Browsing by Author "Yilmaz, Sakir"

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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.
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.
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.
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.
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.
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.
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 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.
Facile Synthesis of Surfactant-Modified Layered Double Hydroxide Magnetic Hybrid Composite and Its Application for Bisphenol a Adsorption: Statistical Optimization of Operational Variables
(Elsevier, 2022) Yilmaz, Sakir
A novel hexadecyltributylphosphonium bromide modified magnetic composite based on calcined Ni-Mn layered double hydroxide (HDTBP@Fe3O4@NiMn-CLDH) was synthesized and evaluated for the removal of bisphenol A (BPA) from aquatic media. The structural features of the synthesized hybrid material were determined by Fourier transform infrared (FTIR) spectroscopy, vibrating-sample magnetometer (VSM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray analysis (EDX). Response surface methodology (RSM) was used to investigate the influences of operational variables and optimize the adsorption process. The BPA adsorption process was developed by considering a central composite design (CCD) under RSM with four independent variables (initial BPA concentration (Co), agitation time, initial pH, and adsorbent dosage). From the statistical results, the optimal adsorption conditions for Co, agitation time, initial pH, and adsorbent dosage were determined as 22.53 mg/L, 80.05 min, 7.07, and 1.14 g/L, respectively, and under these conditions, the maximum yield was obtained as 86.85%. The kinetic study results showed the kinetic data was perfectly represented by the pseudo-second-order model. Furthermore, the isotherm data fitted very well to the Langmuir and Dubinin-Radushkevich (D-R) models. Additionally, the results based on the adsorption thermo-dynamics indicated that the process was spontaneous and endothermic. The findings of the present work indicate that RSM is suitable for optimization of the BPA adsorption process onto HDTBP@Fe3O4@NiMn-CLDH and the synthesized composite has great application potential for the remediation of water polluted with organic contaminants like BPA.
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.
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.
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 Nanoparticles Coated With Aminated Polymer Brush as a Novel Material for Effective Removal of Pb(Ii) Ions From Aqueous Environments
(Springer Heidelberg, 2019) Yilmaz, Sakir; Zengin, Adem; Akbulut, Yeliz; Sahan, Tekin
In the present study, a poly (vinylbenzyl chloride) grafted Fe3O4 nanoparticle (Fe3O4@PVBC) was prepared by surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization and subsequently coated with tris (aminoethyl) amine (TAEA). Then, Fe3O4@PVBC-TAEA nanoparticles were utilized as a novel adsorbent for removal of Pb(II) from aqueous media and optimal adsorption conditions were determined with response surface methodology (RSM). The used adsorbent was characterized by using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). RSM with central composite design (CCD) was carried out to evaluate the effect of initial pH, initial Pb(II) concentration (C-0, mg/L), adsorbent dosage (mg), and contact time (min). The optimum initial pH, C-0, adsorbent dosage, and contact time were found to be 5.88, 46.51mg/L, 17.41mg, and 108.21min, respectively. The maximum removal efficiency and adsorption capacity were 97.07% and 129.65mg/g under these conditions, respectively. The kinetic data revealed that the adsorption mechanism could be best explained by the pseudo-second-order and Weber-Morris models. The isotherm studies found that both the Langmuir and Freundlich isotherm models fitted the experimental data well. The thermodynamic analysis indicated that the adsorption nature is exothermic, applicable, and spontaneous.
Mercury(Ii) Adsorption by a Novel Adsorbent Mercapto-Modified Bentonite Using Icp-Oes and Use of Response Surface Methodology for Optimization
(Elsevier, 2018) Sahan, Tekin; Erol, Funda; Yilmaz, Sakir
The presence of mercury(II) ions in aqueous media is a major concern due to toxicity and the threat to public health and ecological systems. Thus, the development of novel adsorbents that are highly efficient and selective is of critical importance for the removal of mercury(II) ions from aqueous media. The adsorption of mercury(II) from aqueous media by a new adsorbent, 3-mercaptopropyl trimethoxysilane-modified bentonite (B-SH), and the optimization of adsorption parameters was investigated in this study. B-SH was used as a novel sorbent for mercury(II) adsorption, and the analysis of adsorption conditions was performed by response surface methodol-, ogy (RSM). The characterization of B-SH was executed using Brunauer, Emmett and Teller (BET), Fourier Transform Infrared (FTIR) Spectroscopy, Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses. The most important parameters for Hg(II) adsorption were initial pH, initial mercury(II) concentration (C-o), temperature (T (degrees C)), and adsorbent dosage (g). The RSM results showed that the optimal adsorption conditions yielding the best response were 6.17, 36.95 mg/L, 37.28 degrees C, and 0.19 g, for pH, C-o, T (degrees C), and adsorbent dosage, respectively. At optimum adsorption conditions obtained by program, the maximum adsorption capacities and the adsorption yield were 19.30 mg/g and 99.23%, respectively. Among the adsorption isotherm models (the Langmuir, Freundlich and Dubinin-Radushkevich), the adsorption data showed a better fit to the Langmuir isotherm model. The thermodynamic studies revealed that the adsorption process was spontaneous, feasible and endothermic. According to these results, B-SH has high mercury(II) adsorptive removal potential from aqueous media. In addition, a new adsorbent has been added to the literature for the uptake of toxic metals like mercury. (C) 2018 Elsevier B.V. All rights reserved.
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.
A Novel Material Poly(n-Acryloyl Grafted Kaolin for Efficient Elimination of Malachite Green Dye From Aqueous Environments
(Elsevier, 2020) Yilmaz, Sakir; Zengin, Adem; Sahan, Tekin
In the present work, poly(N-acryloyl-L-serine) grafted-kaolin (PNALS@K) synthesized with the surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization method is reported for the efficient removal of malachite green (MG) dye from aqueous environments. The characterization of PNALS@K was carried out by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), energy dispersive x-ray spectroscopy (EDX), and contact angle measurements. The surface characterization analysis indicates there is a thin layer of PNALS on the kaolin surface. Four parameters (starting pH, starting MG concentration (C-o), adsorbent dosage (m), and contact time (t)) were evaluated using response surface methodology (RSM) combined with central composite design (CCD) for the removal of MG by PNALS@K. The optimum adsorption conditions for the removal of MG using PNALS@K were determined as starting pH = 8.92, C-o = 23.49 mg/L, m = 17.44 mg, and t = 72.2 min. The results indicated that PNALS@K has maximum adsorption decolorization performance of 98.90% for MG% removal at the optimal points. Moreover, adsorption data obeyed the Weber-Morris, liquid film diffusion and pseudo-second-order kinetic models. According to the isotherm results, it was also observed that Freundlich isotherm model presented a better fit.
Response Surface Approach for Optimization of Hg(Ii) Adsorption by 3-Mercaptopropyl Trimethoxysilane-Modified Kaolin Minerals From Aqueous Solution
(Korean institute Chemical Engineers, 2017) Yilmaz, Sakir; Sahan, Tekin; Karabakan, Abdulkerim
The optimization of Hg(II) adsorption conditions from aqueous solutions with 3-mercaptopropyl trimethoxysilane-modified kaolin (MMK) used as a new adsorbent was analyzed by response surface methodology (RSM) approach. The MMK adsorbent was characterized by means of energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). According to the quadratic model obtained from central composite design (CCD) in RSM, the optimal conditions for adsorption were found to be 30.83 mg/L, 0.1 g, 7.44 and 31.41 A degrees C for C (o) , adsorbent dosage, initial pH, and T (A degrees C), respectively. With the obtained model, the maximum amount of adsorbed Hg(II) and %Hg(II) removed was calculated to be 30.10 mg/g and 98.01%, respectively. Langmuir and Dubinin-Radushkevich isotherms fitted well the experimental results. Thermodynamic studies revealed that the adsorption was physical, exothermic, spontaneous. The results indicate that MMK a new adsorbent has great potential for the removal of Hg(II) from aqueous media.
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.