Chemistry / Kimya

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Access type: Open accessAuthor: search.filters.author.Polat, Hürriyet

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  • Article
    Citation - WoS: 2
    Citation - Scopus: 3
    A Phenomenological Kinetic Flotation Model: Distinct Time-Variant Floatability Distributions for the Pulp and Froth Materials
    (Elsevier, 2023) Polat, Mehmet; Polat, Hürriyet
    A simple and easy-to-use phenomenological kinetic flotation model, strongly connected with the physics of the process, is proposed in this paper. The model explicitly contains the cell volume, aeration rate, volumetric holdup, mean bubble size, and particle density as input variables. It can be employed to characterize the floatability distributions of the particles in the pulp and the froth separately any time during the flotation process. Two new time-dependent kinetic parameters, the bubble loading factor & phi;(t) and the maximum cell mass transfer capacity Mmax(t) also appear in the model expression. & phi;(t) is a measure of the degree of crowding of the bubble surfaces and accounts for the deviations from the first-order rate equation. Mmax(t) describes the maximum amount of mass that can be transported to the froth phase by the bubble population in the cell. Screen fractionation of each froth product collected at different time intervals during a single kinetic flotation test is sufficient to generate the data required by the model for analysis. Application of the model to this data yields directly time-dependent functions for the floatability of the particles reporting to froth Kf(t) or remaining in the cell Kp(t) for each size fraction separately, without the need for any empirical parameters. The test of the model was carried out using published kinetic flotation data from the literature.
  • Research Project
    Uçucu kül ve doğal zeolitin beraber kullanılarak borun atık sulardan uzaklaştırılması
    (2008) Polat, Hürriyet; Polat, Mehmet; Şekeroğlu, Koray
    Bu proje kapsamında, Yeniköy, Kemerköy, Soma ve Yatağan termik santrallerinden alınan uçucu küllerin, sıcaklık, katı / sıvı oranı ve başlangıç konsantrasyonu gibi parametler kullanılarak bor adsorpsiyon kapasiteleri incelenmiştir. Bor adsorpsiyon deneyleri laboratuvarda hazırlanan simültane sular (10, 25, 50, 100 ve 300 ppm Bor) ve Kızıldere (Denizli) jeotermal tesislerinden (25-30 ppm Bor) alınan borlu sularla yapılmıştır. Yapılan “batch” deneylere dayanarak, uçucu küllerin boru adsopladığı ve özellikle yüzey alanı en geniş olan Yeniköy külü yeterli zaman ve yüzey alanı sağlandığında %99 ‘a varan adsorpsiyon miktarına ulaştığı gözlenmiştir. Tüm küllerin deney sonuçları tek katmanlı adsorpsiyonu belirten “Langmuir” izotermine ve Kaydırılmış İkinci Mertebe parametresine daha uygun olduğu tespit edilmiştir. Yapılan sıcaklık çalışmalarında, Yeniköy ve Kemerköy külleriyle 25o C, 45o C ve 65o C koşullarında yapılan deneylerin verileri kullanılarak, o ΔH ,o ΔG , o ΔS değerleri hesaplanmıştır. Sıcaklıkla azalan adsorpsiyon kapasitesi ve negatif o ΔH değerleri, ekzotermik adsorpsiyon olduğunu belirtmektedir. Aynı zamanda -40,0 kJ / mol’ün altında çıkan (-52,89 ve -48,55 kJ / mol) entalpi ( o ΔH ) değerleri kimyasal adsorpsiyon olduğunu belirtmektedir. Soma ve Yatağan külleri için de Langmuir izotermlerinin uygun olması kimyasal bir adsorpsiyon olduğunu önermektedir.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 11
    The Effect of Protein Bsa on the Stability of Lipophilic Drug (docetaxel)-Loaded Polymeric Micelles
    (Elsevier, 2021) Polat, Hürriyet; Çevik Eren, Merve; Polat, Mehmet
    Polymeric micelles are promising delivery vehicles for improving the efficacy of anticancer drugs and reducing their side effects. However, considering the binding ability of serum albumin, the possible interaction of micelles with the native plasma components in the bloodstream raises serious questions on micellar stability. The stability of barren or drug-loaded copolymeric micelles was investigated systematically in distilled water (DW) and simulated body fluid (SBF) solutions in the presence of a model protein. The copolymer was a Pluronic® series triblock copolymer (P-123), the drug was strongly lipophilic docetaxel (DOC) and the protein was Bovine Serum Albumin (BSA). The effect of such factors as BSA and DOC concentrations and the aging of the micellar solutions was studied. Both the barren and drug-loaded micelles were quite stable in blank DW and SBF solutions for long times up to 10 days. They lost integrity and showed no inclination to re-assemble when the BSA concentration reached a critical value, which was very close to the plasma Human Serum Albumin (HSA) concentration. The presence of DOC in the micellar cores could not prevent disintegration. The results illustrate clearly that ensuring the stability of polymeric micelles in blood plasma should be an important design factor in their use as drug carriers.
  • Article
    Toz Kömürlerin Zenginleştirilmesinde Yağ Aglomerasyonu Yöntemi ve Yenilikler
    (İstanbul Üniversitesi, 2010) Kılınç Aksay, Ece; Arslan, Vedat; Polat, Hürriyet
    Kömürün üretim teknolojisindeki gelişmeler, kömür üretimi sürecinde oluşan ince boyutlu (toz) kömürün miktarını arttırmaktadır. Bu tür toz kömürlerin zenginleştirilerek değerlendirilmesi, hem madencilik maliyetini azaltmakta, hem de önemli bir çevre problemini ortadan kaldırmaktadır. Ayrıca eneıjiye olan gereksinim, her geçen gün teknolojinin ilerlemesiyle doğru orantılı olarak artmaktadır. Dolayısıyla, çevre problemi yaratan sınırlı enerji kaynaklarının, çevre dostu yöntemlerle değerlendirilmesi gerekmektedir. Yağ aglomerasyonu yöntemi, bu yöntemlerden biridir. Özellikle çok ince boyutlu kömür tanelerinin kazanılmasında flotasyona alternatif bir yöntemdir. Bu yöntem, yüksek devirli karıştırıcılar kullanılarak, kömür tanelerinin yağ tarafından ıslatılması ve birbirlerine bağlanarak iri taneler haline getirilmesi prensibine dayanır. Yağın, kömür-su sistemine verilmeden önce, su içerisinde gerek mekanik karıştırma ile gerekse çeşitli yüzey aktif reaktiflerin kullanımı ile emülsiye edilmesi (dağıtılması) veya kömür yüzeyinin yine çeşitli yüzey aktif reaktiflerle hava/yağ sever özellik kazandırılması, yöntemin başarısını hem teknik hem de ekonomik yönden arttırmaktadır. Yağ aglomerasyonu yöntemindeki bu yenilikler, günümüzde linyit gibi düşük kaliteli kömürlerin bile, bu yöntem ile başarıyla zenginleştirilebilmesine olanak sağlamaktadır. Bu makalede, yağ aglomerasyonu yönteminin temel prensipleri, yöntemi etkileyen parametreler ve farklı tip kömürler için yöntemin uygulamasına yönelik araştırmalar detaylı olarak açıklanmış, yöntem ile ilgili yenilikler tartışılmıştır.
  • Article
    Solunabilir Tozun Su Spreyleri Kullanılarak Bastırılmasında Son Gelişmeler
    (2000) Polat, Hürriyet; Polat, Mehmet; Gürgen, Sabit
    Türkiye'de görülen meslek hastalıklarının çoğunu tozun solunmasından kaynaklanan pnömokonyoz oluşturmaktadır. Bu yazının amacı, yeraltı ocaklarında işçi sağlığı açısından sakıncalı olan havada asılı tozların, su spreyleri kullanılarak bastırılması konusunda gelinen aşamayı sunmaktır. Bu amaçla, havada asılı toz ve su damlalarıyla yapılan detaylı çalışmalar ışığında, sprey suyuna katılan yüzey aktif maddelerin istenen verim artışını sağlayamama nedenleri ele alınmakta ve su spreylerinin Türkiye'deki maden ocaklarında kullanım olanakları tartışılmaktadır.
  • Book Part
    Citation - Scopus: 6
    Recent Advances in Chitosan-Based Systems for Delivery of Anticancer Drugs
    (Springer, 2020) Polat, Mehmet; Polat, Hürriyet
    Problems in transporting drug molecules to tumor sites in required dose or constitution lead to low efficacy and significant side effects. Shielding the drug molecules in micelles, liposomes, or nanoparticles is a major line of investigation to improve chemotherapeutic treatment. Though compatibility for proper envelopment of the drug and timely release at the tumor site are required of such a carrier, protecting its own physicochemical and morphological integrity during transport is another precondition. Because of its superior polymerization capability, biocompatibility, pH dependence, and charging characteristics, chitosan has been in the forefront of potential drug carriers. Numerous synthesis routes for chitosan-based nanocarriers have been suggested to the extent that a search of the literature published since 2000 with the keywords “novel + nano + chitosan” in the title results in 527 articles, indicating the bewildering quality and quantity of the new information. This review was carried out not only to peruse this large amount of work on chitosan-based anticancer drug delivery but also to extract manageable patterns from numerous synthesis routes. The main conclusion is that the synthesis methods suggested in literature can be combined into two main routes, and the degree of hydrophobicity of the drug determines which route should be followed. © Springer Nature Singapore Pte Ltd. 2019.
  • Article
    Citation - WoS: 2
    Reduction of Carbon Dioxide During the Synthesis of Metal Nano-Particles in Water
    (Elsevier Ltd., 2003) Polat, Hürriyet; Cohen, H; Meyerstein, D; Rusonik, I.
    An effort was made to synthesize "carbon-free" metal (Fe-0, Co-0, Ni-0) nano-particles via the reduction of their salts with BH4- in aqueous solutions. Surprisingly it was found that when the synthesis is carried out in the presence of CO2, e.g., in aerated solutions, the CO2 is catalytically reduced by BH(4)(-)on the surface of the metal particles. Carbon-free metals can be prepared by reduction under an inert atmosphere. Thus metal surfaces might have acted as catalysts for CO2 fixation, probably via the initial formation of carbon clusters, in the reductive atmosphere in the prebiotic era. (C) 2003 Elsevier B.V. All rights reserved.
  • Correction
    Erratum To: Tannery Wastewater Sediments Produced by Clinoptiolite/Polyacrylamide-aided Flocculation as a Clay Additive in Brick Making
    (Australian Ceramic Society, 2017) Israil, L. I.; Köseoğlu, Kemal; Cengizler, H.; Polat, Hürriyet
    [No abstract available]
  • Article
    Citation - WoS: 13
    Citation - Scopus: 15
    Analysis of Dilution Induced Disintegration of Micellar Drug Carriers in the Presence of Inter and Intra Micellar Species
    (Elsevier, 2020) Polat, Hürriyet; Kutluay, Gülistan; Polat, Mehmet
    Micelles of self-assembling polymeric surfactant molecules are promising nanoscopic carriers for lipophilic and toxic drugs, genes, and imaging molecules. Though it is a must for successful transport, ensuring micelle integrity is a challenge during intravenous injection where micelles must endure abrupt dilutional effects and encounters with native molecules. Therefore, direct observational evidence of how micelles behave during dilution is valuable in manipulating the designs of these carriers for a succesful drug delivery. Morphology and stability of the barren and a drug-loaded (lipophilic probucol) micelles of a polymeric surfactant (Pluronic® P123) were monitored during systematic re-dilution in distilled water and simulated body fluid in the presence of a model protein (bovine serum albumin). It was observed through surface tension, dynamic light scattering, laser velocimetry, transmission scanning and transmission electron microscopy, and atomic force microscopy analyses that the micelles disintegrated to various degrees in all cases upon dilution. The results indicate that dilution effects must be taken into account in designing micellar drug carriers. The assistance of some other means of protection such as encapsulation should be considered for ensuring micelle integrity within the bloodstream. © 2020 Elsevier B.V.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Tannery Wastewater Sediments Produced by Clinoptiolite/Polyacrylamide-aided Flocculation as a Clay Additive in Brick Making
    (Springer Verlag, 2017) Köseoğlu, Kemal; Cengizler, H.; İsrail, L. İ.; Polat, Hürriyet
    Toxic tannery wastewater(s) (TWW) pose(s) a great risk to the environment. This study explores the potential of mitigating the harmful effects of TWW through sedimentation using clinoptiolite in the presence of various anionic, cationic and non-ionic flocculants with different molecular weights and charge densities followed by encapsulation in a brick structure for stability. Compressive strength (CS), size reduction after firing (SRAF), water absorption (WA) and colouring parameters of bricks were determined. X-Ray diffraction (XRD) and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses were conducted on brick bodies. Kinetic leaching experiments were conducted for possible heavy metal release from the bricks. Bricks containing 10 wt% leather waste and 5 wt% clinoptiolite sintered at 800 °C instead of 920 °C possessed similar properties to the standard brick (SB).