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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 Cerium-Doped CuFe-Layered Catalyst for the Enhanced Oxidation of o-Xylene and N,N-Dimethylacetamide: Insights into the Effects of Temperature and Space Velocity(Amer Chemical Soc, 2023) Ocal, Zehra Betul; Keyikoglu, Ramazan; Karagunduz, Ahmet; Yoon, Yeojoon; Khataee, AlirezaVolatile organic compounds (VOCs) are among the most potential pollutant groups that cause air quality degradation because of their toxic effects on human health. Although catalytic oxidation is an effective method for VOC removal, further studies are required to develop more efficient and affordable catalysts. In this study, cerium (Ce) was doped into a CuFe-layered material (Ce-CuFe) to improve the catalytic oxidation efficiencies of N,N-dimethylacetamide (DMAC) and o-xylene. The synthesized catalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. XRD analysis confirmed the successful doping of Ce atoms into the CuFe-layered structure, while in the SEM and TEM images the catalyst appeared as uniformly distributed two-dimensional plate-like particles. The catalytic oxidation performance of the Ce-CuFe was investigated at six temperatures between 200 and 450 degrees C and three space velocities in the range of 31000-155000 mLh(-1)g(-1) for the oxidation of DMAC and o-xylene, which functioned as polar and nonpolar solvents, respectively. At 200 degrees C, the Ce-CuFe catalyst performed 50% greater when oxidizing o-xylene while exhibiting a DMAC oxidation efficiency that was 42% greater than that achieved using undoped CuFe. The Ce-CuFe could remove DMAC and o-xylene with an efficiency higher than 95% at 450 degrees C. Furthermore, Ce-doped CuFe exhibited high resistance against moisture and outstanding reusability performance with only a 5.6% efficiency loss after nine reuse cycles. Overall, the incorporation of Ce into a CuFe-layered material is a promising strategy for the oxidation of various VOCs.Öğe Development of ZnFeCe Layered Double Hydroxide Incorporated Thin Film Nanocomposite Membrane with Enhanced Separation Performance and Antibacterial Properties(Mdpi, 2023) Balcik, Cigdem; Ozbey-Unal, Bahar; Sahin, Busra; Buse Aydin, Ecem; Cifcioglu-Gozuacik, Bengisu; Keyikoglu, Ramazan; Khataee, AlirezaDeveloping thin-film nanocomposite (TFN) membranes by incorporating nanomaterials into the selective polyamide (PA) layer is an effective strategy to improve separation and antibacterial properties. In this study, TFN nanofiltration (NF) membranes were fabricated by interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) with the addition of Zinc-Iron-Cerium (ZnFeCe) layered double hydroxide (LDH). The improved surface hydrophilicity of TFN membranes was investigated by water contact angle analyses and pure water flux measurements. Successful production of the PA layer on the membrane surface was determined by Fourier-transform infrared (FTIR) analysis. Atomic Force Microscope (AFM) images showed that the addition of LDH into the membrane resulted in a smoother surface. The scanning electron microscope and energy-dispersive X-ray spectroscopy (SEM/EDS) mapping of TFN membrane proved the presence of Ce, Fe, and Zn elements, indicating the successful addition of LDH nanoparticles on the membrane surface. TFN 3 membrane was characterized with the highest flux resulting in 161% flux enhancement compared to the pristine thin film composite (TFC) membrane. All membranes showed great rejection performances (with a rejection higher than 95% and 88% for Na2SO4 and MgSO4, respectively) for divalent ions. Additionally, TFN membranes exhibited excellent antibacterial and self-cleaning properties compared to the pristine TFC membrane.Öğe Different metal-doped ZnS quantum dots photocatalysts for enhancing the permeability and antifouling performances of polysulfone membranes with and without UV irradiation(Pergamon-Elsevier Science Ltd, 2022) Vatanpour, Vahid; Karatas, Okan; Amiri, Saba; Rajabi, Hamid Reza; Koyuncu, Ismail; Khataee, AlirezaIn this study, the effect of three different transition metal ion dopants (Mn2+, Fe2+, and Co2+) on the characteristics of zinc sulfide (ZnS) quantum dots (QDs) was investigated and the obtained QDs photocatalysts were applied for the modification of polysulfone (PSf) mixed matrix membranes to reduce membrane fouling. The synthesized QDs and fabricated membranes were fully identified with SEM, TEM, AFM, FTIR analyses, and also underwent porosity and contact angle tests. Flux recovery ratios (FRR) significantly increased from 69.8% (bare) to 85.0% (1% Fe-doped ZnS QDs) after modification of membranes with metal-doped QDs. The contact angles of the prepared membranes decreased with doping of dissimilar metals, therefore hydrophilicity increased, and reversible/non-reversible blockages were improved. Besides, the use of UV irradiation during the washing of the membranes increased the FRR of the photocatalytic activated membranes to 91.2%. Compared to the bare PSf membrane in dye solution filtration, 1% Fe-doped ZnS QDs membrane yielded twice as much flux and 15% higher FRR results. Therefore, the results proved that metal-doped QDs can be used in the modification of PSf membranes with high efficiency.Öğe Electrochemical oxidation of perfluorooctanesulfonate (PFOS) from simulated soil leachate and landfill leachate concentrate(Elsevier, 2023) Karatas, Okan; Khataee, Alireza; Kobya, Mehmet; Yoon, YeojoonThe near-widespread presence of poly- and perfluoroalkyl substances (PFASs) in humans has generated concerns regarding the potential negative impact of these chemicals on human health, as some PFASs are exceedingly persistent and bioaccumulative. Among the perfluorinated PFASs, which exhibit high polarity and strong carbon-fluorine bonds, perfluorooctanesulfonate (PFOS) is one of the frequently encountered species. In this study, the efficiency of electrooxidation (EO) and its application in groundwater simulation were first evaluated as a realistic approach to PFOS removal. After optimizing EO parameters including the solution pH, current density, and the effects of inlet concentration and the anode material, 83 % total organic carbon (TOC) removal was obtained. In groundwater experiments, in which the infiltration of PFOS from soil layers into groundwater was simulated, 79 % TOC removal efficiency was achieved in the more complex groundwater; moreover, an F- ion concentration of 8.78 mg/L was obtained from the decomposition of PFOS. To increase the realism of the simulation, the leachate process was repeated four times, and the EO process was applied to each sequential leachate. In addition, the process efficiency was studied in real landfill leachate wastewater to which PFOS had been added. Despite the challenging wastewater composition, 84 % TOC removal efficiency was achieved. Together, these results indicate that BDD-anodic oxidation may be a practical method to treat PFOScontaminated groundwater and wastewater.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 Fabrication of PSf nanocomposite membranes incorporated with ZnFe layered double hydroxide for separation and antifouling aspects(Elsevier, 2022) Balcik, Cigdem; Ozbey-Unal, Bahar; Cifcioglu-Gozuacik, Bengisu; Keyikoglu, Ramazan; Karagunduz, Ahmet; Khataee, AlirezaHerein, we report the effect of blending of various concentrations of ZnFe layered double hydroxide (LDH) on the filtration, antifouling, and antibacterial performances of Polysulfone (PSf) nanocomposite membranes for BSA and dye separation. ZnFe LDH with a molar ratio of M2+:M3+=3:1 was synthesized by the co-precipitation method. The PSf-ZnFe LDH nanocomposite membranes exhibited higher hydrophilicity (the lowest contact angle value of 64.42 & nbsp;), porosity (up to 58.7), and mean pore radius compared to the pristine PSf membrane. The water flux of the PSf-ZnFe LDH nanocomposite membrane (LDH content of 2.0 wt% of PSf) was 105 L/m(2)h, which is 2.3 times higher than the flux of pristine PSf membrane of 45 L/m(2)h. The rejection ratios for the fabricated membranes were 93%, 83%, and 16% for BSA, reactive red 198, and methylene blue, respectively. Additionally, 2.0 wt% ZnFe LDH incorporated membrane demonstrated better antifouling performance with a flux recovery ratio (FRR) of 95% compared to the pristine PSf membrane with 42% of FRR. Consequently, a bacterial viability inhibition test was utilized to determine the antibacterial properties, and the ZnFe LDH exhibited a high inhibition capacity. The fabricated PSf-ZnFe LDH nanocomposite membranes exhibited a higher filtration, antifouling, and antimicrobial performance as compared to pristine PSf.Öğe High-performance carbon black electrode for oxygen reduction reaction and oxidation of atrazine by electro-Fenton process(Elsevier, 2021) Karataş, Okan; Gengec, Nevin Atalay; Gengec, Erhan; Khataee, Alireza; Kobya, MehmetThe aim of this study is to produce an electrode that can be used in H2O2 production and Electro-Fenton (EF) process by an effective, cheap, and easy method. For this reason, a superhydrophobic electrode with a higher PTFE ratio and high thickness was produced with a simple press. The produced electrode was used in the production of H2O2 and mineralization of Atrazine. First, the effect of pH, cathode voltage, and operation time on H2O2 production was evaluated. The maximum H2O2 concentration (409 mg/L), the highest current efficiency (99.80%), and the lowest electrical energy consumption (3.16 kWh/kg) were obtained at 0.8 V, 7.0 of pH, and 120 min, and the stability of the electrode was evaluated up to 720 min. Then, the effects of the operational conditions (pH, cathode voltage, operating time, and catalyst concentration) in electro-Fenton were evaluated. The fastest degradation of Atrazine (>99%) was obtained at 2.0 V, 3.0 of pH, and 0.3 mM of Fe2+ in 15 min. In the final part of the study, the degradation intermediates were identified, and the characterization of the electrode was evaluated by SEM, XRD, FT-IR, tensiometer, potentiostat, and elemental analyzer.Öğe Layered double hydroxides for removing and recovering phosphate: Recent advances and future directions(Elsevier, 2022) Keyikoglu, Ramazan; Khataee, Alireza; Yoon, YeojoonEutrophication is a widespread environmental challenge caused by excessive phosphate. Thus, wastewater engineers primarily aim to limit the phosphate concentration in water bodies. Layered double hydroxides (LDHs) are lamellar inorganic materials containing tunable brucite-like structures. This review discusses the fundamental aspects and latest developments in phosphate removal using LDH-based materials. Based on the divalent cations, Ca, Mg, and Zn-containing LDHs are largely used along with trivalent cations such as Al and Fe owing to their limited toxicities. However, classical LDHs are affected by the presence of co-existing anions, have a narrow working pH range, and have moderate adsorption capacities. Binary LDHs have been designed to be selective towards phosphate by the addition of a third metal such as Zr4+. Developing LDH composites with magnetic, polymeric or carbon materials are feasible approaches for increasing adsorption capacity, stability, and reusability of LDHs. Biochar as a carrier material for LDHs achieved remarkable phosphate adsorption performance and improved LDH dispersion, anion exchange capacity, and ease of separation. The use of recovered phosphate as an SRF, which is a type of bioavailable fertilizer, is a promising approach.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 Nanoarchitecturing of CuFeLa layered double hydroxide on graphite felt for photo-electrocatalytic degradation of emerging pollutants(Elsevier Science Inc, 2025) Seifi, Azam; Keyikoglu, Ramazan; Karatas, Okan; Cosut, Bunyemin; Khataee, AlirezaDue to the importance of wastewater decontamination from emerging pollutants, various approaches have been established as treatment processes. In the present study, a graphite felt (GF) electrode was modified with a layered double hydroxide (LDH) to degrade rifampicin in a combined photo-electrocatalytic process. The synthesized CuFeLa LDH was deposited on the GF (CuFeLa LDH@GF) via the electrophoretic deposition method. SEM images showed the uniform coverage of GF fibers by two-dimensional flake-like LDH nanoparticles. The CuFeLa LDH coating improved the electron transfer kinetics of GF and reduced charge transfer resistance. The photo-electrocatalytic process employing the CuFeLa LDH@GF cathode could achieve 79.4% and 65.7% degradation efficiency for rifampicin at pH 6 and 8, respectively. The apparent reaction rate constant (kapp) of the process with CuFeLa@GF (photo-electrocatalysis) was 7.98 times that of the raw GF electrode (photo-electrolysis). This was due to the increased production of hydroxyl radicals (center dot OH), which was shown by radical scavenging and center dot OH trapping experiments. Moreover, the coated electrode had a high stability with only a 4.7% performance loss in 5 successive application tests. The liquid chromatography-mass spectrometry (LC-MS/MS) analysis revealed the intermediates produced during the degradation process. The CuFeLa LDH@GF, with its consistent performance under nearly neutral conditions and catalytic activity over extended periods, indicates potential for effective and environmentally friendly approaches to wastewater treatment.Öğe Perfluorooctanoic acid (PFOA) removal from real landfill leachate wastewater and simulated soil leachate by electrochemical oxidation process(Elsevier, 2022) Karatas, Okan; Kobya, Mehmet; Khataee, Alireza; Yoon, YeojoonPoly and perfluoroalkyl compounds (PFASs) are a group of chemicals that are widely used and are difficult to purify. Within this group, perfluorooctanoic acid (PFOA), known for its highly polar and strong carbon-fluorine bonds, is a frequently encountered species in surface water, drinking water, and groundwater. In this study, we investigated the efficiency of electrooxidation (EO) in PFOA removal, optimization of EO parameters, and groundwater simulation in a realistic scenario. The EO optimization experiments were performed with a boron-doped diamond (BDD) anode for different values of pH, current density, and inlet concentration, and the effects of different anode materials were investigated for comparison. Under optimum conditions, total organic carbon (TOC) removal of up to 90% was achieved. In the groundwater simulation, we applied optimized EO parameters after obtaining leachates from the soil. A TOC removal of up to 86% was obtained in the EO of simulated groundwater contaminated with PFOA. In the case of realistic leachate simulation, four different leachate treatments were applied to PFOA-contaminated soil, and high TOC removal was achieved in all matrices. Additionally, the EO with BDD was applied to landfill leachate wastewater supplemented with PFOA to monitor the effectiveness of the process. A TOC removal of 85% was achieved, and it was observed that the number of free F-ions increased. The results showed that the BDD EO has a high potential for the treatment of PFOA-contaminated groundwater.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).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 Peroxydisulfate-assisted sonocatalytic degradation of metribuzin by La-doped ZnFe layered double hydroxide(Elsevier, 2022) Akdag, Sultan; Rad, Tannaz Sadeghi; Keyikoglu, Ramazan; Orooji, Yasin; Yoon, Yeojoon; Khataee, AlirezaMetribuzin is an herbicide that easily contaminates ground and surface water. Herein, La-doped ZnFe layered double hydroxide (LDH) was synthesized for the first time and used for the degradation of metribuzin via ultrasonic (US) assisted peroxydisulfate (PDS) activation. The synthesized LDH had a lamellar structure, an average thickness of 26 nm, and showed mesoporous characteristics, including specific surface area 110.93 m(2) g(-1), pore volume 0.27 cm(3) g(-1), and pore diameter 9.67 nm. The degradation efficiency of the US/La-doped ZnFe LDH/PDS process (79.1 %) was much greater than those of the sole processes, and the synergy factor was calculated as 3.73. The impact of the reactive species on the sonocatalytic process was evaluated using different scavengers. After four consecutive cycles, 10.8 % loss occurred in the sonocatalytic activity of the La-doped LDH. Moreover, the efficiency of the US/La-doped LDH/PDS process was studied with respect to the degradation of metribuzin in a wastewater matrix. According to GC-MS analysis, six by-products were detected during the degradation of metribuzin. Our results indicate that the US/La-doped ZnFe LDH/PDS process has great potential for efficient degradation of metribuzin-contaminated water and wastewater.Öğe Recent advances in boron species removal and recovery using layered double hydroxides(Elsevier, 2023) Akdag, Sultan; Keyikoglu, Ramazan; Karagunduz, Ahmet; Keskinler, Bulent; Khataee, Alireza; Yoon, YeojoonAnthropogenic boron discharge threatens ecosystem health and water quality. Although boron is a micronutrient necessary for plants, animals, and humans, excessive concentrations can have toxic effects. Layered double hydroxides (LDH) are two-dimensional anionic clay materials that exhibit intrinsic anion-exchange properties. In this paper, the use of LDH for the removal and recovery of boron species from water is presented. The main factors that affect boron removal, including the LDH dosage, initial boron concentration, solution pH, temperature, and the presence of other anions, are outlined. For boron removal, LDH containing Mg, Fe, Zn, or Ca cations have been mostly used owing to their limited toxicities and abundance in the environment. The boron removal capacity of LDH can be improved by transforming the layered structure into bimetallic oxides through calcination, increasing not only the surface area but also the interaction with anionic species during their regeneration. The main boron-removal mechanism of LDH is ion exchange with intercalated anions or the surface complexation with the surface groups of the LDH. A major advantage of using LDH for boron removal is the possibility of recovering and reusing the extracted boron. LDH synthesized with boron as the interlayer anion showed slow-release fertilizer properties, suggesting the use of boron-loaded LDH as plant growth regulators.Öğe Recent progress on the phytotoxic effects of hydrochars and toxicity reduction approaches(Pergamon-Elsevier Science Ltd, 2022) Karatas, Okan; Khataee, Alireza; Kalderis, DimitriosHydrothermal carbonization of wet biomasses has been known to produce added-value materials for a wide range of applications. From catalyst substrates, to biofuels and soil amendments, hydrochars have distinct advantages to offer compared to conventional materials. With respect to the agricultural application of hydrochars, both positive and negative results have been reported. The presence of N, P and K in certain hydrochars is appealing and may contribute to the reduction of chemical fertilizer application. However, regardless of biomass, hydrothermal carbonization results in the production of phytotoxic organic compounds. Additionally, hydro chars from sewage sludge often contain heavy metal concentrations which exceed the regulatory limits set for agricultural use. This review critically discusses the phytotoxic aspects of hydrochar and provides an account of the substances commonly responsible for these. Furthermore, phytotoxicity reduction approaches are proposed and compared with each other, in view of field-scale applications.Öğe Synergistic effect of Fe and Co metals for the enhanced activation of hydrogen peroxide in the heterogeneous electro-Fenton process by Co-doped ZnFe layered double hydroxide(Elsevier Sci Ltd, 2022) Keyikoglu, Ramazan; Khataee, Alireza; Orooji, Yasin; Kobya, MehmetHeterogeneous electro-Fenton (EF) is a powerful technology for the removal of emerging organic pollutants from wastewater. However, the development of catalysts with high activity towards the production of (OH)-O-center dot by decomposing H2O2 remains a challenge. Herein, Co-doped ZnFe LDH as a heterogeneous catalyst with 2D plate-like morphology was produced by a co-precipitation method. Co-doping increased the pore volume of ZnFe LDH from 0.188 cm(3)/g to 0.2711 cm(3)/g and pore diameter from 5.305 nm and 9.39 nm. EF process consisted of a hydrothermally activated graphite felt cathode and a platinum plate anode. The Phenazopyridine (PHP) removal efficiency of the EF process in the presence of Co-doped ZnFe LDH is twice that of the electrochemical process. Additionally, Co-doping increased the performance of ZnFe LDH from 60 % to 82 % due to a synergistic effect of redox couples of Fe2+/Fe3+ and Co2+/Co3+. The Co-doped ZnFe LDH/EF process achieved complete removal of PHP in real wastewater in 4 h and at natural pH. After 7 reuse cycles, the catalyst retained 91 % of its performance. The eight by-products of PHP were determined by GC-MS. This work provides a way sustainable approach for the efficient removal of organic pharmaceuticals from wastewaters.Öğe Synthesis of visible light responsive ZnCoFe layered double hydroxide towards enhanced photocatalytic activity in water treatment(Pergamon-Elsevier Science Ltd, 2022) Keyikoglu, Ramazan; Dogan, Irmak Naz; Khataee, Alireza; Orooji, Yasin; Kobya, Mehmet; Yoon, YeojoonIn this study, a ternary layered double hydroxide containing Zn, Co, and Fe transition metals (ZnCoFe LDH) was developed using a co-precipitation procedure. The as-synthesized photocatalyst was evaluated for its perfor-mance in the degradation of methylene blue (MB) under visible light irradiation. The effects of various process conditions including photocatalyst dosage, pollutant concentration, pH, lamp distance, and lamp power were investigated. The ZnCoFe LDH achieved approximately 74% photodegradation efficiency owing to the narrow bandgap of 2.14 eV. The Langmuir-Hinselwood rate constants were calculated as 1.17 min-1 and 3.55 min-1 for photolysis by LED lamp alone and for photocatalysis by LED/ZnCoFe LDH, respectively. The photocatalytic ability of the LDH was attributed to the generation of radical species like center dot OH and O2 center dot-. The photocatalytic degradation intermediates of MB were determined by GC-MS analysis. The catalyst retained its performance throughout seven reuse cycles with only a 4.17% reduction in removal efficiency. The energy per order EEO of the ZnCoFe/LED process in 180 min treatment time was determined as 5.41 kWh.m- 3. order-1. This study shows that ZnCoFe LDH has sufficient activity and photostability for long-term application in photocatalytic water treatment.Öğe Treatment of real printing and packaging wastewater by combination of coagulation with Fenton and photo-Fenton processes(Pergamon-Elsevier Science Ltd, 2022) Sayin, Fatma Ece; Karatas, Okan; Ozbay, Ismail; Gengec, Erhan; Khataee, AlirezaPrinting and packaging process wastewater (PPPW) with high flow rates causes severe damage to the environment due to high organic pollution (3830.0 mg O-2/L of COD and 813.6 mg/L of TOC) and turbidity (9110 NTU). This study examined the efficiencies of coagulation, Fenton, and photo-Fenton procedures, and their combinations in the treatment of PPPW. The three inorganic salts (FeCl3, Al-2(SO4)(3), and Fe-2(SO4)(3)) were used in a wide range of pH (2.5-10) as a coagulant, and FeCl3 was chosen as the optimum coagulant. The 71.3% of TOC removal and the decreasing of turbidity up to 5.8 NTU were obtained at 0.5 g/L FeCl3 and pH of 6.0. Then, Fenton and photo-Fenton processes were applied to the effluent of the coagulation process. The Fenton process engaged the TOC removal efficiencies up to 85.2% in the presence of 7.350 g/L iron catalysts and 36.0 mL/L H2O2. The combined coagulation and Fenton process is a promising way to decrease the COD up to 119 mg O-2/L, meeting the wastewater discharge standards of COD (200 mg O-2/L) in Turkey. However, adding UV sources to the Fenton process showed a little bit of engagement (only %1.4 extra removal). When evaluated for PPPW, it is seen that the usage of combined coagulation and the Fenton process is an important treatment alternative. Furthermore, Zeta potential measurements and size exclusion chromatography were used to understand the removal mechanism.
