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    Application of residual shell biomass of pistachio for dye biosorption from aquatic environment
    (Elsevier Science Bv, 2016) Kepekci, Remziye Aysun; Deniz, Fatih
    [No abstract available]
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    Bioremediation of Contaminated Water with Unnatural Dye using Blue-Green Alga Spirulina Platensis
    (Wiley-Blackwell, 2015) Deniz, Fatih; Kepekci, Remziye Aysun
    Blue-green alga Spirulina platensis as a cheap biosorbent was tested for its ability to remove a common azo dye, C.I. Basic Red 46 (C.I. BR 46), from contaminated water. Dye biosorption was a quick process and biosorption reaction reached equilibrium within 60 min. The pseudo-first-order, pseudo-second-order, logistic, and intraparticle diffusion models were used for the kinetic evaluation. The logistic model presented the best fit to the experimental data. The biosorption data were analyzed using Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models. Langmuir model fitted better to the equilibrium data than Freundlich model. The maximum dye biosorption capacity was obtained as 25.46 mg g-1 for the biosorbent. Dubinin-Radushkevich model showed that the predominant mechanism of the dye biosorption was likely physical biosorption. This study suggests promising biosorption potential of S. platensis for C.I. BR 46 removal from contaminated effluents. 2015 American Institute of Chemical Engineers Environ Prog, 34: 14141419, 2015
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    Bioremoval of Malachite green from water sample by forestry waste mixture as potential biosorbent
    (Elsevier Science Bv, 2017) Deniz, Fatih; Kepekci, Remziye Aysun
    Application of cetyltrimethylammoniurn bromide (CTAB) modified multi-component biosorbent composed of pine, oak, hornbeam and fir sawdust biomasses was investigated to remove Malachite green (MG) as a model pollutant from aqueous solution. The effects of pH, dye concentration, biosorbent amount and contact time on the biosorption performance were explored in a batch biosorption system. The biosorption isotherm data were analyzed using Freundlich, Langmuir, Sips and Dubinin-Radushkevich models while the kinetic data of biosorption were modeled with the pseudo-first-order, pseudo-second-order, Elovich, logistic and intra-particle diffusion models. These studies showed that Sips isotherm and logistic model fitted well to the dye biosorption data. The maximum biosorption capacity of biosorbent was calculated to be 52.610 mg g(-1) at the optimized conditions. Thus, the CTAB modified multi-component sawdust biomass can be employed as cost effective and ecological friendly biosorbent in the treatment of industrial effluents containing such unsafe pollutants. (C) 2017 Elsevier B.V. All rights reserved.
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    Biosorption of Dye from Synthetic Wastewater Using Alga Enriched in Phenolic Compounds
    (Wiley, 2016) Deniz, Fatih; Kepekci, Remziye Aysun
    In the current study, we report the preparation of modified biosorbent from Spirulina platensis microalga via the high light application in order to enhance its dye biosorption capacity. The modified biosorbent was characterized with analyses of content of phenolic compounds, FTIR and SEM. The biosorbent was applied to kinetic and equilibrium studies for removal of C.I. Basic Red 46 (C.I. BR 46) from aqueous solution. The kinetic data were best described by the logistic model, while the equilibrium data were best fitted by Langmuir model. The kinetic and isotherm studies indicated that C.I. BR 46 biosorption onto the modified biosorbent occurred in monolayers and the biosorption process was controlled by physical sorption. The level of phenolic compounds in the high light applied biosorbent was defined approximately eightfold higher than in the native biosorbent. Moreover, the high light application provided an increase in the dye biosorption capacity of about 31%, when compared to the raw biosorbent. The maximum biosorption capacity of modified biosorbent was found to be 33.33 mg g(-1) for C.I. BR 46 at the worked biosorption conditions. Thus, this work reveals that high light application can potentially be used to increase biosorption capacity of biosorbents. (C) 2015 American Institute of Chemical Engineers Environ Prog, 35: 737-742, 2016
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    Biosorption of Food Green 3 by a novel green generation composite biosorbent from aqueous environment
    (Taylor & Francis Inc, 2017) Deniz, Fatih; Kepekci, Remziye Aysun
    A green type composite biosorbent composed of pine, oak, hornbeam, and fir sawdust biomasses modified with cetyltrimethylammonium bromide (CTAB) was first used for biosorption of an unsafe synthetic food dye, Food Green 3 from liquid medium in this study. Batch studies were carried by observing the effects of pH, dye concentration, biosorbent amount, and contact time. The equilibrium data were analyzed using Freundlich, Langmuir, and Dubinin-Radushkevich equations. Freundlich model gave a better conformity than other equations. The maximum dye removal potential of biosorbent was found to be 36.6mg/g based on Langmuir isotherm. The pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models were applied to clarify the process kinetics of biosorption. The mechanism studies suggested the biosorption process obeying Elovich kinetics and involving pore diffusion. The estimated values of biosorption free energy from Dubinin-Radushkevich isotherm (E value <8kJ/mol) and thermodynamic studies (0 < G degrees < -20kJ/mol) implied a spontaneous, feasible, and physical process. Hence, this investigation suggested that the CTAB modified mix sawdust biomass could be a promising biosorbent for biosorption of such problematic dyes from impacted media.
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    Dye biosorption onto pistachio by-product: A green environmental engineering approach
    (Elsevier Science Bv, 2016) Deniz, Fatih; Kepekci, Remziye Aysun
    Wastes from different sources can be utilized as effective materials in wastewater bioremediation. From this point of view, this study was aimed to investigate the possibility of using pistachio shell, a non-conventional cheap biosorbent, obtained as agricultural solid waste for removal of a reactive-azo dye from water. The batch biosorption studies were carried out as a function of dye concentration and contact time. The experimental results showed that the biosorption process was very rapid (nearly 10 min) and the percent yield of biosorption decreased with an increase in dye quantity. Two- and three-parameter biosorption models were employed to describe the experimental kinetic and isotherm data. The results revealed that the biosorption data were best fitted by the pseudo-second order and Sips models. The maximum biosorption capacity was found to be 109.535 mg g(-1). The magnitude of standard Gibbs free energy change was calculated as -5.184 kJ mol(-1) showing that physical forces were involved in the spontaneous biosorption of dye onto the biosorbent. This research suggests that the pistachio by-product can be an effective and low-cost material for the removal of such hazardous dyes from water. (C) 2016 Elsevier B.V. All rights reserved.
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    Efficiency of Modified Composite Biosorbent for Bioremoval of Phosphate Ions in Aqueous Area: Process Modeling Studies
    (Springer/Plenum Publishers, 2017) Deniz, Fatih; Kepekci, Remziye Aysun
    This paper was focused on the biosorption of phosphate ions from aqueous solution onto the cetyltrimethylammonium bromide (CTAB) modified multi-component biosorbent composed of pine, oak, hornbeam and fir sawdust biomasses. A series of batch tests were conducted and the effects of solution pH, ion concentration, quantity of biosorbent and contact time on the bioremoval of phosphate ions were investigated. The biosorption data of kinetic and equilibrium were modeled using various mathematical equations. The phosphate removal increased with increased ion concentration and decreased with increased pH and biosorbent quantity values. The equilibrium state was reached within 120 min of exposure time. The process kinetics was best described by Elovich model while the isotherm data of biosorption best obeyed Freundlich equation. The obtained results revealed that the use of CTAB modified mix sawdust biosorbent presented interesting options for bioremediation of contaminated environments and waste recycling (as nutrient fertilizer and compost material).
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    Elimination of a common hazardous dye from aqueous solution by a novel alkaline-treated multi-component biosorbent
    (Springer, 2017) Deniz, Fatih; Kepekci, Remziye Aysun
    A novel alkaline-treated multi-component biosorbent composed of pine, oak, hornbeam and fir sawdust biomasses was evaluated to eliminate a common hazardous dye [malachite green (MG)] from aqueous solution in this study. Batch biosorption studies were carried out using this base-modified biosorbent under varying biosorption conditions of: pH, MG concentration, modified biosorbent loading and reaction time. The experimental results showed that this easy modification application (using 0.3-M sodium hydroxide) was able to enhance the biosorption potential of natural biosorbent from 35.230 to 78.926 mg g(-1) under the same study conditions. The obtained equilibrium data were modelled using Freundlich, Langmuir, Sips and Dubinin-Radushkevich isotherm models. Also, the biosorption kinetics were analyzed using the pseudo-first-order, pseudo-second-order, logistic and intra-particle diffusion models. It was found that the biosorption data of the isotherm and kinetics were best represented using Sips and logistic models. Hereby, this modified biosorbent can be used for bioremediation of contaminated areas with such deleterious dyes.
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    Equilibrium and kinetic studies of azo dye molecules biosorption on phycocyanin-extracted residual biomass of microalga Spirulina platensis
    (Taylor & Francis Inc, 2016) Deniz, Fatih; Kepekci, Remziye Aysun
    The capability and mechanism of a model azo dye, C.I. Basic Red 46 removal by phycocyanin extraction residue of Spirulina platensis were investigated in this study. The biosorption data were analyzed using Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherm models. Langmuir model was more adequate to represent the data of biosorption equilibrium. The dye biosorption capacity was obtained as 23.06mgg(-1) for the biosorbent. The dye removal potential of phycocyanin-extracted biomass was very close to that of the virgin alga (25.46mgg(-1)). D-R model displayed that the dye was probably to be removed mainly via physical biosorption. The pseudo-first-order, pseudo-second-order, logistic, and intraparticle diffusion models were used for the evaluation of biosorption kinetics. The logistic model presented the best fit to the experimental kinetic data. The intraparticle diffusion model showed that this biosorption process was a complex process involving more than one mechanism. Thus, this waste microalga biomass can be used as a low-cost biosorbent for dye removal.
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    Evaluation of Calabrian pine sawdust by-product as potential dye biosorbent
    (Elsevier Science Bv, 2016) Kepekci, Remziye Aysun; Deniz, Fatih
    [No abstract available]
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    Exploration of Biosorption Potential of Forest Industry By-product for Removal of Reactive Dye from Aqueous Solution
    (Korean Fiber Soc, 2017) Deniz, Fatih; Kepekci, Remziye Aysun
    Natural sawdust of Calabrian pine was explored as low-cost industrial by-product for a hetero-bireactive dye removal from aqueous solution in this study. Batch experiments were carried out to investigate the effects of contact time and dye concentration on biosorption efficiency. Maximum biosorption amounts were achieved almost in the 20-30 min of contact for the studied dye range (50-200 mg l(-1)). An increase in the dye concentration resulted in decrease in the percent dye removal and increase in the biosorption capacity of biosorbent. Different kinetic and isotherm models were used to examine the biosorption experimental data for elucidating the dye removal mechanism. The equilibrium data were best represented by Freundlich isotherm model confirming multilayer coverage. The kinetics of dye biosorption best obeyed the pseudo-second-order equation. The negative value of standard Gibbs free energy change (-3.61 kJ mol(-1)) indicated that physical forces were involved in the spontaneous dye biosorption. Thus, the sawdust as a possible non-conventional biosorbent presented an interesting option for bioremediation of contaminated environments by such unsafe dyes.
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    Promising Biosorbent for Biosorption of a Model Hetero-bireactive Dye from Aqueous Medium
    (Korean Fiber Soc, 2017) Deniz, Fatih; Kepekci, Remziye Aysun
    In this study, residual shell biomass of Corylus avellana L. was used as potential biosorbent for biosorption of a model industrial hetero-bireactive dye. The biosorbent was characterized by FTIR and SEM. The batch biosorption studies were performed as a function of dye concentration and contact time. The biosorption of dye was found to be very quick. Various kinetic and isotherm models were used to evaluate the obtained experimental data. The biosorption kinetic was best represented by the pseudo-second-order model while the biosorption equilibrium was best described by Langmuir model. The maximum dye biosorption capacity of biosorbent based on Langmuir isotherm was obtained as 74.527 mg g(-1). These results showed that the use of such plant waste biomass in biosorption system could be a feasible method for the removal of such recalcitrant dye from industrial effluents to reduce operating costs.