Copolymer resin. VII. 8‐hydroxyquinoline‐5‐sulfonic acid–thiourea–formaldehyde copolymer resins and their ion‐exchange properties

8‐Hydroxyquinoline‐5‐sulfonic acid–thiourea–formaldehyde copolymer resins were synthesized through the condensation of 8‐hydroxyquinoline‐5‐sulfonic acid and thiourea with formaldehyde in the presence of hydrochloric acid as a catalyst and with various molar ratios of the reacting monomers. The resulting copolymers were characterized with UV‐visible, IR and 1H‐NMR spectral data, employed to determine the reactivity of monomers. The average molecular weights of these resins were determined with vapor pressure osmometry and conductometric titration in a nonaqueous medium. The chelation ion‐exchange properties were also studied with the batch equilibrium method. The resins were proved to be selective chelating ion‐exchange copolymers for certain metals. The chelation ion‐exchange properties of these copolymers were studied for Cu²⁺, Ni²⁺, Co²⁺, Pb²⁺, and Fe³⁺ ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymers showed a higher selectivity for Fe³⁺ ions than for Cu²⁺, Ni²⁺, Co²⁺, and Pb²⁺ ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of chelating resins with iminodiacetic acid and its wastewater treatment application

The chelating resins have high potential applications for the selective removal and recovery of metal ions from industrial waste solutions. The hydrophilic acrylate monomer with the iminodiacetic acid chelating group was prepared from glycidyl methacrylate and iminodiacetic acid at 60°C. The microbeads, prepared from acrylate monomer with the iminodiacetic acid chelating group, were employed by inversion suspension polymerization. In the pH range of 2–6, a reasonably good equilibrium sorption capacity is maintained for Cr³⁺ (ca. 2.7 mmol/g) and Cu²⁺ (ca. 1.8 mmol/g) in the chelating resins. The adsorption of Cd²⁺ and Pb²⁺ on microbeads is clearly affected by the pH of the solution, such that these ions' adsorption capacity increased with the pH of the aqueous solution. The adsorption of Cd²⁺ (ca. 1.25–1.87 mmol/g) and Pb²⁺ (ca. 0.99–1.89 mmol/g) showed a maximum at approximately pH = 5 and 6, respectively. The adsorption isotherms of Cr³⁺ and Cu²⁺ adsorbed on microbeads were following the Langmuir isotherm, but the adsorption behavior of Cd²⁺ and Pb²⁺ were not. The concentration of alkaline earth–metal cations on the range of 0–200 ppm had no influence on metal ions adsorbed capacity of chelating resins. Additionally, NTA (nitrilotriacetic acid) had no significant influence on metal ion adsorption by chelating resins. Furthermore, phenol pollutant can be adsorbed effectively by metal ions chelated microbeads; therefore, the microbeads were useful not only in recovering metal ions but also in the treating phenol pollutants in wastewater. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1353–1362, 2002; DOI 10.1002/app.10243     

Synthesis–structure–performance relationship of cocondensed phenol–urea–formaldehyde resins by MALDI‐ToF and 13C NMR

Matrix assisted laser desorption ionization time of flight (MALDI‐ToF) mass spectrometry has consistently confirmed on a number of PUF resins that phenol–urea cocondensates exist in phenol–urea–formaldehyde (PUF) resins. A noticeable proportion of methylene‐linked phenol to urea cocondensates were detected in all the PUF resins tried, alongside methylene bridges connecting phenol to phenol and urea to urea. The PUF, PF, and UF oligomers formed were identified. Variations of the PUF preparation procedure did always yield a certain proportion of the mixed phenol to urea cocondensates. Their relative proportion was determined and related the synthesis procedure used. Comparison of the MALDI‐ToF results with a ¹³C NMR investigation showed that in a real PUF resin in which phenol to urea cocondensates were identified the methylene bridge NMR signal at 44 ppm, characteristic of phenol to urea unsubstituted model compound cocondensates, does not appear at all. This confirmed that this peak cannot be taken as an indication of the existence of phenol and urea condensation under actual resin preparation conditions. The peak indicating cocondensation in PUF resins in which the phenolic nuclei and urea are substituted appears instead at 54.7–55.0 ppm. Thermomechanical analysis has again confirmed that the resin gel times greatly accelerates with increasing urea molar content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and evaluation of chitosan aryl azacrown ethers as adsorbents for metal ions

New azacrown ether chitosan derivatives (CTS–OC, CTS–NC) were synthesized by reaction of aryl mesocyclic diamine with the C6 hydroxyl group or C2 amino group in chitosan. Their structures were confirmed by elemental analysis, infrared spectra analysis, and X‐ray diffraction analysis. The adsorption and selectivity properties of the aryl azacrown ethers chitosan derivatives for Hg²⁺, Cd²⁺, Pb²⁺, Ag⁺, and Cr³⁺ were also investigated. The experimental results showed that the two chitosan–azacrown ethers have good adsorption capacity for Pb²⁺, Cd²⁺, and Hg²⁺. The adsorption capacity of CTS–OC are higher than that of CTS–NC for Pb²⁺ and Cd²⁺. The chitosan–azacrown ethers have high selectivity for the adsorption of Pb²⁺ and Hg²⁺ with the coexistence of Cd²⁺. The selectivity properties of CTS–OC are better than those of CTS–NC. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3093–3098, 2000     

Composite cation exchangers

Sulfonated phenol formaldehyde resins containing different amounts of sulfonated sawdust were prepared. The thermal and chemical stabilities, scientific weight capacity, and apparent capacities for the exchange of Na⁺, Ca²⁺, and Mg²⁺ at different concentrations were detemined for both H⁺ and Na⁺ forms of resins. Composites containing up to 30%–50% of sawdust, while being very much cheaper, are comparable in their properties to the pure polymeric resin. Thus, cheaper exchangers can be prepared by substituting part of the polymer by sawdust.     

Optimizing the conditions of quantitative 13C-NMR spectroscopy analysis for phenol–formaldehyde resol resins

The experimental time of ¹³C-NMR quantitative analysis of phenol–formaldehyde resins was reduced so that quantitativeness was maintained. The quantitative spectra of 14 model resins were obtained using a gated decoupling technique suppressing the NOE. The paramagnetic additive, Cr(acac)₃, was used to shorten relaxation times of carbon atoms. The use of Cr(acac)₃ was optimized in two deuterated solvents, DMSO and acetone. To reach short relaxation times and further the measurement times, the concentration of relaxation reagent, the delay time, and the number of NMR scans were optimized. Quantitativeness was proved by analyzing the spectra of accurate mixture of model compounds, and the spectra of the condensed model resins. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1805–1812, 1998     

Adsorption properties of novel chelating resins containing 2‐amino‐5‐methylthio‐1,3,4‐thiadizole and hydrophilic spacer arms for Hg2+ and Ag+

The adsorption properties, including the adsorption kinetics, adsorption isotherms, and adsorption selectivity, of newly formed chelating resins that contained a heterocyclic functional group and a hydrophilic spacer arm of poly(ethylene glycol) [polystyrene–diethylene glycol–2‐amino‐5‐methylthio‐1,3,4‐thiadizole (PS–DEG–AMTZ) and polystyrene–triethylene glycol–2‐amino‐5‐methylthio‐1,3,4‐thiadizole (PS–TEG–AMTZ)] were studied in detail. The results show that the adsorption kinetics of PS–DEG–AMTZ and PS–TEG–AMTZ for Hg²⁺ and Ag⁺ could be described by a pseudo‐second‐order rate equation. The introduction of a spacer arm between the polymeric matrix and functional group was beneficial for increasing the adsorption rates. The apparent activation energies of the resins for Hg²⁺ and Ag⁺ were within 20.89–32.32 kJ/mol. The Langmuir model could describe the isothermal process of Hg²⁺ and Ag⁺. The competitive adsorption of the resins for Hg²⁺ and Ag⁺ in binary mixture systems was also investigated. The results show that Hg²⁺ and Ag⁺ were adsorbed before the other metal ions, such as Cu²⁺, Zn²⁺, Fe³⁺, Cd²⁺, and Pb²⁺, under competitive conditions. Five adsorption–desorption cycles were conducted for the reuse of the resins. The results indicate that these two resins were suitable for reuse without considerable changes in the adsorption capacity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Time–temperature–transformation cure diagrams of phenol–formaldehyde and lignin–phenol–formaldehyde novolac resins

In this study, the time–temperature– transformation (TTT) cure diagrams of the curing processes of several novolac resins were determined. Each diagram corresponded to a mixture of commercial phenol–formaldehyde novolac, lignin–phenol–formaldehyde novolac, and methylolated lignin–phenol–formaldehyde novolac resins with hexamethylenetetramine as a curing agent. Thermomechanical analysis and differential scanning calorimetry techniques were applied to study the resin gelation and the kinetics of the curing process to obtain the isoconversional curves. The temperature at which the material gelled and vitrified [the glass‐transition temperature at the gel point (_gelT_g)], the glass‐transition temperature of the uncured material (without crosslinking; T_g0), and the glass‐transition temperature with full crosslinking were also obtained. On the basis of the measured of conversion degree at gelation, the approximate glass‐transition temperature/conversion relationship, and the thermokinetic results of the curing process of the resins, TTT cure diagrams of the novolac samples were constructed. The TTT diagrams showed that the lignin–novolac and methylolated lignin–novolac resins presented lower T_g0 and _gelT_g values than the commercial resin. The TTT diagram is a suitable tool for understanding novolac resin behavior during the isothermal curing process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Separation of gold(III) ions from copper(II) and zinc(II) ions using thiourea–formaldehyde or urea–formaldehyde chelating resins

Thiourea–formaldehyde (TF) and urea–formaldehyde (UF) chelating resins were synthesized and these resins were used in the separation of gold(III) ions from copper(II) and zinc(II) base metal ions. In the experimental studies, the effect of acidity on gold(III) uptake and gold(III) adsorption capacities by batch method, and loading and elution profiles of gold(III) ions, gold(III), copper(II), and zinc(II), dynamic adsorption capacities and the stability tests of TF and UF resins by column method were examined. By batch method, the optimum acidities were found as pH 2 and 0.5M HCl, and gold(III) adsorption capacities in the solutions including copper(II) and zinc(II) ions were obtained as 0.088 and 0.151 meq Au(III)/g for UF and TF resins, respectively. On the other hand, by column method, the dynamic adsorption capacities were calculated as 0.109 meq Au(III)/g with TF, 0.023 meq Au(III)/g with UF, 0.015 meq Cu(II)/g with TF, 0.0057 meq Cu(II)/g with UF, and under 6.1 × 10^?5 meq Zn(II)/g with TF or UF. TF resin was more effective in the separation and the concentration of gold(III) ions from copper(II) and zinc(II) ions than UF resin. It was seen that sulfur atoms contributed the gold(III) adsorption comparing with oxygen atoms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Examination of selected synthesis parameters for wood adhesive‐type urea–formaldehyde resins by 13C NMR spectroscopy. III

The varying polymer structures of wood adhesive‐type urea–formaldehyde resins resulting from different formaldehyde/first urea (F/U₁) mole ratios used in the first step of resin manufacture were investigated using ¹³C. As the F/U₁ mole ratio decreased progressively from 2.40 to 2.10 and to 1.80, the viscosity increase due to polymerization during resin synthesis became faster and resulted in decreasing side‐chain branches and increasing free urea amide groups in the resin structure. The resultant UF resins, with the second urea added to an overall F/(U₁ + U₂) of 1.15, showed viscosity decreases when heated with stirring or allowed to stand at room temperature that were also characteristic with the F/U₁ mole ratios used in resin synthesis. The formaldehyde emission levels of particleboards bonded with the freshly made UF resins showed relatively small but similarly characteristic variations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2800–2814, 2001     

Characterization of phenol–urea–formaldehyde resin by inline FTIR spectroscopy

Phenol–urea–formaldehyde (PUF) resins were synthesized by a two‐step polymerization process. The first step was the synthesis of 2,4,6‐trimethylolphenol (TMeP) from phenol and formaldehyde, under alkaline conditions. In the second step PUF resins were synthesized by the reaction of TMeP with urea, under acidic and alkaline conditions. The influence of temperature on the synthesis of TMeP was investigated. The molar ratio between TMeP and urea was varied to study the composition effect on the second step of the PUF synthesis and final product properties. Synthesis of TMeP and PUF resins were monitored by inline FTIR‐ATR system. Analytical methods, such as differential scanning calorimetry, nuclear magnetic resonance, thermogravimetric analysis, and infrared spectroscopy were used for characterization of TMeP and PUF resins. Obtained PUF resins were cured and tested on flexural strength. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

On the correlation equations of liquid and solid 13C‐NMR,thermomechanical analysis,Tg, and network strength in polycondensation resins

Wide‐scope mathematical relationships have been established between the ¹³C‐NMR of liquid polycondensation resins, such as urea–formaldehyde and phenol–formaldehyde resins, and the strength of the network formed by the same resin when hardened under well‐defined conditions, the thermomechanical analysis deflection, the number average molecular mass and the number of degrees of freedom of the average polymer segment between crosslinking nodes in the hardened resin network, the resin network glass transition temperature, its solid‐phase ¹³C‐NMR proton‐rotating frame spin‐lattice relaxation time, and the homogeneous and heterogeneous polymer segment/polymer segment interfacial interaction energy calculated by molecular mechanics. These mathematical relationships allow the calculation of any of these parameters from any of the techniques listed, provided that all of the systems are used under well‐defined conditions. Under different conditions, the values of the numerical coefficients involved change; and, whereas the equations are still valid, a different set of coefficients needs to be recalculated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1703–1709, 1999     

Synthesis of polystyrene‐supported glucosamine resin and its adsorption properties for metal ions

A novel chelating resin polystyrene‐supported glucosamine was prepared by the reaction of chloromethylated polystyrene with glucosamine hydrochlorate, using anhydrous potassium carbonate as catalyst and dimethylformamide as solvent. Infrared spectra and elementary analysis were used to confirm its structure. The adsorption of the resin for Cu²⁺, Ni²⁺, Hg²⁺, Co²⁺, Cd²⁺, and Pb²⁺ was investigated, as well as various factors affecting the adsorption such as time, temperature, ion concentration, and pH. The results showed that the resin had good adsorption capacities for Cu²⁺, Ni²⁺, and Hg²⁺. The adsorption was controlled by liquid film diffusion and adsorption isothermal data could be well interpreted by the Freundlich equation. Values of adsorption activation energy and adsorption Gibbs free energy were calculated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 890–896, 2005     

Separation and recovery of gold(III) from base metal ions using melamine–formaldehyde–thiourea chelating resin

Melamine–formaldehyde–thiourea (MFT) chelating resin has been prepared. Au³⁺ ions uptake behavior and selectivity of the chelating resin were investigated by both batch and column methods. MFT resin showed higher affinity toward Au³⁺ compared with base metal ions, Cu²⁺ and Zn²⁺. The highest Au³⁺ uptake values were obtained at pH 2 and Au³⁺ adsorption capacity of the resin was calculated as 48 mg Au³⁺/g resin (0.246 mmol Au³⁺/g resin) by batch method. It was concluded that Au³⁺ ions could be selectively concentrated from the solution including Cu²⁺ and Zn²⁺ base metal ions by column method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Controlled synthesis of high‐ortho‐substitution phenol–formaldehyde resins

The relationship between the use of 19 kinds of metal catalysts and the proportion of ortho–ortho links of novolac resins was studied. The proportion of ortho–ortho links of novolac resins was characterized with Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR. The effects of different catalysts and different reaction conditions, such as the molar ratio of phenol to formaldehyde, the pH value of the reaction, and the reaction time, were examined. Phenol–formaldehyde resins were synthesized with a certain proportion of the ortho position through the adjustment of the reaction conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 652–658, 2005     

Preparation and characterization of a phosphonylated polypropylene ion exchanger

Because typical ion exchange resins used for treating wastewater contain sulfur binding sites and suffer from application limitations, a new ion exchange system was developed by phosphonylating nonwoven polypropylene fabric (PP). These fabrics were phosphonylated for 0.5, 1, 2, and 4 h; amount of phosphorus on phosphonylated PP increased with an increase in phosphonylation time. After hydrolysis, the appropriate phosphonylated sample was placed in a glass column where a europium (Eu³⁺), lead (Pb²⁺), or mercury (Hg²⁺) salt solution was passed through the fabrics after an equilibration period of 5 min. Filtrate samples were then analyzed by atomic absorption spectroscopy for metal concentration. Results showed that metal binding efficiency for Eu³⁺ increased with an increase in phosphonylation time; Pb²⁺ binding efficiency increased up to 2 h phosphonylation time and then decreased; Hg²⁺ binding efficiency was practically independent of phosphonylation time. PP fabrics were also sulfonated and tested for binding efficiency to determine if phosphorus was a better binding site than sulfur. By comparing the results from phosphonylated PP and sulfonated PP, data showed that phosphonylated PP bound metal ions at a higher efficiency than sulfonated PP. Also, phosphonylated PP had higher binding efficiencies with Eu³⁺ and Pb²⁺ than a commercial exchange resin. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 93–100, 2000     

Removal of heavy‐metal ions from aqueous solution with nanochelating resins based on poly(styrene‐alt‐maleic anhydride)

Chelating resins have been considered to be suitable materials for the recovery of heavy metals in water treatments. A chelating resin based on modified poly(styrene‐alt‐maleic anhydride) with 2‐aminopyridine was synthesized. This modified resin was further reacted with 1,2‐diaminoethan or 1,3‐diaminopropane in the presence of ultrasonic irradiation for the preparation of a tridimensional chelating resin on the nanoscale for the recovery of heavy metals from aqueous solutions. The adsorption behavior of Fe²⁺, Cu²⁺, Zn²⁺, and Pb²⁺ ions were investigated by the synthesis of chelating resins at various pH's. The prepared resins showed a good tendency for removing the selected metal ions from aqueous solution, even at acidic pH. Also, the prepared resins were examined for the removal of metal ions from industrial wastewater and were shown to be very efficient at adsorption in the cases of Cu²⁺, Fe²⁺, and Pb²⁺. However; the adsorption of Zn²⁺ was lower than those of the others. The resin was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction analysis, and differential scanning calorimetry analysis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and properties of water‐soluble sulfonated acetone–formaldehyde resin

Water‐soluble sulfonated acetone–formaldehyde (SAF) resins were synthesized by the reaction among acetone, formaldehyde, and sodium bisulfite. The factors affecting the properties of SAF resins and optimum conditions of preparation were investigated. The SAF resins prepared under proper conditions have good water solubility and high performance as a superplasticizer used in concrete. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3248–3250, 2004     

Influence of the synthesis conditions on the curing behavior of phenol–urea–formaldehyde resol resins

The curing behavior of synthesized phenol–urea–formaldehyde (PUF) resol resins with various formaldehyde/urea/phenol ratios was studied with differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The results indicated that the synthesis parameters, including the urea content, formaldehyde/phenol ratio, and pH value, had a combined effect on the curing behavior. The pH value played an important role in affecting the shape of the DSC curing curves, the activation energy, and the reaction rate constant. Depending on the pH value, one or two peaks could appear in the DSC curve. The activation energy was lower when pH was below 11. The reaction rate constant increased with an increase in the pH value at both low and high temperatures. The urea content and formaldehyde/phenol ratio had no significant influence on the activation energy and rate constant. DMA showed that both the gel point and tan δ peak temperature (T_tanδ) had the lowest values in the mid‐pH range for the PUF resins. A different trend was observed for the phenol–formaldehyde resin without the urea component. Instead, the gel point and T_tanδ decreased monotonically with an increase in the pH value. For the PUF resins, a high urea content or a low formaldehyde/phenol ratio resulted in a high gel point. The effect of the urea content on T_tanδ was bigger than that on the gel point because of the reversible reaction associated with the urea component. Too much formaldehyde could lead to more reversible reactions and a higher T_tanδ value. The effects of the synthesis conditions on the rigidity of the cured network were complex for the PUF resins. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1368–1375, 2005     

Synthesis,characterization, and application of new low‐cost ion exchangers

This paper represents a simple method for preparing and characterizing of low‐cost ion exchangers of sulfonated carbon prepared from Terminalia Chebula‐Retz., (family–combretaceae) as a source of cheap plant material blended with phenol‐formaldehyde as a crosslinking agent. The prepared ion exchange resins (IERs) are characterized by infrared (IR) spectral and thermal studies. All the important physicochemical properties of the ion exchangers have been determined. The synthesized resins have cation exchange capacity upto 1.84 mmol g^?1. The rational thermodynamic equilibrium constant (ln K) are calculated for H⁺ and Zn²⁺ exchanges on the resin having various amount of sulfonated Terminalia Chebula Retz. carbon (STCC). The thermodynamic parameters were calculated, and suitable explanations are given. It is concluded from the present study that PFR sample could be blended with 20% (w/w) of STCC, without affecting its physicochemical, spectral, and thermal properties. Hence blending with STCC will definitely lower the cost of the ion exchange resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4104–4113, 2006