Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
Browse
7 results
Search Results
Article Citation - WoS: 6Citation - Scopus: 10The Size and Concentration Effects of Al2O3 Nanoparticles on PSF Membranes With Enhanced Structural Stability and Filtration Performance(Desalination Publ, 2017-07) Saki, Seda; Uzal, Nigmet; Ates, NurayNanocomposite membranes have attracted attention for their high permeability, rejection efficiency, and thermal and mechanical stability. In this study, novel flat-sheet polysulfone nanocomposite membranes were prepared by a phase inversion method with polyethylenimine and Al2O3 nanoparticles to increase the flux and hydrophilicity. Al2O3 nanoparticles were added to the membrane matrix to enhance the permeability, selectivity, and mechanical resistance. Two different sizes of Al2O3 nanoparticles (20 and 80 nm) were used with different weight percentages of 0.2, 1, and 5 wt%. The effects of the size and concentration of the nanoparticles on the structural properties and filtration performance of the membranes were investigated. Scanning electron microscopy, Fourier transform infrared spectroscopy, porosity, water contact angle, thermogravimetric analysis, viscosity, and tensile strength measurements were used to characterize the prepared membranes. The membrane performance was evaluated with water flux and bovine serum albumin rejection tests. According to the results, the membrane containing 15 wt% polysulfone, 1 wt% polyethylenimine, and 5 wt% 20 nm Al2O3 showed the highest pure water flux, porosity, viscosity, and morphological stability. This membrane may have potential uses in water treatment applications.Conference Object Citation - WoS: 5Citation - Scopus: 6The Selection of Washing Machine Programs With Fuzzy Dematel and Moora-Ratio Multi-Criteria Decision-Making Methods Considering Environmental and Cost Criteria(Elsevier Science inc, 2024-01) Fidan, Fatma Sener; Aydogan, Emel Kizilkaya; Uzal, NigmetThe washing machine is the prevalent white household equipment in contemporary society. These machines provide consumers with a range of program options that encompass several variables, including temperature and detergent type. Nevertheless, the selection made by individual customers about the washing machine program they opt for carries substantial environmental consequences during the use stage of textile products. According to studies on the life cycle of clothes, it has been established that the use stage, following the extraction of raw materials, exerts the most substantial influence on environmental impacts. The objective of this research is to assess the washing machine programs provided by the manufacturer through the application of a comprehensive systematic approach for analysis. The evaluation of scenarios for washing machine programs was conducted using the MOORA-Ratio multi-criteria decision-making process. This evaluation considered various parameters, including environmental impact and cost. The life cycle assessment methodology was employed to quantify the environmental impact of the specified criteria. Based on the comprehensive study conducted by integrating criteria across numerous dimensions, it has been determined that the most favorable scenario wass scenario 1, which was developed for the Cotton 20 C program. The primary objective of this research endeavor is to fill a significant need in the current body of literature by undertaking a comprehensive review of washing machine programs that have not been previously recorded. This study employs a comprehensive methodology to investigate the environmental and economic implications linked to these activities, with the objective of delivering significant insights to producers and users.Article Citation - WoS: 17Citation - Scopus: 24Recovery of Caustic From Mercerizing Wastewaters of a Denim Textile Mill(desalination Publ, 2015-03) Varol, Cihangir; Uzal, Nigmet; Dilek, Filiz B.; Kitis, Mehmet; Yetis, UlkuThe objective of this study was to evaluate caustic recovery from mercerizing wastewater originating from a denim textile producing plant using membrane technology. For this purpose, ultrafiltration (UF) and nanofiltration (NF) processes were considered. In the first stage, in an attempt to control the possible membrane fouling, pretreatment alternatives of flocculation, centrifugation, and microfiltration were evaluated. These pretreatment application alternatives were unsuccessful as they did not provide considerable color and solids removal. In the second stage, UF and NF processes were tested using a tight UF membrane (GR95PP, Alfalaval) and three NF membranes (NP010 and NP030, Microdyn Nadir, and MPF34, Koch Membranes) to accomplish the caustic recovery without applying any pretreatment. The best performance was obtained with NP010 NF in terms of permeate flux along with color and COD rejections. Then, for this membrane the effects of transmembrane pressure (4.03 and 6.23 bar), cross-flow velocity (from 0.40 to 1.40 m/s), and feed temperature (20 and 40 degrees C) were investigated. Temperature positively affected the permeate flux without significant loss in recovery and rejections. Caustic stream produced had about 98-100% of NaOH in the feed at a concentration of 30-40 g/L and therefore was recyclable after a concentration process.Article Citation - WoS: 4Citation - Scopus: 5Predicting Potential of Pressure Retarded Osmosis Power for Different Estuaries in Turkey(Wiley, 2018-11-29) Saki, Seda; Uzal, Nigmet; Gokcek, Murat; Ates, NurayPressure retarded osmosis (PRO) is an alternative renewable energy source recovered from the salinity gradient between the fresh water (feed solution) and salty water (draw solution). In order to implement osmotic power, the site-specific characteristics including the river and sea salinity, annual flow rates, ecological restrictions were taken into account. This study revealed a comprehensive analysis for a theoretical potential of PRO process for different estuaries in Turkey. In this study, the power potential prediction of PRO process for the Ceyhan, Sakarya, and Meric Rivers were analyzed via Gibbs free energy calculations. The net annual energy production is projected to be 167, 164, and 208 GWh/y for Ceyhan, Sakarya, and Meric Rivers, respectively. Meric River has the highest energy production of 208 GWh/yr with 186 m(3)/s mean flow rate and 245 mg/L salinity. These results clearly show that Turkey's rivers having high salinity and flow rate are feasible and applicable for making the osmotic power plant economically. Thereby, it is providing essential direction to the improvement of its design, installation, and operation. The developed methodology for the evaluation of the osmotic power potential of other rivers can be considered as a basis to assess the whole potential on a worldwide level. (c) 2018 American Institute of Chemical Engineers Environ Prog, 38:e13085, 2019Article Citation - WoS: 1Citation - Scopus: 1Pre-Concentration of Municipal Wastewater Using Flocculation-Assisted Direct Ceramic Microfiltration Process: Optimization of Operational Conditions(Springer int Publ Ag, 2022-10) Ozcan, Ozlem; Sahinkaya, Erkan; Uzal, NigmetDirect 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.Article Citation - WoS: 2Citation - Scopus: 2Integration of Direct Microfiltration and Reverse Osmosis Process for Resource Recovery From Municipal Wastewater(Elsevier Science inc, 2023-08) Ozcan, Ozlem; Sahinkaya, Erkan; Uzal, NigmetFor the sustainability of water resources, the recovery of water, organic matter (OM), energy, and nutrients from municipal wastewater become very attractive resources. As direct application of water, nutrient, and energy recovery from municipal wastewater cannot be feasible, the wastewater needed to be concentrated. In this study, the molecular weight distribution of OM content was determined in wastewater samples, up-concentration potential of direct microfiltration (DMF) of municipal wastewater and water recovery were investigated. In OM fractionation studies, around 52% of the chemical oxygen demand (COD) in wastewater was particulate or colloidal (>10 kDa) and 48% was soluble (<300 Da). In DMF tests, the COD concentration was concentrated up to 1,573 mg/L after sequential DMF experiments. Additionally, the theoretic total energy requirement of the DMF process was found around 0.3 kWh/m3 and it would be potentially energy positive. In crossflow experiments, the reverse osmosis (RO) process was performed using DMF effluent. When microfiltration and RO membranes were chemically cleaned, flux recovery rates of 100% and 99% were achieved, respectively. However, the foulants could not be completely removed during the cleaning according to scanning electron microscopy, atomic force microscopy, and attenuated total reflection-Fourier-transform infrared spectroscopy results of the virgin, fouled, and cleaned membranes. This study reveals that the DMF+RO process is a promising technology for the recovery of OM and water from municipal wastewater.Article Citation - WoS: 6Citation - Scopus: 6Arsenic Removal From Aqueous Solutions by Ultrafiltration Assisted With Polyacrylamide: An Application of Response Surface Methodology(Taylor & Francis inc, 2015-10) Varol, Bekir; Uzal, NigmetThe present work deals with removal of arsenic from aqueous solutions by ultrafiltration assisted with polyacrylamide as an environmental friendly complexing polymer. The system performance was evaluated in relation to quality of permeate in terms of operating variables as feed concentration of arsenic ions (C-o, gL(-1)), ratio of polymer to arsenic (r, w/w), and pH of feed solution. The effect of the operating variables and maximum arsenic removal efficiency was determined by adopting design of experiments and response surface methodology under different conditions for this polymer. The experimental data were analyzed with a second order polynomial model validated by statistical analysis. Based on the response model developed, the maximum removal efficiency, close to 100%, of arsenic ions has been obtained at optimum operating parameters as C-o: 150 gL(-1), r: 2, and pH 10.