Browsing by Author "Değermenci N."

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Adsorption of reactive dyes on lignocellulosic waste; characterization, equilibrium, kinetic and thermodynamic studies
(2019-07-10) Değermenci G.D.; Değermenci N.; Ayvaoğlu V.; Durmaz E.; Çakır D.; Akan E.
This study researched the use of the easily obtainable and economic agricultural waste of corn silk (CS) for removal of Reactive Blue 19 (RB19) and Reactive Red 218 (RR218) dyes with the adsorption process. Lignin, holocellulose, α-cellulose, thermogravimetric analysis (TGA), fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analyses were completed with the aim of determining the physical and chemical characteristics of the lignocellulosic adsorbent and ash content was determined. Additionally, the contact duration of adsorption, concentration of dye, temperature and pH parameters were investigated with equilibrium, kinetic and thermodynamic parameters determined to research the mechanism of adsorption. For both reactive dyes the removal efficiency is linked to the effective pH. With initial dye concentration of 200 mg/L, temperature of 25 °C, and adsorbent concentration of 0.25 g/50 mL fixed, maximum removal efficiency was 99% obtained at pH 2.0. The study calculated 6 different two-parameter isotherms and according to the best R2 value, the Temkin and Freundlich isotherm models were selected. The maximum capacity of CS for adsorption of RB19 and RR218 was 71.6 mg/g and 63.3 mg/g at adsorbent dose of 0.25 g/50 mL for initial dye concentration of 500 mg/L, pH 2.0 and 25 °C. According to the kinetic model results calculated with the aid of experimental data, a good adsorption process occurred. Thermodynamic parameters like enthalpy variation (ΔH0), entropy variation (ΔS0) and free Gibbs energy variation (ΔG0) were calculated with the aid of data obtained at different temperatures. As temperature increased dye adsorption was observed to increase confirming this event is endothermic.
Ammonia stripping using a continuous flow jet loop reactor: mass transfer of ammonia and effect on stripping performance of influent ammonia concentration, hydraulic retention time, temperature, and air flow rate
(2021-06-01) Değermenci N.; Yildiz E.
When wastewater containing ammonia is discharged into the receiving environment without any kind of treatment, it causes both environmental problems and negatively affects human health. In this study, the aim was to strip ammonia using air in a continuous flow jet loop reactor (JLR) and investigate the effects of ammonia concentration, hydraulic retention time (HRT), air flow rate, and temperature on ammonia removal within this scope. By changing the ammonia concentration in the influent, no significant change was observed in ammonia removal efficiency. With air flow rate 45 L min−1, temperature 50 °C, pH 11, and HRT 7.5 h, mean 88.1% ammonia removal was achieved. Increasing the HRT, air flow rate, and temperature increased the ammonia removal efficiency. Later the ammonia stripping process in the continuous flow JLR was modeled and the volumetric mass transfer coefficient (KLa) for each parameter was calculated from the model equation. While the experimental parameters of air flow rate and temperature had a significant effect on the mass transfer coefficient, influent ammonia concentration and HRT were determined to have no effect.
Comparison of reactive azo dye removal with UV/H2O2, UV/S2O8²⁻ and UV/HSO5⁻ processes in aqueous solutions
(2022-04-01) Çobanoğlu K.; Değermenci N.
Advanced oxidation processes (AOPs) are an effective choice for removal of reactive azo dyes used in the textile industry due to high solubility and low degradability. Within the scope of this study, reactive orange 122 (RO122) azo dye was removed using the UV-based AOPs of ultraviolet (UV) radiation, UV/hydrogen peroxide (UV/H2O2), UV/persulfate (UV/S2O82−), and UV/peroxymonosulfate (UV/HSO5−). Oxidant concentration, initial solution pH, initial RO122 concentration, different anions (Cl−, NO3− and SO42−), and solution temperature effects were compared. With only UV radiation (254 nm), 19.5% RO122 removal occurred at the end of 120 min. The RO122 removal reduced with the UV/oxidant processes at pH 9. Experimental results revealed RO122 removal followed pseudo-first-order (PFO) kinetics. There was a linear correlation identified between initial oxidant concentration and the PFO kinetic rate constant (k1). Among the three UV-based processes, with oxidant concentration 50 mg/L, temperature 20 °C, and pH 5, RO122 removal efficiency was in the order UV/H2O2 > UV/HSO5− > UV/S2O82−. RO122 removal rate increased as initial oxidant concentration and temperature increased and reduced as initial RO122 concentration increased. Energy requirements and oxidant costs were assessed. The UV/H2O2 process was concluded to be the most efficient and economic process for RO122 removal.
Decolorization of reactive azo dye from aqueous solutions with fenton oxidation process: Effect of system parameters and kinetic study
(2019-11-01) Değermenci N.; Değermenci G.; Ulu H.
The decolorization of Drimaren Orange HF 2GL (DOHF) reactive azo dye from aqueous solutions with the Fenton oxidation process was researched. With the aim of determining optimum conditions, the effects of different operating parameters such as H2 O2, Fe(II), chloride ion and initial DOHF concentration, initial pH and solution temperature on the decolorization were investigated. Optimum conditions were determined as 30°C temperature, pH 3, 300 mg/L DOHF, 15 mg/L Fe(II) and 100 mg/L H2 O2 . The presence of chloride ion had a negative effect on the decolorization, while the increase in reaction temperature caused an increase in the decolorization. Using experimental data, the decolorization kinetics for dye molecules was investigated and the best kinetic model representing experimental data was found to be the Behnajady–Modirshahla–Ghanbary (BMG) kinetic model. Additionally, Fourier transform infrared spectroscopy analysis was performed before and after Fenton oxidation to show degradation of dye molecules.
Decolorization of the Reactive Blue 19 from Aqueous Solutions with the Fenton Oxidation Process and Modeling with Deep Neural Networks
(2020-02-01) Değermenci N.; Akyol K.
The decolorization of Reactive Blue 19 (RB19) from aqueous solutions using the Fenton oxidation process was researched. The effects of different operating parameters, e.g., H2O2, Fe(II), initial dye concentration, pH, and solution temperature, on the decolorization of RB19 were investigated. Increasing, the H2O2 concentration and temperature increased the rate of the decolorization; however, increasing initial RB19 concentration reduced the decolorization. Additionally, modeling of the decolorization obtained by the Fenton oxidation process was researched based on deep neural networks (DNN) architecture providing the best performance in terms of optimum hidden layers and neuron numbers in addition to ideal activation and optimization function pairs. The performances of the models were analyzed on the training, validation, and test data. According to the experimental results, the seven hidden layers DNN model with “relu” activation function and “RMSProp” optimization function provided the best performance with root mean square error (RMSE) of 3.39 and correlation coefficient (R2) of 0.99.
Investigation of Mass Transfer of Ozone in Jet Loop Reactor
(2024-03-01) Cengiz I.; Değermenci N.; Yildiz E.; Barlak M.S.
Performance investigation of a jet loop membrane bioreactor for the treatment of an actual olive mill wastewater
(2016-12-15) Değermenci N.; Cengiz İ.; Yildiz E.; Nuhoglu A.
In this study, following the pre-treatment of olive mill wastewater (OMW), its treatment in a jet loop membrane bioreactor (JLMBR) was investigated. Among the pre-treatment options, the configuration composed of physical settling, cartridge filter and ceramic membrane showed the best performance in terms of investigated parameters. For the JLMBR that was fed by pretreated OMW, up to 93 and 87% removal efficiencies were achieved for the chemical oxygen demand (COD) and total phenol, respectively, at volumetric organic load (VOL) of 17.8 kg COD/m3 day. The calculated specific oxygen uptake rate (SOUR) values were in the range 7.7–34.7 g O2/kg MLVSS h. When even hydraulic retention times (HRT) values decreased by a factor of 1:24, system performance in terms of COD and total phenol removal remained almost stable. Decreasing the sludge retention time (SRT) to three days made considerable perturbations for the system performance, increasing the effluent COD and total phenol values in 900 and 80 mg/L, respectively. The JLMBR showed a high overall performance for the treatment of an actual OMW under the evaluated operational conditions.
Removal of chloridazon pesticide from waters by fenton and photo-fenton processes
(2020-01-01) Ulu H.B.; Değermenci N.; Dilek F.B.
Chloridazon (CLZ), also named as Pyrazon and classified as organochlorine pesticides, is widely used during sugar beets cultivation. CLZ being a pesticide with high solubility in water is likely to end up in surface and groundwater bodies because of its high mobility in soil. Due to its toxic properties, it may cause serious problems in human health and ecological cycle. In the present study, the removal of CLZ pesticide by Fenton and photo-Fenton processes was investi-gated. The effects of parameters such as H2 O2, Fe(II), initial CLZ concentration, pH, and temperature were studied. It was observed that CLZ completely disappeared within 1 h and 20 min by the Fenton and photo-Fenton process, respectively, under optimal conditions. The optimal conditions for each processes were attained as 7.5 mg/L Fe(II), 50 mg/L H2 O2, 40 mg/L initial CLZ, pH 3 and 20°C for Fenton process, and 5 mg/L Fe2+, 50 mg/L H2 O2, 60 mg/L initial CLZ, pH 3 and 20°C for photo-Fenton process. The reaction kinetics of CLZ followed Behnajady–Modirdhahla–Ghanbery kinetic model. Desphenyl CLZ, pyridazine-3,4,5-trione, oxaluric acid, and 5-hydroxyhydantion were identified as CLZ degradation by-products. Accordingly, the degradation pathway was proposed.
Removal of Phosphate from Aqueous Solution Using Anion Exchange Resin: Equilibrium Isotherms and Kinetics
(Korean Fiber Society, 2023) Korkmaz C.; Değermenci G.D.; Değermenci N.
Phosphate removal before discharging wastewater into the receiving environment is important since eutrophication has become an environmental problem on a global scale. In this study, phosphate ion removal from aqueous solutions was investigated using a strong anion exchange resin, Purolite A200E. The efects of initial phosphate ion concentration, initial pH value of the solution, resin dosage, stirring speed, presence of some anions in solution, and temperature on the ion exchange process were researched. Resin dosage, stirring speed, and temperature increases were determined to increase the phosphate removal rate. The highest phosphate removal efciency was observed in the pH interval 7–9. With initial phosphate concentration of 10 and 20 mg/L, 1.50 g/500 mL resin dosage fully removed phosphate at the end of 120 min. However, at phosphate concentrations higher than 20 mg/L, increasing phosphate concentrations caused a reduction in removal efciency. The competitive anion with the most efect on phosphate removal was sulfate while adding bicarbonate did not afect phosphate removal. Pseudo-frst-order (PFO) and pseudo-second-order (PSO) kinetic models were used to assess experimental data. Kinetic studies revealed that the ion exchange process can be explained better by the PFO kinetic model. Equilibrium isotherm data were analyzed with the Freundlich and Langmuir equations, and the Freundlich isotherm model ftted the equilibrium data better.