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Characterization and photocatalytic properties of TiO2-nanosols synthesized by hydrothermal process at low temperature
(Elsevier, 2006) Sayilkan, F; Asiltürk, M; Erdemoglu, S; Akarsu, M; Sayilkan, H; Erdemoglu, M; Arpaç, E
Transparent nanocrystalline pure anatase titania (nano-TiO2) was synthesized by hydrothermal process at 200 degrees C. Photocatalytic activity of the nano-TiO2 as in the form of sol was tested for degradation of Methylene Blue (MB) and Reactive Red 120 (RR-120) in aqueous solutions. Structural and physico-chemical properties of the nano-TiO2 were characterized using powder XRD, SEM, BET, FTIR and elemental analyses. Complete photodegradation of RR-120 was successfully achieved by aid of the nano-TiO2 whereas NIB was not degraded, maybe because of reversible color change in nano-TiO2 sol/MB mixture after the LTV irradiation was stopped. Potocatalytic activity of the synthesized the nano-TiO2 for degradation of RR-120 was compared with Degussa P-25 at optimum conditions determined for RR-120. It was found that the nano-TiO2 can be repeatedly used with higher photocatalytic activity than Degussa P-25. (c) 2005 Elsevier B.V All rights reserved.
Characterization of the hydrothermally synthesized nano-TiO2 crystallite and the photocatalytic degradation of Rhodamine B
(Elsevier, 2006) Asiltürk, M; Sayilkan, F; Erdemoglu, S; Akarsu, M; Sayilkan, H; Erdemoglu, M; Arpaç, E
Pure anatase-TiO2 nanoparticles with 8 nm average crystallite size was synthesized hydrothermally at 200 degrees C in 2 h. The structural and physicochemical properties of nano-TiO2 were determined by powder XRD, FT-IR, BET and SEM analyses. The behavior of anatase nano-TiO2 in catalytic degradation of Rhodamine B (RB) dye in transparent nano-TiO2 sol under UV-light was examined as a function of irradiation power of UV-Iight, irradiation time, amount of nano-TiO2 and initial RB concentration in the sol. Rhodamine B was fully degraded with the catalysis of the nano-TiO2 in a short time as low as 60 min. Photocatalytic activity of the nano-TiO2 for degradation of RB was compared with Degussa P-25 at optimum catalysis conditions determined for the nano-TiO2. It was found that, when compared to Degussa P-25, the nano-TiO2 could be repeatedly used with increasing photocatalytic activity. It was found that the photodegradation obeys the pseudo first-order reaction kinetics with the rate constant of 0.0658 min(-1), and the half period t(1/2) was 10.53 min. (c) 2005 Elsevier B.V. All rights reserved.
Characterization of TiO2 synthesized in alcohol by a sol-gel process: The effects of annealing temperature and acid catalyst
(Tubitak Scientific & Technological Research Council Turkey, 2005) Sayilkan, F; Asiltürk, M; Sayilkan, H; Önal, Y; Akarsu, M; Arpaç, E
The effects of annealing temperature and hydrolysis catalyst on the crystalline form and crystallite size of TiO2 prepared by a sol-gel process were investigated. Three types of TiO2 were synthesized by hydrolysis of titanium(IV)-iso-propoxide with water in n-propanol without catalyst (Type-A) and with HCl as catalyst, where the H+/Ti4+ mol ratio was 0.54 for Type-B and 0.2 for Type-C. Hydrolysis products were thermally treated at 100, 200, 300, 400 and 500 degrees C for 1 h after drying at room temperature. Characterization of the particles was carried out using XRD, BET, TG/DTA and SEM analysis. The pore size distributions were computed by the DFT plus method. The results showed that the acid catalyst and catalyst/alkoxide ratio have a large effect on the formation of anatase TiO2. In particular, it was found that anatase phase TiO2 particles occur at 400 and 500 degrees C for Type-A TiO2, while they do so at nearly 100 degrees C for Type-B and Type-C TiO2. The crystallile size of Type-A, Type-B and Type-C increased from 17.96 to 19.24 nm, from 12.38 to 15.12 nm and from 10.60 to 12.20 nm, respectively, when the thermal treatment temperature was raised from 400 to 500 degrees C.
Heat-resistant hydrophobic-oleophobic coatings
(Wiley, 2006) Uyanik, M; Arpaç, E; Schmidt, H; Akarsu, M; Sayilkan, F; Sayilkan, H
Thermally and chemically durable hydrophobic oleophobic coatings, containing different ceramic particles Such as SiO2, SiC, Al2O3, which can be alternative instead of Teflon, have been developed and applied on the aluminum Substrates by spin-coating method. Polyimides, which are high-thermal resistant heteroaromatic polymers, were synthesized, and fluor oligomers were added to these polymers to obtain hydrophobic-oleophobic properties. After coating, Al Surface was subjected to Taber-abrasion, adhesion, corrosion, and thermal tests. The effects of the particle size of ceramic powders, organic matrix, and heat on the coating material were investigated. Coating material was characterized by FTIR spectrophotometer. Surface properties and thermal resistance of the coating materials were investigated by SEM and TGA analyses. After thermal curing, contact angles of these coatings with H2O and n-hexadecane were measured. It was observed that coatings like ceramic particles are more resistant against scratch and abrasion than the other coatings. Also, they are harder than coatings, which do not include ceramic particles. It was seen that coatings, containing Fluorolink D10H, have high-contact angles with water and n-hexadecane. (c) 2006 Wiley Periodicals, Inc.
Natural pyrophyllite and M(OR)x based MxOy powders as new adsorbents for heavy metal adsorption
(Trans Tech Publications Ltd, 2004) Erdemoglu, M; Sayilkan, F; Erdemoglu, S; Sener, S; Akarsu, M; Sayilkan, H
Heat treated hydrolysis-condensation products of aluminiumtri-sec-butoxide (Al(OBus)(3)) and alcohol modified Al(OBus)(3) were synthesised by sol-gel process. These synthetic powders, natural pyrophyllite and their 3-mercaptoprophyltrimethoxysilane coated forms were utilised as adsorbents for the removal of Cu(II) ions from aqueous solutions. The adsorption increased when natural and synthetic powders coated with SH-Si were used. It was concluded that the dried powders obtained from the hydrolysis-condensation product of Al(OBus)(3) and its alcohol modified form, and coated pyrophyllite would substitute for Amberlite IR 120 Na form resin.
New adsorbents from Ti(OPrn)4 by the sol-gel process: Synthesis, characterization and application for removing some heavy metal ions from aqueous solution
(Tubitak Scientific & Technological Research Council Turkey, 2004) Sayilkan, F; Sayilkan, H; Erdemoglu, S; Sener, S; Akarsu, M
New adsorbents were synthesized by the sol-gel process from the product of a hydrolysis reaction and its coated form of titanium(IV)-n-propoxide for removing some heavy metal ions from aqueous solution. Titanium(IV)-n-propoxide was uncatalyst hydrolyzed with different amounts of water at room temperature and was found to react in a 1:1.6 ratio (mole of Ti:mole of H2O). It was found that the condensation following the hydrolysis reflection was alcohol condensation. The hydrolysis-condensation product was characterized in detail by GC. Karl-Fischer coulometric titrator, NIR-spectroscopy, FT-IR spectroscopy, TG-DTA and elemental analysis. The hydrolysis-condensation product of titanium(TV)-n-propoxide was calcinated at 900degreesC after drying at 100degreesC and some of this product was coated with hydrolyzed NH2-functional silanes [3-(2-aminoethylamino)ethylamino)propyl-trimethoxy silane] (Amino-and [3-(2-aminoethylamino)propylmethyldimetoxysilane] (Amino-2), separately. Adsorption capacities of uncoated and NH2-functional silane coated hydrolysis-condensation products for Fe3+, Cu2+ and Pb2+ ions in aqueous solution were investigated by FAAS. It was observed that the extent of adsorption was influenced significantly by the type and concentrations of coating materials, e.g., Amino-1 coated adsorbent prepared in methyl alcohol as 50% (w/w) and 100% (without methyl alcohol) adsorbed 90-67% and 100% of Fe3+, respectively. while the uncoated form adsorbed only 5%. The adsorption isotherm was determined and the data were analyzed according to the Freundlich model.
Organo-functional modified pyrophyllite: preparation, characterisation and Pb(II) ion adsorption property
(Elsevier, 2004) Erdemoglu, M; Erdemoglu, S; Sayilkan, F; Akarsu, M; Sener, S; Sayilkan, H
Surface modification of clay minerals has become increasingly important for improving the practical applications of clays such as fillers and adsorbents. In this study, the surface of pyrophyllite mineral was modified by coating with 3-(2-aminoethylamino) propyl-methyidimethoxysilane (APMDS) coupling agent and utility of the APMDS-modified pyrophyllite was investigated as an adsorbent for removal of Pb(II) ions from aqueous solutions. XRD, FT-IR and SEM analysis were used to characterise the surface modification and it was suggested that hydrogen bonding takes place between the hydroxyl groups and/or oxygen atoms within the structure of pyrophyllite and hydroxyl groups of APMDS. The APMDS-modified pyrophyllite adsorbed approximately 93% of Pb(II) ions at an initial concentration of 20 mg/l, while natural pyrophyllite did only 35% under the same conditions. The adsorption of Pb(II) increased with increasing pH and reached a maximum value in the pH range 6.5-7. The effects of various factors on the adsorption, such as pH of the solution, contact time, amount of adsorbent and initial Pb(II) concentration, were studied. The adsorption isotherm has been determined and data have been analysed according to the Langmuir model and found to be favourable, i.e., the separation parameter is less than unity (R-L < 1). (C) 2003 Elsevier B.V. All rights reserved.
Removal of inorganic-organic bound Cu(II) from different aqueous solutions by new adsorbents synthesized by sol-gel process
(Taylor & Francis Inc, 2004) Erdemoglu, S; Sayilkan, F; Emre, FB; Akarsu, M; Sener, S; Sayilkan, H
Hydrolysis product of alcohol modified titanium(IV)-n-propoxide and its coated form were prepared as new and regenerable adsorbents for adsorbing and removing Cu(II) ions from its different aqueous solutions. The hydrolysis and alcoholysis products and adsorbents were characterized using GC, H-1-NMR, FT-IR, SEM, and TG-DTA analysis. It was found that Cu(II) ion adsorption rather increased when hydrolysis product of alcohol modified titanium(IV)-n-propoxide was coated with prehydrolyzed 3-mercaptopropyltrimethoxy silane in n-propanol and this coated material was used as adsorbent. Depending on the results of experiments performed at optimum conditions of initial Cu(II) concentration, amount of adsorbent, contact time, and pH, maximum adsorption of Cu(II), i.e., >98% has been achieved under the non-competitive conditions, while almost 60% is achieved under the competitive conditions of Pb(II), Zn(II), Fe(III), and alkali and earth alkali metals. It was also concluded that Cu(II) adsorption efficiency is not affected from the media containing acetate, tannic acid, or Turkish Blue dye. The adsorbent was easily regenerated with 5 N HNO3 solution and used over and over again for the adsorption of Cu(II) ions.
The removal of Pb2+, Cu2+ and Fe3+ from aqueous solution by a new adsorbent synthesized from Ti(OPrn)4 by sol-gel process
(Parlar Scientific Publications (P S P), 2003) Erdemoglu, S; Sayilkan, F; Akarsu, M; Sener, S; Sayilkan, H
Removal of Cu(II), Pb(II) and Fe(III) ions from aqueous solutions was studied by using a new adsorbent synthesised by hydrolysis and subsequent condensation of Ti(OPrII)(4) by sol-gel process. Metal ion adsorption was highly increased when the adsorbent surface was covered with a coating solution of hydrolysed NH2- and SH-functional silanes prepared in methanol. Adsorption conditions for Cu, Pb and Fe ions were optimized. It was concluded that Cu was retained to 100% on SH-functional silane coated adsorbents, whereas Fe(III) and Pb(II), 89% and 100%, resp., on NH2-functional silane coated adsorbents.
Surface modification of pyrophyllite with amino silane coupling agent for the removal of 4-nitrophenol from aqueous solutions
(Academic Press Inc Elsevier Science, 2004) Sayilkan, H; Erdemoglu, S; Sener, S; Sayilkan, F; Akarsu, M; Erdemoglu, M
The surface of naturally hydrophobic mineral pyrophyllite was modified to hydrophilic by treatment with prehydrolyzed N-(2-aminoethyl)3-ammopropyltrimethoxysilane (APEO) coupling agent to prepare a novel and effective adsorbent for the removal of 4-nitrophenol (4-NP) from aqueous solutions. XRD, FTIR, and SEM analyses were used to characterize the surface modification. It was found that after the grafting procedure, heat treatment at 110 degreesC results in condensation reaction between the OH groups of the APEO molecule and the hydroxyl groups and/or oxygen atoms on the pyrophyllite surface and the adsorption of 4-NP by APEO-modified pyrophyllite involves interactions between dissociated 4-NP molecules and protonated amine groups of APEO molecules attached to the mineral surface. Adsorption equilibrium data for 4-NP adsorption on APEO-treated and untreated pyrophyllite were most satisfactorily fitted using the Freundlich adsorption isotherm and adsorption capacity was found to be 0.268 mg/g for modified pyrophyllite whereas it was only 0.105 mg/g for untreated pyrophyllite. (C) 2004 Elsevier Inc. All rights reserved.
The synthesis and application of new adsorbents for removal of heavy metal ions and phenols from aqueous solution
(Parlar Scientific Publications (P S P), 2003) Sener, S; Sayilkan, F; Erdemoglu, SB; Akarsu, M; Sayilkan, H
In this study, a TiO2 adsorbent powder was synthesized from Titan (IV)-n-propoxyallyl acetoacetate by the sol-gel process. This powder and its coated forms (SH-and NH2- functional silanes) were investigated for their phenol, p-chlorophenol, Cu2+, Ph2+ and Zn2+ adsorption. It was found that Pb2+ and Zn2+ adsorption on the adsorbent coated with NH2-functional silane and Cu2+, Pb2+ adsorption on the adsorbent coated with SH-functional silane were nearly complete.
The synthesis and application of Pb-doped GLYMO/chelated-zirconium complex coating materials for UV-light absorption
(Wiley, 2006) Asiltürk, M; Sayilkan, F; Sayilkan, H; Içduygu, G
New glass coating materials containing gamma-glycidoxypropyltrimethoxy- silane/zirconium(IV)-n-propoxide(2-methoxyethylacetoacetate)/lead(II) nitrate were developed for UV-light absorption by sol-gel process. The effect of agitation time, temperature, and Zr complex and Pb2+ ion concentrations on UV light absorption were investigated. Zr complex was characterized by using H-1-NMR, C-13-NMR, and FTIR spectroscopy. Ultraviolet visible spectroscopy was utilized to determine the optical properties of coating materials. Results showed that coated glass has very low transmission in the UV region (300-400 nm) relative to uncoated glass, especially at 150 degrees C for 15 h agitation. UV light transmission of coated glasses treated at 80, 100, 450, or 500 degrees C was not different from uncoated glass. (c) 2005 Wiley Periodicals, Inc.
The synthesis and applications of Cr-doped GLYMO and GLYMO/DAMO surface coating systems for absorbing UV-light by sol-gel process
(Tubitak Scientific & Technological Research Council Turkey, 2005) Asiltürk, M; Sayilkan, F; Içduygu, G; Sayilkan, H
new glass coating system, containing gamma-glycidoxypropyltrimethoxysilane/Cr3+ (system I:GLYMO/ Cr3+) and gamma-glycidoxypropyltrimethoxysilane/N-aminoethyl-3-aminopropyltrimethoxysilane/Cr3+ (System II:GLYMO/DAMO/Cr3+), was synthesized by the sol-gel technique for UV light absorption applications. UV-visible spectroscopy (UV-VIS) was utilized to investigate the optical properties of coating materials. Especially system II showed very low transmission in the UV wavelength regions (300-400 nm) after thermal treatment of the coated surface. The UV transmission property of surfaces did not change at 80, 100, 450 or 500 degrees C, but a T value as low as 0.07% was obtained between 150 and 450 degrees C.
Synthesis, characterization and applications of sol-gel derived zirconium oxide adsorbent powder: Removal from aqueous solution of phenol and p-chlorophenol
(Tubitak Scientific & Technological Research Council Turkey, 2003) Akarsu, M; Sayilkan, H; Sener, A; Sayilkan, F; Arpac, E
Adsorbent powders were prepared from the uncatalysed hydrolysis-condensation reactions of different complexes that were synthesized by the reactions of Zr(OPrn)(4) with different chelating ligands (such as allylacetic acid [AAH], vinylacetic acid [VAH] and citraconic acid [CAH]). The complex products were characterized by FT-IR, H-1-NMR and C-13-NMR spectra. The maximum combination ratios of AAH/Zr(OPrn)(4), VAH/Zr(OPrn)(4) and CAH/Zr(OPrn)(4) were 1.7, 0.9 and 1.3, respectively. The hydrolysis-condensation products of these complexes were calcinated at 900 degreesC and half of them were coated with 3-glycidyloxypropyltrimethoxysilane (GLYMO). The surface area and average pore diameter of the powders were estimated by the analysis of adsorption/desorption BET isotherm data. The adsorption capacities of these powders for aqueous phenol and p-chlorophenol were calculated following spectrophotometric determination. Phenol and p-chlorophenol adsorption on all of the GLYMO-coated adsorbents were satisfactory, e.g., the adsorbent obtained from the hydrolyzed, calcinated and GLYMO-coated form of Zr(OPrn)(2.3)(AA)(1.7) adsorbed 63% of phenol while the uncoated form adsorbed only 10%. The adsorption isotherm has been determined and data have been analyzed according to the Freundlich model.
Two novel adsorbents synthesized by sol-gel process for removing of 4-nitrophenol from aqueous solutions
(Parlar Scientific Publications (P S P), 2005) Sayilkan, F; Sener, S
In this work, a new titanium alkoxide complex [titanium(IV)-n-propoxide-(4-nitrophenoxide)] was synthesized by the reaction between titanium(IV)-n-propoxide [Ti(OPrn)(4)] and 4-nitrophenol (4-NP) in different mole ratios at room temperature. GC, FT-IR and H-1-NMR analyses showed that each Ti(OPrn)4 mole reacts with 2 moles of 4-NP in maximum. This complex was hydrolyzed with 2 moles water per mole of Ti(OPrn)4, and hydrolysis products were characterized by thermal analyses and FT-IR. The optimum conditions for the adsorption of 4-NP on the calcinated powder from its aqueous solutions were determined. Adsorption experiments showed that the calcinated powder is a quite suitable material for the removal of 4-NP.
UV-absorption and thermal properties of Pb-doped glymo/damo-derived coating materials prepared by sol-gel process
(Springer, 2005) Sayilkan, F; Asiltürk, M; Içduygu, MG; Sayilkan, H
[Abstract Not Available]
UV-light absorption properties of Cr-doped polyethyleneglycol (PEG)/?-glycidoxypropyltrimethoxysilane (GPTMS)/chelated-titanium coating materials prepared by the sol-gel process
(Springer, 2005) Sayilkan, F; Asiltürk, M; Içduygu, G; Bayri, A; Sayilkan, H
New hybrid inorganic-organic glass coating materials, which contain polyethyleneglycol/ gamma-glycidoxypropyltrimethoxysilane/ titanium(IV)-n-propoxide(2-methoxyethylacetoacetate)/ chromium(III) nitrate [PEG/GPTMS/Ti(OR)(2-MEAA)/Cr3+] have been developed for UV-light absorption by using the sol-gel process. The effect of agitation time and temperature on UV-light absorption was investigated. The titanium complex was characterized by H-1-NMR and FTIR spectroscopies. UV-Vis spectroscopy was used to investigate the optical properties of the coating materials. The results show that the coated glass has very low transmission in the UV region (300-400 nm) compared to the uncoated glass, especially at 150, 200, 250 and 300 degrees C treatment temperatures after 1- and 18-hour agitation times. The UV-light transmission of the coated glass was not different from the uncoated glass between 80-100 degrees C and 350-500 degrees C.

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