Serap Senel

Mercury removal from synthetic solutions using poly(2-hydroxyethylmethacrylate) gel beads modified with poly(ethyleneimine)

In this study, the Hg2+ adsorption–desorption properties of poly(ethyleneimine) (PEI)-attached poly(2-hydroxyethylmethacrylate) (PHEMA) beads were investigated. Spherical PHEMA beads with an average size of 150–200 μm were obtained by suspension polymerization of 2-hydroxyethylmethacrylate conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, PHEMA beads had a specific surface area of 14.8 m2/g. PEI chains could be covalently attached onto the PHEMA beads with equilibrium binding capacities up to 50 mg PEI/g beads. PEI-attached PHEMA beads were utilized as adsorbent in the adsorption–desorption of Hg2+ ions from synthetic solutions. The adsorption process was fast; 90% of adsorption occurred within 45 min and equilibrium was reached at around 1 h. The maximum Hg2+ adsorption capacity obtained was 1.67 mmol/g at a pH of about pH 5.0. Adsorption behavior can be described at least approximately by the Langmuir equation. The metal-chelating beads can be easily regenerated by 0.1 M HNO3 with higher effectiveness. Adsorption of heavy metal ions from artificial wastewater was also studied. The adsorption capacities were 1.32 mmol/g for Hg2+, 0.34 mmol/g for Ni2+ and 0.42 mmol/g for Cu2+.

Cibacron blue F3G-A-attached uniform and macroporous poly(styrene-co-divinylbenzene) particles for specific albumin adsorption.

Cibacron blue F3G-A-carrying uniform macroporous particles were proposed as an alternative sorbent for specific albumin adsorption. These particles were produced by a multistep polymerization procedure. In the first step of production, the uniform polystyrene seed particles were prepared by a dispersion polymerization method. Next. the polystyrene seed particles were first swollen by dibutylphthalate and then by styrene-divinylbenzene mixture in an aqueous emulsion medium. In the last step (i.e. repolymerization), styrene-divinylbenzene mixture was copolymerized within the swollen seed particles in the absence or presence of a stabilizer (e.g. poly(vinyl alcohol)). Although a considerable amount of non-specific BSA adsorption was observed on the surface of the particles produced in the absence of PVA, zero non-specific albumin adsorption could be achieved with the uniform macroporous particles produced in the presence of PVA. The stabilizer on the particle surface was also used as a ligand in the further derivatization of macroporous particles for specific albumin adsorption. Cibacron blue F3G-A was then covalently attached onto the surface of uniform macroporous particles. Specific albumin adsorption capacities up to 93 mg g(-1) could be achieved with the cibacron blue F3G-A-carrying macroporous particles of 6.25 microm in size.

Heavy Metal Removal from Synthetic Solutions with Magnetic Beads Under Magnetic Field

The aim of this study is to prepare magnetic beads which can be used for the removal of heavy metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate‐vinyl imidazole) [m‐poly(EGDMA‐VIM)] beads were produced by suspension polymerization in the presence of magnetite Fe3O4 nano‐powder. The specific surface area of the m‐poly(EGDMA‐VIM) beads was found to be 63.1 m2/g with a size range of 150–200 µm in diameter and the swelling ratio was 85%. The average Fe3O4 content of the resulting m‐poly(EGDMA‐VIM) beads was 12.4%. The maximum binding capacities of the m‐poly(EGDMA‐VIM) beads were 32.4 mg/g for Cu2+, 45.8 mg/g for Zn2+, 84.2 mg/g for Cd2+and 134.5 mg/g for Pb2+. The affinity order on mass basis is Pb2+>Cd2+>Zn2+>Cu2+. Equilibrium data agreed well with the Langmuir model. pH significantly affected the binding capacity of the magnetic beads. Binding of heavy metal ions from synthetic wastewater was also studied. The binding capacities were 26.2 mg/g for Cu2+, 33.7 mg/g for Zn2+, 54.7 mg/g for Cd2+ and 108.4 mg/g for Pb2+. The magnetic beads could be regenerated up to about 97% by treating with 0.1 M HNO3. These features make m‐poly(EGDMA‐VIM) beads a potential candidate for support of heavy metal removal under magnetic field.

DNA-responsive uniform latex particles based on p-chloromethylstyrene

In this study, DNA binding properties of poly(ethylenimine) (PEI)-attached uniform poly(p-chloromethystyrene) (PCMS) particles were investigated. Spherical PCMS latex particles with an average size of 1.75 μm were obtained by the dispersion polymerization of p-chloromethylstyrene (CMS). PEI was covalently attached onto the PCMS particles via a direct chemical reaction between amine and chloromethyl groups, with the equilibrium binding capacities up to 41 mg PEI/g PCMS. In aqueous media, PEI attached-uniform PCMS particles showed an irreversible aggregation behaviour in the presence of DNA. To predict unknown DNA concentration, the aggregation response of these particles to the presence of DNA was quantified by spectrophotometry. Plain PCMS and PEI attacheduniform PCMS particles were also utilized as sorbents in DNA adsorption experiments conducted at +4°C in a phosphate buffer medium at pH 7.4. DNA immobilization capacities up to 45 mg DNA/g PCMS could be achieved with the PEI attached particles.

Production and characterization of poly(ethylene glycol dimethacrylate-styrene-glycidyl methacrylate) microbeads

Nonswellable and swellable poly(ethyleneglycol dimethacrylate)-based microbeads that could react directly with the biological molecules were produced by a suspension polymerization procedure. For this purpose, ethyleneglycol dimethacrylate (EGDMA) was copolymerized with glycidyl methacrylate (GMA) in an aqueous suspension medium. Benzoyl peroxide and poly(vinyl alcohol) were used as the initiator and the stabilizer, respectively. The copolymerization provided nonswellable, tranparent, and spherical copolymer microbeads in the size range of 100–300 μm. On the other hand, swellable copolymer microbeads in the aqueous medium were obtained by using toluene as a diluent in the same copolymerization recipe. In a separate group of polymerizations, styrene (St) monomer was also included within the monomer phase to regulate the hydrophobicity of resulting microbeads. Nonswellable and swellable poly-(EGDMA-St-GMA) microbeads were obtained by changing the type and concentration of the ingredients within the monomer phase. The effects of glycidyl methacrylate, styrene, and toluene concentrations on the microbead yield, the average size, and the swellability of microbeads were investigated. In the second part of the study, the interaction of produced microbeads with a selected enzyme (i.e., chymotrypsin) was investigated. The most stable chymotrypsin immobilization was achieved with the swellable poly(EGDMA)-based microbeads including styrene.

Uniform Particles for the Reversed-Phase Separation of Proteins with High-Resolution and High-Column Efficiency

Abstract A low‐sized, uniform and polymer‐based high‐performance liquid chromatography (HPLC) packing material capable of making reversed‐phase separation of proteins with high resolution and with high column efficiency was developed. By a multistage‐swelling and polymerization protocol, 5 µm‐uniform‐porous poly(styrene‐co‐divinylbenzene) particles with relatively larger pores particularly suitable for protein separation were synthesized by starting from a low‐sized seed latex with high average molecular weight and by using a diluent phase comprised of dibutylphthalate and toluene. By the use of synthesized beads as packing material in HPLC, high‐resolution liquid chromatograms were obtained in the gradient separation of selected proteins (i.e., ribonuclease‐A, lysozyme, cytochrome C, and albumin). In the chromatographic runs, the flow rate of the mobile phase was increased fourfold by preserving the resolution power of the column material under gradient conditions. The theoretical plate numbers (TPN) up to 12.500 plates/m were observed by using cytochrome C as the analyte. TPN values determined by the proteins were significantly higher relative to the similar uniform packing materials larger in size (i.e., 7.5–10 µm) obtained by different polymerization methods.