İç ortam havasından eş zamanlı partikül madde ve toluen giderimi için nanolif ve aktif karbon içeren filtre sisteminin geliştirilmesi
Simultaneous removal of particle material and toluene from indoor air with development of a filter system containing nanofiber and activated carbon
Yazar: MELİKE ERDEM YAVAŞ
Danışman: DOÇ. DR. DERYA YÜKSEL İMER
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı / Çevre Bilimleri ve Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Çevre Mühendisliği = Environmental Engineering
Dizin: Aktif karbon = Activated carbon ; Filtreler = Filters ; Nanolif = Nanofiber ; Partiküller = Particles ; Toluen = Toluene

Özet:
Günümüzde insanlar zamanlarının %80-90 gibi büyük bir kısmını iç ortamlarda geçirmektedir ve bu nedenle tren, uçak, hastane, restoran, ev ve ofis gibi sıklıkla bulunduğumuz iç ortamların hava kalitesi önemli çalışma konusu haline gelmiştir. İç ortamlarda soluduğumuz hava, en az dış ortamda soluduğumuz hava kadar sağlığımızı etkilemektedir. Özellikle modern binalarda yapılan izolasyon sistemleri taze hava sirkülasyonunu azaltmakta ve bu durum iç ortam havası kirleticilerine olan maruziyeti arttırmaktadır. İç ortamlarda geçirilen zamanın, insan sayısının ve kirletici kaynakların artması ile ''Hasta Bina Sendromu'' ve ''Bina Bağlantılı Hastalık'' gibi bazı sağlık sorunları da ortaya çıkabilmektedir. Bunların yanı sıra iç ortam havası kirleticilerinden partikül maddelerin (PM) ve uçucu organik bileşiklerin (UOB) varlığı solunum yolu hastalıklarına neden olmaktadır. 
İç ortam havasındaki partikül maddelerin birçok kaynağı bulunmaktadır. Yapılan çalışmalarda iç ortamdaki partikül madde ve uçucu organik bileşik konsantrasyonlarının dış ortamdaki partikül madde ve uçucu organik bileşik konsantrasyonları ile paralellik gösterdiği, ayrıca iç ortamlarda kullanılan birçok malzeme, teçhizat ve ekipmanın da kirletici madde kaynağı olabileceği görülmektedir. Günümüzde yaşanan COVID-19 pandemi salgınında en önemli ve en büyük bulaş yolu olarak görülen kaynak ise canlılardır. Ciddi solunum yolu enfeksiyonlarından ölüme kadar sebebiyet verebilen SARS-CoV-2 koronavirüsü de aynı zamanda yaklaşık 0,065 – 0,125 µm boyutları arasında ince tanecik grubunda yer alan bir partikül maddedir. Aynı zamanda bazı uçucu organik bileşikler de kimyasal yapılarından, buhar basınçlarından ve kaynama noktalarından dolayı bulunulan iç ortamlarda solunabilmektedir. Uçucu organik bileşikler, solunum yolu hastalıklarına ek olarak aynı zamanda nörolojik toksisite, göz ve boğaz tahrişi gibi sağlık etkilerine de neden olabilmektedir. 
İç ortamdaki partikül maddelerin ve uçucu organik bileşiklerin gideriminde en etkili yöntemlerden biri olarak görülen filtrasyon teknolojisi adsorpsiyon, oksidasyon ya da her iki mekanizmanın da kullanılması ile işlevselleştirilebilmektedir. Bu tezin de temel çıkış noktası, iç ortam havasında farklı boyutlarda bulunabilen partikül maddelerin, polimer yapılarının nanolif filtrelere entegrasyonu ile adsorpsiyon özelliği kazandırılarak filtrasyon teknolojisi yardımı ile gideriminin sağlanmasıdır. Böylece elektroeğirme yöntemi ile üretilen nanolif hava filtreleri ve aktif karbon kullanılarak yetersiz iç ortam hava kalitesinin iyileştirilmesine yönelik bir çözüm olarak tasarlanmıştır. Tez kapsamında nanolif filtreler üretilirken literatürde poliamid 6 (Naylon 6, PA6) polimeri ile ilgili nanolif hava filtrelerin geliştirilmesine yönelik çalışmaların verimlerinin yüksek olması hem de yüksek dayanım ve fiber oluşturma özelliği sunması nedeniyle ağırlıkça %18 oranında PA6 polimeri kullanılmıştır. Havada bulunan partikül maddelerin filtrasyon mekanizması ile fiber yüzeylerine adsorpsiyonunu sağlayarak kirleticilerin giderimi hedeflenmiştir. PA6 nanolif filtreler, iki farklı mesh (büyük gözenekli) filtre destek tabaka üzerine ve 15-30-45 dakikalık farklı üretim sürelerinde üretilerek filtrelerin hem yapısal karakterizasyonu hem de performanslarına bakılmıştır. Üretilen PA6 nanolif filtreler filtrasyon cihazına yerleştirilerek reaktör sistemi içerisinde PM1,0 ve PM2,5 boyutları için partikül madde giderim etkinliklerine bakılmıştır. Üretilen nanolif filtrelerin en yüksek PM1,0 giderimi  %93, PM2,5 için %94 giderim verimi sergilediği görülmüştür. Bir diğer aşamada farklı adsorbentler denenerek aralarında en iyi UOB giderim performansı gösteren adsorbent belirlenmiştir. Kullanılan klinoptilolit, bentonit, aktif karbon, selüloz nanofibril (CNF), silika jel, polivinil alkol (PVA) adsorbentlerinden aktif karbonun %97,03 giderim verimi ile en iyi performansı sergilediği görülmüştür. Filtre sistemine farklı oranlarda aktif karbon adsorbenti yerleştirilerek uçucu organik bileşik olarak kullanılan toluen kirleticisinin reaktör ortamında giderimi incelenmiştir. Kullanılan cihazın kapasitesine bağlı olarak ve ön denemelere göre 3 ve 5 gram aktif karbon adsorbenti ile toluen giderimleri izlenmiş ve %98'in üzerinde giderim verimi olduğu görülmüştür. Eş zamanlı partikül madde giderimi ve toluen adsorpsiyonu optimum şartlarda hem reaktör hem de gerçek oda ortamında gerçekleştirilmiştir. Böylece en iyi partikül madde giderimi ve toluen adsorpsiyonu sağlayan PA6 nanolif filtre ve aktif karbon oranı kullanılarak optimum koşullarda eş zamanlı giderim sağlanabilmiştir. Eş zamanlı giderimde, seçilen nanolif filtre ve 3 gr aktif karbon kullanıldığında PM1,0 giderimi %97,83, PM2,5 giderimi %97,37 ve 5 gr aktif karbon kullanıldığında PM1,0 giderimi %97,51 ve PM2,5 giderimi %98,95 olarak bulunmuştur. Gerçekleştirilen çalışmalar sonucunda seçilen nanolif filtre ve 3 gr aktif karbon adsorbenti ile gerçek oda koşullarında ölçümler gerçekleştirilmiştir. Farklı kompozisyonlarda üretilen nanolif filtrelerin karakterizasyonu için SEM analizi ile fiber çapları ve yüzey morfolojileri belirlenmiştir, nanolif fiber çaplarının 147 ile 167 nm arasında değiştiği görülmüştür. Nanolif filtrelerin performanslarını belirlemek için ise standart yöntemler ile hava geçirgenliği ve su buharı geçişi deneyleri yapılmıştır. 
Deneysel çalışmalar sonucunda farklı destek tabakaları ve nanolif filtre üretim süreleri ile üretilen filtrelere uçucu organik madde tutunum özelliği kazandırılarak iç ortam hava kalitesinin iyileştirilmesine yönelik partikül madde ve toluen giderimi için filtre malzemeleri geliştirilmiştir.

Abstract:
Nowadays, people spend almost 80-90% of their time indoors. Therefore, indoor spaces such as trains, airplanes, hospitals, restaurants, homes, and offices have become an important research topic. The air we breathe indoors affects our health at least as much as the air we breathe outdoors. In particular, insulation systems in modern buildings reduce fresh air circulation, increasing exposure to indoor air pollutants. With the increase of time spent indoors, the number of people and the sources of pollutants, some health problems such as "sick building syndrome" and "building-related diseases" may occur. In addition, the presence of particulate matter (PM) and volatile organic compounds (VOC), which are indoor air pollutants, causes respiratory illnesses.
There are many sources of particulate matter in indoor air. Studies show that indoor concentrations of particulate matter and volatile organic compounds are equivalent to outdoor concentrations of particulate matter and volatile organic compounds. Many materials and appliances can also be a source of indoor air pollutants. Living things are the source of particulate matter in indoor air, which is considered the most important and largest transmission route in the current COVID -19 pandemic. The coronavirus SARS-CoV-2, which can cause severe respiratory infections and even death, is also one of the particulate matter with a size of about 0.065 - 0.125 µm.
Due to the chemical structure of some volatile organic compounds, such as vapor pressure and boiling point, inhalation of indoor VOCs can cause respiratory diseases. In addition to respiratory illnesses, volatile organic compounds can also cause health effects such as neurological toxicity, eye irritation and throat irritation. One of the most effective ways to improve indoor air quality is to remove pollutants from the environment. If the source cannot be removed from the environment, ventilation is used to reduce the concentration of pollutants in the indoor air. In cases where this is not possible, various air purifiers can be used. Purification mechanisms such as UV purifier, photocatalytic oxidation, ozone generator and filtration can be used to remove pollutants from indoor air. Filtration technology is considered one of the most effective methods for removing particulate matter and volatile organic compounds in indoor air. Filtration technology can be functionalized by adsorption, oxidation, or both mechanisms.
The main approach of this work is to remove particulate matter, which occurs in various sizes in indoor air, using filtration technology by achieving adsorption properties by integrating polymer structures into nanofiber filters. Nanofiber filters fabricated by the electrospinning method can therefore be considered as a solution to improve insufficient indoor air quality and be used in air filters.
The electrospinning method is used to produce nanofiber filters, which are widely used in filtration technology due to their advantageous properties. There are some important parameters in converting a polymer solution into a nanofiber filter by electrospinning method. These parameters play a key role in producing the desired nanofiber filter. Some of them are the properties of the prepared polymer solution, the production process and the working environment. All of these properties can affect the production of nanofibers in different ways. Examples of polymer solution properties include polymer molecular weight, solution viscosity, surface tension, and conductivity. Parameters such as tension, feed rate, collectors, distance between tip and collector, feed rate can be counted among the process parameters. Parameters humidity and temperature can be mentioned as examples of environmental conditions.
In the fabrication of nanofiber filters in this work, 18 wt% of polyamide 6 (nylon 6, PA6) polymer was used because there are studies in the literature on the development of nanofiber air filters in combination with PA6 polymer and because it has high strength and fiber forming ability. If we look at the studies in the literature, PA6 polymer is preferred for the production of ultrafine fibers by electrospinning process because of its properties such as high durability and easy production. 
The aim is to remove pollutants by adsorbing particles in the air to the filtration mechanism. PA6 nanofiber filters were fabricated on different support layers and with different production times, and the efficiency of the filters was studied. Two types of mesh filters were used and 6 nanofiber filters were fabricated by electrospinning method with production times of 15, 30 and 45 minutes. For the first 3 nanofiber filters, coded BW6717 mesh filters were used as the support layer. The code of the nanofiber filter with a production time of 15 minutes is M1, the code of the nanofiber filter with a production time of 30 minutes is M2, and the code of the nanofiber filter with a production time of 45 minutes is M3. The last 3 nanofiber filters used mesh filters with code 4731 as the support layer. The code of the nanofiber filter with a production time of 15 minutes is M4, the code of the nanofiber filter with a production time of 30 minutes is M5, and the code of the nanofiber filter with a production time of 45 minutes is M6.
The produced PA6 nanofiber filters are inserted into the filter system. The efficiency of removal of particles of different sizes in the filtration device in the reactor system where the filter system is located was studied. The measurements were performed for PM1.0 and PM2.5, which belong to the group of fine dust particles that cannot be absorbed by the respiratory tract from the health point of view and have the possibility of inhalation into the lungs. As a result of the measurements performed, the measurements of the control filter and the nanofiber filter were compared for each particle size. It was found that the best result for PM1.0 and PM2.5 dimensions in terms of collection efficiency was obtained for the coded M4 nanofiber filter. The removal efficiency of the M4 nanofiber filter was 93% for the PM1.0 size and 94% for the PM2.5 size. In a further step, studies were conducted on the removal of toluene from volatile organic compounds, another important pollutant in indoor air. Toluene, which was used as a representative VOC, plays an important role in volatile organic compounds, and toluene was found to be relatively safe in a controlled laboratory environment. Moreover, adsorption technique was found to provide better efficiency in removing toluene. By testing different adsorbents, the adsorbent with the best performance was determined. Clinoptilolite, bentonite, activated carbon, cellulose nanofibrils (CNF), silica gel, and polyvinyl alcohol (PVA) nanoadditives were introduced into the filter system. The measurements were performed by injecting the same amount of toluene impurities into the reactor system by inserting the filter system into the filtration device. When the measurement results were evaluated, it was found that among the nano-additives that showed the best performance over time, activated carbon showed the best performance. It was found that 5 grams of activated carbon among the nano-additives used such as clinoptilolite, bentonite, activated carbon, cellulose nanofibrils (CNF), silica gel and polyvinyl alcohol (PVA) showed the best performance with 97.03% removal efficiency. Activated carbon is one of the most widely studied adsorbents in the literature and is considered to be very suitable for the removal of volatile organic compounds due to its small diameter and larger surface area. The adsorption efficiency of toluene, a pollutant used as a volatile organic compound, was studied by injecting it into the reactor system while different ratios of the activated carbon adsorbent were added to the filter system. These experiments were used to determine the optimum amount of adsorbent to be used. It was found that the removal efficiency was above 98% for 3 and 5 grams of activated carbon adsorbent. The toluene retention capacities of the activated carbon were calculated by serial toluene injections for the indicated amounts of activated carbon. For the simultaneous removal of PM1.0 with an M4 nanofiber filter and 3 g of activated carbon, the removal of PM1.0 is 97.83% and of PM2.5 is 97.37%. For simultaneous removal with an M4 nanofiber filter and 5 g activated carbon, PM1.0 removal is 97.51% and PM2.5 removal is 98.95%. In the concurrent removal studies, it was found that at the end of the 30th minute, 5 g of activated carbon resulted in 45.58% better removal than 3 g of activated carbon. At the end of the 60th minute, it was found that 5 g of activated charcoal resulted in 39.51% better performance than 3 g of activated charcoal. At the end of the 90th minute, it was found that 5 g of activated carbon performed 34% better than 3 g of activated carbon. Measurements were then made under real room conditions using an M4 nanofiber filter and 3 g of activated carbon as the adsorbent. 
In addition to the fine dust and toluene removal measurements, a SEM analysis was performed to determine the characterization of the materials used. The fiber diameters and surface morphologies of the fabricated nanofiber filters were determined using SEM analysis to characterize the nanofiber filters fabricated in different compositions. To characterize the nanofiber filters fabricated in different compositions, the fiber diameters and surface morphologies were determined using SEM analysis, and it was found that the diameters of the nanofibers ranged from 147 to 167 nm. At the same time, air permeability tests and water vapor permeability tests were performed on nanofiber filters using standard methods to determine the performance of the materials used. A water vapor permeability test was performed to determine the performance of the activated carbon adsorbent. For the simultaneous removal of fine dust and adsorption of toluene, the fine dust removal, the efficiency of adsorption of toluene, and the characterization and performance tests of the materials used were studied to determine the nanofiber filters, activated carbon, and ratios to be used. Thus, simultaneous removal under optimum conditions was achieved by using the coded M4 nanofiber filter, which showed the best results, and activated carbon ratios of 3 g and 5 g. 
The result shows that filtration technology can be used in the removal of fine dust and adsorption of toluene to improve indoor air quality by achieving selective adhesion to nanofiber filters produced by electrospinning with different support layers and different production times.