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Öğe Bioremoval of fast green FCF dye from aqueous solution using cranberry kernel (Cornus mas L.) as a lignocellulosic biowaste: equilibrium, kinetics, and mechanism(Taylor & Francis Ltd, 2023) Senol, Zeynep Mine; Keskin, Zehra Seba; Sarac, Kamuran; Simsek, SelcukIn this study, the biosorption properties of fast green FCF (FG) dye in an aqueous solution were investigated using cranberry (Cornus mas L.) kernel (CK) as lignocellulosic biowaste. The biosorbent performance of the cranberry (Cornus mas L.) kernel biomass for FG dye molecules was optimized: 500 mg L-1 at natural pH: 6.0 at 25 degrees C. The maximum biosorption capacity for CK biomass was found to be 21.6 mg g(-1) from the Langmuir isotherm model. Biosorption thermodynamics showed that FG dye biosorption to CK biomass was spontaneous, entropy-increasing, and endothermic. The kinetic data were described by the PSO and IPD kinetic models. Thermodynamic parameters were calculated, and it was seen that the biosorption process is spontaneous and endothermic. FT-IR spectrum after biosorption provided data supporting the formation of electrostatic interactions, n-pi interactions, and H-bonds between anionic FG dye molecules and CK biomass. When the results of this study were evaluated as a whole, it was concluded that CK biosorbent is a natural, abundant, low-cost, effective, and potential biosorbent for the removal of FG dye molecules from wastewater.Öğe Bioremoval of rhodamine B dye from aqueous solution by using agricultural solid waste (almond shell): experimental and DFT modeling studies(Springer Heidelberg, 2024) Senol, Zeynep Mine; El Messaoudi, Noureddine; Fernine, Yasmine; Keskin, Zehra SebaThe current study aimed to investigate the biosorption of rhodamine B from aqueous solution using an almond shell as an agricultural solid waste biosorbent. The almond shell biosorbent was characterized via Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) with energy dispersive X-ray (EDX), and point of zero charge (pH(PZC)) analyses. The parameters that influence the biosorption process such as contact time, initial dye concentration, biosorbent dose, temperature, and pH were investigated. According to the correlation coefficient, the data were best outlined by the Langmuir isotherm with adsorption capacity of 14.70 mg g(-1). The adsorption energy found from the D-R model showed that the adsorption process is chemical. The kinetic data were described by the pseudo-second-order kinetic and intraparticle diffusion kinetic models. Thermodynamic parameters were calculated; it was seen that the biosorption process is spontaneous and endothermic. The density functional theory (DFT) calculation results are well-matched with those discovered through experimentation. The results indicate that almond shells could be interesting alternative material used for dye removal from aqueous solutions.Öğe Biosorption of rhodamine B and sunset yellow dyes on cross-linked chitosan-alginate biocomposite beads: Experimental and theoretical studies(Elsevier, 2025) Senol, Zeynep Mine; Arslanoglu, Hasan; Keskin, Zehra Seba; Mehmeti, Valbone; El Messaoudi, NoureddineThis research explores the biosorption of Rhodamine B (Rd-B) and Sunset Yellow (SY) dyes using cross-linked chitosan-alginate (Ch-A) biocomposite beads, combining experimental investigations with theoretical studies to elucidate the biosorption mechanisms. The biocomposite beads were synthesized through an eco-friendly cross-linking method, and their structural properties were characterized using various characterization techniques. Complementary theoretical studies using Monte Carlo (MC) simulations and molecular dynamics (MD) calculations provided insights into the molecular interactions between the dyes and the biocomposite beads. ChA maximal biosorption capacity for Rd-B and SY was determined using the Langmuir model to be 43.6 mg g- 1 and 25.1 mg g- 1, respectively. Kinetic analysis elucidated that the biosorption process for Rd-B followed the pseudo first order (PFO) model and SY followed the pseudo second order (PSO) model. According to the thermodynamic characteristics, Rd-B and SY adsorb spontaneously and endothermically on Ch-A. In conjunction, MC and MD calculations were applied to probe the interactions between Rd-B and SY molecules and the Ch-A biocomposite beads, providing compelling evidence of robust binding interactions such as hydrogen bonds, electrostatic attractions, and it-it interactions. These theoretical insights were subsequently aligned with empirical observations, affirming a significant relation between the theoretical and experimental data. This study highlights the significance of combining experimental data with theoretical models to advance the development of environmentally friendly materials for water purification.Öğe Biosynthesis, Characterization and Antioxidant Properties of ZnO Nanoparticles Using Punica Granatum Peel Extract as Reducing Agent(2023) Keskin, Zehra Seba; Açıkel, ÜnsalThe green synthesis method of nanoparticles using plant extracts attracts great attention as a reliable, low-cost, sustainable, environmentally friendly protocol that prevents or minimizes waste generation. In this study, Punica granatum peel extract was used as the reducing plant material and zinc acetate dihydrate (Zn (CH3COO)2. 2H2O) solution was used as the starting metal. In the synthesis, optimum conditions were determined by UV visible spectroscopy using different metal ion concentrations, plant extract amount, temperature, and pH parameters. For characterization of ZnONPs synthesized at optimum conditions, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Dynamic Light Scattering (DLS), Zeta potential and Atomic Force Microscope (AFM) analyzes were made. It has been determined that the synthesized ZnONPs are spherical, have good stability, high purity, and nanoscale. The free radical scavenging capacity of biosynthesized ZnONPs was evaluated by DPPH analysis with different concentrations. The IC50 value was determined as 250µg ml-1.Öğe Efficient adsorption of Pb(II) ions using novel adsorbent polyacrylamide/coffee ground composite: isotherm, kinetic and thermodynamic studies(Springer, 2024) Keskin, Zehra SebaIn this study, an effective and inexpensive PAA-CG composite was synthesized using polyacrylamide (PAA) and coffee ground (CG) with the help of the in situ polymerization method. The adsorption efficiency of this new composite was investigated in the removal of Pb(II) ions from an aqueous solution. Characterization was done by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy and zero charge point analysis. The maximum adsorption capacity of the PAA-CG composite was calculated as 0.622 mol/kg according to the Langmuir isotherm model. From the obtained data, it was determined that the adsorption mechanism is compatible with pseudo-second-order kinetics and intra-particle diffusion model. The calculated thermodynamic data showed that adsorption is endothermic, spontaneous and entropy increasing.Öğe Evaluation of biosorbent properties of Teucrium polium seeds in Rhodamine B removal; isotherm, kinetic, thermodynamic studies(Taylor & Francis Inc, 2024) Yilmaz, Rabia; Keskin, Zehra SebaWater pollution is a major environmental concern worldwide, particularly due to industrial paint waste. Therefore, treating wastewater from various industrial sources is crucial to restoring environmental quality. In this study, a batch biosorption system was used to investigate the biosorption of Rhodamine B (RhB), a highly toxic dye, on Teucrium polium seeds (TPS). The study examined the effects of different parameters such as initial dye concentration, contact time, initial pH, temperature, and biosorbent amount on RhB removal. To determine the physicochemical properties of TPS, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and zero charge point (PZC) characterization analyses were performed. The maximum biosorption capacity of TPS at pH = 5.5 and 25 degrees C was found to be 4.18 mg g(-1). The study found that the removal rate of RhB was 93.3% at an initial RhB dye concentration of 200 mg L-1. The experimental data showed that the Langmuir isotherm model (R-2 = 0.940) was the most compatible model for biosorption, while the biosorption kinetic mechanism proceeded through the pseudo-second-order (PSO) kinetic model (R-2 = 0.925). Additionally, the study found that intraparticle diffusion, pore diffusion, and film diffusion were effective in the RhB biosorption rate mechanism. Thermodynamic studies revealed that the biosorption was endothermic (Delta H-0>0), spontaneous (Delta S-0>0), and entropy-increasing (Delta G(0) <0). As a result, TPS, which has suitable adsorbent properties for RhB, can be recommended as a new, cost-effective, abundant potential biosorbent.Öğe Fındık ve fındık ürünlerinde doğal olarak oluşan mikoflora ile aflatoksin oluşumlarının araştırılması(Cumhuriyet Üniversitesi, 2012) Keskin, Zehra Seba; Gürsoy, NevcihanFındık (Corylus avellana), insan ve hayvan diyeti için değerli bir besindir. Gıda sanayinde pasta, bisküvi, şekerleme, fındık ezmesi, çikolata yapımında kullanılmakla birlikte Türkiye'de genellikle çerezlik olarak tüketilmektedir.Bu çalışmada, 30 çiğ, 50 kavrulmuş fındık, 20 ezme ve 50 iç zar örneğinde oluşan doğal mikoflora belirlenmiştir. Yapılan mikolojik izolasyonlarda çiğ fındıkta %1,8-2,56 Aspergillus flavus, %42,7-65,44 A. niger; kavrulmuş fındıkta %2,2-12,2 A. flavus, %33,3-74,5 A. niger; ezme örneklerinde %0-13,1 A. flavus, %43,5-100 A. niger; iç zarda ise %2,6-16,2 A.flavus, %44,6-89,4 A. niger belirlenmiştir. Örneklerin nem içerikleri sırasıyla çiğ örnekler için %3,8?4,56, kavrulmuş fındıklar için %2,44?2,9, ezme için %1,2?4,5 ve iç zarlar için %8,04?14,76 olarak tespit edilmiştir. Aflatoksin analizlerinde çiğ fındıkta 2.11?10.03 ppb, kavrulmuş fındıkta 0,1?4,04 ppb, ezme örneklerinde 0,2-6,02 ppb ve iç zar örneklerinde ise 0,7-38,2 ppb seviyelerinde aflatoksin içerikleri saptanmıştır. Çiğ, kavrulmuş fındık ve ezme örneklerinin sadece birinde yasal sınırın üzerinde toksin içeriği bulunurken, iç zar örneklerinin %100'ünde değişik seviyelerde aflatoksin bulaşıklığı bulunmuştur. Fındık iç zarı ile ilgili Türk Gıda Kodeksinde bir sınırlama olmamasına karşın örneklerin yirmibeşinde 10 ppb'nin üzerindeki aflatoksin içerikleri yüksek olarak değerlendirilmiştir.Çalışılan örneklerin istatistiki değerlendirmelerinde Kruskal Wallis ve Mann Whitney U analizleri kullanılmıştır. Farklı gruplardaki örnekler arasında aflatoksin oluşumu ve nem içerikleri bakımından fark anlamlı bulunmuştur (p<0.05).Öğe Nar (Punica granatum) kabuğu özütü kullanılarak ZnO nanopartikül sentezi, biyobozunur nanokompozit film üretimi ve karakterizasyonu(Sivas Cumhuriyet Üniversitesi, 2020) Keskin, Zehra Seba; Açıkel, ÜnsalBu tez çalışmasında petrol kaynaklı polimerlerden elde edilen ambalajlara alternatif olabilecek daha çevre dostu ve geliştirilmiş özelliklere sahip biyobozunur nanokompozit filmlerin hazırlanması amaçlanmıştır. Tezin ilk aşamasında yeşil sentez yöntemiyle ZnO nanopartikülleri (NP) elde edilmiştir. Sentezde indirgeyici bitki materyali olarak nar (Punica granatum) kabuğu ekstraktı, başlatıcı metal olarak ise çinko asetat dihidrat (Zn(CH3COO)2. 2H2O) çözeltisi kullanılmıştır. Sentez için optimum koşullar ise çinko asetat dihidrat derişimi 0,15 M, nar kabuğu ekstrakt miktarı 10 mL, pH 12.0 ve tepkime sıcaklığı 60 0 C olarak belirlenmiştir. Belirlenen optimum koşullar altında sentezlenen ZnO NP'lerin karakterizyonu için SEM, EDX, XRD, FTIR, DLS, zeta potansiyeli ve AFM analizleri yapılmıştır. Sentezlenen ZnO NP' lerin yüksek saflıkta ve nanoboyutta olduğu belirlenmiştir. Tezin ikinci aşamasında biyobozunur bir polimer olan polilaktik asite (PLA), kitosan ve ZnO NP'leri farklı oranlarda ilave edilmiş ve ekstrüzyon yöntemiyle biyobozunur nanokompozit filmler hazırlanmıştır. Elde edilen bu filmlerin karakterizasyonları SEM, FTIR, XRD, AFM, DSC, su buharı geçirgenliği, oksijen geçirgenliği, yüzey temas açısı, migrasyon ve antibakteriyel analizleri ile yapılmıştır. ZnO NP'lerinin ve kitosan partiküllerinin eklenmesiyle elde edilen filmlerin saf PLA filmine göre yapısal, termal, bariyer ve antimikrobiyal özelliklerinin nasıl değiştiği tartışılmıştır. Tez çalışmasında yapılan analizler sonucunda gıda ambalajlamasında kullanılabilecek optimum özelliklere sahip filmlerin PLA/ZnO(0,5) ve PLA/ZnO(1) nanokompozit filmleri olduğu belirlenmiştir.Öğe Prunus mahaleb shell as a sustainable bioresource for carminic acid removal from aqueous solution: Experimental and theoretical studies(Elsevier, 2023/3/5) Keskin, Zehra Seba; Şenol, Zeynep Mine; Kaya Savaş; Şimşek, SelçukThis study focused on the performance of Prunus mahaleb shell (MS) agricultural waste, which is used as an alternative biosorbent for carminic acid (CA) removal from aqueous solution. The effects of different parameters such as pH, initial dye concentration, contact time, biosorbent dosage and temperature on the biosorption of CA dye to the MS biosorbent surface were investigated. The characterization of the biosorbent was done by FT-IR, SEM-EDX and pzc analyses. It was determined that the isotherm and kinetics of CA dye removal were consistent with the Langmuir isotherm and PSO and IPD kinetic models, respectively. The maximum adsorption capacity was calculated as 148 mg g−1 according to the Langmuir isotherm. According to the H0, G0 and S0 results, the biosorption was found to be endothermic and spontaneous. Based on these data, it is concluded that environmentally friendly, inexpensive, simple to use and effective MS biosorbent can be used for CA dye removal.Öğe Synthesis and characterization of a new hybrid polymer composite (pollene@ polyacrylamide) and its applicability in uranyl ions adsorption(Springer International Publishing, 2023/2/14) Şenol, Zeynep Mine; Keskin, Zehra Seba; Şimşek, SelçukIn this study, polyacrylamide-pollen (P@PAA) composite adsorbent was synthesized by in situ polymerization method using polyacrylamide hydrogel and pollen. The adsorptive properties of the P@PAA hybrid polymer composite adsorbent were investigated for the removal of UO22+ ions. The fndings obtained as a result of the structural characterizations showed that the P@PAA composite adsorbent has various functional group variations. The max adsorption capacity of UO22+ ions was 0.695 mol kg−1. The thermodynamic parameters of the adsorption of UO22+ ions onto P@PAA hybrid polymer composite were determined and it was clarifed that the adsorption was spontaneous.
