Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 64Citation - Scopus: 78Utilization of Municipal Plastic and Wood Waste in Industrial Manufacturing of Wood Plastic Composites(Springer Verlag, 2020) Başalp, Dildare; Tıhmınlıoğlu, Funda; Sofuoğlu, Sait Cemil; İnal, Fikret; Sofuoğlu, AysunIn this study, Wood Plastic Composites (WPCs) were produced from post-consumer bulky wastes of recycled plastic and wood in order to minimize waste, decrease environmental effects of plastics, reserve natural resources, and support circular economy for sustainable production and consumption. Five different types of polypropylene (PP) or polyethylene (PE) based recycled plastics and wood obtained from urban household bulky wastes were used in the production of recycled WPC composites, r-WPCs. Virgin WPC (v-WPC) and r-WPC compounds were prepared with wood flour (WF) and maleic anhydride grafted compatibilizer (MAPP or MAPE) to evaluate the effect of recycled polymer type and compatibilizer on the mechanical properties. It was found that tensile strength properties of r-WPCs produced from recycled PP (r-PP) were higher than that of the r-WPCs produced from mixed polyolefins and recycled PE. r-WPCs containing anti-oxidants, UV stabilizers, and compatibilizer with different WF compositions were produced from only recycled garden fraction PP (PPFGF) to determine the optimum composition and processing temperature for pilot scale manufacturing of r-WPCs. Based on tensile, impact, flexural, and water sorption properties of r-WPC compounds with different formulations, the optimum conditions of r-WPC compounds for industrial manufacturing process were determined. Surface morphology of fractured surfaces as well as tensile, flexural and density results of r-WPC compounds revealed the enhancement effect of MAPP on interfacial adhesion in r-WPCs. r-WPC products (crates and table/chair legs) based on bulky wastes were produced using an injection molding process at industrial scale by using 30 wt% WF-filled r-WPC compound. This study demonstrated that r-WPC compounds from recycled bulky plastic and wood wastes can be used as a potential raw material in plastic as well as WPC industry, contributing to circular economy. GraphicArticle Citation - WoS: 19Citation - Scopus: 29Modeling of an Activated Sludge Process for Effluent Prediction—a Comparative Study Using Anfis and Glm Regression(Springer Verlag, 2018) Araromi, Dauda Olurotimi; Majekodunmi, Olukayode Titus; Adeniran, Jamiu Adetayo; Salawudeen, Taofeeq OlalekanIn this paper, nonlinear system identification of the activated sludge process in an industrial wastewater treatment plant was completed using adaptive neuro-fuzzy inference system (ANFIS) and generalized linear model (GLM) regression. Predictive models of the effluent chemical and 5-day biochemical oxygen demands were developed from measured past inputs and outputs. From a set of candidates, least absolute shrinkage and selection operator (LASSO), and a fuzzy brute-force search were utilized in selecting the best combination of regressors for the GLMs and ANFIS models respectively. Root mean square error (RMSE) and Pearson’s correlation coefficient (R-value) served as metrics in assessing the predicting performance of the models. Contrasted with the GLM predictions, the obtained modeling results show that the ANFIS models provide better predictions of the studied effluent variables. The results of the empirical search for the dominant regressors indicate the models have an enormous potential in the estimation of the time lag before a desired effluent quality can be realized, and preempting process disturbances. Hence, the models can be used in developing a software tool that will facilitate the effective management of the treatment operation.Article Citation - WoS: 12Citation - Scopus: 12Peg and Peg-Peptide Based Doxorubicin Delivery Systems Containing Hydrazone Bond(Springer Verlag, 2018) Balcı, Beste; Top, AybenmPEG and mPEG-peptide based drug delivery systems were prepared by conjugating doxorubicin (DOX) to these carrier molecules via hydrazone bond. The peptide, AT1, with a sequence of CG3H6G3E served as mPEG and doxorubicin attachment site. Histidines were incorporated to the sequence to improve pH responsiveness of the carrier molecule. Hydrodynamic diameters (mean sizes) of mPEG-based drug delivery system (mPEG-HYD-DOX) were measured as 9 ± 0.5 and 7 ± 0.5 nm at pH 7.4 and pH 5.0, respectively. Mean size of the aggregates of the peptide containing drug delivery system, mPEG-AT1-DOX, was determined as 12 ± 2 nm at neutral pH. At pH 5.0, on the other hand, mPEG-AT1-DOX exhibited a size distribution between 20 and 100 nm centered at about 40 nm. Comparison of % DOX release values of the drug delivery systems obtained at pH 7.4 and pH 5.0 indicated that mPEG-AT1-DOX has enhanced pH sensitivity. DOX equivalent absolute IC50 values were obtained as 0.96 ± 0.51, 21.9 ± 5.9, and 5.55 ± 0.75 μg/mL for free DOX, mPEG-HYD-DOX, and mPEG-AT1-DOX, respectively. Considering more pronounced pH sensitivity and cytotoxicity of mPEG-AT1-DOX, the use of both pH responsive functional groups and acid cleavable chemical bond between the carrier molecule and drug can be a promising approach in the design of drug delivery systems for cancer therapy.Article Citation - WoS: 23Citation - Scopus: 27Novel Poss Reinforced Chitosan Composite Membranes for Guided Bone Tissue Regeneration(Springer Verlag, 2018) Tamburacı, Sedef; Tıhmınlıoğlu, FundaIn this study, novel composites membranes composed of chitosan matrix and polyhedral oligomeric silsesquioxanes (POSS) were fabricated by solvent casting method. The effect of POSS loading on the mechanical, morphological, chemical, thermal and surface properties, and cytocompatibility of composite membranes were investigated and observed by tensile test, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), protein adsorption assay, air/water contact angle analysis and WST-1 respectively. Swelling studies were also performed by water absorption capacity determination. Results showed that incorporation of Octa-TMA POSS® nanofiller to the chitosan matrix increased the surface roughness, protein adsorption and swelling capacity of membranes. The addition of POSS enhanced significantly the ultimate tensile strength and strain at break of the composite membranes up to 3 wt% POSS loaded samples. An increase of about 76% in tensile strength and of strain at break 1.28% was achieved for 3 wt% POSS loaded nanocomposite membranes compared with chitosan membranes. The presence of POSS filler into polymer matrix increased the plasma protein adsorption on the surface. Maximum protein capacity and swelling was obtained for 10 wt% loaded samples. High cell viability results were obtained with indirect extraction of chitosan/POSS composites. Besides, cell proliferation and ALP activity results showed that POSS incorporation significantly increased the ALP activity of Saos-2 cells cultured on chitosan membranes. This novel composite membranes with tunable properties could be considered as a potential candidate for guided bone regeneration applicationsArticle Citation - WoS: 23Citation - Scopus: 29Dynamic Nature of Supercritical Co2 Adsorption on Coals(Springer Verlag, 2017) Özdemir, EkremAdsorption on non-rigid solids was shown to be a dynamic process. Excess adsorption and desorption isotherms of CO2 on eight Argonne Premium coal samples were measured at 55 °C and pressures up to 14 MPa by manometric method. The excess adsorption isotherms of CO2 on powdered coals showed almost Langmuir-like to rectilinear shape behavior at low pressures up to 9 MPa, and it increased noticeably at pressures higher than 9 MPa. There was a significant hysteresis between the excess adsorption and desorption isotherms for each rank of coals, which was related to the volumetric uncertainties occurring during the adsorption isotherm measurements. The parameters related to the adsorption capacity and micro porous characteristics of the coal were obtained at different pressure ranges by fitting the experimental data to the modified Dubinin-Astakhov (D-A) equation at the increasingly larger pressure ranges, using only the first 4 data points of the excess adsorption isotherm initially, and progressively using additional data points for the subsequent values. It was shown that the curve fit parameters vary with pressure, and therefore, concluded that the adsorption on non-rigid solids such as CO2 on coal is indeed a dynamic process. It was suggested that new adsorption isotherm equations need to be developed considering the dynamic nature of the adsorption on solid adsorbents.Article Citation - WoS: 44Citation - Scopus: 44Chitosan-Polyoxometalate Nanocomposites: Synthesis, Characterization and Application as Antimicrobial Agents(Springer Verlag, 2014) Fiorani, Giulia; Saoncella, Omar; Kaner, P.; Alsoy Altınkaya, Sacide; Figoli, Alberto; Bonchio, Marcella; Carraro, MauroPolyoxometalates (POMs) were used, together with chitosan (CS), to obtain hybrid nanoaggregates. Three representative POMs were efficiently assembled into nanoparticles of few hundred nm diameter, featuring entangled ribbons substructure. In order to establish suitable preparation and stability conditions, the assemblies were characterized in solution by UV-Vis spectroscopy, dynamic light scattering and ζ-potential. The nanoparticles were tested against E. coli (106 CFU/ml) in aqueous solution, showing a synergic activity of the heteropolyacid H5PMo10V2O40 and CS. For such components, a highly porous and antibacterial film was obtained upon lyophilisation of the colloidal mixture.Article Citation - WoS: 29Citation - Scopus: 33Surface Modification of Polysulfone Based Hemodialysis Membranes With Layer by Layer Self Assembly of Polyethyleneimine/Alginate-heparin: a Simple Polyelectrolyte Blend Approach for Heparin Immobilization(Springer Verlag, 2013) Yaşar Mahlıçlı, Filiz; Alsoy Altınkaya, SacideThis study intends to improve blood compatibility of polysulfone (PSF) membranes by generating a nonthrombogenic surface through heparin immobilization. To achieve this task, the support membrane prepared from a blend of PSF and sulfonated polysulfone (SPSF) was modified with layer by layer (LBL) deposition of polyethyleneimine (PEI) and alginate (ALG) and heparin blended with ALG was immobilized only on the outermost surface of the LBL assembly. The results have shown that the adsorption of human plasma proteins and platelet activation on the LBL modified membranes decreased significantly compared with the unmodified PSF and PSF-SPSF blend membranes. Furthermore, blending ALG with a small amount of heparin remarkably prolonged the APTT values of heparin free PEI/ALG coated membranes. It is envisaged that the use of a blend of HEP and ALG only in the terminating layer of the LBL assembly can be an economical and alternative modification technique to create nonthrombogenic surfaces.Article Citation - WoS: 9Citation - Scopus: 13An Exposure–risk Assessment for Potentially Toxic Elements in Rice and Bulgur(Springer Verlag, 2017) Sofuoğlu, Sait Cemil; Sofuoğlu, AysunRice and wheat are rich sources of essential elements. However, they may also accumulate potentially toxic elements (PTE). Bulgur, the popular alternative to rice in the eastern Mediterranean, is produced by processing wheat, during which PTE content may change. This study determined PTE concentrations in rice and bulgur collected from 50 participant households in the City of Izmir, Turkey, estimated ingestion exposure, and associated chronic-toxic and carcinogenic human health risks. Comparison of the determined concentrations to the available standard levels and the levels reported in the literature revealed that Cd, Co, and Pb in rice might be of concern. The estimated health risks of individual participants supported this result with exceedance of respective threshold or acceptable risk levels at the 95th percentile. Population risk estimates indicated that the proportion with higher than the threshold or acceptable risk is about 10%, 24%, and 12% for Cd, Co, and Pb in rice, respectively. Results of this study showed that health risks associated with PTE exposure through bulgur consumption are lower than those of rice, and below the threshold or acceptable risk levels.Article Citation - WoS: 5Citation - Scopus: 8Investigation of Structural Properties of Clinoptilolite Rich Zeolites in Simulated Digestion Conditions and Their Cytotoxicity Against Caco-2 Cells in Vitro(Springer Verlag, 2013) Kavak, Dilek Demirbüker; Ülkü, SemraThe use of the clinoptilolite rich natural zeolites in biomedical applications such as in anticancer therapy, drug or drug support systems and as nutritive supplement is highly dependent on their behavior in digestive conditions. Aim of this study is to investigate structural stability of clinoptilolite rich natural zeolites in simulated digestion conditions and their interactions with digestive media and with Caco-2 (human colon adenocarcinoma) cells. X-ray Diffraction (XRD), Fourier Transform InfraRed (FTIR), Scanning Electron Microscopy (SEM) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) analyses of the clinoptilolite rich zeolite samples showed that zeolites preserved their structural stabilities during in vitro digestion. Slight interactions were detected in UV measurements of the digestive liquid media and FTIR spectra of the intestinal digested media powders. SEM results implied that zeolites might have a role in the aggregation of the digestive enzymes. Cytotoxicity test using colon cancer cells showed that clinoptilolite rich natural zeolites have cytotoxic effect against Caco-2 cells and cytotoxicity did not significantly change with respect to simulated digestion process.Article Citation - WoS: 10Citation - Scopus: 11Removal of Bacteria by Clinoptilolite Rich Mineral and Its Surfactant Modified Forms(Springer Verlag, 2013) Cansever Erdoğan, Beyhan; Ülkü, SemraBatch experiments were carried out to understand the potential values of clinoptilolite rich mineral and its surfactant modified forms in the removal of Gram-positive and Gram-negative bacteria. Zeta potential and Fourier Transform IR analysis were performed to explain the possible interactions between the bacteria and the zeolite samples. The results revealed that hydrogen bonding was significant mechanism in the removal of bacteria with clinoptilolite rich mineral and anionic surfactant modified clinoptilolite rich mineral whereas both attractive electrostatic forces and hydrogen bonding were dominant mechanism in the removal of bacteria with cationic surfactant modified clinoptilolite rich mineral. Cationic and anionic surfactant modified clinoptilolite rich mineral are promising materials in removal of bacteria studies.
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