Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Department: search.filters.department.İzmir Institute of Technology. Chemical EngineeringSubject: search.filters.subject.Ultrafiltration

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 30
    Citation - Scopus: 33
    Preparation and Characterization of Polyacrylonitrile Membranes Modified With Polyelectrolyte Deposition for Separating Similar Sized Proteins
    (Elsevier Ltd., 2012) Yaşar Mahlıçlı, Filiz; Alsoy Altınkaya, Sacide; Yürekli, Yılmaz
    One of the challenges faced by ultrafiltration membranes is to separate proteins with a small difference in their molecular weights. Recently, some researchers tried to overcome this problem by using charged membranes. This study examined the use of layer by layer deposition of polyelectrolytes on the chemically-modified polyacyronitrile membrane to increase the selectivity of the ultrafiltration. The membranes were prepared by wet-phase inversion technique and polyethylenimine (PEI) and alginate (ALG) were chosen as cationic and anionic polyelectrolytes for the modification of the surfaces. Sieving coefficient data were obtained with myoglobin and lysozyme as model proteins. The influences of solution pH, ionic strengths of the protein and polyelectrolyte solution and the number of polyelectrolyte bilayers on both selectivity and throughput were investigated. The highest selectivity and throughput were achieved with the 1-bilayer PEI-ALG coated polyacrylonitrile (PAN) membrane. Increasing the number of coating bilayers or the ionic strength of the protein solution or adding salt into the polyelectrolyte coating solution decreased both the maximum selectivity and throughput of the modified membranes.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 16
    Catalytic Performances of Chemically Immobilized Urease Under Static and Dynamic Conditions: a Comparative Study
    (Elsevier Ltd., 2011) Yürekli, Yılmaz; Alsoy Altınkaya, Sacide
    Immobilized urease has been used for direct removal of urea from aqueous solution and as biological sensing material in the preparation of urea biosensors. The former application is carried out under dynamic condition using ultrafiltration membrane either in tubular form or in flat sheet, while the latter is used in static condition. In this study, the performance of chemically immobilized urease on poly(acrylonitrile-co-sodium methallyl sulfonate) ultrafiltration membrane was determined under both static and dynamic conditions. Results reveal that the immobilization enhanced the thermal and storage stabilities of urease. The hydraulic permeability of urea solution was not influenced by the addition of enzyme layer. The maximum reaction rate measured under pressure in the ultrafiltration unit was found higher compared to the rate observed just under mixing without any pressure applied. The highest urea conversion was found at the lowest transmembrane pressure and the urea concentration in the feed solution. The catalytic activity of the membrane was completely preserved at the end of 450 min of filtration.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 32
    Separation of Whey Components by Using Ceramic Composite Membranes
    (Elsevier Ltd., 2006) Erdem, İlker; Çiftçioğlu, Muhsin; Harsa, Hayriye Şebnem
    Ceramic supports were prepared from alumina powder and dip-coated with zirconia sol. The ceramic composite membranes prepared were characterized with respect to their microstructure/pore structures. The supports were 40% porous of which 87% were open pores. The average particle size of the sol particles was 35 nm. The prepared membrane has good protein lactose separation properties with a relatively high protein content (PR ∼80%) and with relatively low lactose retention (LR ∼7%). The permeate flux value was around 40 l/m2h. These results indicate the possibility of the preparation of ceramic composite membranes for separation of whey components with higher yields.
  • Conference Object
    Citation - WoS: 5
    Citation - Scopus: 5
    Preparation of Ceramic Composite Membranes for Protein Separation
    (Trans Tech Publications, 2004) Erdem, İlker; Çiftçioğlu, Muhsin; Harsa, Hayriye Şebnem
    Ceramic supports were prepared from fine alumina and zirconia powders by dry-pressing and slip-casting. These supports were heat treated in the 1100° - 1200°C temperature range and dip-coated with ceramic sols prepared from alkoxides by using sol-gel methods. The average sol particle sizes were measured as 3-7 nm for zirconia and 30-40 nm for alumina by laser scattering technique. The optimum heat treatment temperature range was determined as 500°-600°C for dip-coated membranes by using TGA (thermo gravimetric analysis) results. The microstructure of the ceramic composite membranes was investigated by SEM (Scanning electron microscope). The clean water permeability (CWP) of the membranes was tested by using deionized water in a filtration set-up. Separation experiments were performed with bovine serum albumin (BSA, Stokes diameter: 7 nm) solution and whey to determine the protein separation capacity of the composite membranes. The CWP of the dry pressed alumina supports heat treated at 1100°C was found to be higher than the permeability of the slip-casted zirconia supports heat treated at 1200°C. The protein retention of the slip-casted zirconia support was determined as 60% by using UV-Vis spectrophotometer (Abs. at 280nm). A protein retention value of 96% was achieved for whey after the modification of the support with dip-coating. The permeate flux was 40 L/m2hour for dry-pressed alumina support dip-coated with zirconia sol calcined at 500°C.