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Öğe Adsorption of phenazine dyes using poly(hydroxamic acid) hydrogels from aqueous solutions(WILEY, 2018) Saraydin, Dursun; Isikver, Yasemin; Karadag, ErdenerSwelling and adsorption properties of poly(hydroxamic acid), (PHA) hydrogels in aqueous solutions of some phenazine dyes such as Neutral Red, Safranin T, and Janus Green have been investigated. PHA hydrogels containing N,N methylenebisacrylamide or ethyleneglycoldimethacrylate were used in experiments on swelling, diffusion and adsorption of the dyes. The equilibrium swelling (S-eq) values of PHA hydrogels in aqueous solutions of the phenazine dyes were calculated as 2.16-33.25 g g(-1). Swelling kinetic parameters such as initial swelling rate, swelling rate constant, and maximum swelling were found. Dye diffusion into hydrogels was found to be non-Fickian in character. Diffusion coefficients are ranged 1.32 x 10(-6) cm(2) s(-1) - 44.70 x 10(-6) cm(2) s(-1). Adsorption of the phenazine dyes onto PHA hydrogels was studied by batch technique. PHA hydrogels in the phenazine dye solutions showed the dark coloration. The data was found that Freundlich isotherm model fits. According the Freundlich constants, the adsorption isotherms are of S-type in Giles classification. All swelling and binding parameters for PHA-EGDMA were found to be higher than those for PHA-NNMBA. The type of crosslinker influenced the swelling, binding, and sorption more than the type of dye. Finally, it can be said that PHA hydrogels may be used a sorbent for removal of dyes. POLYM. ENG. SCI., 58:310-318, 2018. (c) 2017 Society of Plastics EngineersÖğe An Experimental and Computational Evaluation of the Interaction Between Intelligent Ampholyte Acrylamide/Acrylic Acid/2-(Acryloyloxy)ethyl Trimethylammonium Chloride Hydrogel and Dyes(Springer, 2024) Isikver, Yasemin; Saraydin, Dursun; Karakus, NihatNovel intelligent ampholyte hydrogel (IAH) was prepared by a free radical solution redox polymerization of acrylamide, acrylic acid, 2-(acryloyloxy)ethyl trimethylammonium chloride as monomers, and ethylene glycol dimethacrylate as crosslinker. Spectroscopic, thermal, and surface properties of IAH were performed using ATR/FTIR, molecular electrostatic potential maps, TGA and DSC. Swelling studies were performed at increasing pH and temperature. IAH has been identified as intelligent and ampholyte. Cavity sizes of IAH were calculated from SEM photographs by digital image analysis method. Due to the large cavities of IAH, this hydrogel was used for dye sorption. The binding of carminic acid to IAH was L-type according to the Giles classification system, while crystal violet and methyl violet were S-type. Binding parameters of dyes such as binding constant, monolayer coverage, and maximum fractional occupancy were calculated from the Langmuir model or Saraydin model. It was observed that the binding between the dyes used and the IAH was realized by electrostatic interaction, and the hydrogen bonds in the carminic acid increased this bonding. This study could be a pioneering model for the preparation of potential and effective intelligent ampholyte hydrogels for the removal of both anionic and cationic dyes from aquatic environments by electrostatic interaction/H-bonding.Öğe Bio-based Iota-Carrageenan-g-(acrylamide-co-maleic Acid) Smart Graft Hydrogels with Different Crosslinkers and Their Interaction with Uranyl Ions(Springer, 2024) Isikver, Yasemin; Saraydin, Dursun; Sarikaya, cagla NurIn this study, novel smart graft hydrogels (SGHs) were prepared by simultaneous grafting/crosslinking of acrylamide and maleic acid onto iota-carrageenan (CR) in the presence of N,N '-methylenebisacrylamide or 1,4-butanediol diacrylate crosslinkers. The SGHs were characterized by FTIR, SEM, TG, DSC analysis and swelling studies. The sizes of the cavities in the SGHs were determined by digital image analysis using micrographs from the SEM. The average cavity diameters in SGHs are around 10 to 12 mu m and have a heterogeneous distribution. The adsorption of uranyl ion on SGHs was investigated by spectroscopic, kinetic and equilibrium studies. The accuracy of the pseudo-first and pseudo-second-order kinetic models applied to the swelling and adsorption properties of the hydrogels were evaluated by correlation coefficient (R2), mean bias error (MBE), root mean square error (RMSE), reduced chi-square (chi 2) and t-statistic model. The swelling and adsorption kinetics of the hydrogels were found to be consistent with the pseudo-second-order model. The adsorption isotherms of uranyl ion on SGHs were found to be L-type according to the Giles isotherm classification. Freundlich and Langmuir models were applied to these isotherms and adsorption parameters were calculated. From the Langmuir model, the monolayer adsorption capacities of SGH-N and SGH-B were calculated to be 162 and 167 mg g-1, and the maximum fractional occupancy values were calculated to be 99% and 97%, respectively. The pH-responsive swelling and adsorption behavior of the hydrogels was determined and the transition points were determined by applying Saraydin's model to the plotted curves. It was also observed that the amount of uranyl ions adsorbed increased with the increase of adsorbent mass. In conclusion, this study demonstrates that the synthesized SGHs can be used as an effective adsorbent for the removal of uranyl ions from an aqueous solution.Öğe Chemically functionalized poly(AAm-AMPSA) superadsorbent hydrogels for removal of uranyl from aqueous solutions(Springer, 2024) Isikver, Yasemin; Alkan, NihatIn the present study, anionic hydrogels, acrylamide (AAm) monomer, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) comonomer were prepared in the presence of two different cross-linkers. Then, super-anionic hydrogels were prepared by converting the amide groups of neutral AAm in anionic hydrogels to hydroxamic acid with hydroxylamine hydrochloride. The hydrogels were characterized by FTIR, SEM, TG, and DSC analyses. Uranyl adsorption in the hydrogels was investigated by spectroscopic, kinetic, and equilibrium studies. It was determined that uranyl adsorption kinetics in hydrogels were compatible with pseudo-second-order and intra-particular diffusion models. It was determined that the uranyl adsorption isotherms on the hydrogels were L-type according to the Giles isotherm classification. Adsorption parameters were calculated by applying Freundlich and Langmuir models to these isotherms. In addition, it was determined that the amount of adsorbed uranyl increased with the increase in adsorbent mass, did not change with temperature, decreased in the range of pH 2-4, and increased at pH 4-7. It was observed that super-anionic hydrogels had the highest adsorption capacity among these new hydrogels. In addition, molecular electrostatic potential (MEP) mapping was performed to predict the reactive regions of the hydrogels. The results showed that the theoretical and experimental data of hydrogels are in agreement with each other. In conclusion, it can be said that the anionic and super-anionic hydrogels prepared in this study are unique hydrogels with fast and effective properties in removing uranyl.Öğe Environmentally Sensitive Hydrogels: N-isopropyl acrylamide/Acrylamide/Mono-, Di-, Tricarboxylic Acid Crosslinked Polymers(WILEY-BLACKWELL, 2015) Isikver, Yasemin; Saraydin, DursunEnvironmentally sensitive hydrogels responsive to various stimuli such as temperature, pH, ionic strength of the medium and the solvent were prepared by using N-isopropyl acrylamide (NIPAM), acrylamide (AAm) and monomers that have various number of carboxylic acid (XA) functionality using N,N-methylene bisacrylamide (Bis) as crosslinker. Hydrogels were prepared via free radical polymerization reaction in aqueous solution. P(NIPAAm-co-AAm) and p(NIPAAm-co-AAm)/XA hydrogels that contain monoprotic crotonic acid (CA) exhibit a lover critical solution temperature (LCST) at 28 degrees C, whereas p(NIPAAm-co-AAm)/IA (IA:itaconic acid), and P(NIPAAm-co-AAm)/ACA (ACA:acotonic acid) hydrogels exhibit a lover critical solution temperature at 30.7 degrees C and 34.4 degrees C, respectively. Spectroscopic and thermal analyses were performed for the structural and thermal characterizations of the prepared hydrogel. The swelling experiments as equilibrium swelling percentages by gravimetrically were carried out in different solvents, at different solutions temperature, pH, and ionic strengths to determine their effects on swelling characteristic of hydrogels. POLYM. ENG. SCI., 55:843-851, 2015. (c) 2014 Society of Plastics EngineersÖğe In vitro swelling studies in simulated physiological solutions and biocompatibility of NIPAM-based hydrogels with some biochemical parameters of human sera(TAYLOR & FRANCIS INC, 2017) Isikver, Yasemin; Saraydin, Dursun; Aydin, HuseyinIn modern medicine, commonly used biomaterials originating from metals, ceramics and polymers have shown biocompatibility with blood, tissues, cells, etc., in the human body. Polymeric biomaterials are usually understood as polymeric materials and articles made from them which are used in medicine, biotechnology biomedicine, bioengineering, pharmaceutical, veterinary, food industry, agriculture and related fields. In this in vitro study, swellings and the biocompatibility of environmentally sensitive N-isopropyl acrylamide-based (ES) hydrogels such as N-isopropyl acrylamide/acrylamide (ES/0), and N-isopropyl acrylamide/acrylamide/ carboxylic acids (ES/XAc) prepared by free radical polymerization in aqueous solutions has been investigated. Selected carboxylic acids for this study were acrylic, methacrylic, crotonic, itaconic, maleic, mesaconic and aconitic acid. The equilibrium swelling of the hydrogels are investigated in simulated physiological fluids or crystalloid solutions such as HCl-KCl buffer (pH = 1.1), universal buffer (pH = 5.5), phosphate buffer (pH = 7.4), urea, isotonic NaCl, isotonic KCl, 5% dextrose, 5% dextrose+isotonic NaCl, Ringer's lactate, human blood serum and human serum albumin solution at 37 degrees C. For the analysis of biocompatibility, ES hydrogels are incubated in 5 different human sera and their biocompatibilities with some biochemical parameters have been investigated for 24h at 37 degrees C. No significant differences in values before and after the test procedures have been found. It is therefore concluded that environmentally sensitive N-isopropyl acrylamide-based hydrogels are biocompatible for biochemical parameters of human sera.Öğe Poly(acrylamide-sepiolite) composite hydrogels: Preparation, swelling and dye adsorption properties(SPRINGER, 2006) Ekici, Sema; Isikver, Yasemin; Saraydin, DursunPolymer-clay hydrogel composite was prepared on the basis of polyacrylamide (PAAm) gel containing the clay mineral sepiolite. The properties of swelling and dye adsorption of poly(acrylamide-sepiolite) (AAm/Sep) composite hydrogel were investigated. The parameters of swelling and diffusion in water and dye solutions were calculated for the AAm and AAm/Sep hydrogels. It was found that the equilibrium swelling degree of obtained composite higher than that of AAm gel. Spectroscopic analysis of composite and composite-dye systems was done with FT-IR method. Adsorption of monovalent cationic dyes such as Basic Blue 12 (BB-12) Basic Blue 9 (BB-9), and Basic Violet 1 (BV-1), was studied on the composite. In the adsorption experiments, S (Sigmoidal) type for composite gel adsorption isotherms in the Giles classification system was found. Adsorption studies indicated that the amounts of adsorbed dyes on the AAm/Sep composite hydrogel were increased with following order; BB-12 > BB-9 > BV-1. The composite hydrogel may be considered as good candidate for environmental application to retain more water and dyes.Öğe Preparation and Characterization of Nicotine-Selective Hydrogels(WILEY-BLACKWELL, 2016) Isikver, Yasemin; Ecevit, TugbaIn this study, P(NIPAAm-MAm)/A, which is a new smart polymer on which the temperature sensitivity of N-isopropyl acrylamide monomer and pH sensitivities of methacrylic acid (MA) and itaconic acid (IA) monomers unite, were prepared by free radical polymerization. The influence of crosslinkers on the properties of polymer and adsorption was studied using two different crosslinkers. These new environmentally multistimuli responsive hydrogels were characterized by FTIR, TG, and DSC. In order to determine the swelling behaviors of polymers, the equilibrium swelling studies were carried out at different temperatures and pHs. With the aim of studying the usability of the prepared polymers in the adsorption of nicotine and its pharmaceutical derivatives, the effects of temperature, pH, and adsorbent mass on adsorption equilibrium were studied. (C) 2016 Society of Plastics EngineersÖğe Removal of some cationic dyes from aqueous solution by acrylamide- or 2-hydroxyethyl methacrylate-based copolymeric hydrogels(KOREAN FIBER SOC, 2017) Isikver, YaseminIn this study, anionic hydrogels were prepared using a crosslinker (N,N'-methylenebisacrylamide) through a free radical addition reaction in aqueous solutions of neutral acrylamide or 2-hydroxyethyl methacrylate monomer and anionic monomers, mesaconic acid or aconitic acid. Cationic dyes along with safranine (azine-), nile blue (oxazine-) and methylene blue (thiazine-) were selected as models of pollutants, and adsorption of these dyes onto the hydrogels was investigated. To examine the effect of concentration on adsorption, dye solutions prepared with a concentration range of 5-50 mg l (-1) and 0.1 g hydrogel at 25 A degrees C were exposed to the hydrogels until equilibrium was established. Dye adsorption onto the hydrogels was found to be an L type Giles adsorption isotherm. Monolayer sorption capacity and adsorption constant values were calculated from the Langmuir plots. To calculate R-L values, a non-dimensional analysis was used and they were always found to be 0 < R < 1. In other words, the hydrogels were favorable for adsorption of these dyes. Aqueous solutions of dyes were observed to interact with hydrogels in the following order: oxazine > azine > thiazine. Furthermore, the higher the number of carboxyl groups in the hydrogel composition, the higher the adsorbed amount of substance.Öğe STIMULI RESPONSIVE HYDROGELS: NIPAM/AAm/CARBOXYLIC ACID POLYMERS(Sciendo, 2019) Isikver, Yasemin; Saraydin, DursunStimuli-responsive hydrogels (SRH) were prepared by using monomers (i.e. N-isopropyl acrylamide; NIPAM and acrylamide; AAm), comonomers (i.e. methacrylic acid; MPA or mesaconic acid; MFA) and a crosslinker (N, N'-methylene bisacrylamide; N-Bis). SRH have been prepared by thermal free radical polymerization reaction in aqueous solution. Spectroscopic and thermal analyses such as Fourier Transform Infrared Spectroscopy, thermogravimetric analysis and differential scanning calorimetry analysis were performed for SRH characterization. The equilibrium swelling studies by gravimetrically were carried out in different solvents, at the solutions, temperature, pH, and ionic strengths to determine their effect on swelling characteristic of the hydrogels. In addition, cycles equilibrium swelling studies were made with the solutions at different temperatures and at different pH. NIPAM/AAm hydrogel exhibits a lover critical solution temperature (LCST) at 28 degrees C, whereas NIPAM/AAm-MPA and NIPAM/AAm-MFA hydrogels exhibit a LCST at 31 C and 35 degrees C, respectively, and the LCST of NIPAM/AAm-MFA hydrogel is close to the body temperature.Öğe A Study on the Correlation Between Adsorption and Swelling for Poly(Hydroxamic Acid) Hydrogels-Triarylmethane Dyes Systems(SPRINGER/PLENUM PUBLISHERS, 2018) Saraydin, Dursun; Isikver, Yasemin; Karadag, ErdenerThe influence of crosslinker and dye type on the swelling and adsorption characteristics of poly(hydroxamic acid) (PHA) hydrogels have been investigated. PHA hydrogels with crosslinker such as N,N'-methylenebisacrylamide or ethylene glycol dimethacrylate were used in experiments on swelling, diffusion and adsorption of the triarylmethane dye such as Malachite Green, Methyl Violet 6B and Crystal Violet. The equilibrium swelling (S-e) values of PHA hydrogels in the dye solutions were calculated as 2.26-21.57 g g(-1). Some swelling, swelling kinetics, diffusional behavior and diffusional kinetics parameters were found. Diffusional behavior of the triarylmethane dye solutions was investigated. Diffusion behavior analyses determined that dye solution diffusion into hydrogels followed the anomalous Fickian behavior. It was observed that swelling characteristics of hydrogels are highly affected by the by the crosslinker type. Sorption of the triarylmethane dyes onto PHA hydrogels were studied by batch sorption technique at 25 A degrees C. PHA hydrogels in the triarylmethane dye solutions showed the dark coloration. In the experiments of the adsorption, S type adsorption in the Giles classification system were found with an adsorption mechanism well represented by the Freundlich model. It has been found that there is an increasing linear correlation between swelling and adsorption values. The adsorbed amounts of the dyes by PHA-EGM hydrogels were very high (95% of the total concentration of the dyes), whereas the dyes were adsorbed in smaller (77%) amounts by PHA-NBis hydrogels. At the end of this study, it can be said that PHA hydrogels may be used a sorbent for removal of some agents (such as organic molecules) and dye molecules.Öğe Synthesis and characterization of metal ion-imprinted polymers(INDIAN ACAD SCIENCES, 2018) Isikver, Yasemin; Baylav, SabriIn this study, ion-imprinted polymeric materials from an aqueous solution were prepared to remove metal ions (M2+) like Ni2+, Co2+, etc. To prepare ion-imprinted polymers (IIPs), acrylic acid derivatives (XA) like acrylamide (AAm), methacrylic acid and itaconic acid were chosen as monomers. Metal ions formed binary chelate complexes with the help of 8-hydroxyquinoline (8-HQ). The solution containing functional monomers and the binary complex were polymerizedwith the help of various cross-linkers [ethylene glycol dimethylacrylate (EGDMA) or trimethylpropane trimethacrylate (TMPTMA)] and the target ion was removed from this polymer through an applicable method to produce IIPs. Furthermore, the control polymers (CPs) were synthesized through the same method without using metal ion. Characterization of the polymeric materials was investigated through spectroscopic (FTIR/ATR), thermal (TGA, DSC) and surface (SEM and XRD) analyses. Functional monomers, cross-linkers and the target ion's species were changed during preparation of IIPs to observe their effect on imprinting of the target ion. Adsorption of the target ion to the prepared IIPs and the factors affecting the adsorption like concentration, pH, temperature, mass, etc. were studied.
