Browsing by Author "Uzal, Niğmet"

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Characterizing boron-enhanced one-part alkaline-activated mortars: Mechanical properties, microstructure and environmental impacts
(ELSEVIER, 2024) Örklemez, Ezgi; İlkentapar, Serhan; Durak, Ugur; Gülçimen, Sedat; Uzal, Niğmet; Uzal, Burak; Karahan, Okan; Atiş, Cengiz Duran; 0000-0002-8967-3484; 0000-0002-3810-7263; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Gülçimen, Sedat; Uzal, Niğmet; Uzal, Burak
Since alkali activators negatively effect the environmental impact assessment, it is necessary to develop the alternative activators from natural sources with low environmental impact. Therefore, in this study, the usage of boron refined products colemanite, ulexite and boron pentahydrate as activators in slag-based alkali-activated mortar systems was investigated in detail. Flexural and compressive strength tests, isothermal calorimetry measurement, thermogravimetric and differential thermal analysis, inductively coupled plasma mass spectrometry analysis, field emission scanning electron microscopy, and energy dispersive analysis and elemental mapping and X-ray diffraction analysis were carried out on the samples. In addition, sample production was subjected to life cycle analysis (LCA) with a cradle-to-gate approach using two different transportation scenarios. According to the results obtained, it was determined that colemanite, ulexite and boron penta hydrate, when used in optimum proportions, had a positive effect on strength (up to increase 40% compressive strength by 20% ulexite replacement) and could be used as an activator in slag-based alkali-activated systems. The positive results obtained in strength as a result of using boron-refined products are also supported by other test results conducted within the scope of the study. Furthermore, according to the LCA results, it was observed that there was a significant decrease in global warming potential with the substitution of 20% colemanite, ulexite or boron pentahydrate as activators, not only compared to the reference sample but also traditional cementitious systems.
Efficiency of L-DOPA+TiO2 modified RO membrane on salinity gradient energy generation by pressure retarded osmosis
(Pamukkale Üniversitesi, 2024) Ateş, Nuray; Saki, Seda; Gokcek, Murat; Uzal, Niğmet; 0000-0001-8923-2323; 0000-0002-0912-3459; AGÜ, Fen Bilimleri Enstitüsü, Malzeme Bilimi ve Makine Mühendisliği Ana Bilim Dalı; SAKİ, Seda; Uzal, Niğmet
Harvesting energy from the salinity gradient of seawater and river water using pressure retarded osmosis (PRO) has been a major research topic of recent years. However, there is a need for efficient PRO membranes that can generate high power density and are pressure resistant, as the performance of current membranes on the market is poor. In this study, specific energy potential of PRO process using LDOPA+TiO2 modified BW30-LE membrane was evaluated on synthetic and real water samples. Polyamide BW30-LE RO membrane was modified by L-DOPA, L-DOPA+0.5 wt% TiO2 and L-DOPA+1 wt% TiO2. The effect of hydraulic pressure and temperature on generation of power density were evaluated for 5, 10, and 15 bar pressures, as well as 10 °C, 20 °C, and 30 °C degrees. The incorporation of TiO2 nanoparticles with L-DOPA increased the water flux by increasing the surface hydrophilicity and roughness of the membrane surface. The maximum specific power was observed as 1.6 W/m2 for L-DOPA+1 wt% TiO2 modified BW30-LE membrane at 15 bar pressure. Besides, Mediterranean and Aegean, Black Sea water samples were used as draw solution and Seyhan, Ceyhan, Buyuk Menderes, Gediz, Yesilirmak, and Kizilirmak Rivers were used as feed solution. The highest osmotic power density was obtained by using L-DOPA+1 wt% TiO2 modified BW30-LE membrane with Ceyhan River as feed and Mediterranean Sea water as draw solution, which have the highest differences in salinity. In the mixture of Mediterranean and Ceyhan River, the highest power density was obtained at 10 bar pressure at 30 ± 5°C with 0.70 W/m2 .
ILGIN LİNYİT İŞLETMELERİ GÖLETLERİNDE ASİT MADEN DRENAJI VE REHABİLİTASYONU
(Niğde Ömer Halisdemir Üniversitesi, 2016) Delibalta,Mahmut Suat; Uzal, Niğmet; 0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, Mühendislik Bilimleri Bölümü; Uzal, Niğmet
Maden yataklarının aranması, üretimi ve zenginleştirilmesi süreçlerinde uygulanan işlemler; hava, toprak, sukaynaklarını, dolayısıyla çevreyi ve çevrede yaşayan canlıları etkilemektedir. Genel olarak kömür açık işletmemadenciliğinin çevre üzerindeki olumsuz etkileri, yeraltı madenciliği ve cevher hazırlama çalışmalarına oranlaçok daha fazladır.Kömür açık işletmeleri sonrası oluşan üretim çukurlarının dekapaj malzemesiyle doldurulmaması halinde,yüzey suları ve yeraltı su seviyesinin yükselmesi ile küçük veya büyük göletler oluşmaktadır. Düşük pH değeri(asidik karakteristik) ve yüksek metal konsantrasyonu (Al, Ca, Mn, Fe, Cu, Zn, Pb) içeren bu göletlerde, baskınhalde bulunabilen sülfürlü mineraller ve atık malzemeler en önemli çevresel sorunlardan birini oluşturmaktadır.Bu çalışmada, TKİ GLİ Ilgın linyit işletmeleri 5 farklı gölette su karakterizasyonu izlemeleri yapılarak;ortalama pH 6,49-7,81, bulanıklık (NTU) 0,12-63,6, sülfat içeriği 0,05-2,67 mg SO4/L, kimyasal oksijen ihtiyacı4-136 mg O2/L, elektriksel iletkenlik 285 µS/cm-4,68 mS/cm değerleri ve 1839 ppb Mn, 9777 ppb Fe ile enyüksek ağır metal içerikleri tespit edilmiştir. Saha örneklerine ilişkin analizler üç aylık periyotlarla takipedilmiştir. Belirlenen sonuçlar ilgili yasal yönetmelikler çerçevesinde değerlendirilmiştir.
The impact of organic cotton use and consumer habits in the sustainability of jean production using the LCA approach
(SPRINGER, 2023) Şener Fidan, Fatma; Kızılkaya Aydoğan, Emel; Uzal, Niğmet; 0000-0002-2397-3628; 0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü; Şener Fidan, Fatma; Uzal, Niğmet
Due to the rise in clothing consumption per person and growing consumer awareness of environmental issues with products, the textile industry must adopt new practices for improving sustainability. The current study thoroughly investigates the benefts of using organic cotton fber instead of conventional cotton fber. Because of the extensive use of natural resources in the production of cotton, the primary raw material for textiles, which accounts for the environmental efects of a pair of jeans, a life cycle assessment methodology was used to examine these efects in four diferent scenarios. The additional scenarios were chosen based on the user preferences for washing temperatures, drying methods, and the type of cotton fber used in the product. The environmental impact categories of global warming potential, eutrophication potential terrestrial ecotoxicity potential, acidifcation potential, and freshwater ecotoxicity potential were analyzed by the CML-IA method. The life cycle assessment results revealed that the lowest environmental impacts were obtained for scenario 4 with 100% organic cotton fber with an improvement of 87% in terrestrial ecotoxicity potential and 59% in freshwater ecotoxicity potential. All of the selected environmental impacts of a pair of jeans are reduced in all scenarios when organic cotton is used. Additionally, consumer habits had a signifcant impact on all impact categories. Using a drying machine instead of a line dryer during the use phase is just as important as the washing temperature. The environmental impact hotspots for a pair of jeans were revealed to be the eutrophication potential, acidifcation potential, and global warming potential categories during the use phase, and the terrestrial ecotoxicity potential and freshwater ecotoxicity potential categories during the fabric manufacturing including cotton cultivation. The use of organic cotton as a raw material in manufacturing processes, as well as consumer preferences for washing temperature and drying methods, appears to have signifcant environmental impacts on a pair of jeans’ further sustainable life cycle.
Life Cycle Assessment of the Neutralization Process in a Textile WWTP
(Erciyes Üniversitesi, 2020) Şener Fidan, Fatma; Kızılkaya Aydoğan, Emel; Uzal, Niğmet; 0000-0002-0912-3459; 0000-0003-0927-6698; 0000-0002-2397-3628; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Nigmet
Although industrial wastewater treatment plants (WWTP) have become an important part of textile facilities in reducing environmental pollution problems, they also produce sludge and various emissions such as high chemical oxygen demand, color and conductivity which have serious negative impacts on the environment. One of the processes with enormous chemical consumption in industrial WWTP of textile facilities is the neutralization process, which aims to adjust the pH of the wastewater. Neutralization processes needed to be optimized in order to determine its overall environmental impacts and then identify the most environmentally appropriate options. The aim of this study is to compare the environmental impacts of carbon dioxide and sulfuric acid, which are two alternative chemicals used in the neutralization process of textile facilities, using Life Cycle Assessment (LCA) approach. The environmental impacts resulting from the use of these two chemicals proposed according to the Reference document on Best Available Techniques (BREF) Document for Textile Industry were revealed by the CML-IA method and the gate-to-gate method. According to the results, using carbon dioxide instead of sulfuric acid, the best improvement was in the abiotic depletion category with 92%, while the least improvement was in the eutrophication potential with 39%. No improvement was observed in the global warming potential and human toxicity impacts.
Ni-Zn metal-organic framework based membranes for rejection of Pb (II) ions
(ELSEVIERRADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS, 2022) Senol-Arslan, Dilek; Gul, Ayse; Uzal, Nigmet; Yavuz, Emre; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Şenol Arslan, Dilek; Gül, Ayşe; Uzal, Niğmet
The present paper describes a sustainable and affordable supply of clean, and safe water approach to investigate Ni-Zn MOF embedded membrane for rejection of Pb (II) ions in aqueous solution. Ni-Zn MOF powder was prepared by solvo-thermal method, and then the Ni-Zn MOF embedded membranes with various concentrations (0.025 wt%, 0.05 wt% and 0.1 wt%). The membranes were fabricated by a common phase inversion method. Phase solutions of Pb(II) prepared with PVP at different concentrations in aqueous solutions. Water filtration and Pb (II) rejection tests were operated on a batch scale. The prepared Ni-Zn MOF powder characterized by FTIR, SEM-EDX analyses and zeta potential measurements. Ni-Zn MOF membranes were characterized by FTIR, SEMEDX analysis, contact angle, and water permeability measurements. The effects of important parameters on adsorption including concentration and pH were investigated. The obtained results indicated that the maximum rejection of Pb(II) was 98% for a feed solution containing 80 mg Pb/L at pH 8 and assistance with 2 % PVP for 0.05 wt% Ni-Zn MOF membrane. Additionally, it was detected that blend membranes revealed better Pb(II) rejection than pure PSF membrane.
Pre-concentration of Municipal Wastewater Using Flocculation-Assisted Direct Ceramic Microfiltration Process: Optimization of Operational Conditions
(SPRINGER INT PUBL AG, 2022) Ozcan, Ozlem; Sahinkaya, Erkan; Uzal, Nigmet; 0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Niğmet; Özcan, Özlem
Direct ceramic microfiltration (DCMF) is an effective technology to pre-concentrate organic matter (OM) for the subsequent anaerobic energy-recovering processes and a fast, cost-effective, easy treatment process for municipal wastewater. The major problem in DCMF is the rapid fouling of the membrane. In this study, to maximize OM recovery rates and prevent membrane fouling, the DCMF process was alternately paired with dosing of a cationic polyacrylamide (PAM) flocculant and chemically enhanced primary sedimentation (CEPS). The DCMF process tested in three stages: (i) optimization of flocculant concentration (0.5, 1, 1.5, and 2 mg/L PAM) and dosing point, (ii) optimization of operational conditions (pH, filtration/backwash duration, flux, and recovery rate) to control membrane fouling, and (iii) long-term operation of the DCMF process. The influence of PAM dosage points on DCMF fouling behavior was explored, and system operating parameters in terms of OM recovery and TMP change were optimized. The CEPS + DCMF setup was discovered to be a potential option for overcoming fouling. The highest chemical oxygen demand (COD) was 520 +/- 20 mg/L in the concentrated wastewater using CEPS + DCMF experiments for 0.5 mg/L PAM. The highest OM pre-concentration was achieved at 90% recovery rate. After the optimization, COD concentration in the concentrate of the DCMF process reached 822 mg/L for the long-term (20 days) operation. The net potential energy production was calculated as 0.28 kWh/m(3) considering the theoretical COD of 1432 mg/L in the concentrate stream. As a novel approach, the CEPS + DCMF process can be used in place of conventional municipal wastewater treatment processes due to its acceptable OM removal performance, simple operation, small footprint, and potential energy generation.
Rehabilitation of water and environment of the TKI - GELI/YLI opencast mine lakes
(Chamber of Mining Engineers of Turkey, 2013) Delibalta, Mahmut Suat; Uzal, Niğmet; https://orcid.org/0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Niğmet
During the search, production and enrichment process of mining operations the air, soil, water resources and living organisms are affected adversely. In coal opencast production, with the rise of surface water and ground water level large or small ponds are composed. The most important environmental problems of these ponds are low pH (acidic characteristic) and high metal concentrations (Fe, Mn, Al, Cu, Pb, Zn etc.) of these ponds, besides the sulfide minerals containing (S04) and the waste materials. These ponds needed to be rehabilitated for is one the sustainability of natural resources. In this study, the average pH values 6.22-7.79, turbidity (NTU) 0.63-6.71, sulphate content 840-1720 mg/L, KOI 2.27-61.5mg/L and electrical conductivity 1.72 -2.71 mS/cm have been measured during the monitoring study of three different lignite opencast mine post-production lakes of the TKI -GELI and YLI. The results were evaluated within the framework of relevant laws and regulations. Analyses were performed in three-month periods.
Sustainability assessment of denim fabric made of PET fiber and recycled fiber from postconsumer PET bottles using LCA and LCC approach with the EDAS method
(John Wiley and Sons Inc, 2024) Fidan, Fatma Şener; Aydoğan, Emel Kızılkaya; Uzal, Niğmet; 0000-0002-2397-3628; 0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Fidan, Fatma Şener; Uzal, Niğmet
The textile industry is under pressure to adopt sustainable production methods because its contribution to global warming is expected to rise by 50% by 2030. One solution is to increase the use of recycled raw material. The use of recycled raw material must be considered holistically, including its environmental and economic impacts. This study examined eight scenarios for sustainable denim fabric made from recycled polyethylene terephthalate (PET) fiber, conventional PET fiber, and cotton fiber. The evaluation based on the distance from average solution (EDAS) multicriteria decision‐making method was used to rank scenarios according to their environmental and economic impacts, which are assessed using life cycle assessment and life cycle costing. Allocation, a crucial part of evaluating the environmental impact of recycled products, was done using cut‐off and waste value. Life cycle assessments reveal that recycled PET fiber has lower freshwater ecotoxicity and fewer eutrophication and acidification impacts. Cotton outperformed PET fibers in human toxicity. Only the cut‐off method reduces potential global warming with recycled PET. These findings indicated that recycled raw‐material life cycle assessment requires allocation. Life cycle cost analysis revealed that conventional PET is less economically damaging than cotton and recycled PET. The scenarios were ranked by environmental and economic impacts using EDAS. This ranking demonstrated that sustainable denim fabric production must consider both economic and environmental impacts. Integr Environ Assess Manag 2024;20:2347–2365. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).