Deniz Tanyolaç

Cibacron Blue F3GA-attached polyvinylbutyral microbeads as novel magnetic sorbents for removal of Cu(II), Cd(II) and Pb(II) ions

Abstract Magnetic polyvinylbutyral based microbeads containing 12.4 μmol Cibacron Blue F3GA/g were used in the adsorption–desorption of some selected heavy metal ions, i.e., Cu(II), Cd(II) and Pb(II) from aqueous media containing different amounts of these ions (5–500 ppm) and at different pH values (2.0–8.0). Adsorption rates were high, and adsorption equilibria were reached in about 30 min. The maximum adsorptions of heavy metal ions onto the Cibacron Blue F3GA-attached affinity microbeads from their single solutions were 9.6 mg/g for Cu(II), 38.6 mg/g for Cd(II), 86.2 mg/g for Pb(II). When the heavy metal ions competed (in the case of the adsorption from their mixture) the amounts of adsorption were 6.5 mg/g for Cu(III), 20.3 mg/g for Cd(II) and 41.6 mg/g for Pb(II). Under non-competitive and competitive conditions the affinity order of ions was Pb(II)>Cd(II)>Cu(II). Desorption of heavy metal ions was achieved using 0.1 mol HNO3 in 30 min. It was observed that heavy metal ions could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity.

A new low cost magnetic material: magnetic polyvinylbutyral microbeads

In this work, new and feasible magnetic particles were prepared in uniform and spherical form for a diameter range of 125 to 250 μm from a commercial resin Mowital® B30HH (polyvinyl butyral) through a modified solvent evaporation technique. For the production of particles, the most appropriate solvent, stabilization and surface active agents, and stirring rate were determined as chloroform, SDS, pluronic F68 together with PVA and 700 rev./min, respectively. The magnet abundant in nature, magnetite (mean diameter <40 μm), was successfully embedded in the particle structure during polymerization by an elaborate technique and spherical particles with high magnetic quality were realized for possible magnetically fluidized bed or magnetic filtration applications. FTIR studies proved the abundance of hydroxyl groups on the particle surface, which were activated later by glutaraldehyde for bioaffinity separations. Preliminary adsorption runs were conducted with magnetic and non-magnetic microbeads for bovine serum albumin which resulted in remarkable adsorption capacities as high as 86 mg protein per g of magnetic microbeads.

BSA adsorption onto magnetic polyvinylbutyral microbeads

Bovine serum albumin (BSA) adsorption onto novel and feasible magnetic polyvinylbutyral-based microbeads was investigated. The microbeads were made of Mowital® B30HH, a commercial product, in the range 125–250 μm by a modified solvent evaporation technique. Magnetite particles were embedded in the polymer structure for favorable magnetic properties, 4.80 emu/g microbeads of saturation magnetization at 6000 Gauss magnetic field. Glutaraldehyde (GA) was used as a bonding agent to increase stability and as a ligand for protein adsorption. The amount of adsorbed BSA was optimized by changing the medium pH and the initial concentrations of GA and BSA. Dynamic adsorption data of batch runs fitted best to Langmiur kinetics. The parameters qmax, k′f and k′r of the model were estimated through nonlinear regression analysis as 138 mg BSA/g adsorbent, 0.058 ml/(mg BSA · min) and 0.002 min−1, respectively, for magnetic microbeads at pH 5.0 and 25°C. The adsorbed BSA was eluted successfully at pH 8.0 and 25°C. Possibly due to surface roughness and magnetic properties, qmax was found higher than the other adsorbents reported in the literature. The results denote that these microbeads can be an alternative protein adsorbent due to high adsorption capacity and rate, as well as remarkable separation characteristics.

Determination of apparent kinetic parameters for competitive product inhibition in packed-bed immobilized enzyme reactors

Abstract In this study, a simple and effective technique for characterizing Michaelis–Menten type kinetics with competitive product inhibition in packed-bed re-circulated immobilized enzyme reactors is presented, where the use of nonlinear regression techniques for multi-parameter estimation are not required. In order to demonstrate the new technique introduced in this work, enzymatic conversion of lactose in a recycling packed-bed reactor is envisaged where β-galactosidase (lactase, EC 3.2.1.23) enzyme is immobilized on a weak base ion exchanger resin (Duolite A 568). For the experimental conditions used in this research, the total competitive inhibition by product (galactose) model is sufficient to represent the lactose hydrolysis kinetics in a packed-bed reactor.

Preparation of low-cost magnetic nitrocellulose microbeads

Abstract In this work, new magnetic particles were prepared in uniform and spherical form for the range 125 μm D p D p

A new method for determination of apparent kinetics parameters in recirculating packed-bed immobilized enzyme reactors

Abstract In this study, a simple and effective technique for characterizing Michaelis–Menten apparent kinetic parameters in packed-bed immobilized enzyme reactors is presented. The apparent kinetic parameters of immobilized glucose oxidase on weak base ion exchanger resin (Duolite A 568) were determined for different substrate flow rates in a recirculation system and compared with those for soluble glucose oxidase. It was observed that, for the experimental conditions, the immobilized enzyme K ′ m values in a packed-bed reactor were less than the soluble enzyme K m value and were flow dependent. The value of K ′ m decreased with increasing flow rate.

Adsorption of heavy-metal ions on Cibacron Blue F3GA-immobilized microporous polyvinylbutyral-based affinity membranes

Abstract Microporous polyvinylbutyral membranes were prepared by a solvent-casting technique. An affinity dye, i.e. Cibacron Blue F3GA was then immobilized. These affinity membranes with a high water content of 89%, and carrying 3.3 mmol Cibacron Blue F3GA/m 2 membrane were used in the adsorption/stripping of some selected heavy-metal ions (e.g. Cu(II), Zn(II), Cd(II) and Pb(II) from aqueous media containing different amounts of these ions (0.024–4.60 mmol/1) and at different pH values (2.0–9.0). Adsorption rates were very high, and adsorption equilibria were reached in ca. 15 min. The maximum adsorptions of heavy-metal ions onto the Cibacron Blue F3GA-immobilized affinity membranes from their single solutions were 7.0 mmol/m 2 for Cu(II), 16.8 mmol/m 2 for Zn(II), 22.2 mmol/m 2 for Cd(II), and 34.2 mmol/m 2 for Pb(II). Similar behavior was observed when the heavy-metal ions competed (in the case of the adsorption from their mixture), the order of affinity was Pb(II)> Cd(II)> Zn(II)> Cu(II). Heavy-metal ions regeneration was achieved by using 0.1 M HNO 3 in 30 min. It was observed that heavy-metal ions could be repeatedly adsorbed and tripped without significant loss in adsorption capacity.

Para-magnetic polyvinylbutyral particles containing activated carbon as a new adsorbent

In this study, a new type of magnetic particle was prepared in a uniform and spherical form for the range of 750 w m <D p <1000 w m from commercially available polyvinylbutyral (Mowital B30H, Hoechst), magnetite, and activated carbon using solvent evaporation technique. Magnetite (D p <5 w m) was successfully embedded in the adsorbent particles. The surface and cross-sectional views of p -magnetic particles were investigated with a Scanning Electron Microscope (SEM). The intensity of magnetization was measured with a vibrating-sample magnetometer. The adsorption studies of phenol and chromium (Cr(VI)) onto the adsorbent particles were carried out batch-wise. The effects of activated carbon and magnetite percentages on the adsorption capacity were investigated, and different initial adsorbate concentration and pH values were examined. Desorption experiments were carried out with different concentrations of NaOH, and it was determined that approximately 95% of adsorbed ions were desorbed. It was concluded that the para-magnetic polyvinylbutyral particles containing activated carbon and magnetite could effectively be used in the adsorption of organic and inorganic pollutants.

Ozonated Olive Oil with a High Peroxide Value for Topical Applications: In-Vitro Cytotoxicity Analysis with L929 Cells

ABSTRACT Previous studies have shown that ozonated vegetable oils have been used topically for healing of cutenous wounds. The aim of this study is to evaluate the dose dependent use of ozonated olive oil with high peroxide value (OZ) on the viability of cells for preventing side effects in topical applications. To the best of our knowledge, there are no reports investigaing the effect of peroxide value of ozonated olive oil associated with its cytotoxic activity on mouse non-neoplastc fibroblast cell lines (L929). Therefore, the present study was carried out by using OZ alone and/or in combination with glycerol and olive oil. In our study OZ was prepared by using pure olive oil. Both olive oil and glycerol are non-toxic and can be mixed with OZ uniformly. The cytotoxic activity of samples against L929 fibroblasts was assessed using the tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay. The peroxide value of synthesized OZ was found to be in the range of 2700–2900 mEq O2/kg oil. The OZ/olive oil group did not show any cell death at all concentrations tested (p > 0.05) however OZ/glycerol group showed statistically significant reductions in viability at higher concentrations (p = 0.004–0.006) compared to the control group. Conclusively, using OZ/olive oil with a peroxide value of 2700–2900 mEq O2/kg oil for short-term incubation was non-cytotoxic to the L929 fibroblast cell line.