Showing papers in "Reactive & Functional Polymers in 2000"
TL;DR: Chitin is the most abundant natural amino polysaccharide and is estimated to be produced annually almost as much as cellulose, and recent progress in chitin chemistry is quite noteworthy as mentioned in this paper.
Abstract: Chitin is the most abundant natural amino polysaccharide and is estimated to be produced annually almost as much as cellulose. It has become of great interest not only as an underutilized resource, but also as a new functional material of high potential in various fields, and recent progress in chitin chemistry is quite noteworthy. The purpose of this review is to take a closer look at chitin and chitosan applications. Based on current research and existing products, some new and futuristic approaches in this fascinating area are thoroughly discussed.
5,517 citations
TL;DR: In this article, a modified biosorbent was used for palladium recovery in an acidic medium (around pH 2), and the influence of several parameters such as pH and competitor anions were studied with respect to sorption equilibrium.
Abstract: The high nitrogen content of chitosan is the main reason for its ability to sorb metal ions through several mechanisms including ion-exchange or chelation, depending on the metal and the pH of the solution. Glutaraldehyde is used to crosslink chitosan through imine linkage between amine groups of chitosan and aldehyde groups of the crosslinking agent. This modified biosorbent was studied for palladium recovery in acidic medium (around pH 2). The influence of several parameters such as pH and competitor anions were studied with respect to sorption equilibrium. Sorption isotherms were obtained and modeled using the Langmuir and the Freundlich model. This study also examines the effect of palladium concentration, particle size, sorbent dosage, and the extent of crosslinking on sorption kinetics. Kinetic curves are modeled using single diffusion model equations to evaluate the predominance of either external or intraparticle mass transfer resistance. The influence of the acid used to control the pH of the solution was examined in conjunction with the influence of competitor anions. Sulfuric acid proves to be unfavorable to palladium sorption, in comparison with hydrochloric acid. However, the addition of chloride anions in a palladium solution, whose pH is controlled with sulfuric acid, enhances metal anion sorption: results are interpreted with reference to chloropalladate speciation.
263 citations
TL;DR: In this paper, a porous resin loaded with monoclinic or cubic hydrous zirconium oxide was prepared by incorporation of ZrOCl 2 ·8H 2 O into porous spherical polymer beads.
Abstract: A porous resin loaded with monoclinic or cubic hydrous zirconium oxide was prepared by incorporation of ZrOCl 2 ·8H 2 O into porous spherical polymer beads followed by hydrolysis and hydrothermal treatment of the zirconium salt. Hydrous zirconium oxide appeared to deposit inside the pores with relatively large diameter. The adsorption capacity and distribution coefficients for As(III) and As(V) were determined by batch procedures. The hydrous zirconium oxide-loaded resin (Zr resin) showed a strong adsorption for As(V) at slightly acidic to neutral pH region while As(III) was favorably adsorbed at pH around 9 to 10. The removal of low concentrations of arsenic from the model effluents to meet the demand of Japanese industrial effluent standard (0.1 ppm) was successfully achieved by the column operation packed with the Zr resin. The Zr resin was regenerated by treatment of the column with 1 M sodium hydroxide followed by conditioning with 0.2 M acetate buffer solution. The amount of zirconium leached out during the adsorption and regeneration cycles was negligibly small and the column can be used repeatedly.
213 citations
TL;DR: In this article, the capacities for nickel, zinc, and cadmium(II) ions were measured in aqueous nitrate, chloride and sulphate solutions at pH 6.
Abstract: Chitosan beads were cross-linked with a dialdehyde or a tetracarboxylic acid in order to obtain sorbents that are insoluble in aqueous acidic solutions. Further chemical modifications improved the metal ion capacities and selectivities of the products. The capacities for nickel(II), zinc(II) and cadmium(II) ions were measured in aqueous nitrate, chloride and sulphate solutions at pH 6. The selectivities were determined in mixtures of nickel(II), zinc(II), cadmium(II), magnesium(II) and calcium(II) and were recorded as a function of the pH value and the counter-ion. Four of six chitosan derivatives show higher metal uptake rates in sulphate solution than in solutions of nitrate or chloride. They possess, however, poor metal ion selectivities, except in chloride solutions where cadmium(II) is preferentially bonded. In contrast, the other two chitosan derivatives are highly selective for nickel(II) and cadmium(II), respectively. This selective behaviour exists over the pH range 3–6 and is independent of the counter-ion. These products have relatively high capacities even at pH 3. Yet the bonded metal ions are completely released at pH 0.5.
157 citations
TL;DR: In this paper, the fixation of sugar beet pulp, a low-cost material, has been studied after a simple treatment of the sorbent, the results have shown that the mode of fixation depends on the metal, while a nonnegligible part of adsorption could sometimes occur.
Abstract: The fixation of Cu2+, Ni2+ and Pb2+ on sugar beet pulp, a low-cost material, has been studied After a simple treatment of the sorbent, the results have shown that the mode of fixation depends on the metal The key part of the mode of fixation is attributed to ion exchange, while a non-negligible part of adsorption could sometimes occur As far as lead ions are concerned, 25% of their fixation capacities are due to adsorption mechanism at pH 4 The overall uptake is at a maximum at pH 6 and gives up to 60 mg g−1 for Pb2+, 30 mg g−1 for Cu2+ and 12 mg g−1 for Ni2+, which seems to be removed exclusively by ion exchange These capacities increase with the pH Diffusion models have been tested on samples of different particle size, and they have suggested a transfer to the intraparticular sites
119 citations
TL;DR: In this article, the interaction between polyvinylpyrrolidone (PVP) and metal cations has been studied in absolute ethanol and water at room temperature and atmospheric pressure.
Abstract: The interaction between polyvinylpyrrolidone (PVP) and metal cations has been studied in absolute ethanol and water at room temperature and atmospheric pressure. The UV-VIS and IR absorption spectra of metal cations, PVP and PVP-M n + (M n + =Fe 3+ , Co 2+ , Ni 2+ ) were given. It was shown that PVP and metal cations formed unstable complexes, and the coordination stability constants were determined according to the Miller–Dorough method. The stability constants of PVP-Fe 3+ and PVP-Co 2+ were lower than 10 and 0.6, respectively, and that of PVP-Ni 2+ was too low to be estimated. The solid complexes of PVP-Fe 3+ and PVP-Co 2+ were also synthesized under proper conditions.
114 citations
TL;DR: In this paper, dithiocarbamate-incorporated monosize polystyrene based microspheres (2 μm in diameter) were used for selective removal of Hg(II) from aqueous solutions.
Abstract: Dithiocarbamate-incorporated monosize polystyrene based microspheres (2 μm in diameter) were used for selective removal of Hg(II) from aqueous solutions containing different amounts of Hg(II) (10–100 ppm). Adsorption rates were observed as high at the beginning of adsorption and then equilibrium was reached in about 30 min. The maximum Hg(II) adsorption capacity of the dithiocarbamate-incorporated PS microspheres was about 33.2 mg per gram of dry polymer, which was observed at pH 7.0. While non-specific Hg(II) adsorption onto the plain microspheres was 0.85 mg per gram of dry microsphere. The Hg(II) adsorption ability increased with increasing pH, in the range where the solubility of the Hg(II) was not affected by the pH. The preferential (i.e., competitive adsorption) binding of Hg(II) by the microspheres implies that this sorbent system might contain higher-affinity binding sites for Hg(II) than Cu(II), Cd(II) and Pb(II) ions. More than 96% of the adsorbed Hg(II) was desorbed in 15 min by using 0.1 M HNO 3 as an elution agent. The regeneration of the dithiocarbamate-incorporated PS microspheres was also sufficient.
93 citations
TL;DR: In this paper, a grafting of hyperbranched dendritic polyamidoamine, a new class of topological macromolecules, onto the surface of chitosan powder was investigated.
Abstract: To modify the surface of chitosan powder, grafting of hyperbranched dendritic polyamidoamine, a new class of topological macromolecules, onto the surface was investigated. It was found that hyperbranched dendritic polyamidoamine was propagated from chitosan powder surface by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups and (2) amidation of the resulting esters with ethylenediamine to give polyamidoamine dendrimer-grafted chitosan powder. However, theoretical propagation of polyamidoamine dendrimer from chitosan powder surface was hardly achieved, because (a) Michael addition and amination proceeded in heterogeneous systems and (b) the grafting of dendritic polyamidoamine was blocked by grafted chains due to steric hindrance. It was found that the average particle size of hyperbranched dendritic polyamidoamine-grafted chitosan powder was decreased by grafting of dendritic polyamidoamine. Furthermore, living poly(2-methyl-2-oxazoline) and living poly(isobutyl vinyl ether) with controlled molecular weight and narrow molecular weight distribution readily postgrafted to the hyperbranched dendritic polyamidoamine-grafted chitosan powder by termination of the corresponding living polymer cation with terminal amino groups of the dendritic polyamidoamine-grafted chitosan powder.
92 citations
TL;DR: In this article, a new synthesis of ion exchange resins containing thiol groups directly bonded on the aromatic ring is described, which are used to remove the small quantities of mercury (10 ppm) contained in waste water from chloralkali industries which use a mercury cathode (solvay cell).
Abstract: A new synthesis of ion exchange resins containing thiol groups directly bonded on the aromatic ring is described. These resins are used to remove the small quantities of mercury (10 ppm) contained in waste water from chloralkali industries which use a mercury cathode (solvay cell). Optimum conditions have been developed to obtain resins with maximum thiol content groups. Elemental analysis, NMR, and FTIR spectroscopies data have been used to confirm the chemical structure of all products. When used in decontamination of water containing 10 ppm of Hg, we obtained a final Hg concentration of 1 ppb.
89 citations
TL;DR: In this paper, two types of chitosan microparticles (CMs) and their silver-complexes CMs (SCMs) were prepared using different crosslinking agents, i.e. glutaraldehyde and epichlorohydrin, in order to investigate the adsorption and release behaviors of a typical pesticide, methyl parathion (MP).
Abstract: Two types of chitosan microparticles (CMs) and their silver-complexes CMs (SCMs) were prepared using different crosslinking agents, i.e. glutaraldehyde and epichlorohydrin, in order to investigate the adsorption and release behaviors of a typical pesticide, methyl parathion (MP). The pH and concentration dependencies on Ag(I) and MP adsorptions on both the CMs and SCMs were studied. The epichlorohydrin-crosslinked CM apparently showed the superiority of Ag(I) adsorption over the glutaraldehyde-crosslinked CM, nevertheless, adsorption behavior of MP on SCM derived from each CM was observed vice versa. Release behavior of MP from the MP-loaded SCMs was also observed in aqueous acetic acid and sodium acetate buffer solutions at low pH as well as in those containing two kinds of ammonium reagents. The aqueous solutions containing ammonium thiocyanide and ammonia could be applied for MP release from the MP-loaded SCMs without Ag(I) leakage from the particles. Furthermore, from the iteration of adsorption and release experiments of MP, glutaraldehyde-crosslinked SCM provides good reusability for MP removal.
83 citations
TL;DR: In this article, a theoretical kinetic model was developed for evaluation of this slurry reaction and the effects of various parameters on the rate of reaction were evaluated, which was found to be intrinsically kinetically controlled and there were no intraparticle as well as interparticle mass transfer limitations on the reaction rate.
Abstract: Isopropyl lactate is a very important pharmaceutical intermediate. The current practice is to use homogeneous acids as catalysts. These catalysts are hazardous and disposal of liquid acid effluents poses problems. The separation of the liquid catalyst and its reuse is another problem. The current paper deals with the application of heterogeneous catalysts Indion-130, Ambelyst-36, Amberlyst-15, Amberlite-120, Dowex 50W, Filtrol-44, 20% DTPA/K-10 (dodecatungstophosphoric acid supported on K-10 clay) and 20% DTPA/Filtrol-44 (dodecatungstophosphoric acid supported on Filtrol-44 clay). Amongst these Amberlyst-36, Amberlyst-15 and Indion-130 were observed to be most effective. A theoretical kinetic model was developed for evaluation of this slurry reaction. The effects of various parameters on the rate of reaction were evaluated. The reaction was found to be intrinsically kinetically controlled and there were no intraparticle as well as interparticle mass transfer limitations on the rate of reaction.
TL;DR: In this article, the selectivity of different prepared grafted membranes towards some selected metal ions such as Fe, Cu, Pb, etc. which commonly exist in waste water was determined.
Abstract: Radiation graft copolymerization of styrene/maleic anhydride (Sty/MAn) comonomer onto low density polyethylene (LDPE) membrane was investigated. The prepared grafted membranes were treated with different reagents containing various functional groups and studied as a matrix for the purpose of water purification from heavy metals. The metal ion uptake by the functional groups of membranes was determined by the use of X-ray fluorescence (XRF) and atomic absorption (AA). The effect of pH of the metal feed solution and immersion period needed for maximum capacity was investigated. The selectivity of different prepared membranes towards some selected metal ions such as Fe, Cu, Pb,… etc. which commonly exist in waste water was determined. The affinity of the treated grafted films to recover Fe(III), Cu(II) or Pb(II) from their aqueous solutions containing other metal ions such as Cd(II), Ni(II) or Hg(II) was studied. Also the selectivity of treated grafted membranes towards Cu(II), Cr(III) and Fe(III) in a mixture was investigated at room temperature and 70°C. It was found that the thiosemicarbazide-, hydroxylamine·HCl- and NaOH-treated grafted films showed high selectivity towards Cu(II), Cr(III) and Fe(III), respectively, at 70°C. However, the selectivity of such treated grafted membranes was remarkable towards Fe(III) at room temperature. The results obtained suggested that the treated grafted membrane possessed good chelating properties towards different metal ions. This suggests that such membranes could be accepted for practical uses.
TL;DR: In this article, the interaction between chitosan and polyphenols separated from spruce wood bark was discussed, and it was shown that polyphenol release occurred only in an alkaline medium (pH>9) in a two-step process.
Abstract: This paper discusses the interaction between chitosan and the polyphenols separated from spruce wood bark. The chitosan and the polyphenols formed a complex and the release of the polyphenols occurred only in an alkaline medium (pH>9) in a two-step process. Analysis of the release of the polyphenols showed that in the initial stage the diffusion occurs according to the Fick’s law, while in the last stage, the process develops according to a zero-order kinetics.
TL;DR: In this paper, the distribution coefficient (KD) of trace nickel on an iminodiacetate-chelating resin Chelex 100 increased with pH to a peak value close to 2 000 000 ml/g at pH of about 5.
Abstract: The distribution coefficient (KD) of trace nickel on an iminodiacetate-chelating resin Chelex 100 increased with pH to a peak value close to 2 000 000 ml/g at pH of about 5. At higher pH values the KD dropped to 5000 ml/g due to competition of an unidentified complexing agent. In equilibrium of three-component Na/H/Ni ion-exchange system, H/Ni exchange was found to be dominant in the pH range up to 8 and in Na concentration up to 6 mol/l. The practical ion-exchange capacity for nickel was 2.15 mmol/g (4.3 meq/g).
TL;DR: In this paper, the authors investigated the grafting of polymers having pendant peroxycarbonate groups onto ultrafine silica surface and the radical postgraft polymerization of vinyl monomers initiated by the initiating groups of polymer chains grafted onto the surface.
Abstract: The grafting of polymers having pendant peroxycarbonate groups onto ultrafine silica surface and the radical postgraft polymerization of vinyl monomers initiated by the initiating groups of polymer chains grafted onto silica surface were investigated. The grafting of polymers having pendant peroxycarbonate groups onto the silica surface was achieved by the copolymerization of vinyl acetate (VAc) with t-butylperoxy-2-methacryloyloxyethylcarbonate (HEPO) initiated by azo groups introduced onto silica surface: the introduction of azo groups onto silica surface was achieved by the reaction of 4,4′-azobis(4-cyanopentanoic acid) with amino groups previously introduced onto the surface. The percentage of grafting (the proportion of grafted polymer to silica) of poly(VAc–co-HEPO) onto the surface was about 51% at 80.0°C after 3 h. The amount of pendant peroxycarbonate groups of grafted chain was determined to be 0.55 mmol/g. Radical postgraft polymerization of various vinyl monomers, such as methyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, vinyl acetate, and N-vinyl-2-pyrrolidinone was initiated by the pendant peroxycarbonate groups of grafted poly(VAc–co-HEPO) to give the corresponding hyperbranched polymer-grafted silica. It was found that the grafting of hydrophilic or hydrophobic polymers readily controls the surface wettability to water.
TL;DR: In this article, the authors studied the oligomerization of isobutene over Amberlyst-15 catalyst in a mixed gas-liquid phase and found that more than 90% triisobutylene was present in the final oligomer mixture.
Abstract: The purpose of this investigation is to study the oligomerization of isobutene over Amberlyst-15 catalyst in a mixed gas–liquid phase. Reaction conditions were optimised in order to maximise triisobutylene selectivity. Results show that more than 90% (w/w) triisobutylene was present in the final oligomer mixture.
TL;DR: In this article, a comparison between two ways of functionalization has been made: abatch method, corresponding to diffusion of reactants through the pores of small cubes of polymers, and a continuous flow method, forcing reactants to flow through the interconnected porous structure by applied low pressure.
Abstract: This paper describes the preparation and post-functionalization of an emulsion-derived polymeric foam, called polyHIPE ® , bearing pendant vinyl functionalities. The large pores and large channels of polyHIPE allow liquids and solvents to be driven through the molded monolith at very low pressure. In the presence of a free-radical initiator, compounds such as HBr and thiols underwent an anti-Markovnikov addition to the residual vinyl groups. Other reactions such as hydroboration with BH 3 followed by hydrolysis with H 2 O 2 have also been investigated. In this paper, a comparison between two ways of functionalization has been made: a ‘batch’ method, corresponding to diffusion of reactants through the pores of small cubes of polymers, and a ‘continuous flow’ method, forcing reactants to flow through the interconnected porous structure by applied low pressure.
TL;DR: In this article, invertase entrapment of the enzyme in conducting polymer matrices during electrochemical polymerization of pyrrole was carried out by entraining the enzyme to conduct polyazotetrahydrofuran-block polystyrene copolymer matrices.
Abstract: In this study, immobilization of invertase on functionalized polymer electrodes constructed with pyrrole-capped polyazotetrahydrofuran and polytetrahydrofuran-block-polystyrene copolymer matrices was performed. Immobilization in these enzyme electrodes was carried out by the entrapment of the enzyme in conducting polymer matrices during electrochemical polymerization of pyrrole. Sodium dodecyl sulphate was used as the supporting electrolyte in the preparation of enzyme electrodes. The effects of temperature and pH on the activity of the enzyme electrodes were examined, and re-use number studies were performed. The changes in the maximum reaction rate and the variations of the Michaelis–Menten constant were investigated.
TL;DR: In this article, the p-doped behavior of two kinds of water-soluble polythiophenes (PThs) (P3(RSO 3 M) and PEDOTh) has been investigated spectroscopically at various pH under air.
Abstract: Doping behavior of two kinds of water-soluble polythiophenes (PThs) (PTh with a CH 2 CH 2 CH 2 SO 3 M substituent at the 3-position, P3(RSO 3 H)Th, and poly(ethylenedioxythiophene), PEDOTh) has been investigated spectroscopically at various pH under air. The p-doped (or oxidized) state of P3(RSO 3 M)Th is stable at pH=1.0, whereas at pH levels higher than 4, the polymer is undoped. To the contrary, the p-doped state of PEDOTh is stable over a pH range of 1 to 7. Mixing of PEDOTh and a DNA (poly(G-C) 2 ) in a Tris buffer solution leads to a change of the UV-visible spectrum and precipitation of their adduct, supporting formation of an adduct between PEDOTh and poly(G-C) 2 .
TL;DR: In this article, a series of cone structured lower rim dialkylated p-tert-butylcalix[4]arene and their relative telomers were synthesized to estimate extraction of alkali and transition metal cations from an aqueous phase to an organic phase (dichloromethane).
Abstract: A series of cone structured lower rim dialkylated p-tert-butylcalix[4]arene (2a–5a) and their relative telomers (2b–5b) have been synthesized to estimate extraction of alkali and transition metal cations from an aqueous phase to an organic phase (dichloromethane). The complexation studies were made by using a liquid–liquid extraction procedure. It has been deduced from the observations that the monomers 2a, 3a and 5a are selective for Hg2+, whereas 4a is not selective but showed higher affinity towards transition metals than the alkali metal cations. The telomer 2b showed more affinity toward Cu2+, Hg2+ and Pb2+, but the telomer 3b is effective for Hg2+ and Pb2+. The telomers 4b and 5b are not selective but they are efficient extractants for the selected transition metal cations. The results indicate that the ligand groups circularly arranged on the lower rim of calixarene cavity form novel binding sites for transition metal cations.
TL;DR: In this paper, the intraparticle diffusion behaviors of trace concentrations of pentachlorophenate (PCP − ) and other chlorophenates onto a commercially available macroporous polymeric anion exchanger (IRA-900) were discussed.
Abstract: Chlorophenols, quaternary ammonium compounds, benzene and naphthalene sulfonates and benzene carboxylates are examples of environmentally significant synthetic organic compounds which exist as ions in water over a wide range of pH values. This study discusses the sorption kinetics, and more specifically, intraparticle diffusion behaviors of trace concentrations of pentachlorophenate (PCP − ) and other chlorophenates onto a commercially available macroporous polymeric anion exchanger (IRA-900). The anion exchanger is essentially biphasic, i.e. every single exchanger particle contains an enormous number of tiny microgels and an interconnected network of pores. Ion exchange functional groups reside solely within the microgels. For comparison, a gel or microporous anion exchanger is also included in the study. Experimental results reveal a distinctly different type of effect of competing chloride ion concentration on gel and macroporous ion exchangers pertaining to sorption of pentachlorophenate (PCP − ). While the effective intraparticle diffusivity of PCP − for gel-type resin remained unaltered with a change in competing chloride concentration, the same increased significantly for the macroporous exchanger with an increase in chloride concentration. Pore diffusion is considered to be the predominant intraparticle transport mechanism for highly preferred PCP − inside the macroporous exchanger. Under the normal hydrodynamic conditions of a fixed bed column run, intraparticle diffusion was found to be the rate-limiting step. For various chlorophenates, the effective intraparticle diffusivities were inversely correlated to the octanol–water partition coefficients of their parent chlorophenols.
TL;DR: In this article, a new heteropolyacid-based cation exchanger zirconium(IV) selenomolybdate has been synthesized, characterized using I.R., X-ray, TGA, DTA techniques.
Abstract: A new heteropolyacid-based cation exchanger zirconium(IV) selenomolybdate has been synthesized, characterized using I.R., X-ray, TGA, DTA techniques. Its composition was found to be Zr:Se:Mo::2.5:0.7:1.6 and it is quite chemically stable. It exhibits 0.94 meq/g ion-exchange capacity for Na + ions. Its distribution behavior for 16 metal ions has been studied and its utility has been employed by achieving separations Zn 2+ –Cd 2+ , Zn 2+ –Co 2+ , Ni 2+ –Cd 2+ and Ni 2+ –Co 2+ on its column.
TL;DR: In this article, a low molecular weight functional poly(methyl methacrylate) (PMMA-F) using a chain-terminating agent such as thioglycolic acid was found.
Abstract: Microspheres based on synthetic polymers such as poly(methyl methacrylate) (PMMA) and PMMA derivatives are known for their medical applications, particularly for hard tissue repair and regeneration. In the present work, attempts were made to prepare low molecular weight functional poly(methyl methacrylate) (PMMA-F) using a chain-terminating agent such as thioglycolic acid (PMMA-F). It was found that the molecular weight of PMMA-F was very low compared with PMMA prepared without thioglycolic acid. Microspheres were prepared using PMMA-F by the solvent evaporation technique and PMMA (PMMA without the chain-terminating agent thioglycolic acid) microspheres were also prepared for comparison and both microspheres were fully characterized. The presence of characteristic groups in the PMMA (ester) and PMMA-F (ester and carboxylic) microspheres was confirmed using 13 C- and 1 H-FT-NMR spectroscopy. The molecular weight of both microsphere systems was determined using gel permeation chromatography. The FT-IR spectra clearly indicated the presence of carboxylic functional groups in PMMA-F microspheres. Quantitative carboxylic group estimation was carried out using the titrimetric method. Scanning electron micrographs indicated that the microspheres are spherical and porous in nature. The thermal behavior of PMMA and PMMA-F microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis.
TL;DR: In this paper, 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.
Abstract: 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.
TL;DR: In this paper, the ion exchange properties of the titanium silicate, M 2 Ti 2 O 3 SiO 4 · n H 2 O (M=H,Na), towards alkali ions have been examined.
Abstract: The ion-exchange properties of the titanium silicate, M 2 Ti 2 O 3 SiO 4 · n H 2 O (M=H,Na), towards alkali ions has been examined. Potentiometric titration of the highly crystalline phase in the proton form, H 2 Ti 2 O 3 (SiO 4 )·1.6H 2 O, showed a dependency of the exchange on the size and charge of the ion and the pH of the solution. It was found that the accessability of three different ion-exchange sites in the titanium silicate framework controls the uptake of ions: 100% of the total amount of the ion-exchange sites could be occupied at pH 12.5 by sodium and lithium ions, about 75% by potassium and rubidium ions and only 25% by cesium ion. The ion-exchange isotherms of alkali metal ions were determined and the corrected selectivity coefficients as a function of metal loading were analyzed. Sodium titanium silicate exhibits a high affinity for heavy alkali metals with the selectivity order Cs + >Rb + >K + . By studying the cesium and strontium uptake in the presence of NaNO 3 , CaCl 2 , NaOH, NaOH+KOH, and HNO 3 (in the range of 0.01–6 M) the titanium silicate was found to be an efficient Cs + ion exchanger in acid, neutral and alkaline media, which makes it promising for treatment of different types of nuclear waste and contaminated environmental and biological liquors.
TL;DR: In this paper, the effect of particle size and loading of resin on the properties of the heterogeneous cation exchange membranes such as dimensional stability, bursting strength, ion exchange capacity, electrical resistance, transport number etc.
Abstract: As the preparation of interpolymer type ion-exchange membranes involves the use of hazardous chemicals like chlorosulfonic acid and chloromethyl ether, it was envisaged to prepare heterogeneous membranes through a simple technique involving casting of a solution containing a binder and a polyelectrolyte. This paper reports the studies conducted in the preparation of heterogeneous cation-exchange membranes using polyvinyl chloride (PVC) as binder and cation-exchange resin powder as polyelectrolyte by the solution casting method. The effect of the particle size and loading of resin on the properties of the membranes such as dimensional stability, bursting strength, ion-exchange capacity, electrical resistance, transport number etc. have been studied. It has been found that with respect to dimensional stability the properties of the heterogeneous cation-exchange membranes prepared by using resin of suitable particle size and loading, are almost equally good or even better than interpolymer cation-exchange membranes and hence heterogeneous cation-exchange membranes may replace the interpolymer membranes in some of the electrodialysis (E.D.) applications.
TL;DR: In this article, three kinds of strong acid cation exchange resins, Amberlyst 15 (A-15), S-54 and D-72 in the H+ form, were used as the catalysts.
Abstract: The etherification between ethanol (EtOH) and tert-butyl alcohol (TBA) in the liquid phase under atmospheric pressure for the production of ethyl tert-butyl ether was studied. Three kinds of strong acid cation-exchange resins, Amberlyst 15 (A-15), S-54 and D-72 in the H+ form, were used as the catalysts. The effects of temperature, water inhibition, catalyst loading and the reactants molar ratio on the reaction were investigated. The kinetic parameters, such as the activation energy and inhibition coefficient of water were also compared for the catalysts used. Among the catalysts tested, D-72 shows the highest activity, and S-54 shows the highest selectivity and the lowest effect of water inhibition for the production of ethyl tert-butyl ether.
TL;DR: In this paper, the catalytic activity of 2,4,6-trichlorophenol (TCP) catalyzed by iron, manganese, and cobalt octacarboxyphthalocyanine and their polymer-bound derivatives was studied in aqueous solution.
Abstract: Oxidative decomposition of 2,4,6-trichlorophenol (TCP) catalyzed by iron, manganese, and cobalt octacarboxyphthalocyanines and their polymer-bound derivatives was studied in aqueous solution. Iron octacarboxyphthalocyanine scarcely had catalytic activity in oxidative decomposition of TCP by H 2 O 2 , while extremely high catalytic activity was observed in the presence of water-soluble polymers having pyridinium side chains. When iron octacarboxyphthalocyanine complex was covalently bound to the water-soluble cationic polymer, it revealed much higher catalytic activity. 2,6-Dichloro- p -benzoquinone was formed in the initial period of the reaction and was decomposed to further low molecular weight compound. Formic acid, oxalic acid, chloropropenic acid, and two coupling products were found in the resulting solution by GC–MS analysis. Catalytic activity of polymer-bound iron phthalocyanine was strongly influenced by pH and the maximum activity was observed at pH 7. The pH-dependence of the catalytic activity was explained by the dissociation of TCP. Enhancement in catalytic activity by polymer chain was also observed in manganese and cobalt phthalocyanine complexes. Highly efficient dechlorination of TCP was concomitantly achieved by the polymer-bound iron and manganese phthalocyanine complexes, while polymer-bound cobalt phthalocyanine complex hardly cause the dechlorination.
TL;DR: In this paper, a polymer-bound extractant for Hg 2+ remediation in mixed-waste streams is proposed, where 2-aminomethylthiacrowns are immobilized on a polystyrene-divinylbenzene matrix through the pendant arm of the crowns.
Abstract: We are interested in designing polymer-bound extractants for Hg 2+ remediation in mixed-waste streams. Towards this goal, we have synthesized novel polymer extractants where 2-aminomethylthiacrowns are immobilized on a polystyrene–divinylbenzene matrix through the pendant arm of the crowns. Reaction of 2,3-dimercapto-1-propanol with either 4,7-dithiadecane-1,10-di- p -toluenesulfonate or 4,7,10-trithiatridecane-1,13-di- p -toluenesulfonate generated the 2-hydroxymethylthiacrowns, 3 ([14]aneS 4 -OH) and 4 ([17]aneS 5 -OH). Treatment of the 2-hydroxymethylthiacrowns with thionyl chloride, followed by monomethylamine, produced the N-(methyl)-2-aminomethylthiacrowns, 5 ([14]aneS 4 -NR 1 R 2 ) and 6 ([17]aneS 5 -N R 1 R 2 ) (R 1 =Me, R 2 =H). The thiacrown polymers were prepared through the copolymerization of a 4-vinylbenzyl-substituted aminomethylthiacrown, 7 ([14]aneS 4 -N R 1 R 2 ) or 8 ([17]aneS 5 -N R 1 R 2 ) (R 1 =Me, R 2 =4-vinylbenzyl), with divinylbenzene. Extraction of Hg 2+ from aqueous media using the [17]aneS 5 thiacrown polymer 10 with under a variety of conditions ([Hg 2+ ] 4–200 ppm, pH 1.5–6.2) shows that the resin effectively and selectively removes Hg 2+ ions from acidic aqueous solutions with extraction efficiency ∼95%. Mercury recovery and polymer regeneration was also demonstrated using chloroform solutions of diphenylthiocarbazone to strip the bound Hg 2+ from the resin.