Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 17Citation - Scopus: 16Synthesis, Characterization and Adsorption Studies of Phosphorylated Cellulose for the Recovery of Lithium From Aqueous Solutions(Editura Acad Romane, 2021) Recepoğlu, Yaşar Kemal; Yüksel, AslıIn this study, pristine cellulose was functionalized by the phosphorylation reaction to make it suitable for lithium separation. After characterization studies of the synthesized adsorbent with SEM, EDX, FTIR, TGA and XPS, the effects of various parameters on the lithium uptake capacity of the adsorbent were examined. The analysis of equilibrium data by several adsorption models showed that maximum adsorption capacity of the adsorbent was found to be 9.60 mg/g at 25 degrees C by the Langmuir model. As initial concentration and contact time increased, adsorption capacity also increased, however, mild temperature (25-35 degrees C) and pH (5-6) were better for the adsorption of lithium. 80% of lithium adsorption within three minutes proved the fast kinetic nature of the adsorbent. A 99.5% desorption efficiency of lithium was achieved with 0.5 M H2SO4, among HCl and NaCl with different molarities. Phosphorylated cellulose was shown to be a favorable adsorbent for the recovery of lithium from aqueous solutions.Article Citation - WoS: 3Validation on of Local Thermal Equilibrium and Uniform Pressure Assumptions for an Isobaric Adsorption Process in an Adsorbent Bed(Türk Isı Bilimi ve Tekniği Derneği, 2016) Gediz İliş, Gamze; Mobedi, Moghtada; Ülkü, SemraBu çalışmanın amacı, adsorbent yatakta ısı ve kütle transferini analiz etmek için kullanılan yerel ısıl denge ve sabit basınç yaklaşımı varsayımların geçerliliğini araştırmaktır. İçerisinde silika jel partikülleri içeren bir yatak ile su kabı olan bir deney düzeneği tasarlanmış ve adsorpsiyon sürecinde yatağın içinde farklı yerlerde yerel sıcaklık ve basınç ölçülmüştür. Ayrıca, sabit basınç yaklaşımı ve yerel ısıl denge varsayımlara dayalı ısı ve kütle transferi denklemleri çözülmüştür. Sayısal sonuçlar, ilgili deneysel sonuçlarla karşılaştırılmış ve aralarında oldukça iyi bir uyum tespit edilmiştir. Gerçekleştirilen karşılaştırmaya dayanarak, incelenen yatak için iki önemli sonuç şu şekildedir: a) katı madde ve su buharı arasında yerel ısıl denge bulunmaktadır, b) bir yatak içinde parçacıklar arası kütle transferi direnci ihmal edilebilir düzeyde olup konsantrasyonunun ve sıcaklığın belirlenmesi için sabit basınç yaklaşımı geçerlidir. Ayrıca, bu çalışmada sunulan deneysel sonuçlar diğer araştırmacıların sayısal çalışmalarının geçerliliğini doğtulamak için değerli veriler sağlayacaktır.Article Citation - WoS: 2Citation - Scopus: 3Recovery of Proanthocyanidin From Waste of Turkish Traditional Product, Pekmez (molasses)(Japanese Society for Food Science and Technology, 2007) Altıok, Evren; Ülkü, Semra; Ülkü, Semra; Ülkü, Semra; Bayraktar, Oğuz; Bayraktar, Oğuz; Bayraktar, OğuzThe possibility of recovering of proanthocyanidin (PA) from the by-product of Turkish traditional product pekmez (molasses) industry, one of the agro industries, was investigated. In order to obtain optimum extraction conditions, the effects of different solvents and their aqueous forms were studied and the highest PA concentration was achieved as 31 (±0.68)g/L with acetone/water (30: 70, v/v) solution. The correlations between phenolic contents, PA concentrations and antioxidant capacities were shown. Antioxidant capacities of extracts were determined and the comparison of them with synthetic and commercial antioxidants was performed. The antioxidant capacity of PA extract from grape seed of molasses pomace was 93 (±1.43) TEAC values, which was relatively high compared with those of the synthetic antioxidants. Silk fibroin was used as a novel adsorbent to recover the PA from the grape seed extracts. Effect of parameters such as, solid-liquid ratio, pH and initial concentration of PA on the recovery performance was investigated. All parameters were found statistically significant parameters (P < 0.005) and the best adsorption conditions were found to be pH 5.5, initial concentration as 10 g/ml and solid-liquid ratio as 0.1 g/ml, which yielded the maximum percentage of adsorbed PA amount as 85.2%.