Gallik asidin fotokatalitik giderimi: Düşük moleküler ağırlıklı bileşenler kullanılarak doğal organik madde modellemesi
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Date
2019-05-02
Authors
Uyguner-Demirel, Ceyda Senem
Journal Title
Journal ISSN
Volume Title
Publisher
Bursa Uludağ Üniversitesi
Abstract
Hümik asitler gibi, doğal polimerlerin yapısal alt birimlerinden birini temsil eden gallik asitler, sucul sistemlerde doğal organik madde bozunmasının bir ürünü olarak kabul edilmektedir. Bu çalışmada, hümik maddelere yapısal olarak benzerlik gösteren küçük moleküler ağırlıklı gallik asit, model madde olarak değerlendirilmiştir. Gallik asidin fotokatalitik oksidasyonu, i) başlangıç madde konsantrasyonu, ii) fotokatalizör konsantrasyonu ve iii) fotokatalizör tipi gibi temel operasyon parametrelerinin etkisi araştırılarak incelenmiştir. Fotokatalizör olarak TiO2 Degussa P-25, Hombikat UV-100, PC-10, PC-50 ve PC-105 kullanılmıştır. Gallik asidin zamana karşı fotokatalitik olarak giderimi, UV-vis ve floresans spektroskopik parametreler ve toplam organik karbon ölçümleri ile takip edilmiş ve birinci mertebeden kinetik model kullanılarak açıklanmıştır. Gallik asidin kinetik verilerinin, ana molekül olan hümik asidin fotokatalitik bozunma çalışmalarıyla ilişkilendirilebilmesi için karşılaştırmalı bir yaklaşım izlenmiştir. Gallik asidin farklı fotokatalizörler üzerindeki ön adsorpsiyon sonuçları, gallik asidin fotokatalitik giderim hızı ile doğru orantılı olarak ilişkilendirmiştir. Gallik asit giderim hız sabitlerinin UV265 cinsinden karşılaştırılması; P-25> PC-10> UV-100> PC-105> PC-50 şekilinde sıralanırken, toplam organik karbon giderimi için hız sabitleri değişimi; PC-105> UV 100> PC-10> P-25> PC-50 olarak bulunmuştur. Test edilen çeşitli fotokatalizörler arasında PC-105' in, gallik asit giderimi için oldukça aktif olduğu bulunmuştur. PC-10 ve PC-50' nin küçük yüzey alanları göz önünde bulundurulduğunda, bu fotokatalizörlerin varlığında nispeten düşük giderim hızları elde edilmiştir.
Gallic acid is regarded as a product of natural organic matter decay in aquatic systems representing one of the structural subunits of natural polymers such as humic acids. In this work, the photocatalytic oxidation of gallic acid was investigated focusing on the effects of the major operating factors namely; i) initial substrate concentration, ii) photocatalyst loading and iii) photocatalyst type. The photocatalysts used were TiO2 Degussa P-25, Hombikat UV-100, Millennium PC-10, Millennium PC-50 and Millennium PC-105. The photocatalytic removal of gallic acid with respect to irradiation time was followed by UV-vis and fluorescence spectroscopy as well as total organic carbon (TOC) measurements. The removal of photocatalytic oxidation in terms of absorbance measurements at 265 nm (UV265) and TOC was explained using pseudo first order kinetic model. A comparative approach was followed to relate data to previous photocatalytic degradation studies of the parent molecule; humic acids. The initial adsorption of gallic acid on different photocatalysts correlated well with the initial removal rates of gallic acid. The comparison of the intrinsic rates in terms of UV265 could be ordered as; P-25>PC-10>UV100>PC-105>PC-50 whereas for TOC it could be ordered as follows; PC-105>UV-100>PC-10> P-25>PC-50. Among the various photocatalysts tested, PC-105 was found to be highly active for gallic acid removal. Considering the lower surface areas of PC-10 and PC-50, relatively lower initial rates were attained.
Gallic acid is regarded as a product of natural organic matter decay in aquatic systems representing one of the structural subunits of natural polymers such as humic acids. In this work, the photocatalytic oxidation of gallic acid was investigated focusing on the effects of the major operating factors namely; i) initial substrate concentration, ii) photocatalyst loading and iii) photocatalyst type. The photocatalysts used were TiO2 Degussa P-25, Hombikat UV-100, Millennium PC-10, Millennium PC-50 and Millennium PC-105. The photocatalytic removal of gallic acid with respect to irradiation time was followed by UV-vis and fluorescence spectroscopy as well as total organic carbon (TOC) measurements. The removal of photocatalytic oxidation in terms of absorbance measurements at 265 nm (UV265) and TOC was explained using pseudo first order kinetic model. A comparative approach was followed to relate data to previous photocatalytic degradation studies of the parent molecule; humic acids. The initial adsorption of gallic acid on different photocatalysts correlated well with the initial removal rates of gallic acid. The comparison of the intrinsic rates in terms of UV265 could be ordered as; P-25>PC-10>UV100>PC-105>PC-50 whereas for TOC it could be ordered as follows; PC-105>UV-100>PC-10> P-25>PC-50. Among the various photocatalysts tested, PC-105 was found to be highly active for gallic acid removal. Considering the lower surface areas of PC-10 and PC-50, relatively lower initial rates were attained.
Description
Keywords
Gallik asit, Doğal organik madde, Kinetik, Fotokatalitik oksidasyon, TiO2, Gallic acid, Kinetics, Natural organic matter, Photocatalytic oxidation
Citation
Uyguner-Demirel, C. S. (2019). "Gallik asidin fotokatalitik giderimi: Düşük moleküler ağırlıklı bileşenler kullanılarak doğal organik madde modellemesi". Uludağ Üniversitesi Mühendislik Fakültesi Dergisi, 24(2), 595-608.