Niyazi Bicak

Graft copolymer of acrylamide onto cellulose as mercury selective sorbent

Polyacrylamide grafted onto cellulose has been demonstrated to be a very efficient selective sorbent for removal of mercuric ions from aqueous solutions. The mercury-uptake capacity of the graft polymer is as high as 3.55 mmol/g and sorption is also reasonably fast. Thus, 0.2 g of the graft copolymer is able to extract 50 ppm Hg(II) from 50 ml water completely in 8 min. The Hg(II) sorption is selective and no interferences have been observed in the presence of Ni(II), Co(II), Cd(II), Fe(III), Zn(II) ions in 0.1 M concentrations at pH 6. Regeneration of the loaded polymer without losing its original activity can be achieved using hot acetic acid. The graft copolymer described seems very suitable for removal of large amounts of mercury in hydrometallurgical applications and may also be useful for other water treatments.

Modification of crosslinked glycidyl methacrylate-based polymers for boron-specific column extraction

Abstract Terpolymers of glycidyl methacrylate (0.4 mol) with methyl methacrylate (0.5 mol) and divinyl benzene (0.1 mol) in spherical beads form have been modified with N -methyl- d -glucamine in N -methyl pyrrolidone solvent. Polymers with (2.05 mmol g −1 ) functionality have moderate swelling ability (1.81 v / v 0 ) and show excellent boron uptake ability (2.15 mmol g −1 ) for extraction of trace quantities of H 3 BO 3 from aqueous solutions. The resinous polymer with 110–210 μm size has a reasonable breakthrough capacity (0.835 mmol g −1 ) and a sharp elution profile in the column extractions. No interferences come from Ca(II), Mg(II) and Fe(III) ions (0.1 M), though slightly in the presence of these ions due to coprecipitation of borates by the metal hydroxides formed on the resin particles. The capacity of the resin and flow rate do not change even after 20 recyclings in the column extractions. The method has been shown to be promising for large-scale boron extractions from aqueous solutions.

Polymer supported iminodipropylene glycol functions for removal of boron

Polymer supported iminodipropylene glycol functions have been shown to be efficient in chelation with boric acid and can be used for removal of boric acid at ppm levels. Glycidyl methacrylate (GMA)–methyl methacrylate (MMA)–DVB (divinyl benzene) terpolymer beads have been prepared and used as support. The polymer support with 3.4 mmol g−1 oxirane content can be readily modified by reacting with an excess of ethylene diamine, in high conversion yields (99.1%). Reaction of the latter with glycidol gives corresponding resin with aminopropylene glycol functions. The resulting resin has been demonstrated to be an efficient sorbent for removal of boron. The resin has 3 mmol g−1 of boron loading capacity and shows reasonably rapid sorption ability so that boron in 10 ml of H3BO3 solution (50 ppm) can be removed almost completely in less than 12 min of contact time by 0.5 g of polymer sample. Splitting of sorbed boron can be achieved by simple acid leaching (4 M HCl) and regenerated by NaOH solution (0.1 M).

Removal of boron from aqueous solutions by continuous polymer-enhanced ultrafiltration with polyvinyl alcohol

Boron is a highly contaminating metal due to its toxic effects for plants even at very low concentrations. Continuous polymer-enhanced ultrafiltration (PEUF) was applied for removal of boron from aqueous solutions. The effects of operating parameters on the performance of PEUF were investigated. A commercial polymer, polyvinyl alcohol (PVA) was used as the boron-complexing agent. The methodology consists of two steps: complexing boron with PVA following separation of boron and polymer complexes by ultrafiltration process. The pilot scale system utilized for the PEUF process accommodates a spiral-wound cellulose cartridge with 10,000 Da MWCO. The experimental parameters studied are metal/polymer ratio (loading) (0.01–0.5), pH (7–10), and the polymer characteristics such as molecular weight (M n) of the polymer and degree of hydrolysis (DoH). The results showed that PEUF could be a successful alternative method for removal of boron. The permeate flux remained constant at around 19 L/m2 hr throughout the runs and the fluxes were not affected by the operating parameters studied and by the polymer characteristics. When the loading values were decreased, the retention of boron was increased. Also, pH had an important influence as increase in pH resulted in increase in retention of boron. The polymeric M n of the polymer did not have any influence on the retention of boron while an increase in DoH caused a decrease in retention of boron.

Atom transfer radical graft polymerization of acrylamide from N-chlorosulfonamidated polystyrene resin, and use of the resin in selective mercury removal

Polyacrylamide was grafted from N-chlorosulfonamide groups onto crosslinked polystyrene beads using copper-mediated atom transfer radical polymerization (ATRP) methodology. A beaded polymer with a polyacrylamide surface shell was prepared in four steps, starting from styrene–divinylbenzene (10%) copolymer beads of 210–420 mm particle size: chlorosulfonation; sulfamidation with propylamine; N-chlorination with aqueous hypochloride; and grafting using a concentrated aqueous acrylamide solution with a CuBr–tetramethylethylenediamine complex (1:2). The resulting polymer resin with 84 wt% grafted polyacrylamide has been demonstrated to be an efficient mercury-specific sorbent, able to remove Hg(II) from solutions at ppm levels. No interference arises from common metal ions such as Cd(II), Fe(III), Zn(II), and Pb(II). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups.  2002 Elsevier Science B.V. All rights reserved.

A glycidyl methacrylate-based resin with pendant urea groups as a high capacity mercury specific sorbent

Abstract Polymer-supported pendant urea groups have been demonstrated to be very efficient in selective removal of mercuric ions from aqueous solutions. Methyl methacrylate (0.5 mol)–glycidyl methacrylate (0.4 mol)–divinylbenzene (0.1 mol) terpolymer beads have been prepared by suspension polymerisation. Urea functions have been incorporated into the bead polymer (210–420 μm) via a two-step modification of the epoxy groups involving firstly reaction with excess of triethylenetetramine followed by acidic isocyanate. The resulting polymer resin has a urea group loading of 7.8 mmol g−1 and shows excellent mercury binding capacity >6.7 mmol g−1, even in the presence of excess chloride ions. The mercury sorption is strictly selective and Ca(II), Mg(II), Zn(II), Pb(II), Fe(II) and Cd(II) ions (0.2–0.3 M) do not give rise to any interference. The mercury can be recovered from loaded beads using hot acetic acid thereby regenerating the polymer. Recovered samples can be recycled more than 20 times without loss of activity as a result of the hydrolytic stability of the urea group in acetic acid.

Crosslinked polymer gels for boron extraction derived from N-glucidol-N-methyl-2-hydroxypropyl methacrylate

Glycidyl methacrylate was reacted in 2-methyl pyrrolidone solution with N-methyl-D-glucamine (NMG) to produce N-D-glucidol, N-methyl-2-hydroxy propyl methacrylate (GMHP). The reaction proceeded exclusively via ring opening of the oxirane. The resulting vinyl monomer was a waxy product and soluble in water, ethanol, methanol, DMF, and NMP. Copolymerization of GMHP with N, N t - tetraallyl piperazinium dichloride by the inverse suspension method (water in oil), using a toluene/chloroform (3 : 1) mixture as continuous phase, led to crosslinked hydrogels in imperfect bead form. Crosslinking was also achieved without using additional crosslinker. Heating of N-methyl-D-glucamine with 10 % excess of glycidyl methacrylate in NMP at 60 ° C for 4 h, resulting the formation of N-methyl-D-glucamine carrying two methacrylate groups. These dimethacrylate groups serve as a crosslinking agents. In situ redox polymerization of the mixture in water led to transparent hydrogels. These hydrogels in the swollen state have been demontrated to be very efficient sorbents for the removal of boron on ppm levels. The boron loaded polymers can be regenerated by simple acid (0,1 M HC1) and base (0,1 M NaOH) treatment.

Glycidyl methacrylate based polymer resins with diethylene triamine tetra acetic acid functions for efficient removal of Ca(II) and Mg(II)

Abstract Crosslinked terpolymer beads prepared by suspension polymerization of glycidyl methacrylate (GMA) (0.4 mol), methyl methacrylate (MMA) (0.5 mol) and divinyl benzene (DVB) (0.1 mol) mixtures have been modified through epoxy functions in two steps: (i) by treating with excess of diethylene triamine (DETA); and (ii) by subsequent reaction with potassium chloroacetate. The resulting polymer possessing diethylene triamine tetra acetic acid (DTTA) functions (with degree of functionalization DF:1.70 mmol·g −1 ) is an efficient sorbent for removal of Ca (II) and Mg (II) ions in ppm levels. Interestingly when the sodium form of the resin is used in relatively high concentrations (0.1 M) sorbed amounts will be 10–45% in excess of the theoretical capacity due to precipitation of the metal hydroxides on polymer particles beside chelation with the metal ions. Having EDTA-like chelating units, the polymer is able to absorb also heavy metal ions such as Fe (III), Zn (II), Cd (II), Pb (II), Ni (II), Cu (II), Co (II) ions. Not having hydrolysable linkages, metal-free resins can be obtained by acid treatment (4 M HCl) without loosing its activity. The resin with DTTA functions seems to be applicable in large scale water softening processes.

Immobilization of catalase via adsorption on poly(styrene-d-glycidylmethacrylate) grafted and tetraethyldiethylenetriamine ligand attached microbeads

Fibrous poly(styrene-d-glycidylmethacrylate) (P(S-GMA)) brushes were grafted on poly(styrene-divinylbenzene) (P(S-DVB)) beads using surface initiated-atom transfer radical polymerization (SI-ATRP). Tetraethyldiethylenetriamine (TEDETA) ligand was incorporated on P(GMA) block. The multi-modal ligand attached beads were used for reversible immobilization of catalase. The influences of pH, ionic strength and initial catalase concentration on the immobilization capacities of the P(S-DVB)-g-P(S-GMA)-TEDETA beads have been investigated. Catalase adsorption capacity of P(S-DVB-g-P(S-GMA)-TEDETA beads was found to be 40.8 ± 1.7 mg/g beads at pH 6.5 (with an initial catalase concentration 1.0mg/mL). The K(m) value for immobilized catalase on the P(S-DVB-g-P(S-GMA)-TEDETA beads (0.43 ± 0.02 mM) was found about 1.7-fold higher than that of free enzyme (0.25 ± 0.03 mM). Optimum operational temperature and pH was increased upon immobilization. The same support was repeatedly used five times for immobilization of catalase after regeneration without significant loss in adsorption capacity or enzyme activity.

Amine functional monodisperse microbeads via precipitation polymerization of N-vinyl formamide: immobilized laccase for benzidine based dyes degradation.

Densely cross-linked poly(vinylamine) microbeads (∼ 2 μm) were prepared by precipitation copolymerization of N-vinyl formamide and ethylene glycoldimethacrylate in acetonitrile. The formamido groups of the microbeads were hydrolyzed into amino groups. Then, amino-functionalized microbeads were used for covalent immobilization of laccase via glutaraldehyde coupling. The average amount of immobilized enzyme was 18.7 mg/g microbeads. Kinetic parameters, V(max) and K(m) values were determined as 20.7 U/mg protein and 2.76 × 10(-2)mmol/L for free enzyme and 15.8 U/mg protein and 4.65 mmol/L for the immobilized laccase, respectively. The immobilized laccase was operated in a batch reactor for the degradation of two different benzidine based dyes (i.e., Direct Blue 1 and Direct Red 128). The laccase immobilized on the microbeads was very effective for removal of these dyes which interfere with the hormonal system.