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- MakaleYalnız künye2026Scopus SJRQ2Adsorption of Reactive Red 120 dye from aqueous solutions using sepiolite clay with a channel-structured morphology: Mechanism, kinetics, isotherm, and thermodynamic studies
Fırat, Tülay
The effective treatment of dye-containing wastewater remains a major environmental challenge due to the high stability and solubility of reactive dyes. In this study, the adsorption behavior of Reactive Red 120 (RR120), an anionic reactive azo dye, from aqueous solutions was investigated using natural sepiolite clay possessing a channel-structured morphology. Batch adsorption experiments were performed to evaluate the effects of contact time (1–200 min), initial dye concentration (50–500 mg L−1), adsorbent dosage (0.1–1.5 g), solution pH (2–10), and temperature (25–50°C). The adsorption equilibrium was reached within approximately 75 min. The Langmuir isotherm provided the best fit to the equilibrium data, yielding a maximum monolayer adsorption capacity of 168.4 mg g−1 at 298 K. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic, with an activation energy of 32.41 kJ mol−1. Adsorption kinetics were analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, while equilibrium data were evaluated using Langmuir, Freundlich, and Temkin isotherm models. The kinetic data were best described by the pseudo-second-order model, while thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic. FTIR and XRD analyses further supported the important role of the channel-structured framework of sepiolite in RR120 adsorption. Unlike many clay-based adsorbents that require chemical modification, natural sepiolite exhibited high adsorption performance due to its intrinsic fibrous morphology, nano-channel structure, and high surface area. These findings demonstrate that natural sepiolite is a promising, low-cost, and sustainable adsorbent for the treatment of dye-contaminated wastewater.
- MakaleAçık Erişim2021Scopus SJRQ3Optimization of the adsorption of methyl green dye on almond shells using central composite design
Tanaydin, Mehmet Kayra; Goksu, Ali
Almond shells, known as the agricultural industry’s waste, were utilized to adsorb methyl green dye from aqueous solutions. The effects of initial concentration (2–10 mg/L), the adsorbent dosage (0.1–0.5 g), shaking speed (150–250 rpm), pH (4–7), temperature (20°C–50°C), and particle size (137–892 μm) on methyl green adsorption on the almond shell were examined. The response surface methodology was used to optimize the methyl green dye’s adsorption process using the almond shell. The central composite design was utilized to obtain optimum experimental conditions. Performed experiments obtained the isotherm data, and it was analyzed by utilizing the Langmuir, Freundlich, and Temkin isotherm models. The isotherm data can be fitted well by the Langmuir model. The pseudo-second-order model can anticipate the adsorption kinetics. The thermodynamic parameters such as ΔG° ΔH°, and ΔS° were calculated and found to be –2.878, 42.12 kJ/mol, and 0.151 kJ/mol K, respectively. These values demonstrated that the present adsorption process was feasible, spontaneous, and endothermic in the temperature scope of (20°C–50°C). This study indicates that almond shells were considered an efficient adsorbent to remove from the aqueous solutions. The maximum adsorption capacity of the almond shell (1.1 mg/g) was obtained. In this system, the almond shell’s pre-activation process was not preferred because it will create an extra cost. Adsorption kinetics studies showed that the model is represented as a pseudo-second-order of adsorption data.
AtıfScopus19WoS19OpenAlex19
İncele - MakaleYalnız künye2018Scopus SJRQ1F(T, R) theory of gravity
Salti, Mustafa; Korunur, Murat; Acikgoz, Irfan; Pirinccioglu, Nurettin; Binbay, Figen
We mainly focus on the idea that the dynamics of the whole universe may be understood by making use of torsion T and curvature R at the same time. The f(T,R)-gravity can be considered as a fundamental gravitational theory describing the evolution of the universe. The model can produce the unification of the general relativity (GR), teleparallel gravity (TPG), f(R)-gravity and f(T)-gravity theories. For this purpose, the corresponding Lagrangian density is written in terms of an arbitrary function of the torsion and curvature scalars. Furthermore, we use the absence/existence puzzle of relativistic neutron stars and thermodynamical laws as constraining tools for the new proposal.
AtıfScopus15WoS16OpenAlex17İncele - MakaleAçık Erişim2017Scopus SJRQ2Exploring thermodynamics and kinetic parameters of immobilized catalase enzyme via adsorption on krill clay
Nas, Mehmet Salih; Gür, Aycan; Gür, Tugba; Yönten, Vahap
The thermodynamic parameters and immobilization kinetics of catalase enzyme via adsorption onto krill clay were performed in aqueous solution in batch system. The adsorbent was characterized by X-ray fluorescence, scanning electron microscope and Brunauer-Emmett-Teller N-2 adsorption measurements. The effect of some parameters to the adsorption process such as contact time, stirring speed, initial enzyme concentration, initial ionic strength, temperature and pH were analyzed. Maximum adsorption capacity (q(m)) showed a great dependence on pH and initial enzyme concentration. It was found at pH 5.5, and initial enzyme concentration, 0.0075 g L-1 values. Pseudo-first-order, pseudo-second-order and intraparticle diffusion were used to fit the kinetics data on kinetic models. Furthermore, thermodynamic activation parameters such as enthalpy, entropy, Gibbs free energy and activation energy (Delta H degrees, Delta S degrees, Delta G degrees and E-a) which reveal that catalase enzyme adsorption occur spontaneously and in endothermic nature were determined. The obtained results confirmed that the applicability of krill clay is an efficient immobilizing supporter for catalase enzyme and krill clay material can be used as a very effective adsorbent in immobilization of this enzyme from aqueous solutions.
AtıfWoS9OpenAlex13İncele - MakaleYalnız künye2017Scopus SJRQ4Second law of gravitational thermodynamics in the locally rotationally symmetric Bianchi type-II universe
Korunur, Murat
In this work, under the assumption that the universe is locally rotationally symmetric (LRS) Bianchi type-II and filled with anisotropic dark uid (dark energy and dark radiation), we investigate whether the generalized second law of thermodynamics (GSLT) is still valid. We also consider another important condition for LRS Bianchi type-II spacetimes whereby the model expansion is proportional to the shear, which leads to B = An (where n is a constant and A and B are the metric potentials). Based on this, we derive a general circumstance for the GSLT and find that its validity depends on the anisotropies of both the dark uid and the metric potentials. We conclude that the GSLT still holds at all times even if these two anisotropic conditions are removed from the results.
AtıfScopus3WoS3OpenAlex3İncele - MakaleAçık Erişim2017Scopus SJRQ2Adsorption of hazardous crystal violet dye by almond shells and determination of optimum process conditions by taguchi method
Goksu, Ali; Tanaydin, Mehmet Kayra
Almond shells are classified as an agricultural waste of the food industry. In this study, almond shells were prepared as efficient adsorbents for removing Crystal Violet (CV) dye. The effects of adsorbent dosage, pH, initial concentration, shaking speed, temperature and particle size were studied. The Taguchi L25 experimental design method was used to obtain the optimum experimental condition. The data were analyzed using the signal to noise (S/N) ratio and analysis of variance (ANOVA) for removal of CV from aqueous solutions. The isotherm data were obtained from the experiments performed. The obtained isotherm data were analyzed via the Langmuir, Freundlich and Temkin isotherm models of which the Langmuir isotherm model fitted the best. Thermodynamic parameters such as ΔH°, ΔS° and ΔG° were calculated and the results were 18.5 kJ/mol, 0.057 kJ/mol K and –1.514 kJ/mol at 25°C, respectively. The results of this study indicate that almond shells are efficient adsorbents for removing Crystal Violet (CV) from aqueous solutions. The maximum adsorption capacity was found to be 1.075 mg/g on the almond shells. Adsorption kinetics studies showed that adsorption data can be modeled by a pseudo-second-order model. The optimum conditions for the adsorption on almond shells were found to be: adsorbent dosage = 0.5 g, concentration = 4 ppm, pH = 6, shaking speed = 200 rpm and shaking time = 180 min.
AtıfScopus27WoS23OpenAlex25İncele