and actuator applications. In these applications, it is crucial to tune the mechanical and physical properties of a hydrogel in a controllable manner. Here, interpenetrating polymer networks (IPNs) made of a covalently crosslinked network and an ionically crosslinked network were produced to investigate the effective parameters that control the physical and mechanical properties of an IPN hydrogel. Covalently crosslinked polyacrylamide (PAAm) or poly(acrylic acid) (PAA) networks were produced in the presence of alginate (Alg) that was then ionically crosslinked to produce the IPN hydrogels. The effect of ionic crosslinking, degree of covalent crosslinking, AAm : Alg and AA : Alg ratio on the swelling ratio, tensile properties, indentation modulus, and fracture energy of IPN hydrogels was studied. A hollow cylindrical hydrogel with gradient mechanical properties along its length was developed based on the obtained results. The middle section of this hydrogel was designed as a pH triggered artificial muscle, while each end was formulated to be harder, tougher, and insensitive to pH so as to function as a tendon‐like material securing the gel muscle to its mechanical supports. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2504–2513, 2013     

Chemically clean synthesis and characterization of graphene oxide‐poly(acrylic acid–sodium styrene sulfonate) composite thermostable elastic gel encapsulating copper nanoparticles for efficient catalytic reduction of 4‐nitrophenol

The thermostable chemically blended elastic poly‐(acrylic acid–sodium‐styrene‐sulfonate–graphene oxide) super‐absorbent hydrogel was synthesized by additive‐free gamma‐radiation induced polymerization followed by crosslinking method. It showed the best swelling ratio in water due to its porous nature. The composite material adsorbed 98 mg/g Cu(II) at room temperature from the aqueous solution of Cu(II) at pH 5 by the chemi‐adsorption of Cu(II) ions at several energetically heterogeneous functional groups. The copper nanoparticles (CuNPs) of size 12 ± 8 nm had been synthesized in situ by chemical reduction of the pre‐adsorbed Cu(II) ions. The functional groups of composite hydrogel served as complexing agent and nano‐reaction sites. Avoiding any pre‐reduction induction time, the inexpensive CuNPs catalytically completely decolorized the aqueous solution of 4‐nitrophenol (4‐NP) within 60 s in the presence of NaBH₄ at a promising calculated rate constant (9.0 × 10^?2/s) ever reported in the literatures. It is in contrast to the commonly noticeable phenomenon for other CuNPs‐based catalysis of 4‐NP. The composite hydrogel matrix helped to retain the catalytic activity of CuNPs and simultaneously it helped in the osmotic inclusion of 4‐NP into the reaction cites. This composite hydrogel synthesized through a chemically clean method could be utilized for efficient conversion of hazardous chemical 4‐NP to industrially important chemical 4‐aminophenol. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46200.     

Modification of dextran through the grafting of N‐vinyl‐2‐pyrrolidone and studies of physicochemical phenomena in terms of metal‐ion uptake,swelling capacity,and flocculation

The optimum conditions for grafting N‐vinyl‐2‐pyrrolidone onto dextran initiated by a peroxydiphosphate/thiourea redox system were determined through the variation of the concentrations of N‐vinyl‐2‐pyrrolidone, hydrogen ion, potassium peroxydiphosphate, thiourea, and dextran along with the time and temperature. The grafting ratio increased as the concentration of N‐vinyl‐2‐pyrrolidone increased and reached the maximum value at 24 × 10^?2 mol/dm³. Similarly, when the concentration of hydrogen ion increased, the grafting parameters increased from 3 × 10^?3 to 5 × 10^?3 mol/dm³ and attained the maximum value at 5 × 10^?3 mol/dm³. The grafting ratio, add‐on, and efficiency increased continuously with the concentration of peroxydiphosphate increasing from 0.8 × 10^?2 to 2.4 × 10^?2 mol/dm³. When the concentration of thiourea increased from 0.4 × 10^?2 to 2.0 × 10^?2 mol/dm³, the grafting ratio attained the maximum value at 1.2 × 10^?2 mol/dm³. The grafting parameters decreased continuously as the concentration of dextran increased from 0.6 to 1.4 g/dm³. An attempt was made to study some physicochemical properties in terms of metal‐ion sorption, swelling, and flocculation. Dextran‐g‐N‐vinyl‐2‐pyrrolidone was characterized with infrared spectroscopy and thermogravimetric analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

乳化液膜萃取乳酸稀溶液过程中的渗透溶胀及模拟

根据膜相中载体萃取的机理,指出载体在萃取溶质后形成的络合物具有一定的亲水性．采用气相色谱法,分别对含有表面活性剂和载体的膜相在与乳酸溶液接触后的溶水率进行了测定,结果发现其溶水率远高于与无溶质的外相水接触后的膜相溶水率．所以渗透溶胀进人内相的水除表面活性剂分子结合的迁移外还有载体-溶质络合物结合水．从而提出了实际萃取过程中乳化液膜渗透溶胀的反应-溶解-扩散机理,并提出了相应的数学模型,经与实验数据比较,结果吻合较好．     

Gelation and crosslinking characteristics of photopolymerized poly(ethylene glycol) hydrogels

The gelation and crosslinking features of poly(ethylene glycol) (PEG) hydrogels were scrutinized through the UV polymerization processes of poly(ethylene glycol) methacrylate (PEGMA) and poly(ethylene glycol) dimethacrylate (PEGDMA) mixtures. The real‐time evolutions of the elastic moduli of the prepolymerized mixtures with different crosslinking ratios of PEGMA and PEGDMA and the photoinitiator concentrations were measured during photopolymerization. The rheological properties were compared with other properties of the PEG hydrogels, including the relative changes in the C?C amounts in the mixtures before and after UV irradiation, water swelling ratio, gel fraction, mesh size, and mechanical hardness. As the portion of PEGDMA as a crosslinker increased, the final elastic modulus and gel fraction increased, whereas the swelling ratio and scratch penetration depth at the hydrogel film surface decreased because of the formation of compact networks inside the hydrogels. These results indicate that there was a good correlation between the rheological analysis for predicting the crosslinking transition during photopolymerization and the macroscopic properties of the crosslinked hydrogels. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41939.     

Relationship between the separation performances and free volume distributions of polyimide/Ag3O4 composite membranes

First, water, methanol, ethanol, acetone, and methyl t‐butyl ether were used as molecular probes to measure the free volume distribution of a type of polyimide membrane material (HQDEA–DMMDA). The methods were equilibrium swelling and separation membrane technologies. From the Kirchheim theory of free volume distribution, a Gaussian distribution function was determined. The Gaussian distribution function was confirmed with tensile testing and wide‐angle X‐ray diffraction of the polyimide films. Second, polyimide/Ag₃O₄ composite hollow‐fiber membranes were prepared by dry/wet phase inversion. The separation performances of the composite membranes were characterized with a methanol/methyl t‐butyl ether mixture. The change in the separation performances was explained by the free volume distribution function very well. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 871–879, 2005     

Immobilization of 2,5‐dimethyl‐4‐benzoyl‐oxypiperidine succinate over polyacrylic acid (PAA) gels. II. Study of quantitative characteristics of immobilization of succinate of 2,5‐dimethyl‐4‐benzoyl‐oxypiperidine over PAA

By use of a spectrophotometric method the quantity of binding of medicinal compound [succinate of 2,5‐dimethyl‐4‐benzoyl‐oxypiperidine (AK‐29)], over gels of polyacrylic acid, and liberation of medicinal compound (MC) from the gel phase were investigated. It was established that both concentration and pH dependency of AK‐29 sorption over PAA gels pass through a maximum and increase with increasing degree of gel crosslinking. The yield of MC from the gel phase, depending on the conditions, reaches 80% and accelerates at the change of the aqueous phase to a physiological one. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1187–1192, 2005     

表面活性剂分子结构和性能对混合办公废纸脱墨效率的影响

介绍了表面活性剂的分子结构及其性能对混合办公废纸脱墨效率的影响。结果表明表面活性剂溶液的表面张力较低和对彩色油墨润胀较高时，对混合办公废纸的脱墨效率最好。这与表面活性剂的分子结构有关。     

Analysis of variation of molecular parameters of natural rubber during vulcanization in conformational tube model. II. Influence of sulfur/accelerator ratio

A natural rubber (NR) with a conventional sulfur cure system and a ratio of sulfur/accelerator (Ω) equal to 3 was investigated. The network structure of the NR during vulcanization was analyzed using a model of rubber elasticity based on the tube concept, which was applied to the treatment of the stress–strain measurements. The influence of cure time and temperature on the chemical crosslinks density was analyzed. The values were compared with those obtained by means of an equilibrium volume swelling measurement. The differences between samples of NR cured with Ω = 3 and 1.5 were analyzed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2747–2755, 1999