Browsing by Author "Sahan, Tekin"

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Application of Response Surface Methodology (Rsm) To Optimize the Adsorption Conditions of Cationic Basic Yellow 2 Onto Pumice Samples as a New Adsorbent
(Parlar Scientific Publications (p S P), 2017) Ozturk, Dilara; Sahan, Tekin; Bayram, Tuba; Erkus, Ayse
In this study, optimization of medium conditions for CBY2 adsorption by pumice was studied through experimental design. For CBY2 adsorption, initial CBY2 concentration (C-o, mg/L), pH and contact time (min.) were determined as medium conditions. Central Composite Design (CCD) within response surface methodology (RSM) was applied to develop a response surface for optimization of adsorption conditions. The optimum conditions were determined as C-o = 154.28 mg/L, pH = 6.13 and contact time = 47.98 min. Results of experiments determined that at these optimum conditions, optimum adsorbed amount was 12.62 mg/g and adsorption yield was 81.79%. A quadratic model was developed by CCD to represent CBY2 adsorption.
Application of Response Surface Methodology for Optimization of Co(Ii) Adsorption Conditions With Natural Pumice Mineral
(Pamukkale Univ, 2017) Sahan, Tekin; Yilmaz, Sakir
Cobalt (Co) is one of the most important heavy metals found in the wastewaters. Some metals such as Co in wastewater from chemical-based industries can have toxic or harmful effects on life forms. Hence, removal of toxic metals in wastewater causing environmental hazards has a great importance. In this work removal of Co(II) ions with adsorption from aqueous solutions by natural pumice has been investigated in a batch system. Response Surface Methodology (RSM) including the central composite design (CCD) was successfully applied to develop a response surface and optimize the medium conditions affecting significantly the adsorption such as pH, initial Co(II) concentration (Co) and temperature (T, degrees C). In CCD, optimum conditions were determined by the model equation obtained from the quadratic model fitting the experimental results. These optimum conditions were found to be 7.79, 69.84 mg/L and 20 degrees C for pH, Co and temperature, respectively. At these optimum conditions, the adsorption capacity and adsorption yield were calculated as 2.816 mg/g and 40.32%, respectively. Then, the data obtained by the program were confirmed by experiments.
Application of Rsm for Pb(Ii) and Cu(Ii) Adsorption by Bentonite Enriched With -Sh Groups and a Binary System Study
(Elsevier, 2019) Sahan, Tekin
The aim of this study is to remove Pb(II) and Cu(II) ions in binary and single solutions with bentonite enriched with -SH groups (BSH) and to optimize the adsorption conditions by using Response Surface Methodology (RSM). Some parameters (initial pH, initial metal concentration, adsorbent dosage and contact time) affecting the adsorption were optimized with Central Composite Design (CCD) under RSM. Optimum values for removal of Pb(II) and Cu(II) by BSH were obtained from the quadratic model generated from CCD. The optimal points for initial pH, initial concentration, adsorbent dosage and contact time obtained by the numerical analysis were 5.10, 32.98 mg/L, 146 mg and 146.01 min. for Pb(II), while these values were 4.52, 37.9 mg/L, 152.3 mg and 146.12 min. for Cu(II), respectively. At the optimum values, maximum Pb(II) and Cu(II) removal were obtained as 95.05% and 91.4%, respectively. Adsorption data for both metal ions were observed to conform with the pseudo-second order kinetic model and Freundlich isotherm model equation. In addition, owing to observation of the competitive effect in the removal of Pb(II) and Cu(II) ions by BSH, some binary system experiments were carried out under optimum conditions obtained for the single system. The selectivity adsorption order of BSH was determined as Pb(II) > Cu(II). Considering all this, it was shown that BSH has great potential applications for the removal of heavy metal impurities from aqueous solutions.
Bentonite Grafted With Poly(n-Acryloylglycineamide) Brush: a Novel Clay-Polymer Brush Hybrid Material for the Effective Removal of Hg(Ii) and As(V) From Aqueous Environments
(Elsevier, 2021) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin
The present work was conducted to indicate bentonite grafted with poly(N-acryloylglycineamide) (PNAGA@BNT) could be applied as a novel clay-polymer brush hybrid material for the removal of Hg(II) and As(V) from aqueous environments. The PNAGA@BNT synthesized via the surface initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization method was characterized by BET analysis, Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and water contact angle measurements. Hg(II)% and As(V)% removal onto PNAGA@BNT was carried out with response surface methodology (RSM). The effects of the operating parameters, like pH, heavy metal ion concentration (C-o), PNAGA@BNT amount, and mixing time were evaluated by central composite design (CCD). The optimum Hg(II) adsorption conditions from the CCD were found to be 6.54, 24.46 mg/L, 23.98 mg, and 106.83 min for pH, C-o, PNAGA@BNT dosage, and mixing time, respectively. On the other hand, the optimum points obtained for As(V) adsorption from CCD were 4.36, 7.30 mg/L, 25.75 mg, and 83.37 min for pH, C-o, PNAGA@BNT dosage, and mixing time, in their given order. At the optimal points obtained for Hg(II) and As(V) adsorption, the maximum Hg(II)% and As(V)% removal efficiencies were 98.58 % and 90.95 %, respectively. The kinetic models with best fit were the pseudo-second-order kinetic model for Hg(II) and As(V) and Weber-Morris intraparticle diffusion was the dominant mechanism for As(V) and Hg(II). Among the isotherms, the equilibrium data best fit the Langmuir and Freundlich models for Hg(II), and the Dubinin-Radushkevich (D-R) and Freundlich models for As(V). Moreover, thermodynamic studies suggested the adsorption process was exothermic and spontaneous.
Catalytic Performance of Pd-Doped Polymer-Nanoparticle Hybrid Materials for Hydrogen Generation Through Nabh4 Hydrolysis
(Elsevier, 2025) Ecer, Uemit; Zengin, Adem; Sahan, Tekin
Creating an effective catalyst with low cost and excellent catalytic efficiency in NaBH4 hydrolysis for H2 generation will have a huge impact on the field of renewable energy. For this reason, a polymer-supported catalyst was synthesized and characterized for hydrogen generation by NaBH4 hydrolysis. For catalyst synthesis, firstly the clay (K) was given magnetic properties (Fe3O4@K.) Then, Fe3O4@K is functionalized with tannic acid (pTA@Fe3O4@K). Finally, the palladium (Pd)-doped catalyst was obtained (Pd@pTA@Fe3O4@K). The study aimed to use a time-efficient Central Composite Design (CCD) from response surface methodology (RSM) to correlate relationships between the hydrogen generation rate (HGR) and the operating parameters. Under optimum conditions (NaBH4 amount: 3.6 wt%, NaOH amount:2.77 wt%, catalyst amount: 3.29 mg/mL, and Pd loading amount:6.05 wt%), the maximum HGR value was calculated as 5891.34 mL H2/(gcat. min.). Thus, the excellently performing Pd@pTA@Fe3O4@K composite catalyst has significant potential for use in NaBH4 hydrolysis.
A Comprehensive Study of Hydrogen Production From Ammonia Borane Via Pdcoag/Ac Nanoparticles and Anodic Current in Alkaline Medium: Experimental Design With Response Surface Methodology
(Higher Education Press, 2020) Celik Kazici, Hilal; Yilmaz, Sakir; Sahan, Tekin; Yildiz, Fikret; Er, Omer Faruk; Kivrak, Hilal
In this paper, the optimization of hydrogen (H-2) production by ammonia borane (NH3BH3) over PdCoAg/AC was investigated using the response surface methodology. Besides, the electro-oxidation of NH3BH3 was determined and optimized using the same method to measure its potential use in the direct ammonium boran fuel cells. Moreover, the ternary alloyed catalyst was synthesized using the chemical reduction method. The synergistic effect between Pd, Co and Ag plays an important role in enhancement of NH3BH3 hydrolysis. In addition, the support effect could also efficiently improve the catalytic performance. Furthermore, the effects of NH3BH3 concentration (0.1-50 mmol/5 mL), catalyst amount (1-30 mg) and temperature (20 degrees C-50 degrees C) on the rate of H-2 production and the effects of temperature (20 degrees C-50 degrees C), NH3BH3 concentration (0.05-1 mol/L) and catalyst amount (0.5-5 mu L) on the electro-oxidation reaction of NH3BH3 were investigated using the central composite design experimental design. The implementation of the response surface methodology resulted in the formulation of four models out of which the quadratic model was adjudged to efficiently appropriate the experimental data. A further statistical analysis of the quadratic model demonstrated the significance of the model with a p-value far less than 0.05 for each model and coefficient of determination (R-2) of 0.85 and 0.95 for H-2 production rate and NH3BH3 electrroxidation peak current, respectively.
The Concentration of 238u and the Levels of Gross Radioactivity in Surface Waters of the Van Lake (Turkey)
(Springer, 2011) Zorer, Ozlem Selcuk; Sahan, Tekin
Gross alpha and gross beta activities and U-238 concentrations were determined in 18 surface water samples collected from Van Lake. The instrumentations used to count the gross alpha and gross beta activities and to determine the U-238 concentrations were alpha/beta counter of the multi-detector low background system (PIC-MPC-9604) and Inductively Coupled Plasma-Mass Spectrometry (Thermo Scientific Element 2), respectively. Concentrations ranging from 0.001 to 0.021 Bq L-1 and from 0.111 to 2.794 Bq L-1 were observed for the gross alpha and beta activities in surface waters, respectively. For all samples the gross beta activities were higher than the corresponding gross alpha activities. The results indicated that the gross alpha radioactive contamination in water samples was lower than recommended values for the guideline of drinking waters and most of the gross beta activities in water samples were higher than those in the same procedure. The U-238 concentrations ranged from 74.49 to 113.2 mu g L-1 in surface waters. The obtained results have showed that U-238 concentrations are higher than guideline values for uranium.
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 Utilization of Fe(iii)-Based Metal Organic Framework-Coated Cellulose Paper for Highly Efficient Elimination From the Liquid Phase of Paracetamol as a Pharmaceutical Pollutant
(Elsevier, 2021) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin
This work aims to evaluate the potential utilization of Fe(III)-based metal organic framework-coated cellulose paper (MIL-100(Fe)@CP) for the elimination of paracetamol (PCM) from water systems. The characterization of MIL-100(Fe)@CP was examined with Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX). The modeling and optimization studies were examined using response surface methodology (RSM). The effects of adsorption parameters influencing PCM removal such as initial PCM concentration (C-o), pH of solution, agitation time, and adsorbent dosage were evaluated by central composite design (CCD) in RSM. For maximum PCM removal efficiency, the optimum C-o, pH, agitation time, and adsorbent dosage were 35.60 mg/L, 6.44, 167.06 min, and 16.87 mg, respectively. In these conditions, the best PCM removal efficiency was determined as 89.75%. The adsorption kinetic data for PCM were successfully expressed by the Weber-Morris and pseudo-second-order models. Moreover, the isotherm data was best fitted to the Langmuir isotherm model. All results indicate that RSM is efficient in predicting the removal efficiency of PCM onto MIL-100(Fe)@CP and the prepared novel material is a hopeful adsorbent for the highly effective elimination of pharmaceuticals such as PCM from aquatic systems. (C) 2021 Elsevier B.V. All rights reserved.
Efficient Removal of 2,4-Dichlorophenoxyacetic Acid From Aqueous Medium Using Polydopamine/Polyacrylamide Co-Deposited Magnetic Sporopollenin and Optimization With Response Surface Methodology Approach
(Springer, 2023) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin; Gubbuk, Ilkay Hilal
In this study, a novel binary grafted polydopamine/polyacrylamide onto magnetic sporopollenin (PDA/PAAm@Fe3O4@SP) was synthesized in one step polymerization strategy to investigate its removal performance of 2,4-dichlorophenoxyacetic acid (2,4-D). The response surface methodology (RSM) was applied to evaluate the effects of the process factors including pH (2-8), adsorbent concentration (0.5-2 g/L), initial 2,4-D concentration (C-o) (20-80 mg/L), and contact time (30-180 min) for the 2,4-D removal performance. The central composite design (CCD) through RSM was utilized to design the experiments as well as to optimize and model the 2,4-D adsorption process. The ANOVA results clearly shows that the quadratic model (p < 0.0001) was sufficient to the best predicting of the removal performance of 2,4-D (R-2 = 0.99). The optimum conditions for the maximum 2,4-D removal (88.31%) was achieved at pH of 3.51, adsorbent concentration of 0.75 g/L, C-o of 52.85 mg/L, and contact time of 148.53 min. The adsorption kinetic was represented by both Weber-Morris (R-2 = 0.99) and pseudo-second-order models (R-2 = 0.99). The isotherm for 2,4-D completely fitted the Dubinin-Radushkevich (D-R) and Langmuir models with R-2 values of 0.98. The obtained outcomes indicated that the prepared material may be utilized as an alternative adsorbent for the removal of 2,4-D from waterbodies and the RSM method can be utilized as an eco-friendly and low-cost statistical approach for the elimination of 2,4-D.
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.
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.
Hydrogen Generation From Nabh4 Hydrolysis Catalyzed by Cobalt (0)-Deposited Cross-Linked Polymer Brushes: Optimization With an Experimental Design Approach
(Pergamon-elsevier Science Ltd, 2023) Ecer, smit; Zengin, Adem; Sahan, Tekin
Proposing a novel catalyst that achieves catalytic hydrolysis of metal hydrides is an important stage in developing a hydrogen storage system. In this study, a cross-linked gel brush-cobalt (0) composite (Co@P4VPGB@PMC) has been synthesized to obtain hydrogen from NaBH4 solution. The morphology, structure, and composition of the obtained catalyst have been characterized by, FTIR, SEM, EDX, BET, XRD, ICP-MS and XPS. The parameters that significantly affect the hydrolysis of NaBH4 (such as NaBH4 concentration, NaOH amount, catalyst amount, and temperature) have been investigated using response surface methodology (RSM), an optimization method that has gained increasing importance in recent years. The hydrogen generation rate (HGR) was 4499 mL/min gcat for Co@P4VPGB@PMC when the NaBH4 amount was 241.52 mM, NaOH amount 5 wt%, catalyst amount 10.55 mg and temperature 58.9 degrees C. Moreover, the apparent activation energy (Ea)
Improved Anaerobic Digestion Activity of Poultry Dung With Pumice-Supported Trace Elements: Focus on the Statistical Optimization Approach
(Springer Heidelberg, 2023) Yilmaz, Sakir; Sahan, Tekin
In the present study, two types of pumice (TP) supporting Ni (Ni/TP) and Mo (Mo/TP) as trace element additives for anaerobic digestion (AD) of poultry dung (PD) were synthesized using the NaBH4 reduction method. Multiple effects of operating parameters on the AD system were investigated for each material and optimized by using response surface methodology (RSM). Results showed that the operating parameters have important effects on the selected responses (cumulative biogas production (mL), removal yield for chemical oxygen demand (COD% removal), and methane percentage in biogas (CH4% content)). ANOVA results indicated that the obtained quadratic models for each response were statistically significant (p < 0.05). Moreover, the experimental data was in harmony with the predicted data obtained by the models for the responses selected for each material (R-2 > 0.90). The numerical analysis results showed that at the optimum points, the maximum cumulative biogas production, COD% removal, and CH4% content were 7862.75 mL, 60.43%, and 63.49% for Ni/TP and 7372.79 mL, 55.15%, and 62.67% for Mo/TP, respectively. In addition, the impact of bimetallic material on AD was examined, and the results indicated that Ni and Mo have a synergistic effect on the AD process.
Influence of the Medium Conditions on Enzymatic Oxidation of Bisphenol a
(Wiley, 2014) Yalcinkaya, Zeki; Gun, Selim; Sahan, Tekin; Birhanli, Emre; Sahiner, Nurettin; Aktas, Nahit; Yesilada, Ozfer
A multistep response surface methodology (RSM) was successfully applied to optimise the medium conditions for the enzymatic polymerisation of bisphenol A (BPA). The laccase enzyme used as the catalyst was derived from Funalia trogii (ATCC 200800) yeast culture. The enzymatic polymerisation rate of BPA, based on the measurements of the initial dissolved oxygen (DO) consumption rate in a closed batch system, was studied through RSM. Initially the most effective medium factors, which are monomer concentration (mg/L), temperature (degrees C) and solvent content (% methanol), were determined through Plackett-Burman Design (PBD), then the steepest ascent combined with central composite design (CCD) steps were applied to evaluate the optimal reaction conditions for the enzymatic polymerisation. The optimal conditions were evaluated to be 748.46mg/L, 32.24 degrees C and 15.92% for monomer concentration, temperature and solvent content, respectively. A quadratic model was developed through RSM to represent DO consumption in the medium. The maximum DO consumption rate was calculated to be 0.093mg DO/Lmin. Several repetitions were conducted at the optimal conditions to validate the system performance. The data evaluated from the quadratic model were in good agreement with those measured experimentally. The variations between the values did not exceed 10%. The correlation coefficient, R-2, was calculated to be 0.95, which indicates that 95% of results can be explained by model.
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.
Investigation of Pb(Ii) Adsorption Onto Pumice Samples: Application of Optimization Method Based on Fractional Factorial Design and Response Surface Methodology
(Springer, 2014) Sahan, Tekin; Ozturk, Dilara
The adsorption of Pb(II) by pumice samples collected from the Mount Ararat region, located in eastern Turkey, was investigated in a batch system. The combined and individual effects of operating parameters on adsorption were analyzed using a multi-step response surface methodology. In the first step the most effective factors, which are initial Pb(II) concentration, pH, and temperature, were determined via fractional factorial design. Then the steepest ascent/descent followed by central composite design were used to interpret the optimum adsorption conditions for the highest Pb(II) removal. The optimum adsorption conditions were determined to be initial Pb(II) concentration of 84.30 mg/L, pH of 5.75, and temperature of 41.11 A degrees C. At optimum conditions, the adsorption capacity of pumice for Pb(II) was found to be 7.46 mg/g according to a removal yield of 88.49 %. The obtained data agreed with a second-order rate expression and fit the Langmuir isotherm very well. The thermodynamic parameters such as Delta HA degrees, Delta SA degrees, and Delta GA degrees for the Pb(II) adsorption were calculated at four different temperatures. The present results indicate that pumice is a suitable adsorbent material for adsorption of Pb(II) from aqueous solutions.
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.
Magnetic Hydrogel Syntheses and Their Applications in the Environment for the Removal of Toxic Metal Ions
(Amer Chemical Soc, 2009) Ozay, Ozgur; Onder, Alper; Sahan, Tekin; Aktas, Nahit; Baran, Yakup; John, Vijay T.; Sahiner, Nurettin