Poly(acrylamide/laponite) nanocomposite hydrogels: Swelling and cationic dye adsorption properties

Super adsorbent polyacrylamide (PAAm)/nanoclay (laponite, Lap) hydrogels were prepared by in situ free radical polymerization of AAm in an aqueous solution with clay as a crosslinker. The swelling properties and water‐soluble cationic dye adsorption behaviors of the PAAm/laponite (PAAm/Lap) nanocomposite (NC) hydrogels were investigated. The parameters of swelling and diffusion of water in dye solutions were evaluated for the PAAm/Lap NC hydrogels. The adsorption behavior of the monovalent cationic dyes such as Basic Blue 12 (BB 12), Basic Blue 9 (BB 9), and Basic Violet 1 (BV 1), were studied on the NC hydrogels. The effects of the clay content of the hydrogel on its cationic dye uptake behavior were studied. The adsorption studies indicated that the rates of dye uptake by the NC hydrogels increased in the following order: BB 9 > BB 12 > BV 1. This order is similar to the swelling results of the PAAm/Lap NC hydrogel in the dye solutions. The equilibrium uptakes of the different dyes by the PAAm/Lap NC hydrogel were nearly the same. In the dye absorption studies, S‐type adsorption in the Giles classification system was found for the BB 12 and BV 1 dyes, whereas L ‐type was observed for the BB 9 dye. After the heat treatment of PAAm/Lap, the rate of dye uptake and equilibrium dye uptake were increased. The NC hydrogels may be considered as a good candidate for environmental applications to retain more water and to remove dyes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of sodium montmorillonite nanoclay on the water absorbency and cationic dye removal of carrageenan-based nanocomposite superabsorbents

Nanocomposite superabsorbents were synthesized by simultaneously solution copolymerization of acrylamide (AAm) and sodium acrylate (Na-AA) in the presence of carrageenan biopolymer and sodium montmorillonite (Na-MMt) nanoclay. Potassium persulfate (KPS) and methylenebisacrylamide (MBA) were used as initiator and crosslinker, respectively. The structure and morphology of the nanocomposites were investigated using XRD, FTIR, scanning electron microscopy (SEM), and TEM techniques. The influence of nanoclay and carrageenan contents as well as monomer weight ratios on the degree of swelling of nanocomposites was studied. The optimum water absorbency was obtained at 10 wt% of clay, 10 wt% of carrageenan, and 1:1 of monomers weight ratio. The obtained nanocomposites were examined to remove of crystal violet (CV) cationic dye from water. The effect of carrageenan and clay content on the speed of dye adsorption revealed that while the rate of dye adsorption is enhanced by increasing the clay content up to 14 wt% of clay, it was decreased as the carrageenan increased in nanocomposite composition. The results showed that the pseudo-second-order adsorption kinetic was predominated for the adsorption of CV onto nanocomposites. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The results corroborated that the experimental data fit the Freundlich isotherm the best.     

阳离子荧光染料的合成及其性能研究

合成了一种新型双阳离子型荧光染料—反,反-1,4-双{2-[4-(N-乙基)溴化吡啶基]乙烯基}苯(DPPB),采用红外光谱和核磁共振谱仪对其进行了结构表征,通过染色实验研究其在腈纶织物上的染色性能及色牢度,同时研究了其单光子荧光性能。结果表明,DPPB的荧光性能良好,在腈纶织物上有良好的染色性能,所染织物具有蓝绿色荧光效果。     

Preparation of cationic modified collagen extracted from leather wastes and their application in dye flocculation

A series of novel cationic flocculants are designed and synthesized successfully by grafting two monomers onto the collagen backbone, namely acrylamide (AM) and 2‐methacryloyloxyethyltrimethyl ammonium chloride (DMC). Apparently, these effective grafting modifications are well demonstrated by adopting FTIR and H¹ NMR measurements, which could be used to estimate grafting ratios of corresponding monomers approximately. Additionally, significant improvements in positive charge densities and amorphous aggregation structures are also definitely confirmed by Zeta and XRD measurements, respectively. Moreover, thermogravimetric analysis clearly proves the formation of cationic branched chain architectures, whose maximum thermal degradation temperature would significantly decrease with the introduction of AM. In addition, much more porous and rougher surface structures could be visibly observed after successful grafting modifications. Furthermore, when the feeding weight ratio between collagen and DMC is controlled at 1:3, or the equal amounts of AM and DMC are introduced meanwhile the mass ratio between collagen and mixed monomers (DMC + AM) is fixed at 1:4, the samples acquired could both perform the best in decolorizing the model wastewater containing methyl orange (MO) dyes in their groups, and hereby, a corresponding flocculation mechanism is also proposed based on the structural analysis of the formed flocs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45363.     

Preparation of chitosan and carboxymethylcellulose-based polyelectrolyte complex hydrogel via SD-A-SGT method and its adsorption of anionic and cationic dye

The excellent properties of the polyelectrolyte complex hydrogels (PECHs) prepared with polysaccharides only, including polyampholyte, low toxicity, green, and clean production, have endowed them great application potentials as the adsorbents for dye-containing wastewater treatments. In the current study, the PECH of chitosan (CTS) and carboxymethylcellulose (CMC) was prepared by semi-dissolution acidification sol–gel transition (SD-A-SGT) method. The hydrogel was formed by the strong electrostatic interaction of cationic  NH₃⁺ groups of CTS and the anionic  COO⁻ groups of CMC. This simple but efficient means exhibited great potentials in constructing PECHs with uniform composition and controllable sol–gel transitions. Molecular dynamics simulation was first employed to predict the formation process and the microstructure of PECHs prepared by SD-A-SGT method. The structure and properties of the CTS-CMC PECHs were also characterized by Fourier transform infrared spectroscopy, SS ¹³C-NMR, scanning electron microscopy, mechanical tests, and rheological measurements, respectively. Taking the advantage of amphoteric polyelectrolyte properties, adsorption properties of anionic and cationic dyes were investigated using sunset yellow FCF and methylene blue as model dyes, respectively. The PECHs prepared in the present work had good adsorption capacity for both cationic and anionic dyes with maximum adsorption capacity of 212.83 mg/g for sunset yellow FCF and 167.35 mg/g for methylene blue. Therefore, this PECH would be a promising environmentally friendly adsorbent for the treatment of functional molecules with different charges.     

Infiltration of laponite: An effective approach to improve the mechanical properties and thermostability of collagen hydrogel

Rapid aggregate precipitation of collagen and laponite in solution restricted the development of corresponding hybrid materials. Herein, a facile method of immerging collagen hydrogel into laponite dispersion was adopted to prepare hybrid collagen/laponite hydrogel, avoiding the precipitation. Collagen hydrogel shrunk and water content decreased dramatically after laponite solution treatment. According to the images of Scanning electron microscopy and energy dispersive system, the uniformly dispersed laponite in collagen hydrogel was observed, demonstrating infiltration of laponite into collagen hydrogel. X-ray photoelectron spectroscopy results revealed that coordination bonds generated between magnesium in laponite and collagen. Thermogravimetric analysis and Differential scanning calorimetry results displayed thermal decomposition temperature of collagen hydrogel increased from 321 to 342°C, and denaturation temperature rose from 43.8 to 50.8 °C after laponite infiltration. Rheological and compressive tests showed the elastic modulus, fracture stress, compressive modulus and rupture point of hydrogel treated by 10% laponite were 695.2 Pa, 253.3 kPa, 13.5 kPa and 76.7%, respectively, which were about 3.5, 5.5, 45.0, and 1.4 times larger than those of pristine collagen hydrogel. Besides, enzyme degraded rate of collagen was decelerated, and the hydrogel was still nontoxic with the infiltration of laponite. The promising data demonstrated infiltration of laponite was an effective way to fabricate collagen/laponite hybrid materials with desirable properties.     

Multifunctional amphoteric resin to remove both anionic and cationic dyes from aqueous solution

This study reports the synthesis and characterization of a new amphoteric resin, which can be used for the removal of both cationic, methylene blue (MB) and anionic dyes, reactive red-120 (RR-120). The amphoteric resin was characterized by ATR-FTIR, SEM–EDX, TGA/DTA, DLS, BET analysis and also its surface pHpzc was determined. The prepared resin has micro porous structure and its particle size was at the nano level. The prepared amphoteric resin showed high removal affinity for MB in both acidic and basic medium, while for RR-120 high removal affinity in acidic medium. Moreover, it was observed that the amphoteric resin has exhibited almost 100% dye removal up to 600 ppm for MB and up to 300 ppm for RR-120, respectively. The adsorption behavior of both dyes on the amphoteric resin is in agreement with the Langmuir isotherm and the pseudo-second order kinetic model and also electrostatic interaction is dominant in adsorption. Its capacity was slightly low for the MB than that of the commercial activated carbon, but higher for the RR-120. Furthermore, it was observed that the amphoteric resin almost did not lose its high removal efficiency in the concentrated matrix environment for both dyes. After five repeated adsorption–desorption cycles, the high removal efficiency of the resin for the MB (almost 100%) unchanged, but for the RR-120 decreased to 83%.     

Novel polyacrylonitrile nanocomposites containing Na-montmorillonite and nano SiO2 particle

Polyacrylonitrile (PAN)/Na-montmorillonite (Na-MMT)/SiO₂ nanocomposites were prepared via in situ emulsion polymerization. X-ray diffraction (XRD) results suggest that the Na-MMT layers are exfoliated during the polymerization process. As evidenced by the transmission electron microscope (TEM), the Na-MMT and nano SiO₂ particles exhibit good dispersion in the polymer matrix. It was found that the PAN/Na-MMT/SiO₂ nanocomposites exhibit considerably enhanced mechanical properties compared with the PAN/Na-MMT and PAN/SiO₂ nanocomposites.     

Novel fluorene-based light-emitting copolymers containing cyanophenyl pendants and carbazole-triphenylamines: Synthesis, characterization and their PLED application

A series of novel blue light-emitting copolymers PCC-1, PCC-2, and PCC-3, composed of different ratios of electron-withdrawing segments (spirobifluorene substituted with cyanophenyl groups) and electron-donating segments (carbazole-triphenylamines), has been synthesized and characterized. In order to investigate the effect of hole/electron charge transporting segments, two reference polymers PSF and PCF, containing only one charge transporting moiety in the polymer backbone, were also synthesized. Incorporation of the rigid spirobifluorene units substituted with cyanophenyl groups into the polymer backbone improved not only the thermal stabilities but also the photoluminescence efficiencies. The polymers except PSF possess similar hole injection barriers but different hole transporting abilities. With the device configuration of ITO/PEDOT:PSS/polymers:PBD/CsF/Ca/Al, PCC-2 showed the best performance with the lowest turn-on voltage of 3.1 V, the highest luminance of 6369 cd/m², the highest current efficiency of 1.97 cd/A, and the best power efficiency of 1.40 lm/w.     

Novel simple solvent-less preparation,characterization and degradation of the cationic dye over holmium oxide ceramic nanostructures

Pure holmium oxide ceramic nanostructures were prepared via a new simple approach. Nanostructures were synthesized by heat treatment in air at 600 °C for 5 h, utilizing [Ho L(NO₃)₂]NO₃ (L=bis-(2-hydroxy-1-naphthaldehyde)-butanediamine Schiff base ligand), as precursor, which was prepared via a solvent-free solid–solid reaction from different molar ratios of holmium nitrate and Schiff base ligand. The as-prepared nanostructures were characterized by field emission scanning electron microscopy (FESEM), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDX), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. It was found that the calcination temperature and molar ratio of holmium nitrate and Schiff base ligand have significant and key effect on the morphology and particle size of the holmium oxide. To investigate the catalytic properties of as-obtained holmium oxide nanostructures, the photocatalytic degradation of rhodamine B as cationic dye under ultraviolet light irradiation was performed.     

Synthesis of imidazolium salts and their application in epoxy montmorillonite nanocomposites

Considerable research has been conducted in improving the performance characteristics of nanocomposites, however, relatively few attempts have been made to address the thermal stability of nanocomposites. An attempt is being made to improve the thermal properties of nanocomposites by synthesizing imidazolium salts from 2-methyl imidazole and ion exchanging the salts with clay minerals. This study focuses on the role of the chemistry of imidazolium salt(s) used in functionalizing clay and processing conditions in the formulation of epoxy nanocomposites. The nanodispersion of clay in an epoxy matrix is evaluated qualitatively by X-ray diffraction (XRD), transmission electronic microscopy (TEM), and laser scanning confocal microscopy (LSCM). We demonstrate the use of LCSM for quantitative image analysis and to study the dispersion of clay layers, tagged with a fluorescent dye in the epoxy matrix. XRD and TEM results reveal that the hand mixed nanocomposite has tactoid morphology, while ultrasonicated organoclay (without hydroxyl group) epoxy nanocomposite exhibits a mixed morphology, and an ultrasonicated organoclay (with hydroxyl group) epoxy nanocomposite had well dispersed clay distribution in the epoxy matrix. Results from the three complimentary techniques enable the characterization of the clay platelets over several length scales ranging from the micrometer to the nanometer scale.     

Synthesis and characterization of Na‐alginate/acrylamide hydrogel and its application in dye removal

Sodium‐alginate/acrylamide (Na‐alginate/AAm) cross‐linked hydrogel was prepared by using gamma irradiation. The gel content and the water absorbency behavior of the obtained hydrogel were investigated. The thermal and morphological properties of the prepared hydrogel were studied using thermogravimetric analysis and scanning electron microscopy. The thermal stability of Na‐alginate significantly changed when mixed with AAm. The adsorption of basic violet 7 dye on the prepared hydrogel was studied under different experimental conditions. The adsorption process for the basic dye was proven pH dependent. The maximum amount adsorbed (mg/g) of the Na‐alginate/AAm for the dye was found to be 78.1.0 mg/g at pH 9.0. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis,characterization of Fe3O4@glycine doped polypyrrole magnetic nanocomposites and their potential performance to remove toxic Cr(VI)

Fe₃O₄ coated glycine doped polypyrrole magnetic nanocomposite (Fe₃O₄@gly-PPy NC) was prepared via coating of suspended Fe₃O₄ nanoparticles with gly-PPy. FE-SEM and HR-TEM images indicated that Fe₃O₄ nanoparticles were encapsulated by precipitating gly-PPy moieties. Chromium(VI) adsorption followed a Langmuir isotherm with maximum capacity of 238–303 mg/g for a temperature range of 25–45 °C at pH 2. The adsorption process was governed by the ionic interaction and the reduction of Cr(VI) to Cr(III) by the PPy moiety. Results showed that NCs are effective adsorbents for the removal of Cr(VI) from wastewater and can be separated by external magnetic field from the reactor.     

Phase behavior of aqueous two-phase systems of cationic and anionic surfactants and their application to theanine extraction

Phase behavior of aqueous two-phase systems (ATPS) containing cationic (SDS) and anionic (CTAB) surfactants and its application to theanine extraction was studied. Results indicated the ATPS could form under the certain SDS/CTAB molar ratio; there was a reasonable consistency between the conductivity and the formation region of ATPS, and the viscosity was higher in the formation region of ATPS. Additionally, the phase ratio increased with increase of CATB concentration, and the interfacial film between the top phase and the bottom phase was resilient. Moreover, the theanine extraction with ATPS was realized in the waste liquid of tea polyphenol production (WLTPP), and the partition coefficient of theanine decreased with increase of WLTPP concentration, whereas the extraction rate of theanine increased. The partition coefficient decreased with increasing SDS/CTAB molar ratio, and the extraction rate of theanine increased with increase of SDS/CTAB molar ratio.     

Synthesis of dye containing epoxide-amine addition polymers and investigation of their thermal and optical properties

Summary N-alkylated epoxide-amine addition polymers as well as epoxide-amine addition polymers containing carboxylate groups are used for an ion exchange by various anionic dyes such as diamine green, crocein or cationic dyes, respectively like rodamine and malachite green. The polymer-dye salts 1 and 2 are soluble in DMF, DMF/2-methoxy ethanol and other solvents and can be cast into transparent coloured films from these solutions. The glass transition temperatures were found between 90 and 165°C (1) and between 85 and 112°C (2), respectively. The thermal decomposition of polymers 1 and 2 takes place at 300–370°C. Furthermore, non-linear optical properties (third harmonic generation) of the polymer-dye salts 1 and 2 were expected and calculated to be 10^-12–10^-13 esu.For part 38 see [1]     

微胶囊化分散染料及其在纺织上的应用

概述了微胶囊化分散染料的外观特征、合成方法,介绍了分散染料微胶囊在纺织行业的应用。着重介绍了微胶囊化分散染料对涤纶无助剂、免水洗染色的原理以及该项应用技术突出的优点。     

Polyoxalactones and their cationic complexes

Summary Some polyoxalactones were synthesised from the dichlorides of glycolic acids and polyethyleneglycoles in the presence of pyridine. The polyoxalactones were also complexed with some of alkaline and alkaline earth salts and quite stable polyoxalactone-salt complexes were obtained including the Ca⁺⁺ cation. Complexes obtained exhibited mostly 11 type of complex stoichiometry regardles from radius of the cation and the nature of lactone ring.Submitted for the partial fullfillment of Ph.D. degree in Organic Chemistry at Diyarbakir University, 1981.     

Preparation of betaine‐modified cationic cellulose and its application in the treatment of reactive dye wastewater

Betaine‐modified cationic cellulose was prepared through the reaction of cellulose with betaine hydrochloride by an efficient one‐step dry method. Dicyandiamide was used as a dehydrating agent to promote the formation of ester bonds between the reactants. Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy were used to characterize the cellulose betainate. Experiments showed that at a molar ratio of the cellulose glucose unit, betaine hydrochloride to dicyandiamide, of 1:1:0.5 at 150°C for 3 h, the degree of substitution of the cationic group reached 0.80. The adsorption of simulated C. I. Reactive Red 24 and C. I. Reactive Red 195 wastewater on the cationic cellulose was carried out, and the effects of the adsorbent dose, initial dye concentration, and salt concentration on the dye removal efficiency were investigated. The equilibrium adsorption isotherm data of the cationic cellulose exhibited a better fit to the Langmuir isotherm model than the Freundlich one. The experimental results suggest that the prepared cationic cellulose materials show potential application for reactive dye wastewater treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40522.     

A facile route to obtain an acidic hydrogel containing lactate moieties

The idea to develop hydrophilic lactic acid-based polyelectrolyte was presented. A facile route was utilized to prepare smart hydrogels that contained lactate units and carboxylic groups. The hydrogels were obtained through the radical cross-linking reaction between an unsaturated lactate-contained macromonomer and acrylic acid (AA)/itaconic acid (IA) monomer pair. The structure and performances of the hydrogels were characterized with thermogravimetric analysis, dynamic thermal analysis, scanning electron microscopy, swelling tests and adsorption measurements. The equilibrium swelling ratios of the hydrogels in acidic (pH 3.6) and basic (pH 11.5) media reached 25.3 and 62.3 respectively. The pH-sensitive swelling behaviors of the hydrogel confirmed that the hydrogels contained carboxylic groups and they were hydrophilic. The metal ions including calcium, copper, lead and cerium ions were bound into the hydrogels, which also confirmed the existence of the carboxyl groups. Moreover, the swelling ratio and adsorption capacity of the gel prepared from monomer pair were significantly higher than those obtained in absence of IA, which suggested that the properties of the hydrogels could be controllable by simply adjusting the ratio of AA/IA. In addition, the weight loss percentage of the hydrogel was around 37% after two-week in vitro degradation, which indicated the hydrogel contained lactate units.