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71.
Sinem Ortaboy Elif T. Acar Gülten Atun Serkan Emik Tülin B. İyim Gamze Güçlü Saadet Özgümüş 《Chemical Engineering Research and Design》2013
Acrylic monomer based terpolymer/montmorillonite nanocomposite hydrogels (NH-MMTs) synthesized using 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), 2-acrylamido-2-methlypropane sulfonic acid (AMPS) and 2-hydroxyethyl methacrylate (HEMA) in the aqueous montmorillonite (MMT) suspension were employed as adsorbents for U(VI) removal from aqueous solutions. Adsorption efficiency of the NH-MMTs was strongly enhanced by increasing pH in the range of 3–6. Adsorption capacity of the NHs increased with the MMT weight ratio up to 1% and the complete removal of U(VI) from 1 mmol/L aqueous solutions was achieved by 2 g/L polymer but further increase of MMT up to 6% caused a gradual decrease in adsorption percentage up to 57%. Nearly 98% of U(VI) loaded on the adsorbents could be recovered by 0.1 M HNO3. Consecutive adsorption/desorption cycles showed that the NH-MMTs are re-usable. Kinetic results were analyzed using Paterson's and Nernst Planck approximation's based on homogeneous solid phase diffusion (HSPD). Experimental data were fitted to equilibrium isotherm models, Langmuir, Freundlich, Dubinin–Radushkevich and Temkin. SEM, and FTIR analysis of bare and U(VI) loaded adsorbents were used to elucidate adsorption mechanisms. The results showed that the NH-MMTs tested in this study are very promising for the recovery of U(VI) from water. 相似文献
72.
Gamze Güçlü Ebru Al Serkan Emik Tülin B. İyim Saadet Özgümüş Mustafa Özyürek 《Polymer Bulletin》2010,65(4):333-346
In this study, the removal of copper(II) and lead(II) ions from aqueous solutions by Starch-graft-acrylic acid/montmorillonite
(S-g-AA/MMT) nanocomposite hydrogels was investigated. For this purpose, various factors affecting the removal of heavy metal
ions, such as treatment time with the solution, initial pH of the solution, initial metal ion concentration, and MMT content
were investigated. The metal ion removal capacities of copolymers increased with increasing pH, and pH 4 was found to be the
optimal pH value for maximum metal removal capacity. Adsorption data of the nanocomposite hydrogels were modeled by the pseudo-second-order
kinetic equation in order to investigate heavy metal ions adsorption mechanism. The observed affinity order in competitive
removal of heavy metals was found Cu2+ > Pb2+. The Freundlich equations were used to fit the equilibrium isotherms. The Freundlich adsorption law was applicable to be
adsorption of metal ions onto nanocomposite hydrogel. 相似文献
73.
In this study, first polyacrylamide hydrogels were synthesized by free‐radical crosslinking polymerization of acrylamide monomer with N,N′‐methylenebis(acrylamide) as a crosslinker in an aqueous solution at 22°C. Then, a series of hydrogels at various charge densities were prepared by partial hydrolysis of polyacrylamide precursors in a 0.1M sodium hydroxide solution at 60°C. The hydrolysis time was varied between 20 and 180 min. The chemical structures and internal morphologies of the hydrogels before and after alkaline hydrolysis were characterized with attenuated total reflectance/Fourier transform infrared and scanning electron microscopy measurements. The swelling ratio of the hydrolyzed hydrogels was measured in buffer solutions at various pHs. From differential curves of dQv/dpH versus pH (where Qv is the equilibrium swelling ratio of the hydrogels), the volume phase transition pH of the hydrogels was found to be 4.33 ± 0.05, regardless of the charge density of the hydrogels. In water at 22°C, the hydrogels with greater charge density showed a more rapid swelling rate because of their higher porosity and hydrophilicity. Moreover, in buffer solutions with the pH changing from 9.0 to 2.0 at 22°C, the hydrogels with greater charge density also exhibited a more rapid deswelling rate than the hydrogels with less charge density. In conclusion, the postmodification method is a good way of preparing pH‐sensitive hydrogels with fast responsiveness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
74.
The effect of the addition of two commercial pectolytic enzymes on the anthocyanin and chemical composition of Öküzgözü wines was studied. A rapid HPLC-diode array detection (DAD) method was developed for the analysis of anthocyanins in wines. Direct injection of filtered wine samples followed by selective detection at 520 nm allowed quantitation of these compounds in red wines. Thirteen anthocyanin compounds were detected in wines and, addition of the two enzyme preparations improved the extraction of anthocyanins. Moreover, the wines treated with enzymes had higher values in total phenolics, tannins, and colour intensity than the control wines. 相似文献
75.
76.
Bora Timurkutluk Serkan Toros Sezer Onbilgin Habip Gokay Korkmaz 《International Journal of Hydrogen Energy》2018,43(31):14638-14647
In this study, the general formability characteristics of Crofer® 22 APU sheets of different thicknesses (0.2 mm–1.0 mm) are experimentally investigated via tensile, out of plane, Erichsen, cupping and springback tests for a possible application for solid oxide fuel cells in sheet form unlike the conventional bulk form. Holloman equation is also used to fit the experimental stress-strain curves and the anisotropic behavior of the material is considered by determining Lankford parameters. The tensile test results show that the formability is about 0.29 mm/mm for 0.2 mm thick sheets, indicating the suitability of these sheets for the fabrication of interconnectors by a stamping process with desired channel geometry having dimensions similar to conventional channel dimensions. In addition, for a specific combination of process parameters such as blank holder force and lubrication, the formability can be enhanced as proven by Erichsen and cupping test results. Moreover, the formability is found to increase with increasing the sheet thickness and highly anisotropic behavior is observed. In three point bending tests, the negative springback behavior, namely spring-in, is surprisingly observed for a relatively narrow shoulder distance at all thicknesses and set angle values (θ = 90°–120°). 相似文献
77.
78.
This study examined the influence of pin spacer apparatus attachment on compact yarn quality parameters and physical properties of knitted fabrics manufactured using those 100% cotton compact yarns. Two groups of compact yarns were spun on regular compact yarn spinning frame with and without addition of pin spacer apparatus which is placed at the end of the drawing unit of regular compact yarn spinning frame. Totally eight yarns were spun at four different yarn number levels (Ne 24/1, Ne 30/1, Ne 36/1 and Ne 40/1) and two different spinning conditions (with and without pin spacer apparatus). Spun yarn types were then knitted on the industrial sized plain knitting machine. Knitted fabrics were used in the greige and dyed form to evaluate their bursting strength (kPa), dimensional change, abrasion related mass loss (%), pilling resistance, air permeability (mm/s) and colour difference. Test results were then statistically evaluated and influence of pin spacer attachment on yarn quality parameters and fabric properties was determined. In the frame of this experimental work, attachment of pin spacer apparatus improved compact yarn characteristics especially at yarn evenness, imperfection and hairiness values. In case of knitted fabric properties, it was found that pin spacer apparatus attached compact yarn utilization significantly improved air permeability properties of knitted fabrics. 相似文献
79.
80.
Inhibitory Effects of the Active Components Isolated from Satureja Boissieri Hausskn. Ex Boiss. On Human Cervical Cancer Cell Line 下载免费PDF全文