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Öğe A COMPARISON OF BIOSORPTION CAPACITIES OF Cystoseira barbata AND Caulerpa racemosa USING Cd (II) AND Co (II) IONS(Parlar Scientific Publications (P S P), 2014) Cirik, Yeliz Ozudogru; Buyukates, Yesim; Merdivan, MelekThis study was conducted to compare the biosorption capacities of marine brown algae, Cystoseira barbata, and marine green algae, Caulerpa racemosa. These two algae were chemically modified by crosslinking with glutaraldehyde (GA), H3PO4, and HCl, or only washed with distilled water (DW) for use in equilibrium sorption uptake studies with Cd (II) and Co (II) ions. The pH level of the solution, contact time, initial metal concentration, mixed metal aqueous solution and desorption with different eluents were studied. A Langmuir and Freundlich isotherm analysis of the experimental data showed that the maximum metal uptake for two ions by algae were maintained when crosslinking with GA. The optimum pH value was 6 for C. barbata and 5 for C. racemosa. When the duration of the sorption process was 30 minutes, 0.1 M HCl and 0.1 M HNO3 were the most efficient eluents for these algae. FTIR and SEM analyses were performed as well. Results showed that C. barbata and C. racemosa have great potential for use as an eco-friendly agent in the process of removing Cd (II) and Co (II) ions for characterization of biomass.Öğe A comparison of biosorption capacities of cystoseira barbota and caulerpa racemosa using cd (ii) and co (ii) IONS(Parlar Scientific Publications, 2014) Cirik, Yeliz Ozudogru; Buvukates, Yesim; Merdivan, MelekThis study was conducted to compare the biosorption capacities of marine brown algae, Cystoseira barbota, and marine green algae, Caulerpa racemosa. These two algae were chemically modified by crosslinking with glutaral-dehyde (GA), H3PO4, and HC1, or only washed with distilled water (DW) for use in equilibrium sorption uptake studies with Cd (II) and Co (II) ions. The pH level of the solution, contact time, initial metal concentration, mixed metal aqueous solution and desorption with different eluents were studied. A Langmuir and Freundlich isotherm analysis of the experimental data showed that the maximum metal uptake for two ions by algae were maintained when crosslinking with GA. The optimum pH value was 6 for C. barbota and 5 for C. racemosa. When the duration of the sorption process was 30 minutes, 0.1 M HC1 and 0.1 M HNO3 were the most efficient eluents for these algae. FTIR and SEM analyses were performed as well. Results showed that C. barbota and C. racemosa have great potential for use as an eco-friendly agent in the process of removing Cd (II) and Co (II) ions for characterization of biomass. © by PSP.Öğe Adsorption of U(VI) and Th(IV) ions removal from aqueous solutions by pretreatment with Cystoseira barbata(Springer, 2020) Ozudogru, Yeliz; Merdivan, MelekRadioactive wastes from human activities can spread to the environment and pose a serious threat to human health. This paper examined the removal of radioactive U(VI) and Th(IV) ions from aqueous solutions by a modified alga, Cystoseira barbata (Stackhouse) C. Agardh. The effects of pH, contact time, radioactive ion concentration, and temperature were examined on the adsorption and desorption of the radioactive ions by the algae from different solutions. The maximum adsorption capacity (q(ma)x) value was 217.39 mg g(-1) at 45 degrees C for U(VI) and 305.81 mg g(-1) at 45 degrees C for Th(IV). The data were analyzed with Langmuir and Freundlich isotherms. Scanning electron microscopy and Fourier transform infrared spectroscopy analyses were performed to determine the changes on the surfaces of the algae following adhesion of radioactive ions to the algal surfaces. The success rate for recovery of the loaded radioactive materials was more than 90%.Öğe Heavy metals uptake from aqueous solutions using marine algae (Colpomenia sinuosa): kinetics and isotherms(Taylor & Francis Ltd, 2012) Cirik, Yeliz; Bekci, Zehra Molu; Buyukates, Yesim; Ak, Ilknur; Merdivan, MelekThe adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied as a function of contact time, initial metal ion concentration and initial pH. In addition, desorption studies were performed. Characterisation of this adsorbent was also confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Batch adsorption experimental data were analysed using Langmuir, Freundlich and Dubinin-Raduschkevich (D-R) adsorption isotherms. The results indicated that the biosorption equilibrium was well described by both the Freudlich and D-R isotherms. Moreover, sorption kinetics was performed and it was observed that equilibrium was reached in <60 min, which could be described by the pseudo-second-order kinetic model for all heavy metals. The sorption of heavy metals onto the biomass was largely dependent on the initial solution pH. The elution efficiency for heavy metal ions desorption from C. sinuosa was determined for 0.1 M HCl, 1.0 M HCl and 1.0 M HNO3. Desorption efficiency and also adsorption capacity were highest for Pb(II). The results indicate that C. sinuosa has great potential for the removal of heavy metals in an ecofriendly process.Öğe METİLEN MAVİSİNİN MODİFİYE EDİLMİŞ Cystoseira barbata (STACKHOUSE) C. AGARDH KULLANILARAK BİYOSORPSİYONU(2017) Özüdoğru, Yeliz; Merdivan, MelekBu çalışmada, sulu çözeltide bulunan metilen mavisi (MM) boyar maddesinin modifiye edilmiş (0,1M HNO3 ve 1M HNO3 ile) Cystoseira barbata kullanılarak giderilmesine çalışılmıştır. Adsorpsiyona, pH'ın, temas süresinin, farklı derişimlerde bulunan MM çözeltisinin etkileri incelenmiştir. Çalışma sonucunda, ilk 50dk. içerisinde sistemin dengeye geldiği ve adsorpsiyon kapasitesinin pH değişiminden pek etkilenmediği gözlemlenmiştir. Yapılan izoterm çalışmalarında ise, Freundlich izoterm modeline daha çok uyduğu belirlenmiş ve qmax değeri 0,1M HNO3 grubunda daha yüksek (100,6mg/g) bulunmuştur. Yapılan SEM ve FTIR analizlerinde ise, MM boyar maddesinin alg yüzeyinde meydana getirdiği değişikler ve alg yüzeyinde hangi gruplara tutunduğu belirlenmiştirÖğe Removal of methylene blue from aqueous solutions by brown alga Cystoseira barbata(Desalination Publ, 2017) Ozudogru, Yeliz; Merdivan, Melek; Goksan, TolgaThe removal of dyes from wastewater is crucial and considered an environmental challenge. Biosorption is an alternative technology to conventional processes aiming at the removal of toxic metals and dyes from polluted waters. In this study, Cystoseira barbata (Stackhouse) C. Agardh was used to remove the methylene blue (MB) from aqueous solution. The effects of solution pH, contact time and initial MB concentration at different temperatures were investigated. The adsorption reached to equilibrium in 25 min and the pH did not have an important role on the biosorption. The Freundlich isotherm model showed slightly stronger correlation than Langmuir isotherm model especially at 25 degrees C. The maximum adsorption capacity (q(m)) increased in parallel to the rise of temperature and reached to 14.97 mg/g at 45 degrees C. C. barbata can be successfully used for the removal of MB from aqueous solution.
