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A neutral state colorless phosphazene/carbazole hybride dendron and its electrochromic device application
(Elsevier Science Sa, 2015) Sezgin, Meryem; Özay, Özgür; Koyuncu, Sermet; Ozay, Hava; Koyuncu, Fatma Baycan
In this work, a new phosphazene/carbazole hybride dendron (PC) was synthesized and then directly coated onto ITO glass surface to provide a dendritic polymer network, poly-(PC), by using potentiodynamic electrochemical process. Structure of dendron was identified by FT-IR, H-1 and P-31 NMR, and also TOF-MS analyses. The optical and electrochemical properties of PC and its electrochemical crosslinked product were investigated by using UV-vis absorption, fluorescence and CV techniques. A neutral, colorless electrochromic device was constructed in the sandwich configuration [indium tin oxide (ITO)coated glass/anodically coloring material (poly-(PC))//gel electrolyte//cathodically coloring material (PEDOT)/ITO-coated glass] and revealed a short response time (about 0.5 s), high coloration efficiency (981 cm(2) C-1) and high redox stability. (C) 2015 Elsevier B.V. All rights reserved.
A New Approach to Synthesis of Highly Dispersed Gold Nanoparticles via Glucose Oxidase-Immobilized Hydrogel and Usage in The Reduction of 4-Nitrophenol
(Wiley-V C H Verlag Gmbh, 2020) Ozay, Hava; Tarimeri, Nur; Gungor, Zeynep; Demirbakan, Burcak; Ozcan, Burcu; Sezgintürk, Mustafa Kemal; Özay, Özgür
In this study, for the first time in the literature, synthesis of Au(0) nanoparticles supported by a crosslinked gel structure was performed via enzyme-mediated reduction of Au(III) ions without using any chemical reductant. In our newly-developed method, glucose oxidase enzymes immobilized in the crosslinked gelatine structure ensured simultaneous reduction of the Au(III) ions diffused within the gel to Au(0). The Au@Gel obtained was structurally characterised with TEM (Transmission electron microscopy), EDX (Energy dispersive X-ray analysis) elemental mapping, XPS (X-Ray photoelectron spectroscopy) and XRD (X-Ray Diffraction) analyses. The catalytic activity of Au(0) particles with nearly 8 nm size in the Au@Gel was investigated for the reduction of 4-nitrophenol (4-NP) as a model compound in the presence of NaBH(4)as reducing agent. The activation parameters for the reduction reaction of 4-nitrophenol in the presence of Au@Gel catalyst were determined as E-a= 30.16 kJmol(-), Delta H= 27.52 kJmol(-)and Delta S= -197.45 Jmol(-)K(-). The Au@Gel catalyst system, with good catalytic activity, simultaneously has nearly perfect reusability.
A new dual stimuli responsive hydrogel: Modeling approaches for the prediction of drug loading and release profile
(Pergamon-Elsevier Science Ltd, 2019) Ilgin, Pinar; Ozay, Hava; Özay, Özgür
In this study, N-tert-butylmaleimic acid was designed for the first time and synthesized by reaction of maleic anhydride with tert-butylamine and evaluated as a new functional monomer for preparation of new pH-responsive hydrogels. Its structure was verified with FTIR, H-1 and C-13 NMR. A new pH- and temperature-responsive hydrogel p(TBMAC-co-NIPAM), based on TBMAC and NIPAM, was successfully prepared via free-radical copolymerization technique in an aqueous solution. The chemical and structural properties of the hydrogels were identified by FTIR and SEM. The swelling properties of these hydrogels were systematically investigated according to various parameters such as time, temperature, pH and salt effects, and the results show that they are strongly influenced by the content of TBMAC and exhibit strong pH, temperature and salinity sensitivity. In addition, swelling kinetics and water diffusion mechanisms in hydrogels were discussed. In addition, in vitro drug release studies were performed in simulated gastric, isotonic serum and intestinal fluid at two different temperatures (23 and 37 degrees C) by taking R6G as a model drug. Drug loading results were investigated with various isotherm models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich. Various kinetic models such as zero-order, first-order, Higuchi model and Korsmeyer-Peppas models were applied to determine the drug release mechanism. The results indicated that drug release involves non-Fickian transport mechanism. These results suggest that this new pH - and thermo-responsive hydrogel may be used to improve sustained release of drugs.
A novel hydrogel containing thioether group as selective support material for preparation of gold nanoparticles: Synthesis and catalytic applications
(Elsevier Science Bv, 2019) Ilgin, Pinar; Özay, Özgür; Ozay, Hava
In this study, firstly N-metacrylamido thiomorpholine containing thioether group was synthesized as monomer. Then, p(AAm-co-MTM) hydrogels were prepared from the redox polymerization of acrylamide and N-metacrylamido thiomorpholine as a selective support material. p(AAm-co-MTM) hydrogel-gold nanoparticles were obtained as a result of the reduction of the selectively absorbed gold(III) ions by the hydrogel network using NaBH 4 as reducing agent. All materials were characterized using techniques such as SEM, EDX, TEM and XRD analysis. It was determined that p(AAm-co-MTM)-Au composite material has high catalytic activity for the reduction of 4-nitrophenol. The activation parameters of the reduction reaction of 4-nitrophenol using NaBH4 in the presence of p(AAm-co-MTM)-Au catalyst were calculated as E-a = 38.80 kJ/mol, Delta H-# = 36.16 kJ/mol and Delta S-# = - 161.37 J/mol K.
A simple azoquinoline based highly selective colorimetric sensor for CN- anion in aqueous media
(Canadian Science Publishing, Nrc Research Press, 2017) Koc, Omer Kaan; Ozay, Hava
Azoquinoline based sensor AZQ was designed and synthesized as a new molecular ion sensor containing an azo group in its structure. The structural characterization of AZQ was carried out using FTIR, NMR, mass, and elemental analysis. Then, the interaction of AZQ with anions was observed visually and UV-vis measurements were made in EtOH/H2O (1:1, v/v) solvent mixture. As a result of this investigation, it was determined that AZQ is a fast and highly selective sensor for CN-ions. The solution colour of AZQ changed from light yellow to orange only in the presence of CN-ions. The limit of detection of AZQ was calculated as 2.6 mu mol/L from anion titration experiments. Also, to identify the interaction mechanism of AZQ with CN-ions, H-1 NMR spectra of AZQ in the presence of CN-anions were recorded and the structure was proposed for AZQ-CN- host-guest complex.
Adsorption of Malachite Green from Aqueous Solution Using Hydroxyethyl Starch Hydrogel Improved by Graphene Oxide
(Springer, 2022) Onder, Alper; Kivanc, Mehmet Riza; Durmus, Secil; Ilgin, Pinar; Ozay, Hava; Özay, Özgür
This study is the first report of the preparation of hydroxyethyl starch (HES) hydrogels rapidly crosslinked with divinyl sulfone in a single step and single pot. To develop the physical and chemical features of hydrogels, Graphene oxide (GO) nanoparticles were combined with the crosslinked HES. In addition to swelling studies, structural characterization of the samples was conducted with a scanning electron microscope (SEM) and transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis and thermogravimetric analysis (TGA). For the removal of malachite green model dye by GO-HES, the effects of GO content, solution concentration, temperature, contact duration, dosage and pH on varying adsorption features were researched. Additionally, adsorption isotherms, kinetic and thermodynamic systematics were analyzed. The maximum adsorption capacity of GO-HES composite hydrogel was found to be 89.3 mg/g for Langmuir isotherm. The possible adsorption mechanism of the composite hydrogels for malachite green dye involved electrostatic, hydrogen bonding, and pi-pi interactions. In addition to reasonable cost and simple synthesis method, the prepared composite materials have potential use in wastewater treatment as adsorbents for the removal of dye from aqueous solutions due to efficient adsorption capacity.
Ag(0) nanocatalyst stabilized with networks of p(SPA-co-AMPS) for the hydrogen generation process from ethylenediamine bisborane hydrolysis
(Pergamon-Elsevier Science Ltd, 2020) Durgut, Sinem; Ozay, Hava
In this study, the hydrogen generation from the catalytic hydrolysis of the ethylenediamine bisborane (EDAB) was performed. For this purpose, the p(sulfopropyl acrylate potassium salt-co-2-acrylamido-2-methylpropansulfonic acid sodium salt)@Ag(0) (p(SPA-co-AMPS)@Ag) catalyst was prepared. Later the p(SPA-co-AMPS)@Ag containing Ag(0) particles with nanodimensions was used as catalyst in EDAB hydrolysis. Our study is the first in the literature from this aspect, and investigated in detail the effect of catalyst amount, reactive concentration, temperature and dry or swollen nature of the catalyst on the EDAB hydrolysis. At the end of the reaction series, the hydrolysis reaction of EDAB with p(SPA-co-AMPS)@Ag catalyst was determined to have activation energy (E-a) of 43.24 kJmol(-1). Additionally, the turn over frequency (TOF) was 0.560 mol H-2(mol Ag(0).min)(-1) at 30 degrees C. The p(SPA-co-AMPS)@Ag catalyst had perfect reusability with 95% of initial activity after the 5th use for the hydrogen generation from EDAB. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
An innovative approach to use zeolite as crosslinker for synthesis of p(HEMA-co-NIPAM) hydrogel
(Springer Wien, 2022) Durmus, Secil; Yilmaz, Betul; Onder, Alper; Ilgin, Pinar; Ozay, Hava; Özay, Özgür
This study introduced a modified method to synthesize organic-inorganic hybrid crosslinker based on zeolite. First, zeolite nanoparticles were modified with 3-(aminopropyl)trimethoxysilane. Then, the amine-functionalized zeolite has been reacted with the glycidyl methacrylate via an epoxide ring-opening mechanism. The vinyl-functionalized zeolite was applied as a crosslinking agent to form hydrogel network. A novel temperature-sensitive nanocomposite hydrogel was prepared by crosslinking N-isopropylacrylamide as a comonomer and 2-hydroxyethyl methacrylate as a monomer with free-radical polymerization. Results showed that p(2-hydroxyethyl methacrylate-co-N-isopropylacrylamide)/vinyl-functionalized zeolite nanocomposite hydrogel has a chemically crosslinked and porous network structure. The content of crosslinker and monomers had obvious effects on the swelling ratio of the nanocomposite hydrogel. The temperature and salt-sensitive behavior of the hydrogels are also discussed. We offer a multifunctional crosslinker for preparing sensitive materials that can serve biomedical or environmental applications.
Comparison Study of Low Cost Fly Ash Supported Cu, Co and Ni Metal Catalyst Systems for the Reduction of 4-Nitrophenol
(Amer Scientific Publishers, 2013) Ozay, Hava
Low cost fly ash-supported Cu, Co and Ni metal catalyst systems were prepared by the reduction of Cu2+, Co2+ and Ni2+ ion adsorbed raw fly ash particles by using sodium borohydride (NaBH4) as reducing agent in aqueous media and were used in catalytic studies. For this purpose firstly raw fly ash particles were characterized by scanning electron microscopy (SEM), particle size analysis, X-ray diffractometry (XRD), X-ray fluorescence spectrometry (XRF) and inductive coupled plasma-optic emission spectroscopy. Afterwards, the prepared fly ash-metal composite materials were used as catalyst for the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 aqueous solution. The reduction studies were completed at four different temperatures (20-50 degrees C). The activation parameters were calculated from the obtained rate constants for the four different temperatures (20-50 degrees C). The activation energies for the reduction reaction of 4-NP utilizing fly ash-Cu, Co and Ni composites as catalysts were 26.81 kJ mol(-1), 32.89 kJ mol(-1) and 34.98 kJ mol(-1) respectively. The total turnover frequency (TOF) for fly ash-Cu, Co and Ni composite catalysts were 0.278 mol 4-NP (nnol Cu)(-1) (min)(-1), 0.033 mol 4-NP (mol Co)(-1) (min)(-1) and 0.024 mol 4-NP (mol Ni)(-1) (min)(-1), respectively.
Copper and cobalt complexes of octadentate azamacrocycles: Spectrophotometric titration, stopped-flow kinetics and crystallographic study
(2011) Ozay, Hava; Baran, Yakup; Ishii, Youichi
Details of complex formation kinetics are reported for tetrakis(2- hydroxyethyl) substituted cyclen (L 1) and cyclam (L 2) with Cu(II) and Co(II). Stopped-flow kinetics and spectroscopic titration methods were employed for the activation parameters and stability constants, respectively. X-ray studies revealed that the pendant 2-hydroxyethyl groups are not equivalent: two are folded over the macrocycle and maintained by intramolecular hydrogen bonds while the others are extended and pointed away from the macrocyclic cavity. Complex formation kinetics and spectroscopic titration were performed in aqueous acidic buffer solutions. Thermodynamic and kinetic parameters revealed that the ring size of the macrocycles plays an extremely important role for each metal ion studied. Stopped-flow kinetic measurements explained the mechanism of the complex formation process of both Cu(II) and Co(II) which proceed in outer-sphere interactions with ligands. There are two steps in the complex formation of the system studied. The initial step is a second order reaction between the metal ion and macrocycle with a second order rate constant. © 2011 Elsevier B.V.
Dual use of colorimetric sensor and selective copper removal from aqueous media with novel p(HEMA-co-TACYC) hydrogels: Cyclen derivative as both monomer and crosslinker
(Elsevier, 2020) Ozay, Hava; Gungor, Zeynep; Yilmaz, Betul; Ilgin, Pinar; Özay, Özgür
Within the scope of this study, p(2-hydroxyethyl methacrylate-co-tetraacrylic cyclen) (p(HEMA-co-TACYC)) hydrogels were synthesized for the first time in the literature using a tetraacrylic cyclen (TACYC) as both functional monomer and crosslinker. The hydrogels designed especially for Cu2+ ions showed colorimetric sensor behavior selective for Cu2+ ions in all aqueous media (deionized, tap, river and sea water) and in metal ion mixtures. The p(HEMA-co-TACYC) hydrogels forming a stable complex with Cu2+ ions simultaneously showed properties of being a good adsorbent material. The hydrogels have reuse capacity as both sensor and adsorbent material. Changing the amount of TACYC in the hydrogel structure changes the maximum adsorption capacity for Cu2+ ions. The Langmuir and Freundlich adsorption constants for Cu2+ ion adsorption of the hydrogels, acting as selective adsorbent in all aqueous media and metal ion mixtures, were determined.
Graphene nanoplate incorporated Gelatin/poly(2-(Acryloyloxy)ethyl trimethylammonium chloride) composites hydrogel for highly effective removal of Alizarin Red S from aqueous solution
(Springer, 2022) Ozsoy, Fatma; Ozdilek, Batuhan; Onder, Alper; Ilgin, Pinar; Ozay, Hava; Özay, Özgür
The increasing water pollution day by day has increased the importance of developing new adsorbent materials. In this study, composite hydrogel containing gelatin, [2-(Acryloyloxy)ethyl] trimethylammonium chloride (AETAC) and Graphene Nanoplate (GNPt) was developed as an adsorbent for the removal of dyes from wastewater. Fourier Transform Infrared Spectrophotometer, Scanning Electron Microscope, X-Ray Diffractometer results confirmed the crosslinked polymer structure of Gelatin/p(AETAC)/GNPt composite hydrogel (Gel 5). In addition, equilibrium swelling ratio, which is a parameter affecting the adsorption behavior, was 48.22 g(water) /g(gel). The adsorption behavior of Alizarin Red S anionic dyestuff on composite hydrogel from aqueous solutions was investigated under various experimental conditions such as initial dye concentration of solution, amount of adsorbent, contact time, pH of solution, temperature of solution. ARS dye adsorption on composite hydrogel is consistent with Pseudo-Second-Order kinetic model and Langmuir isotherm with max adsorption capacity of 649.35 mg/g. The composite hydrogel with high mechanical strength has high dye removal ability in the ranging pH from 4 to 8. Therefore, it can be said that Gelatin/p(AETAC)/GNPt composite hydrogel has a substantial potential for the removal of anionic dyes from wastewater in a wide pH range.
Highly effective palladium nanocatalyst supported in polymeric networks for the catalytic hydrogen generation from borane-morpholine complex
(Wiley-V C H Verlag Gmbh, 2022) Ozay, Hava; Tercan, Melek; Özay, Özgür; Ilgin, Pinar
This study describes the synthesis of Pd-0 nanoparticles supported in hydrogel networks (SPVI@Pd) and their catalytic activity for the borane-morpholine complex (MB) hydrolysis reaction. In this respect, while our study is one of the limited number of studies reported for the catalytic hydrolysis of MB, it is the first study in which Pd-0 nanoparticles supported in hydrogel networks were used in the catalytic hydrolysis of MB. The synthesized Pd-0 nanoparticles were characterized using structural and morphological characterization techniques and as a result of these analyses, the sizes of Pd-0 nanoparticles were determined average as 7.01 +/- 1.90 nm. The E-a value and the turnover frequency (TOF) value at 303 K for the SPVI@Pd-3.0 catalyzed MB hydrolysis reaction were determined as 49.46 kJ/mol and 187.74 mol(H2)center dot mol(pd)(-1).h(-1). It was also observed that the SPVI@Pd-3.0 catalyst had good catalytic activity even after eight cycles.
Hydrogen production via copper nanocatalysts stabilized by cyclen derivative hydrogel networks from the hydrolysis of ammonia borane and ethylenediamine bisborane
(Pergamon-Elsevier Science Ltd, 2020) Ozay, Hava; Ilgin, Pinar; Özay, Özgür
In this study, p(AAm-co-TACYC) hydrogels were synthesized using TACYC crosslinker. The p(AAm-co-TACYC) hydrogel was used for preparation of Cu(0) nanoparticles as support material. The p(AAm-co-TACYC)@Cu was prepared by chemical reduction of Cu2+ ions in the p(AAm-co-TACYC) networks and was structurally characterized in detail. Later the catalytic activity of p(AAm-co-TACYC)@Cu was investigated for hydrogen production from AB and EDAB hydrolysis. Detailed kinetic studies were performed for both hydrogen storage materials. The p(AAm-co-TACYC)@Cu was a more active catalyst for the EDAB hydrolysis reaction. The E-a values of p(AAm-co-TACYC)@Cu for the AB and EDAB hydrolysis reactions were determined as 68.36 kJ mol(-1) and 39.07 kJ mol(-1), respectively. In addition to the perfect catalytic activity of p(AAm-co-TACYC)@Cu, it had good reusability. After ten consecutive uses for AB and EDAB hydrolysis, the p(AAm-co-TACYC)@Cu still had 88% and 85% of initial activity, respectively. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Novel hexacentered phosphazene compound as selective Fe3+ ions sensor with high quantum yield: Synthesis and application
(Taylor & Francis Ltd, 2019) Özay, Özgür; Ozay, Hava
A novel compound hexa-rhodamine substituted phosphazene (HRP) with six active centers on a cyclotriphosphazene ring was synthesized using the alkyne-azide click reaction. The structure of HRP was characterized using spectroscopic techniques. The optical sensor properties of HRP for metal ions were investigated using UV-Vis and Fluorescence spectroscopy. It was determined that HRP is a selective sensor with colorimetric and fluorescent properties for Fe3+ ions. Limit of detection (LOD) of HRP was determined as 6.94 x 10(-9) M using fluorescence intensities in the presence of different concentrations of Fe3+ ions. It was determined that HRP-Fe3+ complex has high quantum yield and excellent photostability.
Novel hexapodal triazole linked to a cyclophosphazene core rhodamine-based chemosensor for selective determination of Hg2+ ions
(Springer/Plenum Publishers, 2014) Ozay, Hava; Kagit, Reyhan; Yildirim, Mehmet; Yesilot, Serkan; Özay, Özgür
The hexapodal Rhodamine B derivative compound 3 containing a cyclotriphosphazene core was synthesized and characterized by spectroscopic techniques such as FT-IR, H-1, C-13 and P-31 NMR, HR-MS, MALDI MS and microanalysis. Compound 3 is a naked eye selective sensor with colorimetric and fluorescent properties for Hg2+ ions in the presence of other metal ions such as Na+, K+, Ca2+, Ba2+, Mg2+, Ag+, Mn2+, Cu2+, Ni2+, Co2+, Pb2+, Cd2+, Zn2+, Fe2+, Fe3+, and Cr3+. The optical sensor properties of compound 3 were investigated using UV-vis and fluorescence spectroscopy. The lowest detection limit of compound 3 was determined as 3.76 x 10(-9) M (0.75 ppb) for Hg2+ ions. The stoichiometry of compound 3-Hg2+ complex was found to be 1:3 (ligand/metal ion). The reusable test strip was improved by the immobilization of compound 3 into a hydrogel network. The reusability of the sensor and test strip was tested with S2- ion solutions.
Pd nanoreactors with excellent catalytic activity supported in p(SPA) hydrogel networks for hydrogen production from ethylenediamine bisborane
(Pergamon-Elsevier Science Ltd, 2020) Ozay, Hava; Ilgin, Pinar; Sezgintürk, Mustafa Kemal; Özay, Özgür
In this study we synthesized Pd(0) nanoparticles with nearly 20 nm size using p(3-Sulfopropyl acrylate) (p(SPA)) hydrogel as support material. Pd@p(SPA) containing Pd (0) nanoparticles with nearly homogeneous distribution was characterized structurally with TEM, XRD, XPS and elemental mapping. The Pd@p(SPA) was used for the catalytic hydrolysis reaction of ethylenediamine bisborane (EDAB). A series of reactions were completed by changing parameters like the catalyst amount, EDAB concentration and temperature. The Pd@p(SPA) was determined to have turnover frequency (TOF) value of 354 mol H-2.molPd(0)(-1).h(-1) at 30 degrees C for the hydrolysis reaction of EDAB. The activation parameters for the reaction were E-a = 67.79 kJmo1(-1), Delta H-# = 65.15 kJmol(-1) and Delta S-# = -103.26 Jmol(-1) K-1. Pd@p(SPA) also had excellent reusability for the hydrolysis of EDAB. Even after ten reaction cycles, Pd@p(SPA) had 87% catalytic activity. At the same time after four months of storage in an aqueous medium, Pd@p(SPA) still had 100% catalytic activity. (C) 2020 Elsevier Ltd. All rights reserved.
Phosphazene Based Multicentered Naked-Eye Fluorescent Sensor with High Selectivity for Fe3+ Ions
(Amer Chemical Soc, 2014) Kagit, Reyhan; Yildirim, Mehmet; Özay, Özgür; Yesilot, Serkan; Ozay, Hava
A novel on/off fluorescent rhodamine-based hexapodal Fe3+ probe (L) containing a cyclotriphosphazene core was synthesized by an azide-alkyne click-reaction. The synthesized compounds (1-5 and L) were characterized by FT-IR; H-1, C-13, and P-31 NMR; and MALDI MS spectrometry. The optical sensor features for the Fe3+ complex of L were investigated by UV-vis and fluorescence spectroscopy. The stoichiometry of L-Fe3+ complex was found to be 1:3 (ligand/metal ion), and the detection limit of L was determined as 4.8 mu M (0.27 mg L-1) for Fe3+ ions. The reusability of the sensor was tested by the addition of ethylenediamine to L-Fe3+ complex solutions followed by the addition of Fe3+ solution.
Removal of anionic dyes from aqueous media by using a novel high positively charged hydrogel with high capacity
(Taylor & Francis Inc, 2022) Kivanc, Mehmet Riza; Özay, Özgür; Ozay, Hava; Ilgin, Pinar
Poly((methacryloylamino)propyl trimethylammonium chloride-co-vinylimidazole) (p(MAPTAC-co-VI)) hydrogels were synthesized through free radical polymerization of 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC) and 1-vinylimidazole (VI) in aqueous solutions with ammonium persulfate (APS) used as initiator and N,N '-methylenebis(acrylamide) (MBA) as the crosslinking agent. By modifying with HCl, the positive charge density on the hydrogel network structure was increased and quaternized hydrogels (p(MAPTAC-co-VI)-q) were obtained. Traditional swelling and spectrophotometric characterization techniques were used to gain a better understanding of the performance of cationic hydrogels for the removal of anionic dyes. FTIR, SEM, and EDX confirmed the structure of the hydrogel before and after the adsorption process. Later, dye adsorption performance of these p(MAPTAC-co-VI)-q hydrogels was investigated under different adsorption conditions, including initial concentration, temperature, pH values of dye solutions, and adsorption contact time, adsorbent dosage and in real water samples. Various isotherm and kinetic models of dye adsorption by the hydrogel were also studied and the experimental adsorption followed a pseudo-second order model and fitted the Langmuir isotherm well. Thanks to the effective use of existing adsorption sites, high adsorption capacity was achieved for eriochrome black T (EBT) and methyl orange (MO) dyes. The values of q(max) are as follows: 1818.2 mg/g and 1449.3 mg/g, respectively. Thermodynamic parameters indicate that the process was spontaneous and endothermic. P(MAPTAC-co-VI)-q hydrogels can be used as a potential adsorbent for removal of anionic dye molecules, one of the industrial pollutants, from wastewater.
Removal of dye from aqueous medium with pH-sensitive poly [(2-(acryloyloxy)ethyl]trimethylammonium chloride-co-1-vinyl-2-pyrrolidone] cationic hydrogel
(Elsevier Sci Ltd, 2020) Onder, Alper; Ilgin, Pinar; Ozay, Hava; Özay, Özgür
In this study, p([2-(acryloyloxy)ethyl]trimethylammonium chloride-co-1-vinyl-2-pyrrolidinone) (p(AETAC-co-NVP) hydrogels containing positive charge in the structure were synthesized for the removal of anionic dyes from the aqueous media. The swelling behaviors affecting the adsorption properties of hydrogels structurally characterized by FTIR, SEM and EDX/mapping analysis were investigated. The effects of pH, dye concentration, adsorbent amount, dissolved anions and temperature on the adsorption of methyl orange (MO) and alizarin red S(AR) from aqueous media using p(AETAC-co-NVP) hydrogels were investigated. Using data obtained in adsorption studies, the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms and pseudo-first order (PFO), pseudo-second order (PSO), intra-particular diffusion, and Elovich kinetic model analyses were performed. The results showed that the p(AETAC-co-NVP) hydrogel was a good adsorbent for MO and AR anionic dyes and the adsorption process for both dyes complied with the Freundlich isotherm and PSO kinetic model. This situation indicates that the dominant mechanism for the adsorption of MO and AR dyes by the p(AETAC-co-NVP) hydrogel is strong electrostatic interactions and occurs as multilayered adsorption, not only on a planar region. Additionally, to the maximum adsorption values using p(AETAC-co-NVP) hydrogel for MO and AR dyes were reached at pH values of 7.0 and 5.0, respectively. According to all these findings, it can be said that the p (AETAC-co-NVP) hydrogel containing positivelly charged groups is a super adsorbent for adsorption of anionic dyes.

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