Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Effects of drying methods on physicochemical properties and bioactive compounds of wild fruits native to the Gümüşhane flora of NE Türkiye
Bulut, Volkan Numan; Baltaci, Cemalettin; Gundogdu, Ali; Barlak, Esra
Wild fruits are valuable natural sources of bioactive compounds with significant nutritional and functional properties. This study comparatively evaluated the effects of freeze-drying (FD), oven drying (OD), and open-air drying (AD) on the physicochemical properties, total phenolic content (TPC), vitamin C content, and antioxidant properties of five wild fruit species naturally growing in the Gümüşhane region of Türkiye: wild pear (Pyrus elaegrifolia Pall.), hawthorn (Crataegus orientalis), rosehip (Rosa canina L.), cornelian cherry (Cornus mas L.), and barberry (Berberis vulgaris). Drying method markedly affected both physicochemical characteristics and bioactive compounds. Oven drying produced the lowest water activity values (0.10–0.34), indicating enhanced microbiological stability, whereas freeze-dried samples generally showed superior preservation of phenolic compounds and antioxidant activity. The highest TPC was observed in air-dried cornelian cherry (935.59 mg GAE/kg), while freeze- dried rosehip exhibited the highest TPC among freeze-dried samples (907.63 mg GAE/kg). Vitamin C was highly sensitive to thermal processing, and most oven-dried samples showed values below the detection limit (<0.30 mg/kg). In contrast, freeze-dried rosehip retained the highest vitamin C content (1594 mg/kg). Freeze-dried cornelian cherry exhibited the highest DPPH radical scavenging activity (93.45%), whereas oven-dried rosehip showed the highest total antioxidant content (33.38 mg/g). The relatively high antioxidant values observed in some oven-dried samples may also be partially associated with the formation of Maillard reaction products exhibiting antioxidant properties under thermal processing conditions. Correlation and hierarchical cluster analyses revealed statistically significant (p < 0.05) fruit-specific differences in antioxidant behavior and clustering patterns, indicating that the responses to drying treatments were more strongly influenced by fruit matrix composition than by drying method alone. The findings demonstrate that the effects of drying treatments are strongly fruit matrix-dependent and that no single drying method is universally optimal for preserving all quality attributes of wild fruits.
- MakaleYalnız künye2026Valorization of tea industry waste into boric acid–activated carbon for phenol removal from aqueous solutions
Duran, Celal; Ozdes, Duygu; Ozdemir, Olcay; Onal, Yunus; Gundogdu, Ali
The tea industry generates substantial quantities of solid waste with limited high-value industrial applications. In this study, tea industry waste was converted into boric acid-activated carbon (BA–TAC) through a simple one-step chemical activation process and evaluated as an adsorbent for phenol removal from aqueous solutions. BA–TAC exhibited a mixed micro–mesoporous structure with a BET surface area of 592.59 m2 g−1. The adsorption performance was investigated as a function of solution pH, contact time, and initial phenol concentration. Adsorption kinetics were evaluated using pseudo-first order, pseudo-second order, Elovich, Avrami, and intraparticle diffusion models, whereas equilibrium data were analyzed using Langmuir, Freundlich, and Sips isotherms. Linear, pseudo-linear, and non-linear regression approaches were comparatively evaluated, demonstrating the limitations of conventional linearization and the superiority of direct non-linear regression. Moreover, the so-called linearized forms of multi-parameter models such as Sips are not truly linear because iterative parameter estimation remains necessary. The maximum experimental phenol adsorption capacity reached 101.80 mg g−1 despite the moderate BET surface area of BA–TAC. The experimentally determined natural pH and pHpzc values, together with the limited desorption efficiency, indicated that adsorption was governed predominantly by surface chemical interactions rather than electrostatic attraction alone. XPS analysis confirmed the incorporation of boron-containing surface functionalities, highlighting their contribution to phenol adsorption. Overall, this study demonstrates the successful valorization of tea industry waste into a functional boron-modified activated carbon while providing methodological guidance for reliable adsorption kinetics and equilibrium modeling, thereby supporting sustainable waste valorization.
- MakaleAçık Erişim2026Selective Determination of Trace Co(II) and Cu(II) in Food and Environmental Matrices via Carrier Element-Free Coprecipitation Using a Novel Thiosemicarbazone-Derived Schiff Base
Bulut, Volkan N.; Demirci, Hamit; Ozdes, Duygu; Gundogdu, Ali; Bektas, Hakan; Soylak, Mustafa; Duran, Celal
A carrier element-free coprecipitation (CEFC) method was developed for the preconcentration and determination of trace Co(II) and Cu(II) in environmental and food samples using a novel thiosemicarbazone-derived Schiff base ligand (MBITAH). Unlike conventional coprecipitation approaches, the proposed strategy eliminates the need for inorganic carriers, reducing potential interferences and improving selectivity toward the target analytes. Under optimized conditions (pH 7.0, 1.5 mg ligand), quantitative recoveries were achieved with limits of detection of 1.16 and 0.79 µg L⁻1 for Co(II) and Cu(II), respectively. A preconcentration factor of 50 enabled sensitive determination by flame atomic absorption spectrometry (FAAS) with good precision (RSD ≤ 3.7%). The method exhibited good tolerance toward common matrix ions and was validated using certified-reference material (CRM-SA-C Sandy Soil C) and spike/recovery tests, showing agreement with certified values (p > 0.05). Its applicability was demonstrated in sea water, stream water, and food samples (red lentil and bulgur), confirming reliable performance in complex matrices. Compared with previously reported approaches, the proposed CEFC method offers a favorable balance between analytical performance, simplicity, and cost-effectiveness. In addition, greenness assessment using the AGREE tool yielded a score of 0.45, indicating a moderate-to-good level of environmental friendliness.
- MakaleAçık Erişim2023Adsorption of hexavalent chromium from aqueous solution onto corn cobs – activated carbon
Gundogdu, Ali; Bozbeyoglu, Pinar
This study evaluated the performance of a new activated carbon (CCs-AC) produced from corn cobs by boric acid activation for the effective removal of hexavalent chromium, a heavy metal with high potential to pollute the environment, from wastewater. For this purpose, with the help of parameters such as solution pH, contact time, initial Cr(VI) concentration, CCs-AC dose, desorption and temperature, the removal of Cr(VI) ions from aqueous solution by adsorption on CCs-AC was investigated from equilibrium, kinetic and thermodynamic point of view. As a result of the experiments, it was determined that the optimum solution pH was 2.0, the contact time was 4 hours, and the desorption solution was 3.0 M NaOH. From the kinetic data, it was determined that the adsorption was compatible with the pseudo-second order kinetic model and the maximum Cr(VI) adsorption capacity (123.7 mg/g) obtained from the Langmuir isotherm model showed that CCs-AC was of competitive quality with the literature. From the thermodynamic data, the positive ΔH value indicates that the adsorption is endothermic and the value of 12.00 kj/mol indicates that the adsorption is rather chemically driven. The negative ΔG value indicates that the process proceeds spontaneously with an increase in temperature, while the ΔS value indicates an increase in the amount of unused energy.
- MakaleYalnız künye2023Characterization of the Adsorption Mechanism of Cadmium(II) and Methylene Blue upon Corncobs Activated Carbon
Gundogdu, Ali; Bozbeyoglu, Pinar; Imamoglu, Mustafa; Baltaci, Cemalettin; Duran, Celal; Bulut, Volkan N.
A promising new activated carbon (AC) was produced from corncobs (CCs) by boric acid-based chemical activation to remove methylene blue (MB) as an organic pollutant and cadmium ions (Cd2+) as an inorganic pollutant from aqueous solutions. After the produced activated carbon (CCs-AC) was characterized, the adsorption mechanism of CCs-AC, which is one of the most interesting topics in the literature, was the primarily focus. The possible adsorption mechanisms of Cd2+ and MB on CCs-AC from aqueous solutions are discussed with respect to pH, thermodynamic values, and regeneration parameters. The results show that the adsorption of Cd2+ on CCs-AC was favorable at pH values higher than 4. In contrast, the adsorption process was almost pH-independent for MB. Variation of pH showed that the adsorption of Cd2+ on CCs-AC primarily occurs by electrostatic interaction. However, MB adsorption may also involve pi-pi dispersion forces and partial hydrogen bonding. The Cd2+ adsorbed on CCs-AC was quantitatively desorbed by HCl, whereas MB was not desorbed quantitatively by any solution. While a temperature increase has a positive effect on the adsorption of both methylene blue and Cd2+, the thermodynamic results show that MB adsorption is primarily chemisorption (Delta H of 24.28 kJ/mole), while Cd2+ adsorption is mostly physisorption (Delta H of 7.20 kJ/mole). Using Langmuir adsorption isotherms, the MB adsorption capacity of CCs-AC, which primarily has a microporous structure, was 0.88 mmol/g, while the Cd2+ adsorption capacity was 1.28 mmol/g.
- MakaleAçık Erişim2022Geochemical investigation of the potability of surface water in Çit River and related creeks in Avliyana Basin (Gümüşhane, NE Türkiye)
Saka, Fatih; Soylak, Mustafa; Bulut, Volkan Numan; Vural, Alaaddin; Gundogdu, Ali
In the study, physico-chemical parameters of Çit Stream and related creeks in Avliyana Basin (Gümüşhane, NE Turkey) were determined. In terms of physical parameters, it is seen that the Büyük Çit Stream has drinking water quality. According to piper diagram, all of the samples except one have fallen into region of class of CaCO3 and MgCO3 waters. The different one is the mixed water class. It has been determined that the metal content that may pose a risk to water is below the permissible limits. It has been seen that there may be only one point of risk for lead. As a result, physico-chemical aspect of water quality of Çit River and related creeks in Avliyana Basin has been seen to be suitable for drinking water standards.
- MakaleAçık Erişim2020İçme suyu arıtma tesisi atık çamuru üzerinemetilen mavisi adsorpsiyonu ve yapay sinir ağlarıile modellenmesi
Öztürk, Nurcan; Senturk, Hasan Basri; Gundogdu, Ali; Duran, Celal
Bu çalışmada içme suyu arıtma tesislerinde arıtım aşamaları sonucu oluşan İçme Suyu Arıtma Tesisi Atık Çamurunun (İSATAÇ), atık sularda organik kökenli bir kirletici (boyar madde) olan Metilen Mavisinin uzaklaştırılmasında adsorban olarak kullanılabilirliği araştırılmıştır. Adsorpsiyon çalışmalarında kullanılan İSATAÇ fiziksel ya da kimyasal ön işleme tabi tutulmamıştır. Öncelikle İSATAÇ’ın nem, yoğunluk, uçucu madde, sabit karbon, kül tayini yanı sıra elementel, SEM, FT-IR, XRD, XRF ve TGA/DTA analiz gibi çeşitli analitik işlemlerle karakterize edilmiştir. Sonrasında adsorpsiyon deneyleri kesikli sistemle gerçekleştirilmiş ve İSATAÇ’ın sulu çözeltiden bu kirletici türü uzaklaştırma potansiyeli denge, kinetik ve termodinamik parametreler açısından incelenmiştir. Metilen mavisinin uzaklaştırılmasında Langmuir izoterm modelinden elde edilen maksimum adsorplama kapasitesi 62,50 mg g-1 olarak tespit edilmiştir. Bazı deneysel parametrelerin İSATAÇ üzerinde Metilen Mavisi adsorpsiyonuna etkileri göz önüne alınarak Yapay Sinir Ağı (YSA) modeli geliştirilmiş ve İSATAÇ’ın atık sulardan organik kirleticilerin uzaklaştırılmasında kullanılabileceği sonucuna varılmıştır.
- MakaleAçık Erişim2020Adsorption Of Methylene Blue from Aqueous Solution with Sulfuric Acid Activated Corn Cobs: Equilibrium, Kinetics, and Thermodynamics Assessment
Baltaci, Cemalettin; Gundogdu, Ali; Duran, Celal; Bozbeyoglu, Pinar
Three adsorbents with different characteristics were produced in this study by activation of sulfuric acid with different concentrations, from corn (Zea mays L.) cobs, which is an agricultural waste by-product resulting from harvesting. After characterization by the parameters such as Boehm titration, determination of pH-pHpzc, and methylene blue – iodine number, and IR analysis, their methylene blue adsorption potentials from aqueous medium were investigated based on equilibrium, kinetics, and thermodynamics evaluations. This study aims to examine the effects of relatively dilute and concentrated acids on the activation process and to gain an economic value to waste materials through the production of a new adsorbent. It was observed that the initial solution pH did not have a significant effect on the adsorption efficiency. The adsorption process reached the equilibrium at the end of the first 120 minutes, and the kinetic data fit the pseudo-second-order kinetic model. Langmuir adsorption capacity (295.5 mg/g) of the adsorbent produced by activating with 50% sulfuric acid was found higher than those produced with 75% and 98% acids. An increase in ambient temperature effected the adsorption positively. As a result, in this study, very low-cost adsorbents were produced from the waste by-product corn cobs, and a new approach was proposed for cleaning wastewater containing dyestuffs.
- MakaleYalnız künye2020Effect of antimonite mineralization area on heavy metal contents and geochemical fractions of agricultural soils in Gümüşhane Province, Turkey
Sungur, Ali; Vural, Alaaddin; Gundogdu, Ali; Soylak, Mustafa
In this study, the possible impacts of an antimonite mineralization area on agricultural lands with regard to heavy metal concentrations were examined. In this scope, surface soil samples (0–20 cm) were taken from a total of 27 locations including eleven from the Avliyana antimonite mineralization area (Torul, Gümüşhane-NW Turkey) and its surroundings, eleven from agricultural areas and five from the control area. Wet digestion method was used with aqua regia procedure for determining the total heavy metal (Cd, Cr, Cu, Ni, Pb, Zn) concentrations of the soil samples. The geochemical fractions of heavy metals in soil samples were determined by way of a sequential extraction procedure. The total heavy metal contents of the soils were determined as: Ni > Cr > Zn > Cu > Pb > Cd for control soils, Cr > Ni > Zn > Cu > Pb > Cd for agricultural soils and Zn > Cu > Ni > Cr > Pb > Cd for mining area soils. It was determined that especially the values of Zn (57.6 ± 6.2 μg/g) and Cu (52.4 ± 5.8 μg/g) were high at the mineralization area due to hydrothermal alterations that are effective in the formation of mineralization. It was put forth as a result of sequential extraction that the heavy metals examined excluding Pb were observed dominantly in the residual fraction for all data set. On the other hand, it was determined that the non-residual mobile fractions reached from 11% Cr to 78% Pb in control soils, from 20% Cd to 88% Pb in agricultural soils and from 24% Cd to 87% Pb in mineralization area soils. Contamination signals due to mineralization area were monitored by way of the metal content in mobile fractions. Even though the metal concentrations determined in short term are not alarming for agricultural production, signals were observed especially for Cd, Pb, Cu, Ni and Zn elements to be more mobile in mineralization area soils in the long term due to the impact of environmental factors thereby being carried over to and accumulating in agricultural soils. In conclusion, while it is expected that the metal inputs due to mineralization areas may increase in the future, it is suggested to include plant analyses in future studies for determining the impact of the amount of bioavailable metal.
- MakaleYalnız künye2017Environmental impact of Gümüşhane City, Turkey, waste area in terms of heavy metal pollution
Vural, Alaaddin; Gundogdu, Ali; Akpinar, Ibrahim; Baltaci, Cemalettin
The aim of this study is to investigate the occurrence of a heavy metal contamination in a solid waste site of Gümüşhane City, Turkey, to examine the dimensions of the risk of contamination, and to present suggestions for possible solutions. For this purpose, heavy metal contents of soil and leachate samples taken from a Gümüşhane waste site were determined by a new method, microwave plasma-atomic emission spectrometry (MP-AES). When the obtained results are compared with background and control values, it can be seen that the region carries contamination risks, especially in terms of heavy metals such as Zn, Cd, Pb, Cu, Ni, and Co. To examine the environmental effects of the landfill area in more detail, geodeposition index (Igeo), enrichment factor (EF), contamination index (PI), and combined contamination index (IPI) parameters are used. In addition, the samples taken from an area supposed to be free of pollution risk were also analyzed as control samples, and the obtained data were statistically compared with the results of the waste area. It is determined that the results of landfill waste site are dissimilar to those of comparison samples in terms of investigated metals, and that they contained higher values in general.
- MakaleYalnız künye2016A novel carrier element-free co-precipitation method for separation/preconcentration of lead and cadmium ions from environmental matrices
Bulut, Volkan Numan; Demirci, Hamit; Ozdes, Duygu; Gundogdu, Ali; Bekircan, Olcay; Soylak, Mustafa; Duran, Celal
A new separation and pre-concentration method was presented in this study for two trace heavy metal ions, lead (Pb2+) and cadmium (Cd2+) from aqueous solutions, based on a carrier element free co-precipitation (CEFC) method using a triazole derivate, 3-(4-tert-butylphenyl)−5-phenyl-4-(2-hydroxy-5-methoxybenzylamino)−4H-1,2,4-triazole as an organic co-precipitating agent. The method was optimized with some analytical parameters which affect the quantitative recoveries of study metals. According to the results, optimum pH of solution, quantity of co-precipitating agent, centrifugation and incubation time, and sample volume were determined as 6.0, 1.5 mg, 10 min, and 10 min, and 100 mL, respectively. In addition, no significant matrix interferences were observed over the recovery of the metal ions. For analytical figure of merit, RSD values of the method were found as 5.7 and 4.8 for Pb2+ and Cd2+, respectively. LOD values were also calculated as 2.0 µg L−1 for Pb2+ and 0.2 µg L−1 for Cd2+. The accuracy of method was checked with spiked/recovery tests and analysis of a standard reference material. The developed method was finally applied to the real liquid/solid samples under the optimum conditions.
- MakaleAçık Erişim2016Investigation of Hydroxymethylfurfural Formation in Herle
Baltacı, Cemalettin; Ilyasoglu, Huri; Gundogdu, Ali; Ucuncu, Osman
Mulberry pestil and köme are Turkish traditional foods made from herle. Browning leads to quality losses in the herle, and its products. In this study, the effect of thermal treatment on the hydroxymethylfurfural formation and color values in the herle was evaluated. The herle samples were kept at different temperatures (60–110°C) and times (2–6 h). The hydroxymethylfurfural formation was found to increase with increasing time and temperature. The legal limit for hydroxymethylfurfural in the pestil (50 mg/kg) was exceeded at temperatures above 90°C. The lightness (L* value) of the sample decreased with the thermal treatment, indicating browning.
- MakaleAçık Erişim2015Selective separation, preconcentration and determination of Pd(II) ions in environmental samples by coprecipitation with a 1,2,4-triazole derivative
Ozdes, Duygu; Duran, Celal; Serencam, Huseyin; Sahin, Deniz; Gundogdu, Ali; Soylak, Mustafa
A simple, sensitive, facile and low cost methodology, combined with flame atomic absorption spectrometry (FAAS), was employed to evaluate the selective separation and preconcentration of Pd(II) ions in environmental samples by using a triazole derivative as an organic coprecipitating agent without a carrier element. The developed method was systematically investigated in different set of experimental parameters that influence the quantitative recovery of Pd(II) ions. The accuracy of the method was tested by analyzing certified reference material and spike tests. The developed coprecipitation procedure has been applied to road dust, anodic slime, industrial electronic waste materials and water samples to determine their Pd(II) levels.
- MakaleYalnız künye2014Assessment of kinetics, thermodynamics and equilibrium parameters of Cr(VI) biosorption onto Pinus brutia Ten
Ozdes, Duygu; Gundogdu, Ali; Kemer, Baris; Duran, Celal; Kucuk, Murat; Soylak, Mustafa
The aim of the present study was to investigate the sorption potential of pine bark (Pinus brutia Ten.) for removal of Cr(VI) ions from aqueous solutions. The biosorption characteristics of Cr(VI) ions onto bark biomass were examined with respect to the changes in initial pH of the solution, contact time, initial Cr(VI) and bark concentration, bark particle size, temperature, etc. The biosorption isotherms were described by means of Langmuir and Freundlich models and the biosorption kinetics were analysed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The thermodynamic parameters proved that the process was feasible, spontaneous and endothermic in nature.
- MakaleYalnız künye2013Separation and pre-concentration of palladium(II) from environmental and industrial samples by formation of a derivative of 1,2,4-triazole complex on Amberlite XAD-2010 resin
Serencam, Huseyin; Bulut, Volkan Numan; Tufekci, Mehmet; Gundogdu, Ali; Duran, Celal; Hamza, Sibel; Soylak, Mustafa
A simple separation/pre-concentration method was developed for extraction of Pd(II) in various environmental samples, based on its adsorption of 4-phenyl-5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazole-3-yl)thio]methyl}-4H-1,2,4-triazole-3-thyol (PPTTMET) complex on Amberlite XAD-2010 resin in a mini column. The ligand has high affinity for Pd(II) among many other metals that are taken into consideration. The flame atomic absorption spectrometry is employed to determine the concentration of Pd(II). The optimum working conditions which were determined are as follows: 0.05 mol L-1 HNO3 as working medium, 1.0 mol L-1 HCI in acetone as elution solvent, 0.75 mg of PPTTMET amount and 750 mL of sample volume. The system was independent from the flow rates between 3.1 and 23.1 mL min-1. The Pd(II) adsorption capacity of Amberlite XAD-2010 resin was found to be 12.8 mg g-1 and the enrichment factor was calculated as 375. The method was successfully applied for the determination of Pd(II) in motorway dust samples, anodic sludge, gold ore, industrial electronic waste materials and various water samples.
- MakaleYalnız künye2013Heavy metal analysis by moss species in the Black Sea region of Turkey
Koz, Bahadir; Cevik, Ugur; Bulut, Volkan Numan; Kaya, Selim; Gundogdu, Ali; Celik, Necati
The heavy metal analysis of mosses in the Black Sea region of Turkey was determined using atomic absorption spectrometry method. The procedure was also validated by analysis of standard reference material (IAEA-336 Lichen). A qualitative analysis showed that the samples contained chromium, manganese, cobalt, nickel, copper, zinc, and lead. While the mean concentration values of Cr, Mn, Co, Ni, Cu, Zn, and Pb in the moss samples collected from city centers are 60.6, 820, 12.2, 18.8, 293, 181 and 39.8 mg.kg-1, the mean concentration values in the moss samples collected from the city intervals are 43.8, 761, 11.0, 15.6, 242, 170 and 38.4 mg.kg-1, respectively. Since this study was a heavy metal analysis along the highway, evaluation of these elements with their potential hazards for ecology and human was briefly discussed. A strong relationship was observed between Pb concentration and the traffic density.
- MakaleYalnız künye2013Physicochemical characteristics of a novel activated carbon produced from tea industry waste
Gundogdu, Ali; Duran, Celal; Senturk, H. Basri; Soylak, Mustafa; Imamoglu, Mustafa; Onal, Yunus
Tonnes of waste are generated during tea production in Turkey, one of the black tea producing countries in the world. These wastes are not used for any purposes throughout industrial sector. The objective of this study is to bring in economic value to waste materials by producing activated carbons from wastes of a tea plant and to characterize their physicochemical properties. Three types of activated carbons were produced by chemical activation using zinc chloride from tea industry wastes (TIW). Mesoporous structure and surface area rise as the ratio of ZnCl2/TIW increases. When the ratios of ZnCl2/TIW were selected as 1/2:1, 1:1, and 2:1, mesoporous activated carbons are found in the percentages of 10.9%, 39.9% and 77.7% with BET surface areas of 706, 1066 and 1141 m(2) g(-1), respectively. The resultant activated carbons were characterized by analyses of proximate-ultimate, FT-IR, SEM, TGA, methylene blue-iodine numbers, and surface functional groups. (C) 2013 Elsevier B.V. All rights reserved.
- MakaleAçık Erişim2012Dehydrated hazelnut husk carbon: A novel sorbent for removal of Ni(II) ions from aqueous solution
Sivrikaya, Sezen; Albayrak, Sinem; Imamoglu, Mustafa; Gundogdu, Ali; Duran, Celal; Yildiz, Hulya
The present study has been performed to examine the adsorption ability of novel sorbent dehydrated hazelnut husk carbon (DHHC) towards Ni(II) ions from aqueous solution using the batch adsorption technique. The effective factors such as initial pH of the aqueous solution, contact time, initial Ni(II) concentration, adsorbent dosage, and temperature were investigated. The studies were also conducted to understand the effect of some co-existing ions which may be present in aqueous solutions. DHHC showed good adsorption potential for Ni(II) ions. The optimum initial pH value was selected as 5.0. The experimental data fitted well to the Langmuir adsorption isotherm model. Among the kinetic models tested for the adsorption of Ni(II), the pseudo-second-order model showed a good fit of the kinetic data. The thermodynamic parameters including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes indicated that the adsorption of Ni(II) ions onto DHHC was feasible, spontaneous, and exothermic in the temperature range of 25-55°C. The results of this study showed the effectiveness and feasibility of DHHC for the removal of Ni(II) ions from aqueous solution.
- MakaleYalnız künye2012Adsorption of Phenol from Aqueous Solution on a Low-Cost Activated Carbon Produced from Tea Industry Waste: Equilibrium, Kinetic, and Thermodynamic Study
Gundogdu, Ali; Duran, Celal; Senturk, H. Basri; Soylak, Mustafa; Ozdes, Duygu; Serencam, Huseyin; Imamoglu, Mustafa
The ability of activated carbon which was produced by chemical activation using zinc chloride from tea industry wastes (TIWAC) to adsorb phenol molecules from aqueous solution was tested by equilibrium, kinetic, and thermodynamic parameters. Phenol adsorption on TIWAC took place with a high yield at pH values in the range 4 to 8. The optimum contact period was observed as 4.0 h and from the adsorption graphs plotted as a function of time; it was established that phenol adsorption on TIWAC conformed more to a pseudosecond-order kinetic model. Additionally, it was determined that the adsorption rate is controlled by intraparticle diffusion as well as film diffusion. It was established that phenol adsorption on TIWAC can be better defined by the Langmuir adsorption model and its adsorption capacity was 142.9 mg.g(-1) from the linear Langmuir equation. Temperature had an adverse effect on adsorption yield, and hence, the adsorption process was exothermic in our case. Moreover, increasing electrolyte concentration in the medium has a positive effect on adsorption yield. From the data obtained, it was concluded that the removal of phenol from aqueous solution by TIWAC produced from tea industry wastes with a very low cost took place with an extremely high performance.
- MakaleYalnız künye2011Preconcentration of Cd(II) and Cu(II) ions by coprecipitation without any carrier element in some food and water samples
Duran, Celal; Ozdes, Duygu; Sahin, Deniz; Bulut, Volkan Numan; Gundogdu, Ali; Soylak, Mustafa
A simple, rapid, sensitive and environmentally friendly separation and preconcentration procedure, based on the carrier element free coprecipitation (CEFC) of Cu(II) and Cd(II) ions by using an organic coprecipitant, 2-{[4-(4-fluorophenyl)-5-sulphanyl-4H-1,2,4-triazol-3-yl]methyl}-4-{[(4-fluorophenyl) methylene]amino}-5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (MEFMAT) was developed. The analyte ions were determined by flame atomic absorption spectrometric (FAAS) determinations. The optimum conditions for the coprecipitation process were investigated on several commonly tested experimental parameters such as pH of the solution, amount of MEFMAT, sample volume, standing time, centrifugation rate and time. The influences of some anions, cations and transition metals on the recoveries of analyte ions were also investigated, and no considerable interference was observed. The preconcentration factor was found to be 50. The detection limits for Cu(II) and Cd(II) ions based on the three times the standard deviation of the blanks (N:10) were found to be 1.49 and 0.45μgL-1, respectively. The relative standard deviations were found to be lower than 3.5% for both analyte ions. The method was validated by analyzing two certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and spike tests. The procedure was successfully applied to sea water and stream water as liquid samples and tobacco, hazelnut and black tea as solid samples.