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Dyes and heavy metals are typical pollutants causing environmental problems. In this study, the efficiency of GO and GO-EDTA used as adsorbents for Thioflavin T (TFT) and Co(II) metal ion removal from aqueous solution under optimum conditions was investigated. GO-EDTA was characterized by DR-UV/VIS, Raman spectra, FTIR and zero charge points (pHpzc) were determined using pH drift method. The maximum adsorption capacities (qM) of the adsorption process according to the Langmuir isotherm model, one of the isotherm models, refer to GO or GO-EDTA; It is 389.3178 mg g-1 and 1009.5300 mg g-1 for TFT dye, 736.9153 mg g-1 and 1304.3525 mg g-1 for Co(II) ion (pH=7, t= 150 min, 298 K). The kinetic data fit the pseudo-second order model quite well. In the desorption graph, TFT dye desorption was observed to be quite efficient, while the reason for the decrease in the desorption of Co(II) ion was considered to be the strong bond formed as a result of ion exchange at the -COONa end in the EDTA structure. It was supposed that p-p interactions with benzene rings in GO and GO-EDTA structure, hydrogen bonding with functional groups on the structure and electrostatic interactions as a result of ion exchange at the carboxylic acid ends were generally effective in the adsorption mechanism. In conclusion, it was shown that GO and GO-EDTA nanomaterials can be effectively used as advanced adsorbents instead of traditional adsorbents for the removal of organic and inorganic pollutants from aqueous solution. [ABSTRACT FROM AUTHOR]

In recent years, water pollution has become a major problem, especially due to the wastes discharged from different sectors without treatment. Among these, there are various paint wastes used by the textile, leather, paper and cosmetics sectors. Crystal violet (CV) is a widely known cationic dye and is often used as a colorant in industries. CV dye is known to be toxic to humans and animals at 1 ppb. For this reason, it is very important for environmental safety to treat industrial wastewater from crystal violet before discharge. This research aimed to evaluate the efficacy of two different montmorillonite-based nanoclays (B1 and B2) as a low-cost material for the removal of crystal violet dye from aqueous solutions. Structural characterizations of nanoclays were analyzed using FTIR and TGA methods. All parameters that could affect the CV adsorption process were optimized in a batch system. The effects of various factors (adsorbent dose, contact time, solution pH, co-existing ion effects, adsorption temperature, initial dye concentration) on the adsorption process were investigated. Experiments to investigate the mechanism of the CV-nanoclay adsorption system showed that the adsorption kinetics and equilibrium parameters fit better with the Pseudo second-order kinetic model and the Langmuir isotherm model, respectively. The maximum adsorption capacities (qm) of B1 and B2 adsorbents were obtained as 224.63 mg/g at 25°C and 360.30 mg/g at 45°C, respectively. A suitable combination of surface and CV ion charge was obtained at low pH values (=7) of the CV solution. The presence of co-existing NaCl ions did not significantly affect the CV adsorption capacity. When the results were evaluated, it was seen that the montmorillonite-based adsorbents were effective and cost-effective adsorbents for CV dye removal. [ABSTRACT FROM AUTHOR]

The toxicity of antibiotic residues in water resources adversely affects the environment. Recent studies have focused on the removal of organic pollutants such as antibiotics from aqueous solutions with cheap and environmentally compatible adsorbents. In this study, adsorption of oxytetracycline hydrochloride (OTCHCL) on the natural Manisa-Gördes clinoptilolite was investigated in the batch system at 298-323 K. Effects of pH, initial concentration, adsorbent dosage, contact time, stirring speed and temperature on adsorption were examined and optimum parameters were determined. Isotherm models including Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin were applied to analyze the adsorption data. Kinetic constants were determined by pseudo-first order (PFO), pseudo-second order (PSO), intraparticle diffusion and Elovich models. Adsorption of OTC-HCL on natural zeolite fitted well to the Freundlich and pseudo-second order models. The maximum adsorption capacity of natural zeolite was determined as 60.97 mg/g at 323 K. Thermodynamic studies indicated that the adsorption of OTC-HCL on natural zeolite was spontaneous and endothermic. Physicochemical characterization of natural zeolite was conducted by N2 adsorptiondesorption, XRD, FTIR, SEM-EDX analyses before and after adsorption. SBET, specific surface area of the natural zeolite decreased after adsorption process. Characterization results showed that OTC-HCL molecules were successfully adsorbed on the natural zeolite surface. [ABSTRACT FROM AUTHOR]

In this study, the removal of biochar (EAL) obtained from oleaster seeds (elaeagnus angustifolia L.) and crystal violet (CRV) dye, which is a cationic dye, widely used in the industry, was carried out with different parameters. Adsorption values and thermodynamic parameters accordance with the isotherms and kinetics were evaluated with the help of temperature, concentration change, amount of adsorbent, pH and time changes. Temperature, pH, time, amount of adsorbent and concentration parameters on EAL-KRV adsorption were investigated according to the shake/batch adsorption method. Obtained results indicated that the maximum adsorption capacity qmax of EAL-CRV was 10.537 mg/g. It was found that the process proceeds over the pseudo-second order, is endothermic, and conforms to the Langmuir adsorption isotherm. Obtained negative ΔG° values led to the conclusion that EAL is suitable for CRV removal. When EAL was evaluated together with similar adsorbents used for CRV removal in the literature, the maximum adsorption capacity value of EAL was found close to some studies. When all the results were evaluated, it was concluded that EAL can be used in the removal of CRV dye from aqueous solutions. [ABSTRACT FROM AUTHOR]

In this study, a new composite material (MNPHK) was developed with simultaneous hydrothermal carbonization (HTC) and magnetization method using pomegranate pulp (PP) wastes. The effects of carbonization temperature and time on the physicochemical properties of hydrochar such as atomic carbon content, energy density and higher heating value, were investigated. By determining the optimum production conditions, simultaneous HTC and magnetization of the PP were performed under these conditions. MNPHK produced under optimum conditions has been characterized by various spectral methods such as XRF, XPS, SEM/EDX, FTIR and VSM. To determine the pollution removal performance of the produced MNPHK from wastewater, it was used as an adsorbent material in the removal of lead (Pb(II)) ions in the batch system. The experimental data obtained by examining the pH, contact time (kinetic) and temperature (isotherm) factors affecting the adsorption process were evaluated in widely used kinetic (pseudo-first and second-order kinetic model) and isotherm (Langmuir and Freundlich isotherm model) models. It was found that the adsorption kinetics followed the pseudo-second-order kinetic model (PSO) (R²: 0.9840) and the experimental data showed good agreement with the Langmuir isotherm model (R²: 0.9992). The maximum adsorption capacity (qmax) of MNPHK was calculated as 98.45 mg/g according to the Langmuir isotherm model. Thermodynamic studies have shown endothermic and spontaneous adsorption of Pb(II) ions on MNPHK. With the findings obtained as a result of the study, it has been revealed that MNPHK can be used as a low-cost, effective and natural material for the removal of Pb(II) ions from wastewater. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of crystal violet dye from aqueous solution onto montmorillonite was studied and the equilibrium isotherms were determined. Two-parameter equations; the Langmuir, Freundlich, and Temkin isotherms, and three-parameter equations; the Sips, Toth, and Khan isotherms were examined for their ability to model the equilibrium adsorption data. Five error analysis methods were used to determine the optimal isotherm: the sum of the errors squared, a hybrid error function, the average relative error, Marquardt's percent standard deviation, and the sum of absolute errors. The Sips isotherm achieved the best-fit quality with the experimental data and the maximum adsorption capacity was found to be 152.229 mg/g. The sum of the normalized errors showed that the hybrid fractional error function obtained the best overall results. [ABSTRACT FROM AUTHOR]

This study demonstrates the applicability of microscale zero-valent iron (mZVI) in the removal of C.I. Vat Green 1 dye from water by adsorption. mZVI particles were characterized by SEM, EDX, BET surface area analysis and pHzpc. The changes in the surface properties of the mZVI particles used in the analysis were determined by SEM and EDX. Spherical particles smaller than about 5 µm with a surface area of 5.2 m²/g BET supported the high removal efficiency. Changes in particle size and shape and elemental composition after the analysis confirmed the high adsorption efficiency, and the pHzpc value of 5.73 led to high removal efficiency at low pH. In order to evaluate the removal efficiency, adsorption kinetics and isotherms of C.I. Vat Green 1, parameters such as solution pH, iron dosage, reaction temperature and pollutant concentration were investigated by batch series of experiments. While the removal efficiency decreased at pH values greater than 3, mZVI dosages greater than 1 g/L and increased pollutant concentration, the efficiency increased at dosages up to 1 g/L and with temperature increase. It was determined that the optimum pH was 3 and the optimum mZVI dosage was 1 g/L. The results of TOC analysis also confirmed that the removal mechanism is adsorption. It was found that the kinetic data fit the pseudo second order model best. The adsorption equilibrium data were represented by the Langmuir model and the maximum adsorption capacity was found to be 36.50 mg/g. [ABSTRACT FROM AUTHOR]

The primary source of carbon dioxide (CO2) emissions, one of the most important causes of climate change, is fossil fuels used in energy production. Adsorption and especially the use of carbon-based adsorbents have proven to be very effective in reducing CO2 emissions after combustion. Different modifications of carbon nanotubes used for this purpose are used to increase the adsorption capacity. However, when deciding on the most suitable modification type, the adsorption capacity alone is not sufficient, besides many technical criteria, costs also become an issue. Therefore, in this study, four different modifications of multi-walled carbon nanotubes such as polyethyleneimine (PEI), tetraethylenepentamine (TEPA), 3-aminopropyltrieoxylane (APTS), and purine-enhanced PEI were discussed and multi-criteria decision making (MCDM) techniques were used to determine the most appropriate modification type. Considered criteria (pretreatment cost, modification material cost, energy requirement, adsorption capacity, total cycle, decrease in adsorption capacity, desorption temperature, and desorption time) were weighted with SMART (Simple Multi-Attribute Rating Technique) and CRITIC (Criteria Importance Through Intercriteria Correlation) methods. The modification alternatives were compared with the weighting results obtained from both methods using the COPRAS (Complex Proportional Assessment) method. As a result of the study, it was determined that the most suitable option among four different carbon nanotube modifications was PEI supplemented with purine. [ABSTRACT FROM AUTHOR]

In the study, the removal performance of arsenic and antimony by drinking water treatment sludge (DWTS) was investigated. DWTS-200 was produced by thermal modification of the DWTS at three different temperatures (200, 400 and 600℃). The maximum arsenic removal was obtained at 200℃ and 1 hour contact time. The surface area and pore volume of adsorbent were analyzed by BET method; phase compositions were determined by X-ray diffraction (XRD), surface morphologies and elemental analyses were performed by scanning electron microscope (SEM) and energy disperse X-ray spectroscopy (EDS). The results showed that adsorbent had a relatively high surface area (170 m2 g-1) and was predominantly amorphous. The predominant phases were iron, calcite, oxygen, and quartz. The breakthrough volumes were obtained as 6,000 L (133,000 BV) and 640 L (14,000 BV) for 40 μg As L-1 and 80 μg Sb L-1 inlet concentrations. In order to determine the kinetic parameters and predict the breakthrough curves for column design, Thomas and Yoon-nelson models were applied. The column experimental data were fitted well to each model. The maximum adsorption capacity was calculated by Thomas model as 6.53 mg Asg-1, 5.21 mg Sbg-1. Regeneration studies were also shown that DWTS-200 could be reused after regeneration. [ABSTRACT FROM AUTHOR]

Activated carbons are widely used especially in the removal of harmful contents of gases and liquids. Activated carbons constitute one of the important import items for our country. It is foreseen that the production of activated carbons from cheap, easily available and abundant raw materials of various organic origins will make significant contributions to the country's economy. In this study, it is aimed to evaluate semi-bituminous coals (Gediz-Kütahya) containing high sulfur as an alternative area of use in the production of activated carbon. In the study where ZnCl2 was used as the activation chemical, the effects of different working parameters (chemical/coal ratio, impregnation time and grain size) on activated carbon production were investigated. Various properties such as BET surface area, pore distribution, SEM surface properties, adsorption capability etc. of the obtained activated carbon were determined. Comparisons of the obtained activated carbon with the imported activated carbons still used commercially were made, and it was determined that there were significant similarities in properties. Optimum production operating parameters, 1/1 ZnCl2/coal mixture ratio, 24 hours impregnation time and +2 mm particle size coal is treated at 650 oC for 60 minutes under N2 atmosphere, with 733 m2/g BET surface area, micro and meso porosity activated carbon with a total pore volume of 0.460 cm3/g was obtained. As a result of the adsorption tests of the obtained activated carbon, it was determined that 99.2% of the Cu2+ ions in the solution could be removed. It has been understood that the obtained activated carbon can be used in many sectors. [ABSTRACT FROM AUTHOR]

In this study, hydroxyapatites (FSHAp and ESHAp) from natural waste materials (fish bones and egg shells) were successfully synthesized and their physicochemical properties were characterized. Cu(II) ion adsorption potentials of FSHAp and ESHAp particles under different experimental conditions (pH, different adsorbent and Cu(II) concentration, contact time and temperature) were optimized by using the Response Surface Methodology (RSM), and their Cu(II) adsorption capacities were compared. The surface morphology, crystal structure, elemental contents, surface area and pore ratios of produced hydroxyapatitebased adsorbents were determined by using FTIR, SEM-EDX, XRD characterization techniques. Isotherm and kinetic models were calculated to determine their adsorption mechanism, and the results showed that the Cu(II) adsorption process of FSHAp and ESHAp particles was more suitable for the Tempkin and Scarthard isotherm models and the pseudo-second order kinetic model. The optimum adsorption capacity for Cu(II) removal for FSHAp and ESHAp particles were obtained as 19.4 mg/g and 10.6 mg/g, respectively (pH 5.5, 90 mg Cu(II)/L, 2g/L adsorbent concentration, 25℃ and 25 min). Desorption and regeneration studies have shown that adsorbents can be used effectively for up to three consecutive cycles. The results of this study revealed that FSHAp and ESHAp particles can be used as alternative, environmentally friendly, low-cost adsorbents for Cu(II) removal from aqueous environments and environmental improvements in the perspective of zero waste approach. [ABSTRACT FROM AUTHOR]

In this study, the removal of crystal violet dyes from aqueous solutions using chestnut shell was investigated. For this purpose, the effects of parameters such as initial dye concentration, adsorbent dosage, contact time, pH and temperature on adsorption performance were investigated. According to the results obtained, the removal efficiency increased with increasing temperature and adsorbent dosage. It was observed that the removal efficiency decreased when the initial dye concentration increased. In the isotherm studies using equilibrium adsorption data, the best results were obtained in the Langmuir isotherm and the maximum dye adsorption capacity under optimized conditions was calculated as 48.78 mg/g. Kinetic studies were carried out using pseudo-first and pseudo-second-order kinetic models and it was determined that the pseudo-second-order kinetic model was the most appropriate (R²>0.99). Thermodynamic parameters (ΔGo, ΔHo, ΔSo ) showed that the adsorption process was feasible, spontaneous and endothermic. In addition, FTIR analyzes were performed before and after adsorption. These results showed that chestnut shell can be used as an alternative and lowcost material for the removal of crystal violet from aqueous solutions. [ABSTRACT FROM AUTHOR]

In this study, the adsorption performance of activated carbon (AC) produced from the white cap mushroom (Agaricus bisporus) in methylene violet 2B (MV 2B) removal was investigated in order to reveal its potential in wastewater treatment. The activation process was carried out in a nitrogen atmosphere in a tubular furnace using the chemical activation method in the presence of potassium hydroxide (KOH). The parameters of pH, temperature, initial MV 2B solution concentration and amount of adsorbent, which significantly affect the adsorption process, were investigated. Thermodynamic, isotherm and kinetic analyzes were carried out using the data obtained from the experimental results. It is understood that obtained positive value of entalpy (ΔH0) (30.658 kJ mol-1) indicates that the process is endothermic and the numerical value of Gibbs free energy (ΔG0) indicates that a physical adsorption process has taken place. It was determined that the adsorption process was more suitable for Langmuir isotherm model (R² = 0.98989) according to isotherm analysis, and it was controlled by pseudo-second-order reaction according to kinetic analysis.The maximum adsorption capacity of the obtained AC was determined as 303.030 mg g-1 and the surface area was determined as 1741.690 m² g-1 by Brunauer--Emmett--Teller (BET) method. [ABSTRACT FROM AUTHOR]

Arsenic, which is widespread in receiving environments through natural and anthropogenic sources, is one of the most important problems encountered in ground and surface waters in terms of public health in recent years due to its toxic and carcinogenic properties. In this study, the adsorptive removal of arsenic was investigated by using low cost and environmentallybenign adsorbents obtained from natural and waste materials. For this purpose, pumice was chosen as natural material, red mud and steel slag were chosen as waste material. The influence of contact time and adsorbent dosage was investigated using batch tests. 50-95% arsenic removal was achieved with tested adsorbents. Modified Freundlich isotherm was found to provide the best fits to experimental data. Experimental studies have shown that steel slag is the most effective adsorbent in arsenic removal and has a maximum adsorption capacity of 3.058 mgAs g-1. The high arsenic adsorption capacity of the steel slag can be attributed to the high content of iron and calcium oxide. The present study results show that steel slag can be good alternative to commercial activated carbons for the adsorptive removal of arsenic. Moreover, the reuse of this waste material will also provide a doubleside environmental benefit in an inexpensive and effective way. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to remove Cu(II) and Pb(II) ions from solutions using pumice in batch system. Effect of adsorbent amount (0.1-0.5g), effect of concentration of Cu(II) and Pb(II) ion solutions (for Cu(II); 3.2-31.8 ppm, for Pb(II); 10.2-103.6 ppm), pH effect of solutions The effects of variable parameters such as 3-6.1(natural pH) for Cu(II), 3-5.25(natural pH) for Pb(II) were investigated. While 91% copper removal efficiency was obtained under optimum conditions where adsorbent amount was 0.4 g, solution ion concentration was 6.4 ppm and pH value was 6.1, 97.7% lead removal efficiency was obtained under optimum conditions where adsorbent amount was 0.4 g, solution ion concentration was 20.7 ppm and pH value was 5.2. The experimentally found adsorption data were modeled by applying Langmuir, Freundlich, Temkin and Harkins-Jura isotherm models, and the isotherm constants were calculated. In the adsorption of copper and lead ions, the Freundlich isotherm model was determined as the most suitable model for the experimental data. The maximum adsorption capacity of pumice was found to be 2.55 mg g-1 for copper and 10.28 mg g-1 for lead. It was determined that the adsorption kinetics were more compatible with the pseudo-second-order kinetic model. Standard free energy change (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) values were determined at different temperatures.. The results obtained in the study showed that pumice can be an effective, economical and alternative adsorbent material in the removal of heavy metals from aqueous solutions when compared with other adsorbents. [ABSTRACT FROM AUTHOR]

In the present study, the utilization of natural elm (Ulmus glabra) (UGT) and mulberry sawdust (Morus alba) (MAT) as low cost and effective adsorbents in the removal of Rhodamine 6G (R6G), a cationic dye that has a toxic effect on living metabolism, from water and wastewater has been investigated. UGT and MAT, which were used for the first time in the literature as adsorbent in the removal of R6G, have been characterized by various methods. Adsorption experiments have been carried out by batch system and the effects of experimental parameters such as initial aqueous solution pH, equilibrium time, and initial R6G concentration on the adsorption efficiency of R6G have been evaluated. It was observed that the optimum aqueous solution pH was 7.0 and the equilibrium time was 180 minutes for the adsorption of R6G on both adsorbents. Several kinetics (pseudo first and second order kinetic models and intraparticle diffusion model) and isotherm models (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich) have been applied to the experimental data obtained in order to elucidate the adsorption mechanism. It was found that the adsorption kinetics followed the pseudo second order kinetic model and the experimental data showed good agreement with both Langmuir and Freundlich isotherm models. The maximum adsorption capacity of UGT and MAT has been calculated as 50.5 and 31.8 mg g-1, respectively, using the Langmuir isotherm model. As a result of the study, it has been seen that elm and mulberry sawdust can be an effective and low cost alternative to be used in dyestuff removal. [ABSTRACT FROM AUTHOR]

Cu (II) ions, which cause serious diseases such as cancer and liver damage, have an important place, especially in water pollution. To effectively remove these deadly copper (II) ions from aqueous solution, the synthesis of a new functionalized sporopollenin microcapsules (Sp-CPTS-HNMAA) to be used as an adsorbent was aimed. Schiff base (HNMAA), used to functionalize the surface of sporopollenin, was obtained as a result of the reaction of 2-Hydroxy-1-naphthaldehyde and glycine and was characterized by ¹H and 13C NMR. The synthesized Sp-CPTS-HNMAA microcapsule adsorbent was successfully characterized by FTIR, XRD, and SEM techniques. The effects of initial Cu (II) concentration, temperature, pH, anion, contact time, and adsorbent dose were researched in adsorption experiments. The adsorption equilibrium was calculated as 92.73%, with a contact time of 150 min, initial Cu (II) ion concentration of 30 mg L-1, pH = 6, and maximum Cu(II) removal with 0.03 g adsorbent dose. The maximum Cu (II) adsorption capacity of Sp-CPTSHNMAA microcapsule adsorbent was calculated from the Langmuir isotherm and found to be 32.57 mg g-1. Adsorption isotherm and kinetic studies indicated that it fits the Langmuir adsorption isotherm and pseudo-second-order kinetic model. The results of thermodynamic studies show that the adsorption reaction is reversible, spontaneous, and endothermic, and also showed that the adsorption of Cu (II) ions on Sp-CPTS-HNMAA is a chemical adsorption process. [ABSTRACT FROM AUTHOR]

Pollution caused by synthetic dyes in wastewater has become an important problem. Especially the removal of MB used in dyeing cellulosic materials from waste water is an important issue. In this study, PANI/WS composites were presented as inexpensive and useful adsorbent materials. The composites were prepared at various mixing ratios. Chemical structures of the adsorbents were investigated by FTIR and surface morphologies were studied by SEM. The efficacies of pH, adsorbent amount, inceptive dyestuff concentration, time and temperature on MM adsorption capability of composites were examined. Kinetic and isotherm studies were executed at various temperatures. The adsorption behaviour was studied with the help of three main isotherm models. It was seen that the obtained data of isotherms matched more with the Langmuir and Temkin isotherms, respectively. The adsorption capacity of composite adsorbent was experimentally found to be 105 mg/g. The highest adsorption efficiency value was found to be 98.93%. The reaction kinetics were confirmed to match with the pseudo second order kinetic model. [ABSTRACT FROM AUTHOR]

Zonguldak is a major center of coal mines situated on the western BlackSea coast which has largest reserves of hard coal of Turkey, possesing many coal mines in the territory. In this study the investigation of acetone adsorption characteristics of activated carbons at room temperature obtained from Zonguldak-Karadon coal by physical and chemical methods is aimed. The effects of the adsorbent preparation technique, type of activation agent (KOH, NaOH, ZnCl2 ve H3PO4) and activation temperature (400-800?) on acetone adsorption were investigated. Acetone adsorption equilibrium data were compared with different adsorption isotherm models such as, the Brunauer-Emmett-Teller, Langmuir, Freundlich, Harkins-Jura, Dubinin-Radushkevich, Dubinin-Astakhov, Henderson, Halsey and Smith, in order to investigate the acetone adsorption mechanism on various activated carbons obtained from Karadon coal, and the model parameters were determined. The Langmuir model adsorption constant Wm that gives the maximum adsorption capacity was found with the values in the range 0,12-0,63 g/g. Adsorpsiyon characteristic energies E0 evaluated from the Dubinin-Radushkevich model were found in the range 2,87-29,80 kJ/mol. The activated carbons obtained by chemical treatment were found to have higher acetone adsorption capacities than the physically activated ones, and that the adsorption capacity increased proportionally with the total pore volume. The activated carbons obtained by KOH activation of Zonguldak-Karadon coal at 700 ve 800? were found to have the highest acetone adsorption capacities as 45% and 45,99%, respectively. The results of the study have shown that the activated carbons obtained by chemical activation were highly efficient for acetone adsorption and have high commercial potential for use in the removal of acetone vapors. [ABSTRACT FROM AUTHOR]

The objective of this research concerns the adsorption characteristic of the cationic azo dye namely Basic Blue 41(BB41) from aqueous solution was investigated on raw Kütahya Ca- Bentonite. In batch configuration, the effects of experimental parameters, such as contact time (0-300 min.), pH (3-8), Ca-Bentonite dose (0.01-0.1 g) and initial dye concentration (40-100 mg L-1) on the removal efficiency were studied. Optimum conditions from experimentally data, to be concentration of 40 mg L-1, pH: 4.0, contact time: 90 min. and amount of adsorbent to be 0.02 g were obtained. Two parameter (Freundlich, Langmuir and Dubinin-Radushkevich) adsorption isotherm models were applied on obtained experimental result and the model constant were calculated. The best equilibrium model was chosen based on the linear square regression correlation coefficient, R2. The experimental data for the adsorption equilibrium of BB41 has been interpreted with the linearized Langmuir model (R²~1) compared to Freundlich one (R²=0.9333). Maximum adsorption capacity of bentonite was obtained 119.4 mg g-1. [ABSTRACT FROM AUTHOR]

In this study, kaolin supported nano-sized zero-valent iron (K-nZVI) particles were synthesized by borohydride reduction method in presence of kaolin and used for removal of Remazol Brilliant Blue R (RBBR) from aqueous solution. The effects of solution initial pH, K-nZVI dosage, contact time and initial dye concentration for removal of RBBR were evaluated. The removal efficiency was determined to be pH dependent and the maximum removal efficiency of RBBR was obtained at pH 3. RBBR removal efficiency increased with increasing K-nZVI dosage in the dosage range of 0.3 and 1.0 g L-1. The equilibrium was reached at the contact time of 60 minutes. The removal efficiency decreased with the increase of the initial dye concentration. In this study, the suitability of experimental data to Langmuir and Freundlich isotherm models was also investigated and the parameters of these models were calculated. It was found that RBBR adsorption by K-nZVI was suitable for both Langmuir and Freundlich isotherm. The maximum adsorption capacity was determined as 200 mg g-1. [ABSTRACT FROM AUTHOR]

In this study, hydroxyapatite material was prepared for the removal of Remazol N.Blue RGB (RB203) from waters. In the synthesis of hydroxyapatite material, waste hen's eggshell was evaluated as calcium source. Synthesis of hydroxyapatites was performed at three different pH values (pH 9, 10 and 11) using precipitation method. Before and after calcination of eggshells, XRF, XRD and SEM analysis were carried out. Synthesized hydroxyapatites were characterized by TGA-DTA, XRD and FTIR analysis. At the end of the characterization studies, hydroxyapatite structure was obtained better in pH 10 medium, and adsorption studies were carried out with the material prepared at this pH value. The effects of pH (2-12), amount of sorbent (2-10 g/L) and concentration of dye (25-200 mg/L) on adsorption of RB203 using hydroxyapatite were examined. In order to determine the mechanism of adsorption, the Langmuir, Freundlich, Temkin and Henry isoterm equations were used. Comparing the adsorption isotherms in terms of correlation coefficients (R2), it was seen that the Langmuir, Freundlich and Temkin isotherm models were in good agreement with the experimental data. The highest adsorption capacity obtained with the Langmuir isotherm model was 27.93 mg/g. In order to examine the adsorption kinetics, the pseudo-first and the second order kinetic equations were used. The results of adsorption kinetics show that the adsorption of RB203 with hydroxyapatite was better expressed by the pseudo-second order kinetic equation. This study shows that the hydroxyapatite synthesized from waste calcined eggshell is a promising sorbent for adsorption of dye. [ABSTRACT FROM AUTHOR]

This study investigated removal efficiency of nickel in adsorption system by using the process waste obtained from the exit point of ore processing, modified with ultrasound and acid in laboratory. The experimental study was conducted in an intermittent process by taking into account the criteria of different adsorbent dosages (0,1-5 g/100 mL), pH (2-10), contact times (0-150 minutes) and mixing speeds (100-400 rpm). During experimental optimization, 100 mg/L initial nickel solution concentration, pH original (5.8), adsorbent dose 8 g/L, contact time 40 minutes, mixing speed 200 rpm, temperature 298 Kelvin (250C) was determined. Chemical properties and SEM images pertaining to modified process waste (MPA) were specified. In nickel removal, it was observed that the obtained results were found more concordant with Langmuir Isotherm models as evidenced by correlation coefficients. Kinetics data were obtained from treatment results, and qmax value obtained for MPA was found as 25.77 mg/g. [ABSTRACT FROM AUTHOR]

In this work, rice husk and burned rice husk were used as low cost adsorbents to remove a cationic dye, Basic Yellow 51(BY51), from aqueous solution by adsorption. Characterization of rice husk and burned rice husk was carried out with Scanning Electron Microscope and Fourier Transform Infrared Spectroscopy. The effects of operational parameters on the efficiency of dye removal including initial dye concentration, contact time, pH, and temperature were investigated. All series experiments were carried out in batch mode. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models and monolayer adsorption capacity was calculated. Kinetic data were studied using pseudo first order and pseudo second order kinetic models and dye removal was found to follow the pseudo second order kinetic model closely. Thermodynamic parameters such as enthalpy change (H°), entropy change (S°) and free energy change (G°) were also investigated. Free energy change showed that adsorption of Basic Yellow 51 was spontaneous at all studied temperatures for rice husk and burned rice husk. It is proposed that rice husk and burned rice husk may be suitable as adsorbents for removal of cationic dyes from aqueous solution. [ABSTRACT FROM AUTHOR]

In this study, it is aimed to investigate the equilibrium and kinetic data of the malachite green adsorption onto the peanut shell. XRD, SEM and FTIR analyzes were carried out by determining the surface properties of peanuts. The effects of initial malachite green concentration, adsorbent amount and temperature were evaluatedon the adsorption yield. The best fitting isotherm model was the Langmuir and kinetics model was pseudo-second order for malachite green adsorption onto peanut shell. Adsorption experiments showed that the maximum malachite green adsorption capacity of agricultural waste is 41.49 mg.g-1. [ABSTRACT FROM AUTHOR]

The removal of Ni(II) and Cr(VI) ions from aqueous solutions using chemically modified apricot kernel shells (P. armeniaca L.) was investigated in this research. Chemical modification methods effects on the adsorption capacity improvement for removal of heavy metals have been investigated. Structures of apricot kernel shells materials before and after modifications was examined by the FTIR and SEM analyses. HCl, NaOH and Fenton reactives were used for the modification processes. The investigation of kinetic, isotherm and thermodynamic parameters were also studied for HCl, NaOH and Fenton modified apricot kernel shells The rejeneration processes were studied for the determination of apricot kernel shells' reusability after the adsorption processes. Additional costs for applied modification processes were calculated and they were compared with the classical methods. The chemical oxygen demand (COD) residues in treated water by raw apricot kernel shells materials decreased from 910-1430 mg/L to 10-90 mg/L with the modification processes. The removal efficiencies changed with heavy metal concentration in water sample and increased up to 92% for apricot kernel shells materials. The adsorption capacities were found between 1 mg/g and 90 mg/g according to type of adsorbent and modification methods. As a result, it was revealed that adsorption capacities and costs of apricot kernel shells were compatible with conventional adsorbents. [ABSTRACT FROM AUTHOR]

By development of industrial activities, there has been an increase of heavy metal pollution in surface waters. During biological purify cation processes, the heavy metals have high toxic effects, especially on the microorganisms. Apparently, the heavy metals accumulating within plants watered using agriculture waters, and within the aquatic living things cause an accumulation in human beings. Because of this reason, the treatment of heavy metals from wastewaters that will be used in biological treatment as well as the purifications of water releasing to the environment gains importance. In this study, the removal of cadmium pollution using packed adsorption columns has been investigated. Oak valonia and horse chestnut have been used as adsorbents. At the result of the study, adsorption capacities of oak valonia and horse chestnut were determined as 26.32 and 14.59 mg cadmium /g adsorbent respectively. Also, there is maximum adsorption capacity in pedincula of oak valonia and this value is 40.24 mg cadmium/g adsorbent. [ABSTRACT FROM AUTHOR]