A high yield of graphene oxide (GO) was chemically synthesized from graphite powder utilizing adjusted Hummer's method. The contents of acidic functional groups in GO were determined using potentiometric titration. Composite hydrogels dependent on graphene oxide/poly(2-acrylamido-2-methylpropanesulfonic acid)/polyvinyl alcohol (GO/PAMPS/PVA) were synthesized utilizing a 60Co gamma irradiation source at different doses. The synthesized graphene oxide and composite hydrogels were portrayed via X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared analysis. The morphology of composite hydrogels was characterized by scanning electron microscope. The gel % and swelling % for the prepared hydrogel demonstrated that the swelling % of hydrogel increased with raising AMPS content. Whereas the increment of GO and increasing the irradiation dose lead to a reduction in the swelling %. The influences of pH, GO percentage, initial dye concentration, the adsorbent dosage, contact time, and temperature on the adsorption of basic blue 3 dye were evaluated and the adsorption capacity was 194.6 mg/g at optimum conditions; pH = 6, GO/PAMPS/PVA composite hydrogels with 5 wt% of GO, initial dye concentration = 200 mg/L, adsorbent dose = 0.1 g, solution volume = 50 mL after 360 min at room temperature (25°C). The adsorption of dye onto the GO/PAMPS/PVA composite hydrogels follows Pseudo-second-order adsorption kinetics, fits the Freundlich adsorption isotherm model. 相似文献
Graphene oxide (GO)/poly(vinyl alcohol) (PVA) hydrogel (PGOH), which possesses good tensile and reusable absorption properties, has been prepared by the freezing–thawing method. The presence of GO visibly decreases the swelling ratio of PGOH and significantly enhances the tensile properties of PGOH due to the formation of hydrogen bonds between the GO and PVA. The maximum tensile strength and the equilibrium adsorption capacity of methylene blue (MB) of PGOH with 0.5?wt-% GO (PGOH-0.5) is found to be 15, being 4.1 times higher than that of pure PVA hydrogel. The spontaneous adsorption obeys the intraparticle diffusion kinetic model. In addition, PGOH-0.5 exhibits a promising cycling absorption performance. The 1st and 5th cycle of dye removal for PGOH-0.5 reached to 92 and 70%, respectively. Such enhancement in adsorption can be attributed to π–π stacking and strong electrostatic attraction between GO and MB. 相似文献
ABSTRACTPoly (vinyl alcohol)/graphene oxide (PVA/GO) gamma irradiated nanocomposite films and hydrogels were prepared. In composite films, GO was initially irradiated by gamma ray in order to improve interactions between GO and PVA. The film containing 1?wt-% GO was very strong where tensile modulus and tensile yield strength were 45 and 115% higher than those of pure PVA. In the second set of experiments PVA/GO hydrogels were made by irradiating PVA/GO suspensions by gamma ray at various doses. It was an interesting finding that GO increased the gel portion of hydrogels through contribution of H-bonds between PVA and GO. The hydrogels prepared at 20?kGy had remarkable water swelling ratio that reached as high as 20 at water temperature of 80°C. The hydrogel metal ion adsorption capability was tested on Cu2+ ions. It was shown that the GO contributed significantly to the adsorption capacity of PVA hydrogels. 相似文献
In this study, swelling behavior of polyelectrolyte poly(hydroxamic acid) (PHA) hydrogels have been investigated in aqueous thiazin dye solutions. PHA hydrogels were prepared by free radical polymerizations of acrylamide with some cross-linkers such as N,N′ methylenebisacrylamide (NBisA) and ethylene glycol dimethacrylate (EGDMA); then they were used in experiments on swelling and diffusion of some water-soluble cationic dyes such as methylene blue (MB), thionin (T), and toluidin blue (TB). Swelling experiments were performed in water at 25°C, gravimetrically. The equilibrium swelling percent (S%) values of PHA hydrogels were calculated as 238–2705%. Some swelling kinetic parameters such as initial swelling rate, swelling rate constant, and maximum (theoretical) swelling percent were found. Diffusional behavior of dye solutions was investigated. Dye diffusion into hydrogels was found to be non-Fickian in character. Diffusion exponent (n) is over 0.50. For sorption of thiazin cationic dyes, MB, T, and TB to PHA hydrogels were studied by batch sorption technique at 25°C. PHA hydrogels in the dye solutions showed the dark coloration. In the experiments of the adsorption, S-type adsorption in the Giles classification system was found. 相似文献
Different amounts of graphene oxide (GO) were incorporated to N,N-dimethylaminoethyl methacrylate (DMAEMA), fabricating a series of pH and temperature dual sensitive PDMAEMA/GO hybrid hydrogels by in situ polymerization. Their microscopic network structures as well as swelling properties and Cr(VI) adsorption were characterized. The equilibrium swelling ratios (ESR) of hydrogels increased significantly with 0.5 wt% GO feeding of DMAEMA amount, and then decreased with further GO loading increasing. All hydrogels showed obvious deswelling when pH value of swelling mediums increased from 5 to 10 gradually. At pH 7, hydrogels revealed slight ESR increment with temperature up to 50 °C, above which obvious deswelling occurred. In pH 8 buffer, 0.5 wt% of GO loading triggered lower critical solution temperature (LCST) to decrease by 3 °C, and 2–7 °C increment was observed when 1–6 wt% of GO was loaded, as compared with that of GO-free PDMAEMA hydrogel. Cr(VI) adsorption of hydrogels was also improved by the introduction of GO to some extent, and the maximum Cr(VI) adsorption of 180 mg/g was realized, indicating that the obtained PDMAEMA/GO hybrid hydrogels possess excellent adsorption performance. 相似文献
A series of hybrid hydrogels based on poly(vinyl alcohol) (PVA)/agar/poly(ethylene glycol) (PEG) prepared by a solution casting method using e‐beam irradiation are investigated to determine the effect of agar and PEG content (1, 2, and 4 wt%) on their physicomechanical and rheological properties. The gel content of the hydrogels decreases with increasing agar and PEG contents. The equilibrium swelling of PVA hydrogel decreases on blending with agar while adding PEG to PVA/agar increases the swelling by about 400%. No obvious change in the dehydration behavior of the hybrid hydrogels is observed on changing agar and PEG contents. The solid‐like rheological behavior of the hydrogels is not significantly affected by agar content, while it approaches a liquid‐like behavior at high PEG loading. The tensile strength of the hybrid hydrogels is improved by increasing agar content, while its elongation‐at‐break is decreased. On the other hand, the opposite results are found regarding the influence of PEG and its content on the mechanical properties of the hybrid hydrogels.
In this study, removal of methylene blue (MB) from aqueous solution by poly(AMPS-co-IA) hydrogels was examined by batch equilibration technique. The effects of monomer ratio, concentration of initiator and
crosslinker, pH, adsorption time, initial dye concentration and adsorption temperature on the removal of MB were studied.
The results show that the removal of MB was highly effected by preparation conditions of hydrogel. The maximum removal was
observed at 10/90 IA/AMPS monomer ratio, 1.0% KPS, and 10.0% MBAAm concentrations. Removal of MB was strongly affected by
pH. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied. It was concluded that adsorption
of MB on hydrogel followed pseudo-second-order kinetics. It was found that the adsorption isotherm of the MB fit Langmuir-type
isotherms. From the Langmuir equation, the adsorption capacity was found as 1,000 mg/g for MB dye. Thermodynamic parameters
suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. Ten adsorption—desorption
cycles demonstrated that the hydrogels were suitable for repeated use without considerable change in adsorption capacity.
The results revealed that this hydrogels have potential to be used as an adsorbent for the removal of MB from aqueous solution. 相似文献