Browsing by Author "Karagoz, Mustafa Hamdi"

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First Evaluation of Microplastic Pollution in the Surface Waters of the Van Bay From Van Lake, Turkey
(Taylor & Francis Ltd, 2022) Atici, Ataman Altug; Sepil, Ahmet; Sen, Fazil; Karagoz, Mustafa Hamdi
Increasing pollution of plastics smaller than 5 mm (microplastics [MPs]) in seas and oceans as well as in inland waters around the world has recently been a significant threat to water resources. In this study, MP pollution levels were investigated using a 335 mu m mesh manta trawl in November 2019 in Van Bay. Water samples were collected from 15 stations. MP particles ranged from 641424 to 1426638 per km(2) in surface waters (ranged from 2.35 to 5.09 MPs/m(3) in water columns). The most frequently observed MP type, size, shape and colour classes were fiber (40.5%), <0.1 mm (52.3%), irregular (40.8%) and blue (57.1%), respectively. The highest MP abundance was observed at 14 and 15 stations where lake current were effective. Station 6 were also under serious plastic pollution pressure beacuse it was located close to Akkopru and Kurubas Rivers that pass through the densely populated city center. The chemical structure of all examined MPs showed presence of polyethylene (60.2%), followed by polypropylene (20.4%), polyethylene terephthalate (17.2%) and poly(methyl acrylate) (2.2%). The MPs were also examined using scanning electron microscopy to understand the surface characteristics. In conclusion, our study revealed that the surface waters of Van Bay are highly contaminated with MPs.
Investigation of the Specific Retention Volume of the Probe Volume and the Effects on the Polymer-Probe System by Inverse Gas Chromatography
(Hindawi Ltd, 2019) Karagoz, Mustafa Hamdi
In this study, the effects of probe quantities on retention volume and the physical and thermodynamic results of polymer-probe systems were investigated. For this purpose, by using inverse gas chromatographic method. Alcohols and alkanes with different chemical and physical properties were injected as probes on homopolymer (2-cyclohexylidene-1,3-dioxolane-4-yl-methyl methacrylate) (CHMMA). Probe quantities of 0.3, 0.6, and 0.9l were selected, and an injection was made at every 10 degrees C between 40 and 150 degrees C. In addition, 3l volume probes were tried but reproducible results were not obtained in these volumes and the detector was observed to be out of order after several injections. It has been observed that the specific retention volume of alcohols and alkanes partially increased by increasing the injection amount. A linear relationship was observed between probe quantities and specific retention volume. This linear relationship is apparent from the specific retention volume values, where the probes are independent of the physical and chemical structures. It was observed that the results obtained in all three injections were close to each other and within acceptable limits. The glass transition temperature of the polymer was determined to be a Tg of 60 degrees C. The thermodynamic data calculated for the injection of different amounts of probes were close to each other.
Magnetically Separable Pd(0)-Polymer Brush on Rgo for Efficient Nitrophenols Reduction
(Wiley-v C H Verlag Gmbh, 2025) Karakoyun, Necdet; Zengin, Adem; Karagoz, Mustafa Hamdi
In this study, a facile and effective method is reported for the fabrication of a polydopamine/polyacrylamide co-deposited on magnetic reduced graphene oxide (PDOPA/PAAm@mag-rGO) composite, which offers a new host material for dispersing palladium nanoparticles (Pd NPs) for catalytic reduction of nitrophenols. PDOPA/PAAm was grafted onto mag-rGO through one-step dopamine-triggered polymerization in a short time (45 min) at room temperature. PDOPA/PAAm@mag-rGO not only was used as support but also supplied compatibility and stabilizing Pd N Ps deposition, which enhanced the catalytic properties. The catalytic efficiency of the Pd-PDOPA/PAAm@mag-rGO was carried out with the reduction of 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol by using NaBH4 as a reducing agent at room temperature. The reduction rate of the aforementioned nitrophenols was as follows: 4-nitrophenol>2-nitrophenol>2,4-dinitrophenol. Moreover, the catalyst showed high stability and catalytic efficiency over five sequential uses in the reduction reaction. Magnetic analysis reveals that the as-prepared catalyst had superparamagnetic properties, which allow the easy recovery of the catalyst from the reaction medium via an external magnet. This study also indicates that polymer brushes and noble metal nanoparticles combined with magnetic reduced graphene oxide can play an efficient composite material for the fabrication of multifunctional and multi-component graphene-based materials for diverse catalytic applications.
Thermodynamic Interactions and Characterization of Poly (Acetyl Benzofuran Methylmethacrylate) and Poly(Acetyl Benzofuran Methylmethacrylate-Co by Invers Gas Chromatography
(Chem Soc Pakistan, 2018) Karagoz, Mustafa Hamdi; Bolat, Ozkan
In this study, the thermodynamic and physical properties of poly(acetyl benzofuran methylmethacrylate) [poly(ABM)], poly(acetyl benzofuran methylmethacrylate% 41-co-acrylonitrile) [poly(ABM% 41-co-AN)] and poly(acetyl benzofuran methylmethacrylate% 71-co-acrylonitrile) [poly(ABM% 71-co-AN)] were researched by using inverse gas chromatography. Two groups of alcohols and alkanes with different chemical natures and polarities were used to determine certain properties of [poly(ABM), poly(ABM% 41-co-AN) and poly(ABM% 71-co-AN)]-solute systems. The specific retention volume, V-g(0), glass transition temperature, Tg; adsorption enthalpy, Delta Ha; the sorption enthalpy, Delta H-1(S); sorption free energy, Delta G(1)(S); sorption entropy, Delta S-1(S); the weight fraction activity coefficients of solute probes at infinite dilution, Omega(infinity)(1), partial molar enthalpy of solute probes at infinite dilution, Delta H-1(infinity); and Flory-Huggins interaction parameters, chi(infinity)(12); between polymer and solvents were determined in the temperature range of 493-343 K for poly(ABM) and 473-343 K for poly(ABM% 41-coAN)-poly(ABM% 71-coAN). Also, the solubility parameters of poly(ABM), poly(ABM% 41-coAN) and poly(ABM% 71-coAN) at infinite dilution were found out by plotting the graph of [delta(2)(1) - (Delta G(1)(infinity)/V-1)] versus solubility parameters, delta(1), of the probes.