Bożena N. Kolarz

Highly polar polymeric sorbents: Characterization and sorptive properties towards phenol and its derivatives

Abstract Six porous copolymers of acrylonitrile (AN)/divinylbenzene (DVB) and methacrylonitrile (MAN)/DVB have been synthesised by suspension polymerization in the presence of inert diluents. They have different specific surface area (460–720 m 2 /g for AN/DVB and 560–730 m 2 /g for MAN/DVB) and contain various amounts of the strongly polar nitrile groups. Their sorptive properties have been studied using dilute (0.5 mmol) solutions of phenol and its derivatives ( o -chlorophenol, o -, m - and p -nitrophenol, 2,3- and 2,6-dimethylphenol, p -hydroxyphenol). It has been found that sorption of the most hydrophobic compounds and compounds capable of forming strong intramolecular hydrogen bonds does not depend on the polarity of the polymer surface. Sorption of phenol and m - and p -nitrophenol is stronger on sorbents having more polar groups. The influence of these groups on the sorption process is highly significant in the case of hydrophilic, water soluble sorbates such as p -hydroxyphenol. Polymeric sorbents were characterized using elemental analysis, inverse gas chromatography and their porous structure was characterized by nitrogen adsorption at 77 K.

Immobilization of lipase on various acrylic copolymers

Abstract Polymer carriers with various degrees of hydrophobicity, porosity, and polarity were studied for immobilization of lipase from Candida rugosa. Copolymers and terpolymers were prepared by suspension polymerization of six monomers, ethyl and butyl acrylate, acrylonitrile, methyl methacrylate, 2-hydroxypropyl methacrylate and vinyl acetate, and three crosslinking agents, divinylbenzene, ethylene glycol dimethacrylate and trimethylolpropane triacrylate, in the presence of various diluents. Immobilization of lipase was carried out via glutaraldehyde chemical binding or by adsorption. It was found that the best results were obtained for carriers of butyl acrylate, ethyl acrylate or 2-hydroxypropyl methacrylate crosslinked with ethylene glycol dimethacrylate.

Gold sorption on weak base anion exchangers with aminoguanidyl groups

Abstract Two resins with different matrices, both bearing aminoguanidyl ligands, were obtained and used for gold sorption from hydrochloric acidic and from alkali solutions. Resin 1 was a aminoguanidine derivative of poly(acrylonitril-co-vinyl acetat-co-divinyl benzene) terpolymer (AN/VA/DVB), (67:27:10 wt.%), and Resin 2 the same derivative of gel expanded poly(vinylbenzyl chloride-co-divinylbenzene) copolymer (VBC/DVB). The resins sorption capacity and sorption isotherms of both resins were determined for AuCl 4 − and Au(CN) 2 − anions. Resin 2 revealed the best sorption of gold from acidic and alkali solutions: 68 and 23 mg/g, respectively. The effect of the HCl concentration on AuCl 4 − removal from solution was investigated. Gold was recovered quantitatively from both resins using a 5% thiourea solution in 0.1 HCl. Both resins remained ability of multiple gold sorption and desorption under acidic conditions.

Acrylic resins with complexes of guanidyl groups and copper(II)

Abstract Heating of acrylonitrile, vinyl acetate and divinylbenzene porous copolymers (AN-VA-DVB) with aminoguanidine salts in alkaline medium leads to aminolysis and hydrolysis of the nitrile groups and hydrolysis of acetyl groups. As a result, an amphoteric chelating resin with guanidyl and carboxyl groups at a concentration of ca. 13and 2–4 mmol/g, respectively, is obtained. The resin possesses a porous structure with a mean pore radius of 5.6 nm in swollen state. The sorption of Cu(II) ions increases with increasing content of functional groups, and reaches 120–170 mg/g at pH 5. The equilibrium sorption is attained after 300 min. The infrared (IR) spectra of resins confirm that both guanidyl and carboxyl groups form complexes with Cu(II) ions. From analysis of the sorption degree of Cu(II) ions it can be concluded that statistically two groups (carboxyl or/and guanidyl) participate in the complexation. Electron paramagnetic resonance (EPR) spectra of the resins suggest that at low pH the complexes of Cu(II) ions with carboxyl groups dominate. At the pH range 3–8 the formation of Cu(II) complexes with carboxyl and guanidyl groups is evident. At pH > 9 three or four nitrogen atoms participate in coordination sphere around Cu(II).

Structure and sorption properties of porous copolymers of acrylonitrile and divinylbenzene

Abstract The effect of the chemical structure of porous copolymers formed from actrylonitrile (AN) and divinylbenzene (DVB) containing various weight fractions of polar units (12, 19, 26, 40 and 58% AN) on their physicochemical and sorption properties has been examined. With increasing content of the polar units in the copolymers, their Kovats indices increase, suggesting the presence of stronger interactions of the polar sorbates with the copolymer surface. The sorption degrees of phenols and anilines have been found to depend more on the surface polarity than on its total area. The Hammett equation describes the sorption process well, thus suggesting that physical interactions are dominant. The selectivity of sorption, expressed in terms of the process constant in the Hammett equation, decreases as the content of AN units increases.

Anion exchangers with alkyl substituted guanidyl groups ☆: Gold sorption and Cu(II) coordination

Abstract Two methods of introducing guanidyl groups into polymer matrix were investigated in this work: the reaction of cyanamide (alkyl substituted cyanamides) and carbodiimides with amino groups in modified polystyrene. The new anion exchangers (AEG) with alkyl substituted guanidyl groups contain 1.5–2.3 mmol/g of ligands and exhibit high selectivity towards Au(CN) 2 − anions. From the solution containing 2 ppm of gold the sorption is as high as 30 mg/g. Furthermore, AEG reveal high affinity towards tetrachloroaurate anions. The log K in diluted solution is about 5. The values of gold sorption as dicyanoaurate or tetrachloroaurate anions on AEG with alkyl substituted hydrogen atoms in guanidyl groups is two–four times higher than sorption on anion exchangers synthesized previously by exchange of chlorine with guanidine or aminoguanidine. The EPR studies of Cu(II)-loaded AEG were undertaken to correlate the structural properties of the formed complexes with the nature of the ligands, the ligand concentration, water regain of the resins and pH.

Determination of thermodynamic data for the interaction of aliphatic alcohols with poly(styrene-co-divinylbenzene) using inverse gas chromatography

The thermodynamic functions of mixing, the weight fraction activity coefficients at infinite dilution and the Flory-Huggins interaction parameters were determined for systems of normal aliphatic alcohols (C1C6) interacting with poly(styrene-co-divinylbenzene) (5, 10 and 20wt% divinylbenzene). The Hildebrand solubility parameters δ2 of the copolymers were calculated. The values obtained directly from the free energy of mixing were found to agree best with literature data. In the range 455–480 K they were 14.8, 15.7 and 17.8 MPa12, respectively, for the copolymers crosslinked with 5, 10 and 20wt% of divinylbenzene.

New selective resins with guanidyl groups

Abstract Conditions of reaction between nitrile groups of acrylonitrile/vinyl acetate/divinylbenzene (ANNA/DVB) copolymer and aminoguanidine bicarbonate (AGB) leading to N-substituted amides have been optimized. It has been found that the highest concentration of amino groups can be achieved carrying out aminolysis in the presence of a butanol/water mixture as solvent. Resin obtained under such conditions has 2.20 mmol/g of amino groups and 2.40 g/g water regain. Modified resins display a smaller average pore diameter (5.6 nm) than starting ANNA/DVB copolymer (11.2 nm), indicating that the pore surface is covered with amide gel. When water is used as solvent in aminolysis reaction the degree of modification is smaller and the structure of the resulting resin is similar to that of the starting copolymer. Sorption of Cu(111) on obtained resins is high and proportional to amino group concentration, whereas sorption of Au(CN)2 under alkaline conditions in the presence of excess KCN depends on the structure of the acrylic resin but not on amino group content. Resins which have been modified with AGB in the presence of a butanol/water mixture are 9-times (49.3 mg/g of dry resin) more effective in gold cyanide removal than those modified in water. Other polymers such as: methacrylic acid/trimethylolpropane trimethacrylate (TMPMA), glycidyl methacrylate/TMPMA, glycidyl methacrylate/trimethylolpropane triacrylate and vinylbenzylchloride/styrene/divinylbenzene have been investigated as matrices for aminoguanidine ligands. In the case of the latter polymer, containing 2 wt% of crosslinking agent, sorption of gold cyanide is 55.0 mg/g.

Sorption of aurocyanide and tetrachloroaurate onto resin with guanidine ligand—an XPS approach

The guanidine ligand attached to vinylbenzyl chloride matrix as well as its sorption ability to tetrachloroaurate and dicyanoaurate ions were investigated upon using X-ray photoelectron spectroscopy. The form of metallic gold, Au(0), was not observed on gold loaded resin surface when solutions of tetrachloroaurate or potassium dicyanoaurate were used. Complete elution of gold was achieved for both regeneration media: thiourea solution and mixture of sodium hydroxide and benzoate. The results demonstrate that XPS can also be a powerful technique for the analysis of the oxidation state of sorbed metal and can be a suitable method for the confirmation of functional groups incorporated in the polymer.

Influence of the structure of chelating resins with guanidyl groups on gold sorption

Abstract The chemical composition and structure of copolymers determines modification degree, concentration of ligands, their accessibility and hence capacity and selectivity of chelating resins. In order to investigate all such influences, a new series of copolymers have been obtained: one with increased polarity and hydrophilicity of polymer surface has been synthesized from vinyl benzyl chloride (VBC), methyl methacrylate (MM) and divinylbenzene (DVB) mixture, another one with toluene and hexadecane as inert diluents. As was expected copolymers synthesized in the presence of hexadecane, which is thermodynamically poor for the mixture of monomers, are porous with small pores (less than 1.8 nm radius) and with macropores (radius bigger than 17 nm). After modification with aminoguanidine bicarbonate, resins with the ligand concentration in the range 1–2 mmol/g are more hydrophilic but porosity decreases due to the elasticity of networks. The copolymers and resins obtained in the presence of toluene have a gel expanded structure. The ability of resins to remove dicyanoaurate complexes has been tested under the following conditions: an excess of potassium cyanide, 50 mg/l of dicyanoaurate concentration and ratio of aminoguanidine ligands to gold complexes 7.7:1. Under these conditions the sorption for the concentration of ligands of 1.2 mmol/g was about 23 mg/g and for 2.0 mmol/g it was 30 mg/g. Sorption of gold increases with increased ligand content. Sorption of gold at pH 7 is higher than at pH 9.5 and at 13.5 comparable to that at pH 9.5. Lowering dicyanoaurate concentration to 5 mg/l decreases the sorption of gold, but when the ligand to dicyanoaurate anions ratio is 1.1:1 the sorption reaches 30 mg of gold/g, which corresponds to a distribution coefficient of 6900. However, better sorption at low ligand to dicyanoaurate ratio is accompanied by much lower extraction degree and distribution coefficient.