Browsing by Author "Alacabey, Ihsan"

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Cryogel-Immobilized Catalase as a Biocatalyst with Enhanced Stability Against Microplastics
(MDPI, 2025) Erol, Kadir; Alkan, Mehmet Huseyin; Alacabey, Ihsan
Catalase is a pivotal antioxidant enzyme that decomposes hydrogen peroxide and reduces oxidative stress. However, its low thermal and operational stability limits applications in challenging environments, particularly those contaminated with emerging pollutants such as polystyrene-based microplastics (PS-MPs). In this study, cryogels composed of Poly(2-hydroxyethyl methacrylate-co-allyl glycidyl ether) [Poly(HEMA-co-AGE)] were synthesized and evaluated as immobilization matrices to enhance catalase stability. Cryogels containing varying AGE concentrations were characterized using FT-IR, SEM, TEM, TGA, and BET analyses. The formulation with 250 mu L AGE exhibited optimal physicochemical properties, including improved water retention, increased surface area, and high immobilization capacity (356.3 mg center dot g(-1)). Immobilized catalase maintained superior activity under PS-MP-induced stress across a range of concentrations (0-1.0 mg center dot mL(-1)), temperatures (4-60 degrees C), and exposure times (up to 5 h). Kinetic modeling revealed a significant improvement in substrate affinity, with Km decreasing from 54.9 to 17.1 mM, while Vmax decreased moderately. Long-term stability tests showed that immobilized catalase retained similar to 80% activity after 70 days at 4 degrees C and 55% after 15 reuse cycles. Desorption studies confirmed the reusability of the cryogel system. These findings suggest that Poly(HEMA-co-AGE) cryogels provide a robust and reusable platform for catalase stabilization, offering potential for applications such as wastewater treatment and biosensing in microplastic-contaminated systems.
Citation - WoS: 11
Citation - Scopus: 11
Effective Removal of Dyes from Aqueous Systems by Waste-Derived Carbon Adsorbent: Physicochemical Characterization and Adsorption Studies
(Nature Portfolio, 2025) Kuyucu, Ali Ender; Selcuk, Ahmet; Onal, Yunus; Alacabey, Ihsan; Erol, Kadir
Due to their cost-effectiveness and high surface area, activated carbons are commonly used for the adsorption of dyes from aqueous solutions. In this study, activated carbon was synthesized from walnut shell waste via KOH activation (1:3 ratio), yielding a surface area of 2347.4 m(2)/g. Reactive Blue 19 and Reactive Red 195 adsorption behavior were studied under varying experimental conditions. These included natural pH values (6.8-7.2), dye concentrations between 50 and 1250 mg L-1, and adsorbent dosages ranging from 0.1 to 1.0 g. Adsorption equilibrium was achieved within 150 min. The maximum adsorption capacities were found to be 1227.17 mg g(-1) for RB 19 and 235.74 mg g(-1) for RR 195. Isotherm modeling was conducted using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models, with Freundlich providing the best fit for both dyes, indicating multilayer adsorption on heterogeneous surfaces. Thermodynamic analysis revealed that the adsorption processes were spontaneous and endothermic, with negative Gibbs free energy (Delta G degrees), positive enthalpy (Delta H degrees), and positive entropy (Delta S degrees) values. These results highlight the high adsorption performance and practical potential of walnut shell-derived activated carbon for dye removal from wastewater.
Citation - WoS: 7
Citation - Scopus: 7
Efficient Removal of Ciprofloxacin From Water Using High-Surface Activated Carbon Derived From Rice Husks: Adsorption Isotherms, Kinetics, and Thermodynamic Evaluation
(MDPI, 2025) Demirdag, Esra; Demirel, Mehmet Ferit; Benek, Veysel; Dogru, Elif; Onal, Yunus; Alkan, Mehmet Huseyin; Alacabey, Ihsan
Activated carbon is widely recognized as an effective material for removing pollutants, especially pharmaceutical residues, from water. In this study, high-surface-area activated carbon derived from rice husks (RHAC) was synthesized via KOH activation and used for the adsorption of ciprofloxacin, a widely used fluoroquinolone antibiotic. Its adsorption behavior was systematically investigated through batch experiments varying the pH, adsorbent dosage, contact time, initial concentration, and temperature. The RHAC exhibited a high surface area of 1539.7 m(2)/g and achieved a maximum adsorption capacity of 398.4 mgg(-1). The Freundlich isotherm best describes its adsorption equilibrium, suggesting multilayer adsorption on a heterogeneous surface. Kinetic modeling revealed that the adsorption process followed a pseudo second-order model (R-2 = 0.9981), indicating chemisorption as the rate-limiting mechanism. Thermodynamic parameters (Delta H degrees = 6.61 kJ/mol, Delta G degrees < 0) confirmed that the process was endothermic and spontaneous. These findings demonstrate that RHAC is a highly efficient, low-cost, and sustainable adsorbent for removing ciprofloxacin from aqueous environments.
Citation - WoS: 12
Citation - Scopus: 13
Pumice Particle Interface: a Case Study for Immunoglobulin G Purification
(Springer, 2021) Alacabey, Ihsan; Acet, Omur; Onal, Burcu; Dikici, Emrah; Karakoc, Veyis; Gurbuz, Fatma; Odabasi, Mehmet
Cryogels with embedded natural adsorbent are new trend of chromatographic media for separation of biomolecules. In this report, experimental determination of immunoglobulin G (IgG) purification by Cu2+-attached pumice particles unified cryogel (Cu2+-PPUC) was performed. For this purpose, after preparation of Cu2+-attached pumice particles, they were unified with 2-hydroxyethyl methacrylate monomers to produce Cu2+-PPUC through polymerization of gel-forming precursors at subzero temperatures. IgG separation experiments were accomplished in a continuous column system. The highest binding capacity (596.8 mg/g) was obtained by working with 0.02 M phosphate buffer at pH 6.0. The chemical analysis of pumice was examined by X-ray fluorescence spectrometer. Scanning electron microscopy was performed to identify the morphology of Cu2+-PPUC. Langmuir adsorption model was best fitted to interaction when compared to Freundlich model. Temkin model was utilized to characterize adsorption, energetically. Purification ability of Cu2+-PPUC for IgG was shown with high selectivity via reducing SDS-PAGE electrophoresis.