Publications by authors named "Nahit Aktas"

In this study, six different organo-hydrogels containing agar-glycerol (AG)-based garlic oil (GO) were synthesized using two different crosslinkers (, methylenebisacrylamide (MBA), glutaraldehyde (GA)) to ensure the controlled release of ceftriaxone (Ce) and carboplatin (Cp). Synthesized organo-hydrogels were characterized by FT-IR. Afterward, swelling behaviors were investigated in DI, tap water, ethanol, acetone, ethanol/DI water (1:1), acetone/DI water (1:1) and gasoline environments and different pH.

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In this study, it was aimed to investigate the synthesis, characterization and drug release behaviors of organo-hydrogels containing pH-sensitive Agar (A), Glycerol (G), Sweet Almond oil (Wu et al. in J Mol Struct 882:107-115, 2008). Organo-hydrogels, which contained Agar, Glycerol and different amounts of Sweet Almond oil, were synthesized via the free-radical polymerization reaction with emulsion technique using glutaraldehyde or methylene bis acrylamide crosslinkers.

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The very recent Covid-19 pandemic has made the need to understand biocompatible polymers as support material in drug delivery systems and controlled release clearer, especially for organo-hydrogels. This study aims to synthesize various new polymeric materials called gels, hydrogels, and organo-hydrogels according to the monomer used and to investigate their use as drug release systems. The agar-glycerol (AG) pair was used to synthesize the polymers, N, N, methylene bisacrylamide (MBA, m) and glutaraldehyde (GA, g) were used as cross-linkers and peppermint oil (PmO) was included to obtain the organo-hydrogels.

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A novel molecularly imprinted polymer was synthesized on magnetic halloysite nanotube via surface initiated reversible addition-fragmentation chain transfer polymerization in the presence of 2-aminoethylmethacrylamide, 2-Cyano-2-propyl benzodithioate, ethylene glycol dimethacrylate (EGDMA) and azobis(isobutyronitrile) for sensitive and selective spectrophotometric determination of metoclopramide in urine samples. The synthesized imprinted polymer was characterized by several surface characterization techniques and the results indicated there was a thin polymer network on the magnetic halloysite nanotube. The rebinding properties of the molecularly imprinted magnetic halloysite nanotube were also investigated in detail and the maximum adsorption capacity and imprinting factor were found to be 37.

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In this study, a highly sensitive and selective sample pretreatment procedure using molecularly imprinted silica nanoparticles was developed for the extraction and determination of quercetin in red wine samples coupled with high-performance liquid chromatography with ultraviolet detection. The imprinted silica nanoparticles were prepared in the presence of N-acryoyl-l-aspartic acid (functional monomer), quercetin (template), azobisisobutyronitrile (initiator) and methylene bisacrylamide (cross-linker) and methanol/water (porogen) via surface-initiated reversible addition-fragmentation chain transfer polymerization. Surface characterization was performed and several imprinting parameters were investigated, and the results indicated that adsorption of quercetin on the imprinted silica nanoparticles followed a pseudo-first-order adsorption isotherm with a maximum adsorption capacity at 26.

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At present, commercial pure Titanium (Ti) and microstructured pre-alloyed Titanium-Nickel (TiNi) powders are employed as a sensitive electrochemical hydrogen peroxide (HO) sensor. Surface characterization of these materials are performed by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical characterization is achieved via cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) on Ti and TiNi modified glassy carbon electrode (GCE).

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Magnetic molecularly imprinted nanoparticles were prepared through surface-initiated reversible addition fragmentation chain transfer polymerization by using metronidazole as a template. The molecularly imprinted magnetic nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The adsorption characteristics were also investigated and the kinetics of the adsorption of metronidazole on the imprinted nanoparticles were described by the second-order kinetic model with the short equilibrium adsorption time (30 min).

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In this work, microgels based on tris(2-aminoethyl) amine (TAEA) and glycerol diglycidyl ether (GDE) via simple microemulsion polymerization was prepared as p(TAEA-co-GDE) microgels were used as adsorbent for removal of dichromate (Cr (VI)) and arsenate (As (V)) ions from different aqueous environments. The p(TAEA-co-GDE) microgels were demonstrated very efficient adsorption capacity for Cr (VI), and As (V) that are 164.98 mg/g, and 123.

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Gum Arabic (GA) microgels were successfully prepared via reverse micellization method with high yield (78.5±5.0%) in 5-100μm size range using divinyl sulfone (DVS) as a crosslinker.

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From a natural polyphenol, Tannic acid (TA), poly(TA) nanoparticles were readily prepared using a single step approach with three different biocompatible crosslinkers; trimethylolpropane triglycidyl ether (TMPGDE), poly(ethylene glycol) diglycidyl ether (PEGGE), and trisodium trimetaphosphate (STMP). P(TA) particles were obtained with controllable diameters between 400 to 800nm with -25mV surface charge. The effect of synthesis conditions, such as the emulsion medium, pH values of TA solution, and the type of crosslinker, on the shape, size, dispersity, yield, and degradability of poly(Tannic Acid) (p(TA)) nanoparticles was systematically investigated.

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Article Synopsis
  • The study focuses on creating micron-sized poly(vinylbenzyl chloride) beads and modifying them to enhance their adsorption capabilities for contaminants.
  • The modified beads effectively removed organic dyes and heavy metal ions from water, showcasing their potential as water treatment adsorbents.
  • The adsorption process followed the Langmuir model, indicating high efficiency in removing arsenate and dichromate ions from various water sources.
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A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90°C for 2h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.

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Hydrogels are resourceful materials and can be prepared in different morphology, size, surface charge and porosity adopting different polymerization techniques and reaction conditions. The cationic poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)) microgels were synthesized by photo-initiated inverse suspension polymerization technique. These microgels were utilized as absorbents for the removal of toxic arsenate (As) from different aqueous environments.

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Cationic poly(Acrylonitril-co-Acrylamidopropyl-trimethyl Ammonium Chloride) (p(AN-co-APTMACl)) hydrogels in bulk were synthesized by using acrylonitrile (AN) and 3-acrylamidopropyl-trimethyl ammonium chloride (APTMACl) as monomers. The prepared hydrogels were exposed to amidoximation reaction to replace hydrophobic nitrile groups with hydrophilic amidoxime groups that have metal ion binding ability. Those replacements were increased the hydrogels absorption capacity for As(V) and Cr(VI).

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In this study, we report the preparation of poly(tannic acid) (p(TA)) particles by crosslinking with glycerol diglycidyl ether (GDE) and trimethylolpropane triglycidyl ether (TMPGDE). The p(TA) particles are negatively charged as obtained by the zeta potential measurements, -27mV. P(TA) particles are found to be an effective antioxidant material as 170mgL(-1) of p(TA) particle demonstrated the antioxidant equivalency of 82.

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Exploring optimum and cost-efficient medium composition for microbial growth of Candida intermedia Y-1981 yeast culture growing on whey was studied by applying a multistep response surface methodology. In the first step, Plackett-Burman (PB) design was utilized to determine the most significant fermentation medium factors on microbial growth. The medium temperature, sodium chloride and lactose concentrations were determined as the most important factors.

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4-vinyl pyridine (4-VP) based hydrogels with 2-hydroxyethylmetacrylate (HEMA) and magnetic composites were prepared and tested for use in the removal of UO(2)(2+) and Th(4+) ions from aqueous environments. It was found that the absorption of these metal ions from aqueous environments decreased with an increase in the amount of HEMA contained within p(4-VP-co-HEMA) hydrogels between 0.498 mmol for pure p(4-VP) and 0.

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p(4-vinylpyridine) (p(4-VP)) hydrogels were prepared in bulk (macro, 5 × 6 mm) and in nanosizes (370 nm) dimensions. The prepared hydrogels were used to remove organic aromatic contaminates such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), phenol (Ph) and nitrobenzene (NB) from an aqueous environment. Important parameters affecting the absorption phenomena, such as the initial concentration of the organic species and the absorbent, absorption rate, absorption capacity, pH and the temperature of the medium, were evaluated for both hydrogel sizes.

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Polymeric 4-VP (p(4-VP)) particles were synthesized in an oil-in-water microemulsion system using various amounts of ethylene glycol dimethacrylate (EGDMA) as crosslinker. The prepared p(4-VP) particles were chemically modified to obtain positively charged particles as polyelectrolytes. Furthermore, these p(4-VP) particles were used for in situ Ag and Cu metal nanoparticle syntheses to provide dual action with an additional advantage as bactericidal particles.

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A multi-step response surface methodology was successfully applied to optimize the biosorption conditions for the maximum removal of Cu(II) ions from aqueous solutions using Trametes versicolor fungi as a biosorbent. In the first step, the most effective medium factors, which are pH, temperature and initial Cu(II) concentration, on biosorption of Cu(II), were determined through Plackett-Burman Design. Then steepest accent followed by central composite design steps were utilized to evaluate the optimum biosorption conditions for the maximum Cu(II) ions removal.

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Hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were synthesized via photopolymerization technique and used for the preparation of magnetic responsive composite hydrogels. These composite hydrogels with magnetic properties were further utilized for the removal of toxic metal ions such as Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from aqueous environments. It was revealed that hydrogel networks with magnetic properties can effectively be utilized in the removal of pollutants.

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Response surface methodology (RSM) was successfully applied to enzymatic bio-transformation of 1-naphthol. The experiments were conducted in a closed system containing acetone and sodium acetate buffer, with laccase enzyme. Laccase enzyme used as catalyst was derived from Trametes versicolor (ATCC 200801).

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The electrochemical oxidation of water-based paint wastewater was investigated batch-wise in the presence of NaCl electrolyte with carbon electrodes for the first time in literature. The electrochemical treatment conditions were optimized using response surface methodology where potential difference, reaction temperature and electrolyte concentration were to be minimized while chemical oxygen demand (COD), color and turbidity removal percents and initial COD removal rate were maximized at 100% pollution load. The optimum conditions were satisfied at 35 g/L external electrolyte concentration, 30 degrees C reaction temperature and 8 V potential difference (64.

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Kluyveromyces marxianus Y-8281 yeast culture was utilized for the biological treatment of deproteinated whey wastewater in a batch system. Removal of lactose was optimized by the utilization of response surface methodology, RSM. The empirical model developed through RSM in terms of effective operational factors of medium pH, temperature, lactose and ammonia concentrations was found adequate to describe the treatment of deproteinated whey.

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Poly(catechol) was synthesized in batch runs with laccase from Trametes versicolor (ATCC 200801). The polymerization reaction was conducted in a closed, temperature controlled system containing acetone and sodium acetate buffer for pH control. The effects of the solvent mixture, monomer (catechol), enzyme, medium pH and temperature on the polymerization rate were investigated with respect to initial reaction conditions and depletion rate of dissolved oxygen in the medium.

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