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    Application of Response Surface Methodology for Optimization of Copper Removal Using a Novel Polymeric Adsorbent
    (Springer, 2022) Unugul, Tuba; Nigiz, Filiz Ugur; Bozbas, Seda Karayunlu
    Depending on the increase in the world population, the need for consumption and industrial resources is increasing day by day. In the wastewater caused by industrial production, a serious amount of heavy metals and water pollution caused by inorganic dyestuffs occur. In this study, graphene nanoplate/natural zeolite/sodium alginate bio-composite adsorbent was prepared and copper removal from wastewater by adsorption method was investigated. The characterization of the adsorbent was carried out by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and Brunauer-Emmett-Teller. In addition to batch adsorption tests, isotherm, kinetic and thermodynamic studies, experimental optimization was carried out with experimental parameters determined by the surface response methodology. Four experimental parameters (adsorbent dosage, metal concentration, solution pH, and contact time) were evaluated in a versatile way to determine the efficiency of heavy metal adsorption. The highest copper removal was obtained as 92.9% and 91.4%, respectively, in the experimental and model study at the adsorbent dosage of 0.5 g, the solution pH of 4.5, and the copper concentration of 20 ppm. The parametric results was meet with the optimization results with an R-2 value of 0.9834. The three most commonly used adsorption isotherms at 25 degrees C were calculated. The high R-2 value was found to be 0.9834 for the Langmuir isotherm model. It was determined that the adsorption kinetics matched the pseudo-second-order kinetics.
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    Öğe
    Evaluation of Halloysite Nanotube-Loaded Chitosan-Based Nanocomposite Membranes for Water Desalination by Pervaporation
    (Springer Int Publ Ag, 2022) Unugul, Tuba; Nigiz, Filiz Ugur
    In this study, halloysite nanotube (HNT)-loaded chitosan-based nanocomposite membranes were synthesized and used for pervaporative desalination of water. Structural and morphological properties of the nanocomposite membranes were investigated. The effects of the HNT content, feed temperature, and feed NaC1 concentration on the flux and salt rejection were investigated. As the HNT content was increased, the degree of swelling decreased. At all temperature values, higher than 99% of salt rejections were achieved. The flux value increased from 1.63 to 4.89 kg/m(2)h, when the HNT content increased from 0 to 20 wt% at 30 degrees C. While the highest salt rejection value was obtained as 99.90% using the 10 wt% HNT-loaded nanocomposite membrane, the highest flux value was obtained as 5.81 kg/m(2)h using the 20 wt% HNT-loaded membrane at 50 degrees C. The pervaporation desalination results showed that HNT simultaneously increased the swelling resistance and the separation capability of the chitosan membrane.
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    Öğe
    Polyvinyl Alcohol/Zr-based Metal Organic Framework Mixed-matrix Membranes Synthesis and Application for Hydrogen Separation
    (Springer, 2024) Nigiz, Filiz Ugur; Unugul, Tuba
    Membrane gas separation is an environmentally friendly and economical method used to separate valuable gases, industrial process gas wastes, and carbon dioxide from mixed gases. The most important part of this method is the membranes. Gas separation membranes are expected to have high separation and permeability performance, high mechanical strength, easy and fast production capability, and low prices. Polymer-based membranes are mostly preferred depending on the ease of modification capability. In this study, a zirconium-based metal organic framework (Zr-MOF, MIL-140 A) was synthesized and used as a filler within polyvinyl alcohol (PVA) matrix for the selective separation of hydrogen (H2) from carbon dioxide (CO2). The effect of MIL-140 A addition on the mechanical, structural, and morphological properties of PVA was evaluated. The MIL-140 A significantly improved the mechanical strength of the membrane. According to the gas separation results, the increasing concentration of MIL-140 A increased the selective separation performance of the nanocomposite membrane. The highest mechanical strength (43.1 MPa) and best film-forming ability were obtained with 3 wt% MIL-140 A loaded membrane. The ideal H2/CO2 selectivity and hydrogen permeability were obtained as 5.6 and 944 Barrer, respectively at 2 bar feed pressure and room temperature. The highest ideal H2/CO2 selectivity was obtained as 6.3 with the H2 permeability of 959 Barrer when the MIL-140 A ratio was 4 wt%.
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    Öğe
    Preparation and Characterization an Active Carbon Adsorbent from Waste Mandarin Peel and Determination of Adsorption Behavior on Removal of Synthetic Dye Solutions
    (Springer International Publishing Ag, 2020) Unugul, Tuba; Nigiz, Filiz Ugur
    In this study, carbonized mandarin peel (CMP) was prepared and characterized and the adsorption behavior of the activated carbon for methylene blue (MB) and methyl orange (MO) removal was investigated. Adsorbent (CMP) was characterized by means of scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), thermo-gravimetric analyses (TGA), and Fourier transform infrared spectroscopy (FTIR). In the adsorption studies, the effects of initial dye concentration, solution pH, adsorbent dosage, and contact time on dye removal were investigated. In the same conditions, MB showed higher adsorption capacity than that of the MO. Therefore, the isotherms, kinetics, and thermo-dynamical adsorption studies were performed for MB. The appropriate adsorption isotherm for MB using CMP was determined as Langmuir isotherm. The kinetic values are well defined by the pseudo-second order kinetic model. The highest MB removal of 99.77% was obtained with CMP concentration of 5 g/L when the dye concentration was 5 mg/L at pH value of 6.9. After solvent regeneration, the adsorbent maintained 95.17% of its regeneration activity. The results show that CMP can be used as a low-cost and natural adsorbent to remove synthetic dye from the effluent of the textile wastewater.