Search

Water pollution caused by dyes is a significant global problem. Adsorption technique is successfully applied for the removal of dyes from water. In this technique, the use of effective adsorbents is very important. Here, agar/κ-carrageenan composite hydrogel adsorbent prepared through free radical cross-linking reaction in the presence of tri (ethylene glycol) divinyl ether as a cross-linker and characterized by using FTIR, SEM and TGA measurements was used to remove Methylene Blue from water. FTIR results exhibited that electrostatic interaction and hydrogen bonding formation were the main interactions in the adsorptive removal of Methylene Blue by agar/κ-carrageenan hydrogel. Pseudo second order and Langmuir models were found to be the most suitable kinetic and isotherm models, respectively. Maximum dye adsorption capacity of 242.3 mg·g−1 was obtained at 35 °C and pH 7. Thermodynamic parameters were calculated to understand the nature of adsorption process. Different solvents were applied for the regeneration of dye adsorbed-agar/κ-carrageenan hydrogel and the most suitable solvent was determined as ethyl alcohol. The results demonstrated that agar/κ-carrageenan hydrogel is a promising adsorbent for the removal of cationic dyes from water.

In this study, carbon nanotube-based adsorbents, oxidized multi-walled carbon nanotube (OMWCNT) with non-magnetic property and OMWCNT-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites with magnetic property, having different structural and surface properties were prepared and their adsorptive properties for the removal of toxic diquat dibromide (DQ) herbicide from water by adsorption were determined in detail. For each adsorption system, the effects of initial DQ concentration, contact time and temperature on the adsorption processes were determined. Equilibrium time was found to be 300 min for DQ solutions. OMWCNT showed faster adsorption and higher maximum adsorption capacity value than magnetic adsorbents. With increasing initial herbicide concentration from 5.43 mg.L−1 to 16.3 mg.L−1, the values of initial sorption rate exhibited a decrease from 29.1 mg.g−1.min−1 to 4.28 mg.g−1.min−1 for OMWCNT-DQ system, from 1.21 mg.g−1.min−1 to 0.823 mg.g−1.min−1 for OMWCNT-Fe3O4-DQ system and from 0.674 mg.g−1.min−1 to 0.612 mg.g−1.min−1 OMWCNT-κ-carrageenan-Fe3O4 system. Maximum adsorption capacity value of OMWCNT was approximately 2.8-fold higher than magnetic OMWCNT-Fe3O4 and 5.4-fold higher than magnetic OMWCNT-κ-carrageenan-Fe3O4 at 25 °C. Adsorption kinetic and isotherm data obtained for all adsorption systems were well-fitted by pseudo second-order and Langmuir models, respectively. Thermodynamic parameters indicated that the adsorption of DQ onto carbon nanotube-based adsorbents was spontaneous and endothermic process. Furthermore, OMWCNT having the highest herbicide adsorption capacity could be regenerated and reused at least five times. This study showed that carbon nanotube-based adsorbents with magnetic and non-magnetic property were of high adsorption performance for the removal of DQ from water and could be promising adsorbent materials for the efficient removal of herbicides from wastewaters.

In this study, agar/κ-carrageenan/montmorillonite (MMT) hydrogels were prepared to examine their usability as wound dressing materials and to see the effect of MMT amount on some properties of agar/κ-carrageenan hydrogel materials. Hydrogels were characterized by SEM-EDX, TEM and DSC analyses. By increasing the MMT content within hydrogel matrix from 0% to 5%, the decomposition temperature of the hydrogel material was increased from 256.6 °C to 262.1 °C. Swelling amount of hydrogels in d -glucose solution (2682%) was found to be much higher compared with other physiological solutions such as physiological saline solution (937%), synthetic urine solution (746%) and simulated wound fluid (563%). The release studies of analgesic lidocaine hydrochloride (LDC) and antibiotic chloramphenicol (CLP) drugs from hydrogel systems demonstrated that the release amount of LDC and CLP from hydrogels could be controlled by MMT amount within hydrogel matrix. The concentrations of drugs within hydrogel sample stored at 4 °C for 6 months did not exhibit a significant change. Hydrogel materials containing CLP exhibited good antibacterial activity against E. coli and S. aureus. Cytotoxicity test results indicated that hydrogels were biocompatible with MG-63 cells. The ultimate compressive stress of agar/κ-carrageenan hydrogel with LDC and CLP and agar/κ-carrageenan/MMT hydrogel including 5% MMT with LDC and CLP was measured as 38.30 kPa and 47.70 kPa, respectively. The experimental results revealed that prepared agar/κ-carrageenan and agar/κ-carrageenan/MMT hydrogels have great potential for wound care applications.

Carvedilol is a drug used in the treatment of serious cardiovascular diseases. Therefore, the development of a new method for analyzing the therapeutic and toxic concentrations of carvedilol in hum...

In the present study, polyethyleneimine (PEI) coated superparamagnetic iron oxide nanoparticles (SPIONs) having the size of 15 nm in diameter with high magnetic saturation (60 emu/g) have been prepared by co-precipitation method. The synthesized PEI-Fe3O4 nanoparticles have been fully characterized by transmission electron microscope (TEM), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. The free amine groups on the PEI-Fe3O4 surface has been covalently functionalized with carboxymethyl cellulose (CMC) by the catalysis of N,N'-Dicyclohexylcarbodiimide (DCC) and N, N'-Dimethylpyridin-4-amine (DMAP) coupling to produce CMC-Fe3O4 nanocarriers. The prepared CMC-Fe3O4 nanocarriers have been loaded with a well-known anti-tumor drug doxorubicin (Dox) and investigated its loading and releasing profiles from the nanocarrier. The CMC acted as an excellent nanocarrier for Dox with a loading efficiency ≈ 86%. The drug releasing profile has been studied at different pH values (3.5; 5.5; and 7.4). When the pH of the release medium (phosphate buffer solution) was changed from 7.4 to 5.5 or 3.6, the drug release has been increased which indicates that the drug releasing is pH dependent. No sponsor

In this study, magnetic oxidized multiwalled carbon nanotube (OMWCNT)-κ-carrageenan-Fe3O4 nanocomposite was prepared as a new adsorbent and characterized by specific surface area, Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) measurements. Magnetic adsorbent displayed a super-paramagnetic property. Cationic Crystal Violet (CV) and anionic Reactive Black 5 (RB5) dyes were used to evaluate the adsorption ability of magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite. The effect of contact time, initial dye concentration, pH and temperature on the adsorption process was investigated. The equilibrium time was determined to be 300 min. An increase in the initial dye concentrations and the temperature of dye solutions led to an increase in the adsorption amounts of magnetic adsorbents. A decrease in the adsorption amount of CV dye was observed at low pH values, on the contrary to RB5 dye. For the adsorption of CV and RB5 dyes onto magnetic adsorbent, the adsorption kinetics followed the pseudo second-order model. Langmuir isotherm model exhibited the best fitting with the experimental isotherm data obtained at 25, 35 and 45 °C. Thermodynamic parameters showed that adsorption processes are spontaneous and endothermic. On the contrary to anionic RB5 dye, the adsorption capacity of magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite for cationic CV dye is higher than that of magnetic OMWCNT-Fe3O4 nanocomposite. Therefore, magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite may be used as a potential adsorbent to remove the cationic dyes from aqueous solution.

In the present study, for the first time, agar/κ-carrageenan and agar/κ-carrageenan/montmorillonite hydrogel materials were prepared by the free-radical crosslinking reaction of agar and κ-carrageenan in the presence of triethylene glycol divinyl ether (TEGDE) as the crosslinker agent. Here, montmorillonite (MMT) modified with phenylalanine was used as additive agent. Agar/κ-carrageenan hydrogel materials with and without MMT were characterized by FTIR, SEM and XRD analyses. The effect of free radical initiator (ammonium persulfate, APS) concentration, crosslinking agent (TEGDE) concentration, reaction temperature, polysaccharide ratio and MMT concentration on the swelling performance and surface property of hydrogel material was investigated and optimum reaction conditions were determined. Maximum equilibrium swelling capacity of the agar/κ-carrageenan hydrogel was found to be 2523 % under the optimum conditions ([APS] = 5 × 10−4 M, [TEGDE] = 5 × 10−4 M, T = 70 °C and magar:mκ-carrageenan = 1:4). An increase of the MMT content within hyrogel matrix led to a decrease in the swelling values of hydrogels. All of the hydrogels prepared in various formulations exhibited non-Fickian swelling behavior. New hydrogel materials obtained from this study could be potential candidates for biomedical applications.

In this study, carbon nanotube-based adsorbents, oxidized multi-walled carbon nanotube (OMWCNT) with non-magnetic property and OMWCNT-Fe

In this study, the adsorption of Basic Red 9 (BR9) from aqueous solution onto sepiolite was investigated. Batch experiments were carried out to determine the effects of various parameters including contact time, initial dye concentration, temperature and pH on the adsorptive removal of BR9 by sepiolite. Both kinetic and isotherm data were obtained. The kinetic and isotherm data fitted very well with the pseudo second-order kinetic model and Freundlich isotherm model, respectively. The calculated thermodynamic parameters indicated that the adsorption process was spontaneous, favorable, and exothermic. The pH of dye solution and electrostatic interaction do not play an important role on the adsorption process. The increase in the adsorption amount of BR9 led to a decrease in the zeta potential of sepiolite. The interaction between sepiolite and BR9 was investigated by Fourier transform infrared (FTIR) spectroscopy. Desorption of BR9 from spent adsorbent was studied in water, ethyl alcohol and benzyl alcohol. The highest desorption amount was obtained by benzyl alcohol. This study revealed that sepiolite could be used as effective and low-cost adsorbent in the treatment of wastewater contaminated with triarylmethane dyes.

The adsorption characteristics of toxic Basic Red 9 (BR9) onto expanded vermiculite were determined. The effect of contact time, initial dye concentration, pH and temperature on the adsorption process was investigated. The adsorption amount of BR9 onto expanded vermiculite increased with increasing initial dye concentration and pH, but it displayed a decrease with increasing temperature. The adsorption kinetics of BR9 followed the pseudo second-order model. Freundlich model provided the best fitting with the experimental adsorption isotherm data obtained at 25, 35 and 45 °C. Thermodynamic parameters indicated that the adsorption process was exothermic, occurred spontaneously and led to an increase in the randomness at the solid/solution interface. The desorption of dye from spent adsorbent was investigated in water, ethyl alcohol and benzyl alcohol. The sign of the zeta potential value of clay changed from negative to positive due to the adsorption of BR9 onto expanded vermiculite. The adsorption of BR9 led to some changes in the FTIR spectrum of adsorbent material. The maximum adsorption capacity of expanded vermiculite for BR9 adsorption is comparable with other adsorbents reported in the literature. Therefore, expanded vermiculite as an efficient and economical adsorbent may be used for the removal of dyes from wastewaters.

In this study, gelatin-based conductive hydrogels doped with carbon nanotube (CNT), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and silver (Ag) nanoparticle were prepared for use in biopotential measurements. Gelatin was modified by various concentrations of methacrylic anhydride (MA) to obtain photo-crosslinkable gelatin methacrylate (GelMA) polymer with low (21%), medium (44%) and high (78%) methacrylation degree. Chemical modification of gelatin was characterized by 1H-NMR spectroscopy. It was observed that mechanical properties of the GelMA hydrogels were highly dependent on methacrylation degree. Ultimate compressive stress of low, medium and high methacrylated gelatin hydrogel was measured to be 9.97 ± 0.14 kPa, 17.83 ± 1.73 kPa and 38.23 ± 2.96 kPa, respectively. Surface morphology of hydrogels was visualized by scanning electron microscope (SEM). The pore size of methacrylated gelatin hydrogel significantly reduced with the addition of CNT, PEDOT:PSS and Ag nanoparticle into the hydrogel matrix. The results of thermal gravimetric analysis showed that conductive hydrogels were of higher thermal stability than nonconductive GelMA hydrogel. The suitability of the prepared hydrogels for biopotential measurements was determined by equivalent impedance measurements. Impedance values of hydrogel samples were obtained in the frequency range of 20 Hz–500 Hz. The hydrogel materials prepared in this study exhibited high impedance at low frequencies and low impedance at high frequencies. The results of this study showed that the hydrogels produced with Ag nanoparticle are more suitable electrode materials for physiological measurement systems such as electrocardiography (ECG) and electroencephalography (EEG).

The effect of montmorillonite and carvacrol (as an antimicrobial agent) on the wettability, mechanical, gas barrier, thermal and color properties of methyl cellulose-based nanocomposite films was investigated. To make a comparison among the film samples, methyl cellulose (MC) film and methyl cellulose/montmorillonite (MC/MMT) and methyl cellulose/carvacrol/montmorillonite (MC/CRV/MMT) nanocomposite films with different clay concentration were prepared. The interactions among MMT, CRV and film matrix were characterized by FTIR spectroscopy. The contact angle value of MC film showed an increase of 2.5 fold with the incorporation of 60 wt.% MMT into the film matrix. The addition of clay into the film matrix increased the melting point of MC film and improved the mechanical properties of film material. The tensile stress of pure MC film exhibited an increase of 9.2 MPa in the presence of 60 wt.% MMT. With the addition of MMT into the film matrixes, water vapor permeability values of MC film and MC/CRV film were decreased by 28% and 13%, respectively. The incorporation of 60 wt.% MMT into the film matrix caused to a decrease of 47 fold for MC film and 16 fold for MC/CRV film in the oxygen permeability of film sample. The addition of CRV into MC film and MC/MMT nanocomposite films with different clay concentration reduced the mechanical strengths of film materials. Oxygen permeability values of MC film and MC/MMT nanocomposite films decreased with the inclusion of CRV into the film matrix.

In this study, magnetic oxidized multiwalled carbon nanotube (OMWCNT)-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were synthesized and used as adsorbent for the removal of Methylene Blue (MB) from aqueous solution. Magnetic nanocomposites were characterized by using of specific surface area, Fourier transform infrared, X-ray diffraction, vibrating sample magnetometry, thermal gravimetric analysis, scanning electron microscope and transmission electron microscope measurements. The results of characterization analyses exhibited that OMWCNT was successfully modified with κ-carrageenan. Furthermore, OMWCNT-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were of a super-paramagnetic property. Adsorption studies revealed that the data of adsorption kinetics and isotherm were well fitted by the pseudo second-order kinetic model and Langmuir isotherm model, respectively. The adsorption amounts of magnetic adsorbents increased with contact time and initial dye concentration. Compared with magnetic OMWCNT-Fe3O4 nanocomposite, magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite showed a better adsorption performance for the removal of MB from aqueous solution. Therefore, OMWCNT-κ-carrageenan-Fe3O4 nanocomposite may be used as a magnetic adsorbent to remove the cationic dyes from wastewaters.