Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Impact of Titania Phase Structure and Surface Reactivity on the Photocatalytic Degradation of Various Dyes and Textile Wastewater(National Institute of Science Communication and Policy Research, 2023) Yurtsever, Hüsnü Arda; İloğlu, Onur; Çiftçioğlu, MuhsinTitania (TiO2) powders have been prepared by precipitation method in different precipitation media which contain sulfate, nitrate or organic species. Photocatalytic degradation of different dyes and a real textile wastewater have been conducted with these powders along with commercial powder Degussa P25 for comparison. Ethyl alcohol (organic medium), sulfuric acid (sulfate medium) and nitric acid (nitrate medium) have been used to dissolve titanium precursor for the precipitation of TiO2 in ammonia solution. UV-Vis DRS and XPS results indicate that S doping in sulfate medium precipitated powder and N doping in nitrate medium precipitated powder has been occurred and the presence of S or N containing impurities on the grain boundaries have been improved light absorption of TiO2 significantly. However, these powders have exhibited low surface reactivities. The highest surface reactivity has been obtained with the powder precipitated in organic medium which also has the highest crystallite sizes (76 nm rutile and 34 nm anatase crystallites) with relatively low rutile weight percentage (10.0%). The surface-normalized rate constants of this powder are 0.02038 min-1.m-2 in real textile wastewater degradation and 0.0161 min-1.m-2 in methyl orange degradation, which are 0.01563 and 0.0091 min-1.m-2, respectively, for Degussa P25. Results have shown that this powder show 30-70% higher surface reactivities compared to Degussa P25. The main structural difference of organic medium precipitated powder and Degussa P25 has been found to be the anatase-rutile weight ratio and crystallite size of rutile phase whereas band gap energy of Degussa P25 is lower and other properties are not significantly different.Article Citation - WoS: 31Citation - Scopus: 34Insights Into Engineered Graphitic Carbon Nitride Quantum Dots for Hazardous Contaminants Degradation in Wastewater(Elsevier, 2023) Gören, Ayşegül Yağmur; Recepoğlu, Yaşar Kemal; Vatanpour, Vahid; Yoon, Yeojoon; Khataee, AlirezaIncreased environmental pollution is a critical issue that must be addressed. Photocatalytic, adsorption, and membrane filtration methods are suitable in environmental governance because of their high selectivity, low cost, environment-friendly nature, and excellent treatment efficiency. Graphitic carbon nitride (g-C3N4) quantum dots (QDs) have been considered as photocatalysts, adsorbents, and membrane materials for wastewater treatments, owing to their stability, adsorption capacity, photochemical properties, and low toxicity and cost. This review summarizes g-C3N4 QD synthesis techniques, operating parameters affecting the removal performance in the treatment process, modification effects with other semiconductors, and benefits and drawbacks of g-C3N4 QD-based materials. Furthermore, this review discusses the practical applications of g-C3N4 QDs as adsorbents, photocatalysts, and membrane materials for organic and inorganic contaminant treatments and their value-added product formation potential. Modified g-C3N4 QD-based material adsorbents, photocatalysts, and membranes present potentially applicable effects, such as removal of most waterborne contaminants. Excellent results were obtained for the reduction of methyl orange, bisphenol A, tetracycline, ciprofloxacin, phenol, rhodamine B, E. coli, and Hg. Overall, this paper provides comprehensive background on g-C3N4 QD-based materials and their diverse applications in wastewater treatment, and it presents a foundation for the enhancement of similar unique materials in the future.Article Citation - WoS: 16Citation - Scopus: 13Energy storage performance of nitrogen-doped reduced graphene oxide/co-doped polyaniline nanocomposites(Springer, 2022) Altınışık, Hasan; Getiren, Bengü; Çıplak, Zafer; Soysal, Furkan; Yıldız, NurayThe design and exploration of carbon-based electrode materials have become highly significant for developing supercapacitor technology, which has attracted considerable attention in energy storage systems. Here, nitrogen-doped reduced graphene oxide (N-rGO) – Polyaniline (PANI) nanocomposites were synthesized by a facile two-step method in which in situ polymerization of aniline monomer was performed on hydrothermally synthesized N-rGO nanosheets in DBSA and H2SO4 medium for co-doping of PANI chains. The effects of various acid concentrations (DBSA:H2SO4 0.5 − 0.25:1 n/n) and N-rGO:aniline ratios (N-rGO:aniline 1:4–10 m/m) used in the preparation of the electrode material on the capacitive properties were investigated. It is found that the co-doped N-rGO-PANI nanocomposites exhibit a high specific capacitance of 346.3 F g− 1 at 1 A g− 1, remarkable rate capacity (99.9%, 1–10 A g− 1) and excellent cycle stability at 5 A g− 1 (81.3%, 5000 cycles) in a two-electrode system. As a result, constructing co-doped PANI chains and N-doped rGO provided a viable and simple way to improve the capacitive performances of supercapacitors.Article Citation - WoS: 1Citation - Scopus: 1Inhibition of Caco3 Growth and Synthesis of Submicron Particles by Preferential Adsorption of Additive Ca2+ Ions on Fresh Precipitates(Royal Society of Chemistry, 2022) Majekodunmi, Olukayode T.; Kılıç Özdemir, Sevgi; Özdemir, EkremThis study demonstrates a method to inhibit the growth of CaCO3 and synthesize submicron particles in a chemical precipitation process under ambient and high supersaturation conditions. Equimolar CaCl2 and Na2CO3 solutions were mixed in a model tubular reactor at a constant flow rate, and the precipitates were continuously dispersed in stirred 250 mL of 10 mM Ca(OH)2 solution. This approach resulted in the synthesis of colloidally stable submicron CaCO3 particles for a precipitant concentration ≤75 mM. Varying the precipitates’ retention time in the tubular reactor had no significant effects on the particle size and colloidal stability. Time-dependent changes in the mean size, crystal form, morphology and specific surface area of the synthesized particles were also studied. For a precipitant concentration of 75 mM, the particles were monodispersed and porous spindle-like scalenohedral crystals which gradually grew in all faces as more precipitates were fed into the Ca(OH)2 solution. The mean hydrodynamic size of the particles was ∼850 nm at the 8th minute. However, in the absence of additive Ca2+ ions, the particles obtained at the 8th minute were polydisperse mixtures of vaterite and rhombohedral calcite particles greater than 4 μm in size. The results show that free additive Ca2+ ions are irreversibly adsorbed onto the particles as the precipitates dissolve and recrystallize into smaller crystals upon reaching the Ca(OH)2 solution.Article Citation - WoS: 6Citation - Scopus: 7Designing Robust Xylan/Chitosan Composite Shells Around Drug-Loaded Msns: Stability in Upper Git and Degradation in the Colon Microbiota(Elsevier, 2023) Zeybek, Nüket; Büyükkileci, Ali Oğuz; Güleç, Şükrü; Polat, Mehmet; Polat, Hürriyetong residence times, near-neutral pH values, and release triggered by the enzymatic action of the resident microbiota offer unique opportunities for improved drug delivery in the colon. The fact that a delivery agent must also pass through the complete GI tract without degradation presents a challenge due to widely changing pH conditions. In this study, a promising colon-targeted drug delivery system was composed of a xylan/chitosan composite shell formed on curcumin-loaded mesoporous silica nanoparticles (MSNs). A novel synthesis approach was employed to facilitate precipitation of negatively charged xylan on negatively charged MSNs by concurrent chitosan polymerization. Curcumin-loaded xylan/chitosan-coated MSNs (C-MSNs) were determined to contain nearly 42% xylan by the inclusion of chitosan in a one-to-one ratio with xylan. The xylan/chitosan composite shell demonstrated excellent stability in the acidic upper GI tract. The hydrolysis of glycosidic bonds by resident microbiota was the triggering mechanism for xylan degradation and curcumin release in the colon. The presence of xylan has the further benefit of increasing the number of beneficial bacteria and improving short-chain fatty acid production for improved colon health.Article Citation - WoS: 9Citation - Scopus: 9Hollow Nano-caco3's Voc Sensing Properties: a Dft Calculation and Experimental Assessments(Elsevier, 2023) Bayram, Abdullah; Farzaneh, Amir; Esrafili, Mehdi D.; Okur, Salih; Özdemir, EkremAir is the most critical and necessary for life, and air quality significantly impacts people's health. Both indoor and outdoor pollution frequently contain volatile organic compounds (VOCs). Such contaminants provide immediate or long-term health risks to the living system. The present study investigates sorption characteristics of VOCs on hollow nano calcite (CaCO3) particles with 250 nm and 40 nm pore sizes to remove from the air ambient using the quartz crystal microbalance (QCM) technique at room temperature both experimentally and theoretically. The results were supported by density functional theory (DFT), and adsorption-desorption characteristics were studied with Langmuir adsorption isotherms. The QCM measurements showed a stable signal without having hysteresis, and the response of polar VOCs on hollow nano-CaCO3 particles such as ethanol, propanol, and humidity with higher polarity was less compared to solvents such as chloroform and dichloromethane, which revealed that the surfaces of CaCO3 particles have mostly non-polar properties. CaCO3 surface and VOC molecule interactions overlap with the Langmuir model. With DFT calculations, VOC and water molecule adsorption changes the CaCO3 Egap. Our findings show that the ΔEgap values increase as chloroform > dichloromethane > propanol > ethanol > water. This order suggests that the sensing response of the hollow CaCO3 structure is linearly proportional to the adsorption energies of VOC and water. The linear adsorption characteristics, high sensing response, and short recovery time illustrated that the newly synthesized nano-CaCO3 could be implemented as a new VOC adsorbent material for health, environmental sustainability, and in vitro microbiome cultures.Article Citation - WoS: 1Citation - Scopus: 2A New-Generation Poly (ether Imide Sulfone) Based Solvent Resistant Ultrafiltration Membrane for a Sustainable Production of Silica Nanopowder(Elsevier, 2023) Güngörmüş, Elif; Alsoy Altınkaya, SacideThe work presented here demonstrated the feasibility of using a membrane to improve the sustainability of silica nanopowder production. Due to superior chemical resistance, high thermal-oxidative stability, and good processability, poly (ether imide sulfone) has been used for membrane production and modified with amine-functionalized TiO2 nanoparticles. The membrane demonstrated good long-term leaching stability in 40% ethanol and silica synthesis solution and maintained its permeability and rejection characteristics under static and dynamic conditions. Additionally, the high antifouling property of the membrane allowed recovering 99.5% of the nanoparticles. Backwashing with water resulted in a high flux recovery ratio (>93%), and gravity-settling without energy can easily separate silica nanoparticles and water in the backwashing solution. Compared to classical freeze-drying and oven-drying methods, integrating membrane into silica nanopowder production can reduce energy consumption by a factor of 81 and 53. At the same time, the utility cost can be saved by 80% and 69%. Additionally, the solvent and catalyst recovered in the permeate stream can be reused in the synthesis, reducing disposal and purchasing costs. In conclusion, membrane-assisted nanopowder production can minimize the adverse effects caused by commonly used conventional drying methods and make the process more sustainable and environmentally friendly.Article Citation - WoS: 12Citation - Scopus: 14Extraction of Monophenols and Fractionation of Depolymerized Lignin Oil With Nanofiltration Membranes(Elsevier, 2023) Croes, Tim; Dutta, Abhishek; De Bie, Robin; Van Aelst, Korneel; Sels, Bert; Van der Bruggen, BartOrganic solvent nanofiltration membranes were employed to fractionate birch derived reductive catalytic fractionated (RCF) lignin oil. This lignin oil is highly depolymerized, with most, if not all chemical compounds lighter than 3 kDa. Sixteen commercially available membranes were investigated for the fractionation, in combination with methanol and ethyl acetate as solvents. Membrane performances were quantified using Gaussian fits of gel permeation chromatograms and separation factor calculations. The separation factor was found to be primarily based on affinities instead of size-exclusion. The silicon-based membranes from Borsig (Germany) and PuraMem S600 from Evonik (UK) proved best at separating lignin into different functional fractions, showing monomer separation factors up to 7.4 and providing a permeate fraction with 88 % phenolic monomer purity. These membranes were further examined in batch diafiltration and two-stage filtration. This increased the separation factor from 7.4 to 25.4, and the monomer purity of the permeate to 95 %, proving that membrane purification of the lignin-derived monophenols is technically feasible.Article Citation - WoS: 3Citation - Scopus: 4Microfluidic-Assisted Preparation of Nano and Microscale Chitosan Based 3d Composite Materials: Comparison With Conventional Methods(Wiley, 2022) Kimna, Ceren; Değer, Sibel; Tamburacı, Sedef; Tıhmınlıoğlu, FundaAlthough nanofillers contribute to improved physical characteristics and biological functionalities of polymer-based biomaterials, their dispersion in polymer matrices is still a challenging issue in terms of obtaining consistency for the inherent properties. To tackle this problem, homogenization techniques are applied to disperse the nanofillers in such polymers, however, these methods can cause undesired changes especially in the rheological properties and the physical structure of the biopolymer matrices. Recently, as a novel homogenization technique, microfluidization has been used to homogenize polymer nanocomposites to minimize these limitations. In this study, two different nanocomposite structures as chitosan/montmorillonite (CS/MMT) and chitosan/polyhedral oligomeric silsesquioxane nanocages (CS/POSS) were homogenized with microfluidization and investigated in terms of physical alterations. Furthermore, the effect of microfluidizer technique on material characteristics was compared with conventional homogenization techniques, i.e., ultrasonic bath and sonication in terms of solution, nano – (e.g., hydrodynamic size, drug encapsulation) and macroscopic material characteristics (e.g., porosity, mechanical properties, swelling and thermal degradation). It was found that the microfluidizer homogenization improves the physical characteristics in both nano and macroscale materials: Nanospheres obtained from CS/MMT composites showed enhanced stability, uniform size distribution (<100 nm, PDI: [removed]50%) whereas 3D porous CS/POSS scaffolds showed improved structural uniformity (i.e., homogeneous and interconnected microstructure) and enhanced thermal and mechanical properties. The obtained results indicate that the microfluidizer homogenization ensures a successful nanofiller dispersion in polymer matrices, thereby improving the biomaterial characteristics impressively compared to the sonication methods.Article Citation - WoS: 6Citation - Scopus: 8Effect of the Combination of Organic Acid Solutions on Tinplate Corrosion(Elsevier, 2022) Yıldırım, Koray; Kızılkaya, Ali CanTinplate corrosion as a result of canned food is typically tested in industry by tinplate in synthetic media based on single organic acids. However, the combination of organic acids, which is present in applied conditions, is not previously investigated in terms of its effect on tinplate corrosion mechanism. In this manuscript, we combine structural characterization of tinplate surfaces with electrochemical measurements, to investigate the corrosion mechanism of tinplate under acetic acid-NaCl, citric acid-NaCl, and a combined acetic acid, citric acid and NaCl media. The results show that the combined acid media causes does not result in a pronounced formation of a protective passivation layer, in contrast to the single acid based media. Our findings demonstrate the combined effects of the organic acids in corrosive media has to be taken into account for tinplate corrosion, as they can alter the corrosion mechanism. Furthermore, we show that combination of organic acids can accelerate tinplate corrosion testing in packaging industry. Thus, our findings can contribute to the design of new aging media for tinplate corrosion testing.
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