Browsing by Author "Ecer, Umit"

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Application of Ann and Rsm for Rhodamine B and Safranine-O Decolorization on Zinc-Carbon Battery Waste Derived Ag/Cofe-ldh Catalyst
(Amer Chemical Soc, 2024) Ecer, Umit; Ulas, Berdan; Yilmaz, Sakir
The present work is first aimed at recovering graphite from carbon rods of waste zinc-carbon (Zn-C) batteries for applications such as wastewater treatment, in order to contribute to the development of a sustainable environment. Then, a composite material, cobalt-iron layered double hydroxide combination with reduced graphene oxide, and with subsequent Ag nanoparticles deposition via NaBH4 reduction method (Ag/CoFe-LDH/rGO) was prepared for the catalytic activity of Rhodamine B (RhB) and Safranine-O (SO) as model contaminants from aquatic media. The catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO in the presence of NaBH4 was studied to model and optimize the process parameters (NaBH4 amount, reaction time, initial dye concentration (C-o), and catalyst dosage) via central composite design (CCD)-response surface methodology (RSM). Also, an artificial neural network (ANN) model was developed to estimate the catalytic activity of each dye using an RSM data set. The catalytic activities of 99.54% and 99.96% were obtained for RhB and SO dyes, respectively, under the optimal conditions: NaBH4 amount 12.32 mM, reaction time 3.19 min, C-o 33.46 mg/L, and catalyst dosage 1.24 mg/mL for RhB dye; NaBH4 amount 16.76 mM, reaction time 3.06 min, C-o 15.10 mg/L, and catalyst dosage 1.46 mg/mL for SO dye. The optimum conditions of process parameters by ANN with gray wolf optimizer (GWO) were in good agreement with the points determined the RSM-CCD. These results demonstrate that RSM and ANN approaches can be applied practically and efficiently to maximize the catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO in the existence of NaBH4. On the other hand, from the kinetic and thermodynamic studies, the positive activation enthalpy, Delta H-# and the negative activation entropy, Delta S-# values for each dye demonstrated that the catalytic performance was endothermic and less random at the solid/liquid interface.
Constructing Hnt-Ac Supported Coni Nanoparticles for Hydrogen Generation Toward Nabh4 Hydrolysis: Optimization With Rsm-Ccd
(Springer, 2024) Ecer, Umit; Yilmaz, Sakir; Ulas, Berdan; Kaya, Sefika
In this study, activated carbon (AC) obtained from waste hazelnut shell and halloysite nanotube (HNT) were used to prepare HNT-AC support material by hydrothermal method. CoNi/HNT-AC catalyst was synthesized by reducing Co and Ni on HNT-AC by chemical reduction method. CoNi/HNT-AC has been characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N-2 adsorption-desorption, elemental mapping, and transmission electron microscopy (TEM) methods. The optimum reaction conditions for hydrogen generation through NaBH4 hydrolysis on CoNi/HNT-AC catalyst were determined using response surface methodology (RSM). The proposed quadratic model for NaBH4 hydrolysis on CoNi/HNT-AC was found to be statistically significant with a correlation coefficient of 0.96. Under the optimum reaction conditions of 40.76 mg catalyst, 0.18 M NaBH4, and 8.64 wt% NaOH, the hydrogen generation rate (HGR) and activation energy (E-a) were obtained as 1114.16 mL/gcat. min. and 24.15 kj/mol, respectively.
Conversion From a Natural Mineral To a Novel Effective Adsorbent: Utilization of Pumice Grafted With Polymer Brush for Methylene Blue Decolorization From Aqueous Environments
(Elsevier, 2019) Yilmaz, Sakir; Zengin, Adem; Ecer, Umit; Sahan, Tekin
The present work reports the adsorption yield of methylene blue (MB) from aqueous environments using pumice (PMC) coated with poly(N-[Tris (hydroxymethyl)methyl]acrylamide), PTHAM@PMC, by surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization. The synthesized PTHAM@PMC particles were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR), scanning electron microscopy (SEM) and water contact angle measurements. Results revealed that a homogeneous polymer layer was grafted on the PMC surface. Response surface methodology (RSM) with central composite design (CCD) was performed to optimize and to investigate the influence of independent parameters such as initial pH, initial MB concentration (C-o, mg/L), adsorbent dosage (m, mg), contact time (t, min) and temperature (T, degrees C) for MB% removal with PTHAM@PMC. The results based on CCD indicated that the optimum initial pH, C-o, m, t and T are 8.95, 52.53 mg/L, 40.5 mg, 67.28 min and 33.52 degrees C, respectively. The maximum removal efficiency of 98.68% and the maximum adsorption capacity of 68.998 mg/g were reached at these optimal points. Additionally, the kinetic, isotherm and thermodynamic studies were performed and the obtained results were evaluated. The great advantage of this work is that polymer brush grafted pumice had high adsorption capacity, fast adsorption kinetics, and high removal of MB. Considering all of these, it is thought that the constructed pumice with polymer brush will allow the improvement of novel procedures for the adsorption process.
Decolorization of Rhodamine B by Silver Nanoparticle-Loaded Magnetic Sporopollenin: Characterization and Process Optimization
(Springer Heidelberg, 2022) Ecer, Umit; Sahan, Tekin; Zengin, Adem; Gubbuk, Ilkay Hilal
Silver nanoparticles (Ag NPs) were reduced on the surface of magnetic sporopollenin (Fe3O4@SP) modified with polydopamine to enhance the degradation capability for Rhodamine B (RhB). The polydopamine-coated Fe3O4@SP (PDA@Fe3O4@SP) acts as a self-reducing agent for Ag+ ions to Ag-0. The structural properties of the synthesized nanocomposite were determined using Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), and vibrating sample magnetometer (VSM). The systematic study of the degradation process was performed using Response Surface Methodology (RSM) to determine the relationship between the four process variables, namely, initial RhB concentration, NaBH4 amount, catalyst amount, and time. Optimum points were determined for these four parameters using both matrix and numerical optimization methods. Under optimum conditions, RhB was decolorized with a yield of 98.11%. The apparent activation energy (E-a) and rate constant (k) for the degradation were 24.13 kJ/mol and 0.77 min(-1), respectively. The reusability studies of the Ag@PDA@Fe3O4@SP exhibited more than 85% degradation ability of the dye even after five cycles. As a result, Ag@PDA@Fe3O4@SP possessed high catalytic activity, fast reduction rate, good reusability, easy separation, and simple preparation, endowing this catalyst to be used as a promising catalyst for the decolorization of dyes in aqueous solutions.
Effective Clay Material Enriched With Thiol Groups for Zn(Ii) Removal From Aqueous Media: a Statistical Approach Based on Response Surface Methodology
(2020) Yılmaz, Şakir; Ecer, Umit; Şahan, Tekin
In the present work, the removal of Zn(II) ions from aquatic environments onto 3- mercaptopropyl trimethoxysilane modified kaolin (MK) was investigated in a batch system. Moreover, the optimization and effects of independent parameters such as pH, initial Zn(II) concentration (Co, mg/L) and contact time (min) on the uptake of Zn(II) onto MK were examined by response surface methodology (RSM). Central composite design (CCD) in RSM, the most popular statistical technique, was successfully applied to optimize and model the selected parameters (pH, Co, contact time) for Zn(II)% adsorption onto MK. The number of experiments based on CDD was 20, a total of 20 sets which included fourteen factorial points and six center points were performed to obtain the maximum Zn(II) uptake from aqueous solutions. The optimum points obtained from CCD were 6.39, 50.09 mg/L and 76.10 min for pH, Co, and contact time, in their given order. In these optimal conditions, the maximum removal percentage was found to be 86.19%. The results indicated that the removal yield of Zn(II) from aqueous media onto MK was successfully performed by CCD in RSM. It can be concluded that MK is also a promising material for the uptake of other heavy metals similar to Zn.
Evaluation of Metal-Organic Framework/Layered Double Hydroxide-Embedded Sodium Alginate Beads for Effective Removal of Tartrazine Dye: a Comparative Analysis of Rsm and Ann
(Elsevier, 2025) Yilmaz, Sakir; Ecer, Umit; Ulas, Berdan; Yagizatli, Yavuz
NiFe-layered double hydroxide supported metal-organic framework-embedded alginate bead composite (MIL-88 A/NiFe-LDH@SA) was developed and investigated for the removal of tartrazine food dye (TTZ). Structural characterizations of MIL-88 A/NiFe-LDH@SA were determined by the measurement of FTIR, XRD, BET, SEM, and EDX. Response surface methodology (RSM) and artificial neural network (ANN) were applied to predict the removal of TTZ dye. The optimization of the relevant parameters was obtained via the central composite design (CCD) in RSM. The numerical optimization revealed that a maximum removal efficiency of 94.82 % was achieved at Co of 8.02 mg/L, pH of 3.74, adsorption duration of 4.72 h, and adsorbent amount of 1.33 mg/mL. A comparative analysis was also performed for RSM and ANN models. The findings show that both models can accurately predict TTZ removal efficiency. However, based on the statistical analysis results, ANN demonstrated a higher level of accuracy than RSM in predicting TTZ removal. The kinetic studies also revealed that the adsorption well obey the pseudo-second order (PSO). The isotherm studies indicated that the LangmuirFreundlich (L-F) model was proper for explaining the adsorption behavior of TTZ on MIL-88 A/NiFeLDH@SA. Thermodynamic studies conducted that the adsorption process is spontaneous and exothermic.
Fabrication and Characterization of Poly(Tannic Acid) Coated Magnetic Clay Decorated With Cobalt Nanoparticles for Nabh4 Hydrolysis: Rsm-Ccd Based Modeling and Optimization
(Pergamon-elsevier Science Ltd, 2023) Ecer, Umit; Zengin, Adem; Sahan, Tekin
Hydrogen generation from sodium borohydride (NaBH4) hydrolysis in the presence of metal catalysts is a frequently used and encouraging method for hydrogen storage. Metal nanoparticle-supported catalysts are better recyclability and dispersion than unsupported metal catalysts. In this study, the synthesis and characterization of a polymer-supported catalyst for hydrogen generation using NaBH4 have been investigated. For the synthesis of polymeric material, first of all, kaolin (KLN) clay has been magnetically rendered by using the co-precipitation method (Fe3O4@KLN) and then coated with poly tannic acid (PTA@Fe3O4@KLN). Then, the catalyst loaded with cobalt (Co) nanoparticles have been obtained with the NaBH4 reduction method (Co@PTA@Fe3O4@KLN). The surface morphology and structural properties of the prepared catalysts have been determined using methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS) and vibrating sample magnetometer (VSM). The optimization of the most important variables (NaBH4 amount, NaOH amount, catalyst amount, and metal loading rate) affecting the hydrolysis of NaBH4 using the synthesized polymeric catalysts was carried out using response surface methodology (RSM). Depending on the evaluated parameters, the desired response was determined to be hydrogen production rate (HGR, mL/g min). HGR was 1540.4 mL/gcat. min. in the presence of the Co@PTA@Fe3O4@KLN at optimum points obtained via RSM (NaBH4 amount 0.34 M, NaOH amount 7.9 wt%, catalyst amount 3.84 mg/mL, and Co loading rate 6.1%). The reusability performance of the catalyst used in hydrolysis of NaBH4 was investigated under optimum conditions. It was concluded that the catalyst is quite stable.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Fabrication of Magnetic Biochar-Mil Cobalt Composite Material Toward the Catalytic Reduction Performance of Crystal Violet
(Elsevier, 2024) Ecer, Umit; Yilmaz, Sakir
A magnetic biochar-MIL-68(Fe)-supported cobalt composite material (Co@MIL-68(Fe)@Fe3O4@CM-BC) was synthesized and used as a novel and effective catalyst for the catalytic reduction of crystal violet (CV) in aqueous environments. The prepared material was thoroughly characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and vibrating-sample magnetometer (VSM) techniques. Four operating parameters, including the CV dye concentration, time, catalyst dosage, and NaBH4 amount, were evaluated by employing central composite design (CCD) based on response surface methodology (RSM) for the catalytic reduction of CV. In the catalytic reduction of CV dye, the optimum conditions were determined as 15.67 mg/L CV dye concentration, 80.24 s time, 0.341 mg/mL catalyst dosage, and 14.56 mM NaBH4 amount with CV reduction efficiency of 99.98 %. The catalytic reduction kinetic of CV was studied by applying the pseudo-first-order model, and the apparent rate constant (kapp) values were obtained under different temperature (293-323 K). It was observed that kapp values increased upon increment of temperature. From kinetic studies, the activation energy was measured as 37.18 kJ/mol. Moreover, thermodynamic results showed that the activation entropy (Delta S#) and enthalpy (Delta H#) were obtained as -179.49 J/mol K and 34.62 kJ/mol, respectively. The thermodynamic parameters suggest that the catalytic reduction of CV was favorable and endothermic in nature. Regeneration tests indicated that the activity of Co@MIL-68(Fe)@Fe3O4@CM-BC was retained after five uses. Based on all of the results, the prepared material is a good candidate for the treatment of wastewater containing dyes like CV.
Highly Efficient Cd(Ii) Adsorption Using Mercapto-Modified Bentonite as a Novel Adsorbent: an Experimental Design Application Based on Response Surface Methodology for Optimization
(Iwa Publishing, 2018) Ecer, Umit; Yilmaz, Sakir; Sahan, Tekin
We report the optimization with response surface methodology (RSM) for adsorption conditions required for removal of Cd(II) from an aqueous environment with 3-mercaptopropyl trimethoxysilane-modified bentonite (MMB). Central composite design (CCD) in RSM was used to optimize the most significant adsorption variables of initial pH, temperature (degrees C), initial Cd(II) concentration (C-o, mg L-1) and adsorbent dosage (g). With the quadratic model equation obtained from CCD, the optimum values were determined as initial pH 6.40, temperature 20 degrees C, C-o 49.55 mg L-1 and adsorbent dosage 0.17 g. Under optimum conditions, the optimum adsorption amount of Cd(II) was 27.55 mg Cd(II)/g adsorbent and adsorption yield was 94.52%. The obtained results showed that the Langmuir and Dubinin Radushkevich (D-R) adsorption isotherms were more suitable for adsorption equilibrium data. The kinetic studies indicated that the pseudo-second-order kinetic model was fitted to the adsorption kinetic data. Additionally, thermodynamic studies indicated that the adsorption process was spontaneous and exothermic. As a result, MMB can be chosen as an effective adsorbent for treating heavy metals such as Cd(II) in wastewater and removing them from aqueous solutions. Furthermore, it is thought that it will positively contribute to the literature since the adsorbent-adsorbate combination (MMB-Cd(II)) is used for the first time.
Investigation of Mercury(Ii) and Arsenic(V) Adsorption Onto Sulphur Functionalised Pumice: a Response Surface Approach for Optimisation and Modelling
(Taylor & Francis Ltd, 2022) Ecer, Umit; Yilmaz, Sakir; Sahan, Tekin
Recently, millions of people are under the harmful influences of seriously toxic metals, all of which lead to irreversible damages to nature and living species' health. Therefore, the development of novel adsorbents with high affinity for target metals is critical to their removal from aqueous media. In this study, the effect of initial metal concentration (C-o), initial pH, adsorbent dosage and contact time for Hg(II) and As(V) adsorption were investigated using the Central Composite Design. In this context, pumice minerals with surface enriched by -SH groups(P-SH) were prepared with an effective and simple chemical method. As a result of the experimental studies, the optimum points for parameters affecting the adsorption of both metals were obtained with the model equation produced via Response Surface Methodology (RSM). With the numerical optimisation, the optimum values for Hg(II) removal were 6.33, 36.94 mg/L, 0.15 g and 120 min., and the optimum values for As(V) removal were 3.94, 7.17 mg/L, 0.15 g and 155.4 min. for initial pH, C-o, adsorbent dosage, and contact time, respectively. Hg(II) and As(V) adsorption yield in the obtained optimum conditions were determined as 92.14% and 88.02%, respectively. Under the optimum conditions, kinetic and isotherm studies were carried out for adsorption of both metals with P-SH. It was observed that the adsorption kinetics data for both metals were consistent with the pseudo-second-order equation and equilibrium data compatible with Freundlich and Langmuir isotherm models.Given all this, P-SH is thought to have potential applications for removing heavy metals from wastewater and will have important contributions to similar studies to be conducted.
Magnetic Clay\zeolitic Imidazole Framework Nanocomposite (zif-8@fe3o4@bnt) for Reactive Orange 16 Removal From Liquid Media
(Elsevier, 2021) Ecer, Umit; Zengin, Adem; Sahan, Tekin
This study was performed to evaluate the removal from wastewater of reactive orange 16 (RO16) with magnetically separable zeolitic imidazole frameworks coated magnetic bentonite nanocomposites (ZIF(8)@Fe3O4@BNT). Various microscopic and spectroscopic analyses were carried out to reveal the surface characteristics of the nanocomposite. Point of zero charging (pHPZC) of ZIF-8@Fe3O4@BNT was obtained as 8.84. The dependence of RO16 removal yield on initial pH, initial dye concentration (Co), adsorbent dose and contact time was investigated using the central composite design (CCD) included in response surface methodology (RSM). With the obtained quadratic model equation from CCD, the optimum values were determined as initial pH of 3.9, initial concentration (Co) of 19.76 mg/L, adsorbent amount of 12 mg (480 mg/L), and contact time of 150 min. The maximum removal efficiency of 98.5% and the maximum adsorption capacity of 40.5 mg/g were reached at these optimal points. Adsorption kinetic analysis and equilibrium experiments showed that the best fit was reached with the pseudo-second-order and Langmuir isotherm models, respectively. Also, thermodynamic parameter changes for RO16 removal were calculated, and the results showed that the adsorption was favorable, spontaneous, and exothermic. With all of these, the fact that ZIF-8@Fe3O4@BNT has high recovery efficiency for RO16 removal, fast kinetics and can be separated easily and quickly with the help of a magnet before and after treatment provide significant advantages for wastewater treatment.
Modelling and Optimization of As(Iii) Adsorption Onto Thiol-Functionalized Bentonite From Aqueous Solutions Using Response Surface Methodology Approach
(Wiley-v C H verlag Gmbh, 2018) Yilmaz, Sakir; Ecer, Umit; Sahan, Tekin
The aim of the present work was to investigate thiol-functionalized bentonite (TFB) as a novel adsorbent for the adsorption of As(III) from aqueous environments and to determine optimal adsorption conditions. The response surface methodology (RSM) was applied to analyze the most significant variables for adsorption including initial pH, temperature (degrees C, T), initial As(III) concentration (mgL(-1), C-o), adsorbent dosage (g, m) and contact time (min., t). The optimum adsorption conditions according to the RSM were found to be 5.98, 42.87 degrees C, 31.02 mgL(-1), 0.33g and 127.48 min for initial pH, T, C-o, m and t, respectively. Under these conditions obtained by the model, the maximum percentage of As(III) adsorption and adsorption capacity were found to be 91.01% and 8.56 mgg(-1), respectively. The kinetic studies showed that As(III) adsorption followed a pseudo-second-order kinetic model and the rate was controlled by both intraparticle and film diffusion. Experimental data were compared with linear isotherm models and it was found that the adsorption data has better fit to the Langmuir isotherm model. Furthermore, the thermodynamic studies showed that the adsorption of As(III) was endothermic, possible and natural. Based on all these conclusions, it can be said that TFB has high potential for As(III) removal from aqueous environments.
An Optimization Study for Bio-Removal of Lead From Aqueous Environments by Alkali Modified Polyporus Squamosus
(2021) Yılmaz, Şakir; Ecer, Umit; Şahan, Tekin
Rapidly increasing industrialization and urbanization cause serious environmental pollution. Discharge of polluting material from various industries such as smelting, mining, ore processing, and metal plating into the environment without treatment causes serious pollution and can have dangerous effects on the environmental balance. The utilization of low-cost adsorbents from biological materials as a replacement for costly traditional methods for adsorption of heavy metal pollutants from wastewater was reviewed. This study aimed to investigate the biosorption of Pb(II) ions from aqueous solutions with NaOH-modified Polyporus squamosus biosorbent and optimize the biosorption conditions. Firstly, the parameters most influencing the response of the biosorption for Pb(II) (initial Pb(II) concentration (Co), pH, temperature and biomass dose) were determined using Central Composite Design (CCD). The optimum conditions were evaluated as 60.76 mg/L, 6.3, 25 °C, and 0.23 g for Co, initial pH, temperature and biomass dose, respectively. From the optimum conditions, the adsorption yield and the adsorption capacity were obtained as 93.8% and 23.63 mg/g, respectively
A Response Surface Approach for Optimization of Pb(Ii) Biosorption Conditions From Aqueous Environment With Polyporus Squamosus Fungi as a New Biosorbent and Kinetic, Equilibrium and Thermodynamic Studies
(desalination Publ, 2018) Ecer, Umit; Sahan, Tekin
We report optimization with response surface methodology (RSM) for Pb(II) biosorption conditions from aqueous solutions with powdered natural Polyporus squamosus biosorbent. Brunauer, Emmett and Teller and Fourier transform infrared analyses were performed primarily to determine and investigate the biosorbent surface properties. Central composite design (CCD) in RSM was used to optimize the most important biosorption parameters of pH, initial Pb(II) concentration (C-o, mg L-1), contact time (min) and temperature (degrees C). With the quadratic model equation obtained from CCD, the optimum values were determined as C(o)74.55 mg L-1, pH 5.75, temperature 20 degrees C and contact time 112.6 min. In these conditions, the optimum adsorbed amount of Pb(II) was 13.65 mg Pb(II) per gram of biosorbent and biosorption yield was 89.4%. It was determined that the biosorption kinetic data fitted the pseudo-second-order kinetic equation and biosorption equilibrium data agreed well with the Freundlich isotherm model. Additionally, the thermodynamic parameters showed that biosorption was exothermic. Finally, by performing competitive biosorption from artificial wastewater containing multiple metals, the variation in Pb(II) biosorption capacity of P. squamosus in the presence of different metal ions was investigated.
Synthesis and Catalytic Performance of Pd Nps-Doped Polymer Brushes for Optimization and Modeling of Nabh4 Hydrolysis
(Elsevier Sci Ltd, 2025) Ecer, Umit; Zengin, Adem; Sahan, Tekin
Sodium borohydride (NaBH4) is considered one of the most promising materials for hydrogen (H-2) production. For this, designing a high-performance and cost-effective catalyst is an important step in developing a sustainable hydrogen source. Here, firstly, cross-linked polymer brushes were grafted on the surface of pumice minerals (P4VP/PMC). Then, Pd nanoparticles were reduced on the surface using the NaBH4 reduction method (Pd-P4VP/PMC). The composition and structure of the catalyst were analyzed using diverse techniques. Response surface methodology (RSM) was used to optimize and model the impact of the main factor interactions during the hydrolysis process. According to the quadratic model obtained, catalyst concentration 2.192 mg/mL; temperature 57.3 degrees C; NaBH4 concentration 186.6 mM, and NaOH 5.435 wt% were determined to be optimum values using the matrix method. At these values, the maximum hydrogen generation rate (HGR) was 8732.85 mL H-2/(g(cat.) min.) Also, reusability was tested and after five cycles the catalytic activity of Pd-P4VP/PMC was reduced by only similar to 30 %. As a result, the synthesized catalyst exhibited relatively low activation energy (26.85 kj/mol) and high HGR (8732.85 mL H-2/(g(cat.) min.)), clearly demonstrating the superiority of Pd-P4VP/PMC as a catalyst for hydrogen generation from hydrolysis of NaBH4.
Synthesis and Characterization of an Efficient Catalyst Based on Mos2 Decorated Magnetic Pumice: an Experimental Design Study for Methyl Orange Degradation
(Elsevier Sci Ltd, 2021) Ecer, Umit; Sahan, Tekin; Zengin, Adem
In this work, firstly magnetic pumice (Fe3O4@PMC) composite was prepared by chemical co-precipitation method. Afterward MoS2 decorated Fe3O4@PMC (MoS2@Fe3O4@PMC) with high catalytic efficiency was successfully synthesized to be used in the degradation of methyl orange (MO) in the presence of NaBH4. Several spectroscopic and microscopic analyses were carried out to better understand the surface characteristic properties of the catalyst. The effects and interactions of some influencing parameters (initial dye concentration (C-o, mg/L), NaBH4 amount (M), catalyst amount (mg/mL), and time (s)) on the degradation process were evaluated and optimized using response surface methodology (RSM). Under the obtained optimum conditions (C-o 12.62 mg/L, NaBH4 amount 0.38 M, catalyst amount 0.388 mg/mL, and time 150.34 s), the de-colorization efficiency for MO was found to be 98.66%. The obtained experimental data for degradation efficiency are in close agreement with statistically predicted values (96%). The reaction rate constant of the MoS2@Fe3O4@PMC catalyst, which has a high catalytic effect for MO degradation under optimum conditions, was calculated as 1.357 min(-1). Also, the apparent activation energy for the MO degradation was obtained to be 13.29 kJ/mol. Moreover, the obtained nanocomposite shows outstanding reusability and excellent catalytic activity even after five cycles, offering a facile and active process for the degradation of toxic organic pollutants in the presence of NaBH4. This study presents a fast, inexpensive, magnetically separable, reusable, and highly efficient catalyst for the degradation of pollutants in wastewater without any noble metal clusters.
Synthesis, Characterization and Application of Iron-Supported Activated Carbon Derived From Aloe Vera Leaves To Improve Anaerobic Digestion of Food Waste: an Optimization Approach
(Elsevier Sci Ltd, 2023) Yilmaz, Sakir; Ecer, Umit; Sahan, Tekin
The study evaluated the effect of iron-supported activated carbon derived from Aloe vera leaves (Fe/AV-AC) as an additive for anaerobic digestion (AD) of food waste (FW). The modelling of the AD system and optimization of the process parameters were performed using response surface methodology (RSM). Cumulative biogas production (CBP), methane content (CH4%), and removal of chemical oxygen demand (COD%) of 7861.59 mL, 65.67%, and 63.65%, respectively, were obtained at optimum conditions (total solids of FW (TS%): 11.81%, Fe ratio loaded on AV-AC: 9.15 wt%, and Fe/AV-AC amount: 986.18 mg/L). The addition of Fe/AV-AC allowed higher biogas production and faster volatile fatty acids (VFAs) consumption. Biogas yield from FW-AD improved by 60.27% with Fe/AV-AC compared to without the additive, while theoretical methane increased by 44.33%. From the results, Fe/AV-AC improved AD and RSM is a suitable approach to optimize the AD of FW.
Synthesis, Characterization, and Application of Ag-Doped Mercapto-Functionalized Clay for Decolorization of Coomassie Brilliant Blue: Optimization Using Rsm
(Elsevier, 2023) Ecer, Umit; Yilmaz, Sakir; Sahan, Tekin
Herein, we report the use of silver nanoparticles (AgNPs) supported on mercapto-functionalized clay for the decolorization of Coomassie brilliant blue (CBB). The effect of four parameters (NaBH4 amount, CBB concen-tration, time, and catalyst amount) on the decolorization efficiency and the optimization of the process was investigated. Under optimum conditions (8.76 mM, 20.86 mg/L, 115.82 s and 0.23 mg/mL for NaBH4 amount, CBB concentration, time, and catalyst amount, respectively), the decolorization efficiency for CBB was 97.73%. The kinetic results indicated decolorization rate was increased toward the temperature (293 to 323 K). The thermodynamic parameters show that the process is endothermic and favorable.
Towards More Active and Stable Pdagcr Electrocatalysts for Formic Acid Electrooxidation: the Role of Optimization Via Response Surface Methodology
(Wiley, 2019) Ulas, Berdan; Caglar, Aykut; Yilmaz, Sakir; Ecer, Umit; Yilmaz, Yonca; Sahan, Tekin; Kivrak, Hilal
In this study, multiwall carbon nanotube (MCNT)-supported Pd (Pd/MWCNT) catalysts are prepared by using NaBH4 reduction method. In order to maximize the oxidation and reduction of H2SO4, synthesis conditions (Pd ratio, molar ratio of NaBH4/K2PdCl4, volume of deionized water, and duration of agitation) are optimized by using response surface methodology (RSM). The optimum synthesis conditions are determined as 58.2% of Pd by weight, 154.6 molar ratio of NaBH4 to K2PdCl4, 19.48 mL of deionized water, and 186.16 min of agitation duration. The effect of electrochemical measurement conditions on the oxidation kinetics of Pd/MWCNT is also investigated by RSM. The optimum electrochemical measurement conditions are found as 10 mu L of catalyst mixture, 90 degrees C of H2SO4 solution, and 5.5 M H2SO4. The Pd/MWCNT, Pd50Ag50/MWCNT, and Pd65.6Ag33.6Cr0.80/MWCNT catalysts prepared under optimized conditions are characterized by using X-ray diffraction, transmission electron microscopy, N-2 adsorption-desorption, and inductively coupled plasma mass spectrometry. The crystallite sizes of these catalysts are found as 4.85, 5.66, and 5.26 nm for Pd/MWCNT, Pd50Ag50/MWCNT, and Pd65.6Ag33.6Cr0.80/MWCNT catalysts, respectively. Isotherms of all these catalysts are found to be similar to Type V isotherms with H3 hysteresis loop. The average particle size of Pd50Ag50/MWCNT and Pd65.6Ag33.6Cr0.80/MWCNT catalysts are determined as 5.2 and 9.2 nm, respectively. Electrochemical performance of as-prepared catalysts is evaluated by using cyclic voltammetry and chronoamperometry. The formic acid electrooxidation (FAEO) activities are found as 18.9, 27.8, and 51.6 mA/cm(2) for Pd/MWCNT, Pd50Ag50/MWCNT, and Pd65.6Ag33.6Cr0.80/MWCNT, respectively. Pd65.6Ag33.6Cr0.80/MWCNT shows the highest activity and stability. Optimization of synthesis conditions and electrochemical measurement parameters allow us to obtain very good electrochemical activity and stability for FAEO reaction compared with anode catalysts in the literature.