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Öğe Assessment of groundwater contamination risk with scenario analysis of hazard quantification for a karst aquifer in Antalya, Turkey(Springer, 2020) Cil, A.; Muhammetoglu, A.; Ozyurt, N. N.; Yenilmez, F.; Keyikoğlu, Ramazan; Amil, A.Karst aquifers usually have high vulnerability to groundwater pollution. This study aims to assess the risk of groundwater contamination in karst aquifers by two index overlay methods of intrinsic vulnerability (COP and PI) and to discuss the importance of hazard index values on risk assessment. Altinova region of Antalya, with intensive agricultural activities, was chosen as the pilot study area (PSA) for application. Seasonal monitoring studies were conducted at 25 sampling wells for many water quality parameters in addition to soil characteristics and depth to groundwater. The areas for low, moderate and high levels of vulnerability and risk were determined, where more than 90% of the PSA was classified as having moderate to very high vulnerability levels according to COP and PI methods. For validation of risk analysis results, nitrate concentrations were correlated with risk intensity values. Both methods were successful to assess the vulnerability and risk to groundwater pollution with high correlation. In addition, the impacts of hazard index values on groundwater pollution risk were investigated for two scenario conditions which represent the increase in the relative amount of pollutants caused by the greenhouses. As a result, the karstic part of the PSA was assessed to have a high risk of groundwater contamination by the COP method, where immediate control measures are necessary. In conclusion, the selection of suitable vulnerability methods for karst aquifers and assignment of realistic hazard index values are highly effective on risk analysis results to represent the actual conditions.Öğe Boyar maddelerin molekül ağırlığının elektrooksidasyon ve elektrokoagülasyon proseslerinde renk giderme verimine etkisi(Bursa Teknik Üniversitesi, 2018) Keyikoğlu, Ramazan; Can, Orhan TanerBoyar maddeler, çeşitli cisimleri (kumaş, elyaf vb.) renkli hale getirmek için kullanılan organik bileşiklerdir. Farklı kimyasal yapıya ve molekül ağırlığına sahip birçok farklı boyar madde endüstriyel uygulamalarda kullanılmaktadır. Özellikle yüksek çözünürlüğe sahip reaktif boyalar zengin parlak renk gamları ve birçok şekilde uygulanabilme kolaylıkları nedeniyle tekstil boyamada çok tercih edilmektedir. Tekstil boyama endüstrisinde, üretimin çeşitli adımlarında çok miktarda su, sentetik boya ve çeşitli kimyasallar kullanılır ve bunun sonucunda farklı molekül yapılarında kompleks kirleticileri içeren atıksu meydana gelir. Özellikle suda çözünürlüğü yüksek ve sabitlenme oranları düşük olan boyar maddeler uygulama sırasında tamamen tutunmadan hidrolize olmaları nedeniyle çok miktarda tutunmamış boya atık haline gelir. Alıcı su ortamında atık boyanın oluşturacağı renk nedeniyle ışık geçirgenliği azalarak fotosentez faaliyetleri engellenir ve oksijen tükenmesi meydana gelir. Ayrıca toksik ve mutojenik boyar maddelerin su kütlelerinde bulunmaları sucul yaşamı olumsuz etkiler. Kanalizasyon sistemine arıtılmadan bırakılmaları kentsel atıksu arıtma tesislerinin biyolojik proseslerinde sorunlara yol açabilir. Bu nedenle boyar madde içeren atıksuların su sistemlerine bırakılmadan önce arıtılmaları için yenilikçi, uygun maliyetli ve etkili atıksu artım teknolojilerine ihtiyaç vardır. Bu çalışmada boyar maddelerin elektrooksidasyon ve elektrokoagülasyon prosesleri ile giderilmelerinde molekül ağırlıklarının etkisi araştırıldı. Bu amaçla, molekül ağırlıkları sırasıyla 1304,80 g/mol, 1026, 25 g/mol ve 626 g/mol olan Reactive Blue 198 (RB198), Reactive Yellow (RY145) ve Reactive Blue 19 (RB19) boyar maddeleri seçildi. Deneylerde kullanılan sentetik boya solüsyonları her boyar maddeden 50 mg alınarak 1 L saf su içerisinde çözdürülmesi ile hazırlandı. Laboratuvar ölçekli deneyler 1000 mg/L NaCl içeren 500 mL boya çözeltileri kullanılarak kesikli sistem ile gerçekleştirildi. Elektrokoagülasyon (EC) deneyleri, 5 alüminyum elektrot içeren elektorkoagülasyon reaktörü (3 anot, 2 katot), güç kaynağı ve manyetik karıştırıcı kullanılarak yürütüldü. Elektrooksidasyon (EO) deneyleri, anot olarak bor katkılı elmas elektrot (BDD), katot olarak ise Ti/IrRuO2 elektrotlarını içeren EO reaktörü ve DC güç kaynağı kullanılarak yürütüldü. Her iki prosesin giderim performanslarına molekül ağırlıkları ile birlikte akım yoğunluğunun etkisi de araştırıldı. Boya giderim verimleri UV/vis spektrofotometre ile ölçülen absorbans değerlerinden konsantrasyonların hesaplanması ile bulundu. Çalışma sonuçlarından; Boyar madde molekül ağırlığının büyüklüğü bunların elektrokimyasal yöntemlerle (elektrokoagülasyon ve elektrooksidasyon) sulardan gideriminde avantaj sağladığı görüldü. Elektrokimyasal proseslerden elektrokoagülasyon ise boyar madde gideriminde elektrooksidasyona göre daha kısa sürede ve daha düşük işletme maliyeti ile giderim yapabilmektedir. Ancak elektrokoagülasyonda oluşan flok çamurlarının giderilmesi gerektiği unutulmamalıdır.Öğe Comparison of the effects of various supporting electrolytes on the treatment of a dye solution by electrocoagulation process(Elsevier, 2019) Keyikoğlu, Ramazan; Can, Orhan Taner; Aygün, Ahmet; Tek, AhuLaboratory experiments were conducted to investigate the effect of some supporting electrolytes on the treatment of Reactive Black 5 (RB5) by electrocoagulation using aluminum and iron electrode couples. Electrolytes, which contain Cl-, SO42-, NO- anions and Na+, K+, NH4+ cations, were compared in terms of color removal efficiencies. The presence of SO42- led to poor performances with aluminum electrodes yielding a removal efficiency close to 45% at 8.33 A/m(2). Similarly, the presence of NO3- when iron electrodes were used adversely affected the process performance. The removal efficiency with KNO3 was 49.1% at 8.33 A/m(2). Overall Cl- containing electrolytes performed well achieving almost complete decolorization (99.9%) regardless of the electrode type. The performance of Al electrode considerably improved in the presence of NH4+, achieving 98.0% and 99.1% removal efficiencies at the current densities of 4.17 A/m(2) and 8.33 A/m(2), respectively in 10 min treatment duration.Öğe Enhancing the permeability and antifouling properties of cellulose acetate ultrafiltration membrane by incorporation of ZnO@graphitic carbon nitride nanocomposite(Elsevier Sci Ltd, 2021) Vatanpour, Vahid; Faghani, Somayeh; Keyikoğlu, Ramazan; Khataee, AlirezaThis study reports the modification of cellulose acetate (CA) membrane with zinc oxide (ZnO)@graphitic carbon nitride (g-C3N4) nanocomposite to improve the antifouling and separation performance. Different combinations of the CA-based membranes such as CA/g-C3N4, CA/ZnO, and CA/ZnO@g-C3N4 were fabricated using the non solvent induced phase separation (NIPS) method. Membranes were analyzed for their morphology (SEM), porosity, pore size, contact angle, permeability, rejection, and antifouling properties. According to the SEM images of CA/ZnO@g-C3N4, the formation of pear-shaped macro voids and finger-like canals originating from the top layer was evident. Nanocomposite blended membrane with 0.25 wt.% ZnO@g-C3N4 achieved the largest pore radius (3.05 nm) and the lowest contact angle (67.7 degrees). With these characteristics, 0.25 wt.% ZnO@g-C3N4 membrane obtained a pure water flux of 51.3 LMH, which is 2.1 times greater than the bare CA and high BSA and dye rejections with 97.20% and 93.7% respectively. Finally, the antifouling resistance of the CA membrane was greatly improved with FRR increasing from 73.7% to 94.8%, which was accompanied by a significant decrease in the fouling resistance parameters.Öğe Integrated management of pesticides in an intensive agricultural area: a case study in Altinova, Turkey(Springer, 2019) Muhammetoglu, A.; Keyikoğlu, Ramazan; Cil, A.; Muhammetoglu, H.Pesticide contamination of groundwater is a common critical problem faced by many countries due to excessive and unconscious applications. As a result of increasing concerns about pesticides, several qualitative and quantitative risk assessment models/indicators were developed and applied. In this study, a practical approach was presented for the protection of groundwater from pesticide contamination. The first phase is the assessment of the specific vulnerability of groundwater to pesticide contamination using the DRASTIC-Pesticide model. The second phase is the monitoring and assessment of groundwater quality to verify vulnerability assessment. The third phase is to assess the impacts of pesticides on the environment and human health using a commonly applied pesticide risk indicator, the environmental impact quotient (EIQ). The pilot study area (PSA) is the Altinova region at Antalya city of Turkey which exhibits intensive agricultural activities and covers an approximate surface area of 75 km(2). A total of 25 groundwater wells were chosen for monitoring of groundwater quality where four sessions of seasonal field measurements were conducted for 1 year. Two sessions of water quality analyses were also performed for many physical, bacteriological, and chemical parameters, including pesticides. Additionally, soil samples were analyzed, site surveys were conducted, and other relevant information (topographical, geological and meteorological characteristics, pesticide use and toxicological data sets, etc.) was gathered. The PSA was determined to have high vulnerability to contamination of groundwater, and it was verified through monitoring results. The commonly used pesticides in the PSA were ranked according to their risks to select pesticides with the least environmental impacts.Öğe Machine Learning for Advanced Design of Nanocomposite Ultrafiltration Membranes(American Chemical Society, 2021) Fetanat, Masoud; Keshtiara, Mohammadali; Low, Ze-Xian; Keyikoğlu, Ramazan; Khataee, AlirezaAlthough the incorporation of nanoparticles into ultrafiltration polymeric membranes has shown promising outcomes, their commercial implementation has yet to be fulfilled due to inconsistency in data, lack of a reliable recipe for the optimum filler content, and reluctance in disrupting the production line which requires significant time and resources. There is a growing demand among membrane communities for a design platform that can accelerate the discovery of new nanocomposite membranes. In this work, a feed-forward ANN (artificial neural network) model that has one hidden layer and the Bayesian regularization training algorithm were chosen for designing a graphical user interface platform to predict the ultrafiltration nanocomposite membrane performance, that is, solute rejection, flux recovery, and pure water flux, thereby saving time and resources used in membrane design. Experimental data (735 samples from 200 reports published between 2006 and 2020) were derived from the literature for training, validation, and testing of the ANN models. The results indicated that the best 30 ANN models produce the most accurate estimation of membrane performance using the seven input variables of polymer concentration, polymer type, filler concentration, average filler size, solvent concentration (in the dope solution), solvent type, and contact angle on the unseen data set. Furthermore, a sensitivity analysis was performed on the achieved models to identify the most effective input variables for each nanocomposite membrane performance. This work has the potential to be extended to other mixed matrix membrane types that are going to be used for microfiltration, nanofiltration, reverse osmosis, and so forth.Öğe Machine learning for design of thin-film nanocomposite membranes(Elsevier B.V., 2021) Fetanat, Masoud; Keshtiara, Mohammadali; Keyikoğlu, Ramazan; Khataee, Alireza; Daiyan, Rahman; Razmjou, AmirIn this study, a novel machine learning approach is proposed for estimation of the permeate flux and foulant rejection in nanocomposite filtration membranes. Nine independent variables are fed to artificial neural networks (ANNs) including support, nanoparticles concentration, concentration of organic phase trimesoyl chloride (TMC) in-n-hexane (TMC in n-hexane), operation pressure, contact angle, thin layer thickness, location of the nanoparticles (NPs), post-treatment temperature and duration, and permeate flux and foulant rejection were derived as the outputs of the ANNs. The proposed method was evaluated on two datasets across training, validation and test datasets, and an unseen dataset. 2250 different initial weights and number of the neurons in the hidden layer for the proposed ANN models were considered and compared to find the optimized ANN models. The mean squared error (MSE) and coefficient of determination (R2) were employed to select the best 20 ANN models for further analysis. The proposed ANN models resulted in accurate estimates for both permeate flux and foulant rejection with R2 of 0.9958 and 0.9412 in all data included in the training, validation and test datasets and R2 of 0.9938 and 0.9811 in unseen dataset, respectively. In addition, results of sensitivity analysis revealed that post treatment temperature and contact angle were found the most important input variables for estimation of permeate flux and foulant rejection. The proposed method can provide valuable insights for formulating permeate flux and foulant rejection and considering the effects of each experimental condition on nanocomposite filtration membranes without doing real experiments, which is time-consuming and expensive.Öğe Peroxydisulfate activation by in-situ synthesized Fe3O4 nanoparticles for degradation of atrazine: Performance and mechanism(Elsevier, 2020) Keyikoğlu, Ramazan; Karataş, Okan; Khataee, Alireza; Kobya, Mehmet; Can, Orhan Taner; Soltani, Reza Darvishi CheshmehHerein activation of persoxydisulfate (PDS) was achieved by in-situ synthesized Fe3O4 nanoparticles (NPs) from a sacrificial iron anode in an electrochemical (EC) cell. The as-synthesized Fe3O4 NPs were characterized to be in spherical and in the nano size. The performance of the process, EC-Fe3O4/PDS, was investigated in terms of atrazine (ATZ) degradation. Optimum process conditions were determined as initial pH of 5, electrolyte (Na2SO4) concentration of 1 mM, a current density of 1.67 A m(-2), PDS concentration of 0.5 mM and initial ATZ concentration of 10 mg L-1. At optimum conditions, the EC-Fe3O4/PDS process could effectively degrade 80% of ATZ in an aqueous solution within a short reaction time of 20 min. The electrical energy consumption of the process was found to be quite low with 0.0307 kWh/m(3). Based on the LC/MS analysis, the degradation pathway of ATZ with seven transformation products was proposed. Finally, a possible mechanism of the EC-Fe3O4/PDS process was put forward, which includes the activation of PDS and the role of radicals in the degradation of ATZ. In conclusion, the combination of Fe3O4 NPs catalyzed PDS oxidation with the EC process was very effective in the degradation of ATZ to dechlorinated final products. The strong synergistic effect makes this process superior to conventional methods due to the high degradation efficiency with low electrical energy and chemical consumption. Application of this method, with very low current density, may not only minimize the electrical energy consumption but also help reduce the sludge production due to the lower iron dissolution.Öğe A review on dendrimers in preparation and modification of membranes: progress, applications, and challenges(Elsevier, 2021) Karataş, Okan; Keyikoğlu, Ramazan; Gengec, N. Atalay; Vatanpour, V.; Khataee, A.Although membrane technologies have been used for different purposes because of their selective permeability and suitability for modifications, fouling is the most important limiting parameter. Intensive research is being conducted to solve the membrane fouling problem, and in this context, dendrimers, as a macromolecule, have attracted wide interest with their unique chemical and structural properties. This review provides a comprehensive overview of the production methods, challenges, and applications of dendrimer-modified membranes. Modification methods include grafting, coating, and addition of dendrimers as a hydrophilic additive. These modifications, especially using polyamidoamine dendrimers, have improved separation performance, selectivity, and antifouling properties in microfiltration, ultrafiltration, reverse osmosis, forward osmosis, nanofiltration, and gas separation membranes. We also highlight the use of various nanomaterials in membrane modifications along with dendrimers because of the different structures and properties they can offer. Finally, the development prospects and key challenges of the dendrimer-modified membranes are briefly discussed.Öğe A review on treatment of membrane concentrates generated from landfill leachate treatment processes(Elsevier, 2021) Keyikoğlu, Ramazan; Karatas, Okan; Rezania, Hamidreza; Kobya, Mehmet; Vatanpour, Vahid; Khataee, AlirezaLandfill leachate (LL) is highly toxic wastewater and comprises various pollutants such as organic compounds, biological organisms, xenobiotics, heavy metals, inorganic salts, and ammonia. The integration of conventional methods with membrane processes has become indispensable due to the enforcement of stricter regulations for the LL discharge. The integrated membrane technologies achieve a pollutant removal efficiency of higher than 95% with a large volume of treated leachate and a low capital cost investment. However, the drawback of these processes is the production of a membrane concentrate with even more hazardous characteristics. This review presents the state of the art methods along with the recent improvements to the existing processes for the treatment of membrane concentrates. The techniques are mainly divided into two categories of conventional, advanced methods and the hybridization of them. The operating conditions, performances of the individual processes along with wastewater characteristics were summarized in detail. Generally, the leachate concentrate properties such as salinity, COD, BOD5/COD ratio, and toxicity are essential parameters for the selection of appropriate treatment methods. It was found that single treatment processes are not able to reach desirable membrane concentrate treatment and need an engineered combination of these techniques to achieve satisfactory removal efficiencies.Öğe The role of dye molecular weight on the decolorization performance of the electrocoagulation(Springer, 2021) Keyikoğlu, Ramazan; Can, Orhan TanerComparative results of color removal performances of Reactive Blue 198 (RB198), Reactive Yellow (RY145) and Reactive Blue 19 (RB19) by electrocoagulation process are presented. Our primary objective was to investigate whether the dye molecular weight affects color removal performance. Dye removal costs of each dye were calculated and compared. Experiments were performed at current densities of 1.04, 2.08, 4.17 and 10.42 A/m(2) in electrocoagulation (EC) reactor with aluminum electrodes connected parallel monopolar configuration. Laboratory-scale experiments were run in batch mode with 0.5 L synthetic dye solution volume and 50 mg/L initial dye concentration. Results showed that the color removal efficiencies were directly influenced by the molecular weight of the dyes. The color removal efficiency of the dye with the greatest molecular weight (RB198) was the highest, whereas the color removal efficiency of the dye with the smallest molecular weight (RB19) was the lowest. Moreover, results indicated that the operating cost of RB198 was significantly lower (2.91 $ per kg dye removed) than RY145 (6.61 $ per kg dye removed) and RB19 ($6.72 per kg dye removed) at a current density of 4.17 A/m(2).
