Chapter 2: High Capacity Removal of Mercury(II) Ions by Poly(Hydroxyethyl Methacrylate) Nanoparticles

Nanotechnology is an enabling technology that deals with nanometer-sized objects [1]. It is expected that nanotechnology will be developed at several levels: materials, devices, and systems. The level of nanomaterials is the most advanced at present, both in scientific knowledge and in commercial applications. A decade ago, nanoparticles were studied because of their size-dependent physical and chemical properties [2]. Now, they have entered a commercial exploration period [3]. Many published works focused on the synthesis of micrometer-sized polymer matrices [4]. Only limited work has been published on the application of nanosized particles in the adsorption of heavy metal ions. Nanosized particles can produce larger specific surface area and, therefore, may result in high binding capacity for metal ions. Therefore, it may be useful to synthesize nanosized particles and utilize them for the removal of heavy metal ions [5–10].

Surface modification can be accomplished by physical and chemical binding or surface coating of desired molecules, depending on the specific applications [11]. Surface modification is an active research area in the fields of microelectronics, biotechnology, and material science. Properties such as adhesion, wettability, biocompatibility, and binding affinity of the surface can be altered and tuned to the specific requirements by chemical or physical modification of the surfaces [12]. Nowadays, modified materials are well known and have been investigated intensively due to their potential applications in many areas such as biology, medicine, and environment. Surface modification of particles by organic compounds can be achieved via organic vapor condensation, polymer coating, surfactant binding, and direct silanization. Direct silanization is attractive for improving stability and control of surface properties [13].

Mercury is a common pollutant of water, resulting from the burning of coal by power plants, and in the inappropriate disposal from batteries, paints, lights, and industrial by-products. Mercury poisoning is becoming more important because of the extensive contamination of water and fish and the increasing consumption of fish in the human diet [14]. Mercury is cytotoxic, exerting its effect by depleting the thiol reserves in the mitochondria, resulting in cell death. It is extremely neurotoxic and leads to dizziness, irritability, tremor, depression, and memory loss [15]. It is also toxic to the kidneys and colon, the two main sites of excretion. Mercury is released very slowly from the body with a half-life of at least 60 days, resulting in increasing amounts with chronic consumption of contaminated fish [16].

In the gastrointestinal tract, methylmercury (MeHg) is absorbed to approximately 95%, Hg²⁺ to approximately 7%, and elemental Hg to less than 0.01%. The absorption of elemental mercury (Hg°) in the lung is approximately 80%. Within tissues, MeHg is slowly demethylated to Hg²⁺. Elemental mercury is rapidly oxidized to the mercurous form (Hg⁺) and then to the mercuric form (Hg²⁺) in blood by catalase [17]. However, the time that this transformation takes is sufficient for Hg° to reach the tissues of the central nervous system, which is its primary target organ [18]. The kidney is considered the target organ for the Hg⁺ and Hg²⁺, but these forms are also known to accumulate readily in virtually all ectodermal and endodermal epithelial cells and glands. At the target tissues, the mercury entities exert various cytotoxic effects as a result of binding to sulfhydryl groups [19].

The goal of this study is to report the synthesis of poly(hydroxyethyl methacrylate) (PHEMA) nanoparticles carrying reactive imidazole containing 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) and their use in the adsorptive removal of mercury(II) ions from synthetic solutions by metal chelation. PHEMA nanoparticles (150 nm in diameter) were produced by a surfactant-free emulsion polymerization technique. Then, IMEO was attached to the nanoparticles as a metal complexing agent. PHEMA-IMEO nanoparticles were characterized by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Removal studies were conducted to evaluate the binding capacity of Hg²⁺ onto the PHEMA-IMEO nanoparticles. Elution of Hg²⁺ and regeneration of the silanized nanoparticles were also tested.

2. Materials and Methods

2.1. Chemicals

Hydroxyethyl methacrylate (HEMA, Sigma Chem. Co., St. Louis, USA) and ethylene glycol dimethacrylate (EGDMA, Aldrich, Munich, Germany) were distilled under vacuum (100 mmHg). 3-(2-imidazoline-1-yl)propyl (triethoxysilane) (IMEO, molecular weight: 274.43 g/mol) was purchased from Sigma. Poly(vinyl alcohol) (molecular weight: 100,000, 98% hydrolyzed) was purchased from Aldrich (Munich, Germany). All other chemicals were of the highest purity commercially available and were used without further purification. All water used in the experiments was purified using a Barnstead (Dubuque, IA, USA) ROpure LP^® reverse osmosis unit with a high flow cellulose acetate membrane (Barnstead D2731), followed by a Barnstead D3804 NANOpure^® organic/colloid removal and ion exchange packed bed system.

2.2. Synthesis of PHEMA Nanoparticles

Surfactant-free emulsion polymerization was carried out according to the literature procedure with minor modifications as reported elsewhere [20]. Briefly, the stabilizer, PVAL (0.5 g), was dissolved in 50 ml deionized water for the preparation of the continuous phase. Then, the monomer mixture HEMA/EGDMA (0.6 ml/0.01 ml) was added to the dispersion, which was mixing in an ultrasonic bath for about half an hour. Potassium persulphate (KPS, initiator) concentration in monomer phase was 0.44 mg/ml. Prior to polymerization, an initiator was added to the solution and nitrogen gas was blown through the medium for approximately 1–2 min to remove dissolved oxygen. Polymerization was carried out in a constant temperature shaking bath at 70 °C under nitrogen athmosphere for 24 h. After the polymerization, the nanoparticles were washed with methanol and water several times to remove the unreacted monomers. For this purpose, the nanoparticles were precipitated and collected with the help of a centrifuge (Zentrifugen, Universal 32 R, Germany) at the rate of 18,000 g for 1 h and resuspended in methanol and water several times. Then, the PHEMA nanoparticles were further washed with deionized water.

2.3. Silanization of PHEMA Particles

Silane is a coupling agent and its bifunctional molecule bonds to both the exposed composite filler particles and the bonding resin [21]. The silane compounds readily react with the surface hydroxyl groups of the different supports [22]. It is assumed in the literature that the silane molecules are first hydrolyzed by the trace quantities of water present either on the surface of the support or in the solvent, followed by the formation of a covalent bond with the surface [23]. For the silanization, PHEMA nanoparticles and IMEO (mol ratio 1:10) were mixed and stirred at 25 °C for about 4 days. At the end of this period, stirring was stopped. The silanization reaction takes place at 25 °C without any catalyst as shown in Fig. 2.1. The resulting silanized nanoparticles were centrifuged and washed with dichloromethane. Then, the nanoparticles were resuspended in distilled water. To evaluate the degree of silanization (i.e., IMEO loading), the PHEMA nanoparticles were subjected to Si analysis using flame atomizer atomic absorption spectrometer (AAS, AAnalyst 800, Perkin Emler, USA). The reaction between the PHEMA and IMEO is given in Fig. 2.1.

2.4. Characterization Experiments

The average particle size and size distribution were determined using Zeta Sizer (Malvern Instruments, Model 3000 HSA, England).

The nanoparticles were imaged in dry state using TEM (FEI Company Tecnai^™, G2 Spirit, Biotwin, 20–120 kV). The microscope sample was prepared by placing a drop of the polymer dispersion on a carbon-coated Cu grid, followed by solvent evaporation at room temperature.

FTIR spectra of the IMEO, the PHEMA, and the PHEMA-IMEO nanoparticles were obtained using a FTIR spectrophotometer (Varian FTS 7000, USA). The dry nanoparticles (about 0.1 g) were thoroughly mixed with KBr (0.1 g, IR Grade, Merck, Germany) and pressed into a tablet form and the spectrum was recorded. To prepare a liquid sample (e.g., IMEO) to FTIR analysis, first place a drop of the liquid on the surface of a highly polished KBr plate, then place a second plate on top of the first plate so as to spread the liquid in a thin layer between the plates, and clamps the plates together. Finally, wipe off the liquid out of the edge of plate, and then record the spectrum.

Figure 2.1 Schematic presentation of the reaction between PHEMA and IMEO.

To evaluate the degree of silanization, the PHEMA nanoparticles were subjected to Si analysis using flame atomizer AAS.

The surface area of the PHEMA nanoparticles was calculated using the following expression:

Here, N is the number of nanoparticles per milliliter; S is the % of solids; ρ_s is the density of bulk polymer (g/mL); d is the diameter (nm). The number of nanoparticles in per milliliter suspension was determined using mass–volume graph of nanoparticles. From all these data, specific surface area of the PHEMA nanoparticles was calculated by multiplying N and surface area of one nanoparticle.

2.5. Hg²⁺ Adsorption Studies

Adsorption of Hg²⁺ from aqueous solutions was investigated in batch experiments. Effects of Hg²⁺ concentration and pH of the medium on the adsorption rate and capacity were studied. 100 mL aliquots of aqueous solutions containing different amounts of Hg²⁺ (in the range of 10–500 mg/L) were treated with the nanoparticles at different pH (in the range of 2.0–7.0) (adjusted with HCl-NaOH). The nanoparticles (100 mg) were stirred with a mercury nitrate salt solution at room temperature for 2 h. All glassware for adsorption experiments were washed with 1 M HNO₃ and rinsed thoroughly with deionized water. The concentration of the Hg²⁺ in the aqueous phase was measured using an AAS. A Shimadzu Model AA-6800 Flame Atomic Absorption Spectrophotometer (Japan) was used. For mercury determinations, Mercury Vapor Unit (MVU)-1A was used. Deuterium background correction was applied throughout the experiments, and the spectral slit width was 0.5 nm. The instrument response was periodically checked with a known Hg²⁺ standard solution. The adsorption experiments were performed in replicates of three and the samples were analyzed in replicates of three as well. For each set of data present, standard statistical methods were used to determine the mean values and standard deviations. Confidence intervals of 95% were calculated for each set of samples to determine the margin of error. The adsorption capacity of the nanoparticles was calculated according to the mass balance on mercury ion.

2.6. Competitive Adsorption

Competitive heavy metal adsorption from aqueous solutions containing Hg²⁺, Cd²⁺ and Pb²⁺ was also investigated in a batch experimental system. A solution (100 ml) containing 50 mg/L of each metal ion was treated with the nanoparticles (100 mg) at a pH of 5.0 in the flasks and stirred magnetically at 100 rpm. The temperature was maintained at 25 °C. After a sufficient amount of time for equilibration, the solution was centrifuged, and the supernatant was removed and analyzed for remaining metal ions. The amounts of adsorbed heavy metal ions were then determined by difference. Equilibration time was relatively short; the adsorption experiment (from initial contact to final determination) was completed in 30 h.

2.7. Desorption and Repeated Use

Desorption of Hg²⁺ ions were studied with 0.5% thiourea in 0.05 M HCl solution. The nanoparticles were placed in this desorption medium and stirred continuously (at a stirring rate of 600 rpm) for 15 min at room temperature. The desorption ratio was calculated from the amount of Hg²⁺ ions adsorbed on the nanoparticles and the final concentration of Hg²⁺ ions in the desorption medium. To test the reusability of the nanoparticles, adsorption–desorption procedure of Hg²⁺ ions was repeated 20 times using the same nanoparticles. To regenerate after desorption, the nanoparticles were washed with 0.1 M HNO₃.

3. Results and Discussion

Nanoparticles can produce larger specific surface area and therefore may result in high metal-complexing ligand loading. Therefore, it may be useful to synthesize nanoparticles with large surface area and utilize them as suitable carriers for the adsorption of metal ions. The specific surface area was calculated as 1779 m²/g. PHEMA nanoparticles with an average size of 150 nm in diameter and with a polydispersity index of 1.171 were produced by surfactant-free emulsion polymerization. It is apparent that the PHEMA nanoparticles are perfectly spherical with a relatively smooth surface and uniform as shown by the TEM images (Fig. 2.2). The small polydispersity index suggests that nucleation is fast compared to particle growth, and also the absence of a secondary nucleation step. In addition, the total monomer conversion was determined as 98.5% (w/w) for PHEMA nanoparticles. PHEMA nanoparticles were highly dispersive in water by ultrasonication due to hydroxyl groups on the surface of nanoparticles. The dispersion state of the particles was confirmed visually by the observed white color of the suspension. The aqueous dispersion of nanoparticles was stable for several days.

Figure 2.2 Transmission electron microscopy image of PHEMA nanoparticles.

FTIR spectra of the IMEO, the PHEMA, and the PHEMA-IMEO are shown in Fig. 2.3. In the FTIR spectrum of the IMEO, the strong absorption bands at 1605 cm⁻¹, assigned to the characteristic n(C=N) vibrations, indicated a strong band at 2928 and 2974 cm⁻¹ n(C–H) (Fig. 2.3A). The n(O–H) stretching vibration in PHEMA, observed in the 3600–3410 cm⁻¹ range as broad absorptions, indicated a strong band at 1730 cm⁻¹ due to n(C=O) group and the 2954 cm⁻¹ n(C–H) stretching of CH3 indicated the 1268 cm⁻¹ n(C–O) stretching vibration (Fig. 2.3B). The characteristic n(C=O), n(C=N), and n(C–H) stretching vibration bands of the PHEMA-IMEO are observed at 1728 cm⁻¹, 1660 cm⁻¹, and 2954 cm⁻¹, respectively (Fig. 2.3C). In addition, the n(Si–O–C) vibration band is observed at 1264 cm⁻¹. As a result, the peak position of 1264 cm⁻¹ is related to n(Si–O–C) and the observance of C=N bands of the PHEMA-IMEO at 1660 cm⁻¹ and the shifts of the C=N vibration to higher frequencies of 1660 cm⁻¹ due to the silanization of nanoparticles.

Figure 2.3 FTIR spectra of (A) IMEO; (B) PHEMA; (C) PHEMA-IMEO.

3.1. Effect of Hg²⁺ Concentration

Figure 2.4 shows the equilibrium concentration of Hg²⁺ dependence of the adsorbed amount of the Hg²⁺ onto the both PHEMA and PHEMA-IMEO nanoparticles. Adsorption of Hg²⁺ onto the PHEMA nanoparticles was very low (approximately 0.144 mg/g) because PHEMA nanoparticles do not contain any binding sites for complexation of Hg²⁺. This very low adsorption value of Hg²⁺ may be due to weak interactions between Hg²⁺ and hydroxyl groups on the surface of the PHEMA nanoparticles. However, IMEO incorporation into the polymer structure significantly increased the adsorption capacity to 746 mg/g. The adsorption values increased with increasing equilibrium concentration of Hg²⁺, and a saturation value is achieved at an ion concentration of 180 mg/L, which represents saturation of the active binding sites on the PHEMA-IMEO nanoparticles.

Figure 2.4 Effect of Hg²⁺ concentration on adsorption of Hg²⁺ on the PHEMA and PHEMA-IMEO nanoparticles; IMEO loading: 1021 µmol/g; pH: 5.0.

IMEO content of the adsorbent nanoparticles used in this group of experiments was 247 µmol/g. The maximum Hg²⁺ adsorption capacity achieved in the studied range is approximately 221.8 mmol per unit mass of the nanoparticles. This seems to give a stochiometry of one IMEO group per one mercury ion.

Different polymeric adsorbents carrying metal-chelating ligands with a wide range of adsorption capacities for mercury ions have been reported (Table 2.1). Comparing the maximum adsorption capacities, it seems that the adsorption capacity achieved with the novel IMEO-incorporated PHEMA nanoparticles is rather satisfactory.

Table 2.1 Comparison of adsorption capacities of different adsorbents

3.2. Effect of pH

The most critical parameter for metal adsorption is pH as it influences both the polymer surface chemistry and the solution chemistry of soluble metal ions. Due to the deprotonation of the acidic groups of the metal complexing ligand (IMEO molecules), its adsorption behavior for metal ions is influenced by the pH value, which affects the surface structure of adsorbents, the formation of metal hydroxides, and the interaction between adsorbents and metal ions. Therefore, to establish the effect of pH on the adsorption of Hg²⁺ onto both the PHEMA and the PHEMA-IMEO nanoparticles, we repeated the batch adsorption equilibrium studies at different pH in the range 2.0–7.0. In this group of experiments, the equilibrium concentration of Hg²⁺ and the adsorption equilibrium time were 43 mg/L and 2 h, respectively. The pH dependence of adsorption values of Hg²⁺ is shown in Fig. 2.5. In the case of PHEMA nanoparticles, adsorption is pH independent. But it is indicated that the adsorption of Hg²⁺ onto the PHEMA-IMEO nanoparticles was pH dependent. The results show that mercury adsorption by the PHEMA-IMEO nanoparticles was very low at pH 2.0 but increased rapidly with increasing pH and then reached the maximum at pH 5.0. The competitive adsorption of hydrogen ions with Hg²⁺ ions for imidazole groups at lower pH values accounts for the observed low adsorption capacity. Because the imidazole groups are most likely protonated at a low pH, the nanoparticles are positively charged, resulting in a strong electrostatic repulsive force between the IMEO on the nanoparticles and positively charged metal ions. Hg²⁺ adsorption around pH 3.0–4.0 was also low. It is well known in adsorption mechanisms that a decrease in solubility favors an improvement in adsorption performance.

Figure 2.5 Effect of pH on adsorption of Hg²⁺ on the PHEMA and PHEMA-IMEO nanoparticles; IMEO loading: 1021 µmol/g; equilibrium concentration of Hg²⁺: 43 mg/L.

3.3. Competitive Adsorption

As seen in Table 2.2, adsorbed amounts of Hg²⁺ ions are higher than those obtained for Cd²⁺ and Pb²⁺, not only in weight basis but also in molar basis. The adsorption capacities are 238.8 mg/g for Hg²⁺, 45.9 mg/g for Cd²⁺, and 19.6 mg/g for Pb²⁺. From these results, the order of affinity is Hg²⁺ > Cd²⁺ > Pb²⁺. This trend is presented on the basis of mass (mg) metal adsorption per gram adsorbent, and these units are important in quantifying respective metal capacities in real terms. However, a more effective approach for this work is to compare metal adsorption on a molar basis; this gives a measure of the total number of metal ions adsorbed, as opposed to total weight, and is an indication of the total number of binding sites available on the adsorbent matrix, to each metal. In addition, the molar basis of measurement is the only accurate way of investigating competition in multicomponent metal mixtures. Molar basis units are measured as µmol per gram of dry adsorbent. It is evident from Table 2.2 that the order of capacity of PHEMA-IMEO nanoparticles is as follows: Hg²⁺ > Cd²⁺ > Pb²⁺. It is clear from Table 2.2 that the PHEMA-IMEO nanoparticles showed more affinity to Hg²⁺ ions.

Table 2.2 Competitive adsorption of Hg²⁺, Cd²⁺, and Pb²⁺ from their mixture onto PHEMA-IMEO nanoparticles (IMEO loading: 1021 μmol/g; pH: 5.0)

3.4. Behavior of the Elution

The regeneration of the adsorbent is likely to be a key factor in improving process economics. To be useful in metal remediation processes, metal ions should be easily eluted under suitable conditions. Elution of the Hg²⁺ from the metal-chelating nanoparticles was performed in a batch experimental setup. Various factors are probably involved in determining rates of Hg²⁺ elution, such as the extent of hydration of the metal ions and polymer microstructure. However, an important factor appears to be binding strength. When HNO₃ is used as an elution agent, the coordination spheres of chelated Hg²⁺ ions is disrupted and subsequently Hg²⁺ ions are released from the polymer surface into the desorption medium. In this study, the elution time was found to be 15 min. Elution ratios are very high (up to 99%). The ability to reuse the PHEMA-IMEO nanoparticles was shown in Fig. 2.6. The adsorption behavior is stable for 10 cycles of use and it could be used at least 25 times. The adsorption capacity of the recyled nanoparticles can be maintained at 96% level at the 25th cycle. This means that the newly synthesized nanoparticles have great potential for industrial removal applications.

Figure 2.6 Adsorption–elution cycles for Hg²⁺; Hg²⁺ equilibrium concentration: 43 mg/L; pH: 5.0.

References

[1] Ma ZY, Guan YP, Liu XQ, Liu HZ. Synthesis of magnetic chelator for high-capacity immobilized metal affinity adsorption of protein by cerium initiated graft polymerization. Langmuir 2005;21:6987–94.

[2] Sun L, Dai J, Baker GL, Bruening ML. High-capacity, protein-binding membranes based on polymer brushes grown in porous substrates. Chem Mater 2006;18:4033–39.

[3] Dai J, Bao Z, Sun L, Hong SU, Baker GL, Bruening ML. High-capacity, protein-binding membranes based on polymer brushes grown in porous substrates. Langmuir 2006;22:4274–81.

[4] Peng K, Hidajat K, Udin MS. Adsorption of bovine serum albumin on nanosized magnetic particles. J Colloid Interface Sci 2004;271:277–83.

[5] Choi SW, Kwon HY, Kim WS, Kim JH. Thermodynamic parameters on poly(D, L-lactide-co-glycolide) particle size in emulsification–diffusion process. Colloids Surf A 2002;201:283–89.

[6] Lu S, Ramos J, Forcada J. Self-stabilized magnetic polymeric composite nanoparticles by emulsifier-free miniemulsion polymerization. Langmuir 2007;23:12893–900.

[7] Li X, Hernandez JP, Haque SA, Durrant JR, Palomares E. Functionalized titania nanoparticles for mercury scavenging. J Mater Chem 2007;17:2028–32.

[8] Takafuji M, Ide S, Ihara H, Xu Z. Preparation of poly(l-vinylimidazole)-grafted magnetic nanoparticles and their application for removal of metal ions. Chem Mater 2004;16:1977–83.

[9] Lu C, Liu C. J Removal of nickel(II) from aqueous solution by carbon nanotubes. J Chem Technol Biotechnol 2006;81:1932–40.

[10] Qi L, Xu Z. Lead sorption from aqueous solutions on chitosan nanoparticles. Colloids Surf A 2004;251:183–90.

[11] Singh RP, Way JD, Dec SE. Silane modified inorganic membranes: Effects of silane surface structure. J Memb Sci 2005;259:34–46.

[12] Bilkova Z, Slovakova M, Horak D, Lenfeld J, Churacek J. Enzymes immobilized on magnetic carriers: Efficient and selective system for protein modification. J Chromatogr B 2002;770:177–81.

[13] Öztürk N, Günay ME, Akgöl S, Denizli A. Silane-modified magnetic beads: Application to immunoglobulin G separation. Biotechnol Prog 2007;23:1149–56.

[14] Garcia MF, Garcia RP, Garcia NB, Sanz-Medel A. On-line preconcentration of inorganic mercury and methylmercury in sea-water by sorbent-extraction and total mercury determination by cold vapour atomic absorption spectrometry. Talanta 1994;41:1833–39.

[15] D’Itri PA, D’Itri FM. Mercury contamination. New York: Wiley; 1977.

[16] Lai EPC, Wong B, Vandernoot VA. Preservation of solid mercuric dithizonate samples with polyvinyl chloride for determination of mercury (II) in environmental waters by photochromism-induced photoacoustic spectrometry. Talanta 1993; 40:1097–105.

[17] Berglund M, Lind B, Björnberg KA, Palm B, Einarsson O, Vahter M. Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment. Environmental Health A 2005;4:1–11.

[18] Aschner M, Aschner JL. Mucocutaneous lymph-node syndrome – Is there a relationship to mercury exposure. Am J Dis Child 1989;143:1133–34.

[19] Martin MD, Williams BJ, Charleston JD, Oda D. Spontaneous exfoliation of teeth following severe elemental mercury poisoning: Case report and histological investigation for mechanism. Oral Surg 1997;84:495–501.

[20] Öztürk N, Akgöl S, Arisoy M, Denizli A. Reversible adsorption of lipase on novel hydrophobic nanospheres. Sep Purif Technol 2007;58:83–90.

[21] Lin CT, Lee SY, Keh ES, Dong DR, Huang HM, Shih YH. Influence of silanization and filler fraction on aged dental composites. J Oral Rehabil 2000;27:919–26.

[22] Soares CJ, Giannini M, De Oliveira MT, Paulillo LAMS, Martins LRM. Effect of surface treatments of laboratory-fabricated composites on the microtensile bond strength to a luting resin cement. J Appl Oral Sci 2004;12:45–50.

[23] Silberzan P, Leger L, Ausserre D, Benattar JJ. Silanation of silica surfaces. A new method of constructing pure or mixed monolayers. Langmuir 1991;7:1647–51.

[24] Lezzi A, Cobianco S, Roggrero A. Synthesis of thiol chelating resins and their adsorption properties toward heavy metal ions. J Polym Sci A 1994;32:1877–83.

[25] Denizli A, Özkan G, Arica MY. Preparation and characterization of magnetic polymethylmethacrylate microbeads carrying ethylene diamine for removal of Cu(II), Cd(II), Pb(II), and Hg(II) from aqueous solutions. J Appl Polym Sci 2000;78:81–9.

[26] Denizli A, Kesenci K, Piçkin E. Dithiocarbamate-incorporated monosize polystyrene microspheres for selective removal of mercury ions. React Funct Polym 2000;44:235–43.

[27] Jyo A, Matsufune S, Ono H, Egawa H. Preparation of phosphoric acid resins with large cation exchange capacities from macroreticular poly(glycidyl methacrylate-co-divinylbenzene) beads and their behavior in uptake of metal ions. J Appl Polym Sci 1997;63:1327–34.

[28] Salih B, Say R, Denizli A, Genc O, Piskin E. Determination of inorganic and organic mercury compounds by capillary gas chromatography coupled with atomic absorption spectrometry after preconcentration on dithizone-anchored poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) microbeads. Anal Chim Acta 1998;371:177–85.

[29] Binman S, Belfer S, Shani A. Metal sorption properties of sulfur-chlorinated jojoba wax bound to polystyrene beads. J Appl Polym Sci 1997;63:625–33.

[30] Kesenci K, Say R, Denizli A. Removal of heavy metal ions from water by using poly(ethyleneglycol dimethacrylate-co-acrylamide) beads. Eur Polym J 2002;38: 1443—48.

[31] Hwang DC, Damodaran S. Metal-chelating properties and biodegradability of an ethylenediaminetetraacetic acid dianhydride modified soy protein hydrogel. J Appl Polym Sci 1997;64:891–906.

[32] Denizli A, Arpa C, Bektas S, Genc O. Adsorption of mercury(II) ions on Procion Blue MX-3G-attached magnetic poly(vinyl alcohol) gel beads. Ads Sci Technol 2002;20:91–106.

[33] Liu CY, Chang HT, Hu CC. Complexation reactions in a heterogeneous system. Inorg Chim Acta 1990;172:151–58.

[34] Shah S, Devi S. Preconcentration of mercury(II) on dithizone anchored poly(vinyl pyridine) support. React Funct Polym 1996;31:1–9.

[35] Cestari AR, Airoldi C. Chemisorption on thiol—silicas: divalent cations as a function of ph and primary amines on thiol—mercury adsorbed. J Colloid Interf Sci 1997;195:338–42.

[36] Delacour ML, Gailliez E, Bacquet M, Morcellet M. Poly(ethylenimine) coated onto silica gels: Adsorption capacity toward lead and mercury. J Appl Polym Sci 1999;73:899–906.

[37] Rivas BL, Maturana HA, Molina MJ, Gomez-Anton MR, Pierola IF. Metal ion binding properties of poly(N-vinylimidazole) hydrogels. J Appl Polym Sci 1998;67:1109–18.

[38] Arpa C, Saglam A, Bektas S, Patir S, Genc O, Denizli A. Adsorption of mercury(II) ions by oly(hydroxyethyl methacrylate) adsorbents with thiazolidine groups. Ads Sci Technol 2002;20:203–13.

[39] Navarro RR, Sumi K, Fujii N, Matsumara M. Mercury removal from wastewater using porous cellulose carrier modified with poly(ethyleneimine). Water Res 1996;30:2488–94.

[40] Denizli A, Şenel S, Alsancak G, Tuzmen N, Say R. Mercury removal from synthetic solutions using poly (2-hydroxyethyl methacrylate) gel beads modified with poly (ethyleneimine). React Funct Polym 2003;55:121–30.

[41] Becker NSC, Eldridge RJ. Selective recovery of mercury(II) from industrial wastewaters .1. Use of a chelating ion-exchanger regenerated with brine. React Polym 1993;21:5–14.

[42] Atia A, Donia AM, Yousif AM. Synthesis of amine and thio chelating resins and study of their interaction with zinc(II), cadmium(II) and mercury(II) ions in their aqueous solutions. React Funct Polym 2003;56:75–82.

[43] Denizli A, Garipcan B, Emir S, Patir S, Say R. Heavy metal ion adsorption properties of methacrylamidocysteine-containing porous poly(hydroxyethyl methacrylate) chelating beads. Ads Sci Technol 2002;20:607–17.

[44] Say R, Garipcan B, Emir S, Patir S, Denizli A. Preparation and characterization of the newly synthesized metal-complexing-ligand N-methacryloylhistidine having PHEMA beads for heavy metal removal from aqueous solutions. Macromol Mater Eng 2002;287:539–45.

..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.

Table of Contents for Chapter 2: High Capacity Removal of Mercury(II) Ions by Poly(Hydroxyethyl Methacrylate) Nanoparticles

Create new playlist

Sign In

Sign Up

CHAPTER 2

1. Introduction