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.

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.

The Antioxidant Response System in Wheat Exposed to Pesticides and its Combined-induced Oxidative Damage.

The aim of the present study was to analyze the alterations in the, antioxidant enzyme activities (such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and level of glutathione (GSH) and lipid peroxidation (LPO) of wheat acutely treated with CP and DM treatments at low, high doses and their combination. CP and DM were administered to wheat in different doses of 1, 1.5, 5 and 35 mg kg-1 given alone and combination. After 3 weeks, antioxidant enzyme activities, and the level of GSH and LPO were recorded and analyzed. Antioxidative defense mechanisms and LPO in wheat display different responses depending on different pesticide treatments and doses. Biochemical analysis showed that exposure of the CP and DM cause plant tissue damage. It is suggested that appropriate ecotoxicological risk assessment should be made in the areas where DM is proposed to be used in pest control when compared to CP. In the present study, we also concluded that the effect of the combined of CP and DM on the oxidative stress may be synergistic.

Novel hexapodal triazole linked to a cyclophosphazene core rhodamine-based chemosensor for selective determination of Hg(2+) ions.

The hexapodal Rhodamine B derivative compound 3 containing a cyclotriphosphazene core was synthesized and characterized by spectroscopic techniques such as FT-IR, (1)H, (13)C and (31)P NMR, HR-MS, MALDI MS and microanalysis. Compound 3 is a naked eye selective sensor with colorimetric and fluorescent properties for Hg(2+) ions in the presence of other metal ions such as Na(+), K(+), Ca(2+), Ba(2+), Mg(2+), Ag(+), Mn(2+), Cu(2+), Ni(2+), Co(2+), Pb(2+), Cd(2+), Zn(2+), Fe(2+), Fe(3+), and Cr(3+). 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 × 10(-9) M (0.75 ppb) for Hg(2+) ions. The stoichiometry of compound 3-Hg(2+) 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 S(2-) ion solutions.

Phosphazene based multicentered naked-eye fluorescent sensor with high selectivity for Fe3+ ions.

A novel on/off fluorescent rhodamine-based hexapodal Fe(3+) 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; (1)H, (13)C, and (31)P NMR; and MALDI MS spectrometry. The optical sensor features for the Fe(3+) complex of L were investigated by UV-vis and fluorescence spectroscopy. The stoichiometry of L-Fe(3+) complex was found to be 1:3 (ligand/metal ion), and the detection limit of L was determined as 4.8 µM (0.27 mg L(-1)) for Fe(3+) ions. The reusability of the sensor was tested by the addition of ethylenediamine to L-Fe(3+) complex solutions followed by the addition of Fe(3+) solution.

Utilization of smart hydrogel-metal composites as catalysis media.

Various metal nanoparticles such as, Cu, Co, Ni, and Fe were prepared inside poly(1-vinyl imidazole) p(VI) hydrogel by the absorption of the corresponding metal ions from aqueous solutions and the reduction with suitable reducing agents such as NaBH(4) and/or NaOH. TGA and ICP-AES were used to determine the metal particle content of p(VI)-M (M: Cu, Co, and Ni) composites. The prepared hydrogel-metal nanoparticle composites were proven to be resourceful as reaction container for the catalysis of various organic reactions. It was illustrated that p(VI)-M hydrogel-metal composites can be successfully used in the hydrolysis of NaBH(4) for the generation hydrogen form NaBH(4) and NH(3)BH(3). Additionally, p(VI)-M composites were also illustrated in the catalysis of different organic reactions; e.g., these hydrogel-M are very effective in the reduction nitro aromatic compounds such 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP) to their corresponding amine forms in the presence of aqueous NaBH(4). Various parameters in the catalysis of hydrogen production and 4-NP reduction were determined.

Novel hydrogel particles and their IPN films as drug delivery systems with antibacterial properties.

Poly(acrylonitrile) (p(AN))-based materials such poly(acrylonitrile-co-(3-acrylamidopropyl)-trimethylammonium chloride (p(AN-co-APTMACl)), poly(acrylonitrile-co-4-viniyl pyridine) (p(AN-co-4-VP)) and poly(acrylonitrile-co-N-isopropylacrylamide) (p(AN-co-NIPAM)) core-shell nanoparticles were prepared. The core materials, AN, in p(AN-co-4-VP) nanoparticles, were amidoximated and the shell materials, 4-VP, were quaternized to generate p(AN-co-4-VP)(+) and p(AN-co-4-VP)(++), single and double positively charged core-shell nanoparticles, respectively. Furthermore, interpenetrating microgels-hydrogel (IPN) polymeric networks were prepared by mixing double quaternized p(AN-co-4-VP)(++) core-shell particles with acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) before polymerization. A model drug, fluorescein sodium salt (FSS) was used in absorption/release studies from these IPNs. Moreover, the prepared and chemically modified particles were tested against Staphylococcus aureus ATCC6538, Pseduomonas aeruginosa ATCC9027, Bacillus subtilis ATCC6633, and Escherichia coli ATCC8739, and found that some of these particles had antibacterial properties against tested bacteria.

P(4-vinyl pyridine) hydrogel use for the removal of UO(2)(2+) and Th(4+) from aqueous environments.

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 0.027 mmol for pure p(HEMA). The characterization of the hydrogels was determined by swelling experiments, FT-IR and thermal analysis. The effects of initial metal ion concentration, hydrogel amount and the temperature of the medium on absorption of the ions were investigated. Langmuir and Freundlich isotherms were constructed for the absorption of UO(2)(2+) and Th(4+). Both isotherms demonstrated that these metal ions complied with monolayer absorption kinetics.

Aromatic organic contaminant removal from an aqueous environment by p(4-VP)-based materials.

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. The absorption capacity of bulk and microgels were found to be 4-NP>2-NP>Ph>NB. Furthermore, p(4-VP) microgels were embedded in poly(acrylamide) (p(AAm)) bulk hydrogel as a microgel-hydrogel interpenetrating polymer network and proved to be very practical in overcoming the difficulty of using the microgels in real applications. Moreover, it was demonstrated that separately prepared magnetic ferrite particles inserted inside p(4-VP) microgels during synthesis allowed for trouble-free removal of p(4-VP)-magnetic composite microgels from the aqueous environment by an externally applied magnetic field upon completion of their task.

Effect of nitrogen on root release of phytosiderophores and root uptake of Fe(III)-phytosiderophore in Fe-deficient wheat plants.

Root release of phytosiderophores (PSs) is an important step in iron (Fe) acquisition of grasses, and this adaptive reaction of plants is affected by various plant and environmental factors. The objectives of this study were to study the effects of varied nitrogen (N) supply on (1) root and leaf concentrations of methionine, a precursor in the PS biosynthesis, (2) PS release from roots, (3) mobilization and uptake of Fe from (59) Fe-labeled Fe(III)-hydroxide [(59) Fe(OH)(3) ] and (4) root uptake of (59) Fe-labeled Fe(III)-deoxymugineic acid (DMA) by durum wheat (Triticum durum, cv. Balcali2000) plants grown in a nutrient solution. Enhanced N supply from 0.5 to 6 mM in a nutrient solution significantly increased the root release of PS under Fe deficiency. High N supply was also highly effective in increasing mobilization and root uptake of Fe from (59) Fe-hydroxide under low Fe supply. With adequate Fe, N nutrition did not affect mobilization and uptake of Fe from (59) Fe(OH)(3) . Root uptake and shoot translocation of Fe supplied as (59) Fe(III)-DMA were also stimulated by increasing N supply. Leaf concentration of methionine was reduced by low Fe supply, and this decline was pronounced in high N plants. The results show that the root release of PS, mobilization of Fe from (59) Fe(OH)(3) and root uptake and shoot translocation of Fe(III)-PS by durum wheat are markedly affected by N nutritional status of plants. These positive N effects may have important implications for Fe nutrition of human populations and should be considered in biofortification of food crops with Fe.

P(4-VP) based nanoparticles and composites with dual action as antimicrobial materials.

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. The synthesized p(4-VP) particles with positive charges and metal constituents were tested for potential antibacterial action against various bacteria such as Staphylococcus aureus ATCC6538, Pseudomonas aeruginosa ATCC9027, Bacillus subtilis ATCC6633, Escherichia coli ATCC8739. It was found that p(4-VP) particles, especially the positively charged forms had potential as antibacterial materials. The synthesized particle dimensions were characterized with TEM, and DLS measurements. Chemical modification of the particles was confirmed by FT-IR spectroscopy and zeta potential measurements, and the metal nanoparticle contents were determined with thermogravimetric (TGA) studies.

Removal of toxic metal ions with magnetic hydrogels.

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. The results verified that magnetic iron particle containing p(AMPS) hydrogel networks provide advantageous over conventional techniques. Langmuir and Freundlich adsorption isotherms were applied for toxic metal removal and both isotherms were fit reasonably well for the metal ion absorptions.

Effects of leachant temperature and pH on leachability of metals from fly ash. A case study: Can thermal power plant, province of Canakkale, Turkey.

Lignite powered electric generation plants result in increasing environmental problems associated with gaseous emissions and the disposal of ash residues. Especially, low quality coals with high ash content cause enormous quantities of both gaseous and solid fly ash emissions. The main problem is related to the disposal of fly ash, which, in many cases, contains heavy metals. It is known that toxic trace metals may leach when fly ash is in contact with water. In this study, fly ash samples obtained from the thermal power plant in the town of Can in Turkey were investigated for leachability of metals under different acidic and temperature conditions. The experimental results show that a decrease in pH of the leachant favors the extraction of metal ions from fly ash. A significant increase in the extraction of arsenic, cadmium, chromium, zinc, lead, mercury, and selenium ions from the ash is attributed to the instability of the mineral phases. These heavy metals concentrations increase with respect to increasing acidic conditions and temperature. Peak concentrations, in general, were found at around 30 degrees C.