Gram Of Resin Research Articles

Anion exchange recovery of rhenium from industrial liquors followed by direct synthesis of a rhenium halide salt

In the present study, the sorption of perrhenate ions from sulfuric acid liquors was studied using three types of polymer ion exchange resins. An anion exchange resin type 1 (a copolymer of 2-methyl-5-vinylpyridine with divinylbenzene (VP-DVB)) as well as two polyfunctional resins containing anion and cation exchange functional groups, namely, type 2 (a carboxylated VP-DVB with pyridine-2-carboxylic acid (picolinic acid) functional group) and type 3 (an aminophosphorylated VP-DVB with pyridine-2-[(methylamino)methyl]phosphonic acid functional group), were studied. The resins before and after rhenium sorption were characterized by FT-IR spectroscopy and XPS spectroscopy. The incorporation of additional acidic functional groups into the polymer matrix of the VP-DVB resins led to a slight decrease in the rhenium anion exchange capacity. At the same time, polyfunctional resins make it possible to strip rhenium with hydrochloric acid. A completely new process for the preconcentration of rhenium as a halide compound, which will contribute to the low-cost production of metallic rhenium, can be implemented using these new polyfunctional resins. Column sorption experiments using real uranium leach liquors demonstrated an exchange capacity of 33.2 mg of Re per gram of resin and a concentration factor in the eluate of ∼2500. The possibility of anion exchange recovery of rhenium from uranium leach liquors by Type 3 resin followed by direct precipitation of potassium hexachlororhenate from hydrochloric acid desorption liquor was demonstrated. The present study provided a new resin for rhenium recovery with excellent adsorption and elution characteristics, which is a promising candidate for practical applications.

Ion Exchange MIEX® GOLD Resin as a Promising Sorbent for the Removal of PFAS Compounds

Per- and polyfluoroalkyl substances (PFASs) are synthetic compounds, which have been widely produced, used, and recently identified as extremely toxic chemicals, and are responsible for serious environmental and human health risks. In this study, the removal efficiency of MIEX® GOLD resin was tested against six PFAS compounds including perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS). The removal of PFASs and the regeneration of resin (NaCl-saturated methanol) were achieved via adsorption and desorption mechanisms. In all cases, the removal efficiency was greater than 99% where the volume ratio of 1 ppm PFAS to resin was maintained at 50-bed volume. Furthermore, the adsorption capacity of MIEX® GOLD resin was studied for PFOA and PFHxS and achieved 1.05 ± 0.01 g PFOA adsorption and 1.01 ± 0.04 g PFHxS adsorption per gram of resin. In addition, a detailed study on the interference of natural organic matter (NOM) and inorganic matter was carried out against PFHxA, PFOA, and PFOS. The presence of 10 ppm NOM (5 ppm tannic acid + 5 ppm humic acid) and 25 ppm inorganic matter (5 ppm nitrate + 20 ppm sulfate) showed no noticeable interference in the removal of selected PFAS compounds. Compared to sulfonic acid-containing PFASs, the interference of organic and inorganic matter on carboxylic acid-containing PFASs was slightly higher. The regeneration of PFAS-adsorbed resin was studied using a mixed solution containing 70% methanol and saturated NaCl. Desorption of PFHxS, PFOS, and PFOA was found to be 98.3, 100, and 43.3%, respectively. The results again indicate that the resin regeneration is strongly affected by the functional group of PFASs; i.e., resin with sulfonic acid-containing PFAS is much easier to regenerate than carboxylic acid-containing PFAS compounds. All the PFAS analyses were performed by using mass spectroscopy and liquid chromatography–mass spectroscopy. In conclusion, this study confirms the remarkable efficiency of MIEX® GOLD resin in removing PFAS compounds, even in the presence of a high concentration of organic and inorganic interferences, and its capacity to be regenerated for repeated usage. These advantages make MIEX® GOLD a promising product for the remediation of PFAS-contaminated water. This study in the broader sense proves that MIEX® GOLD is a promising adsorbent and provides the ground for future study to treat contaminated groundwater.

Amino-Li-Resin-A Fiber Polyacrylamide Resin for Solid-Phase Peptide Synthesis.

Amino-Li-resin is a new and unique polyacrylamide resin presented in the form of fibers and is found to be well suited for solid-phase peptide chemistry. Although amino-Li-resin swells much better in polar solvents, it is also compatible with some non-polar solvents. It comes with a high loading of functional amino groups, thus maximizing its productivity in terms of the amount of peptide per gram of resin. In addition to its mechanical stability, this resin shows excellent stability in basic and acidic reagents; thus, allowing its broad applicability for the synthesis of a wide range of biomolecules. Finally, the appropriateness of amino-Li-resin for solid-phase peptide synthesis (SPPS) has been demonstrated for the synthesis of several model peptides, including difficult sequences and those containing hindered amino acids, all of which afforded excellent crude purity, as shown by high-performance liquid chromatography (HPLC) analysis.

Effective removal of methyl orange dye using aliquat 336 impregnated Amberlite XAD-2 resin

Methyl orange (MO) dye was removed using Amberlite XAD-2 resin modified by wet impregnation method with Aliquat-336. The modified resin was characterized by FTIR, FE-SEM, SEM with EDX, and pH of zero charge. Experimental parameters such as time, initial dye concentration, pH, temperature, resin dose and presence of NaCl salt affecting the adsorption rate were studied. 2 g.L −1 of resin was found to be optimum for 20 mg.L −1 MO dye. A maximum of 40.93 mg dye was removed per gram of resin. Langmuir, Freundlich, and Temkin isotherms were used to predict the equilibrium points at four temperatures. Pseudo-second-order fitted the kinetic data ( R 2 = 0.982). The resin could be reused for five successive cycles effectively. Also, the prepared resin was used for the removal of a cationic dye, rhodamine-B and an industrial dye, Pink S8EB.

Highly efficient plutonium scavenging by an extraction chromatography resin containing a tetraaza-12-crown-4 ligand tethered with four diglycolamide pendent arms

An efficient extraction chromatography resin, containing tetraaza-12-crown-4 functionalized with four diglycolamide moieties, was evaluated for the separation of plutonium. This chromatography resin yielded very large distribution coefficients for Pu4+ (>105) in 0.5 – 6 M HNO3 feed solutions. Various physicochemical properties such as sorption kinetics, Pu4+ sorption mechanism, and its sorption capacity were investigated. The sorption kinetics, following a pseudo-second-order model, showed that about 10 minutes of equilibration was sufficient for >99.9% sorption of Pu4+. The sorption of Pu4+ on the resin followed the Langmuir monolayer model, which was confirmed by a theoretical calculation based on the kinetic model. The Pu4+ sorption on the resin was driven by a large exothermic enthalpy change (ΔH = −31.4±2.2 kJ/mol) and a positive entropy change (ΔS = 224±15 J/mol/L). The resin could sorb a maximum of 12.1±0.8 mg of Pu per gram of resin, which is equivalent to 1:2 metal/ligand complex on the resin. The Pu4+ from the resin phase was completely stripped with 0.5 M oxalic acid. A possible application of this resin for the separation / pre-concentration of Pu4+ was successfully demonstrated in the column mode.

The Effect of Resin and NH4OH Addition in The Making of Ammonium Silica Fertilizer from Geothermal Sludge

Geothermal sludge is a waste product from geothermal where it contains SiO2 which can be used as fertilizer. In this study, the making of silica ammonium fertilizer was carried out by taking salicy acid from geothermal sludge by extracting and adding resin which was then modified with NH4OH addition. Extraction was done using 1000 ml of KOH 1 N to dissolve 60 grams of Geothermal Sludge. Resins are added with variations in resin weight, namely, 5, 10, 20, 30, and 40 grams. NH4OH was added with variations in concentrations namely 3, 6, 9, 12 and 15% with a ratio of filtrate and NH4OH solution of 1: 1. The resulting ammonium silica inorganic liquid fertilizer products were analyzed for free silica and ammonia levels. The results of this study indicate that the levels of free silica and ammonia are influenced by the weight of the resin used and the concentration of ammonium hydroxide mixed. From the results of the research, it was found that inorganic silica liquid fertilizer with the highest SiO2 content in ammonium silica liquid fertilizer occurred when adding 20 grams of resin with the addition of NH4OH with a concentration of 15% which was 1,831.87 mg / L while the highest NH3 content in fertilizer liquid ammonium silica occurs when adding 40 grams of resin with the addition of NH4OH with a concentration of 15% which is equal to 252,312.80 mg / L.

Low resolution benchtop nuclear magnetic resonance for the follow-up of the removal of Cu2+ and Cr3+ from water by amberlite IR120 ion exchange resin

Water pollution by heavy metals is a major environmental concern. For example, copper and chromium are produced by metal and electronic industries and must be removed from wastewater. But Cu2+ and Cr3+ are also paramagnetic ions which previously allowed the use of Magnetic Resonance Imaging (MRI) and Nuclear Magnetic Resonance (NMR) relaxometry to follow their migration in several matrixes and their adsorption on different compounds. In this work, the removal of Cu2+ and Cr3+ from water by amberlite IR120 resin is studied with T2 relaxometry. The ion exchange process obeys a pseudo-second-order kinetics model, while the equilibrium isotherms can be fitted by the Langmuir theory providing values of 79 and 10.1 mg/g for the maximum metal content per gram of resin for Cu2+ and Cr3+ respectively. The equilibrium constants are 2.07 and 0.61 mM−1 for Cu2+ and Cr3+ respectively. pH does not influence the removal capacity of the resin in the studied range (pH 2–4.5). The longitudinal and transverse relaxation of the wet resin are shown to be biexponential. The relaxation rate of the fast relaxing water fraction of the wet resin is correlated with its Cu2+ or Cr3+ content. This paves the way of column experiments in which the gradual loading of the resin with Cu2+ or Cr3+ could be followed on-line by NMR relaxometry.

Improved Performance of Silicon Rubber Insulation With Coal Fly Ash Micro Filler

This paper presents the effect of coal fly Ash filler (CFA) on the electrical properties of silicon rubber composite. The observed electrical properties are volume resistance, surface resistance, and the surface breakdown voltage. The temperature The effect on the surface breakdown voltage of silicon rubber with CFA filler also was observed. The type of silicon used is RTV 683. The filler concentrations of the matrix are 0,​​10.20,30,40 per-hundred gram of resin (phr). The test results show that the surface resistance increased significantly with the increasing of CFA loading filler. The increasing of volume resistance is nonlinear; the volume resistance tends to decrease when the CFA loading filler exceeds 30 phr. Flashover test results show that flashover inception voltage (FOIV) increases with the increasing of CFA filler concentration and the increasing of temperature.

Recovery of metals from an acid leachate of spent hydrodesulphurization catalyst using molecular recognition technology

Acid leaching of spent hydrodesulphurization (HDS) catalysts solubilizes efficiently all metals present in the catalyst; however, this methodology poses subsequent difficulties in achieving metals separation with high purity. In the present work, molecular recognition technology, using SuperLig® 167 resin, was applied to recover Ni, Mo and Al from H2SO4 leachate of spent HDS catalyst.Batch tests showed a good resin affinity to Ni, in acid, with a maximum capacity of 1.35mmol/g. The separation of Al, which was in excess, was efficient, but Mo was also retained by the resin.Column studies, using 6g of resin and performed at three flow rates (1.0, 1.5 and 2.1mL/min), showed that the lower flow rate was better to treat a higher volume of solution. At 1.0mL/min, each gram of resin treated almost 40mL of solution with 97% and 100% of Ni and Mo retention, respectively. Elution with NaOH 0.25mol/L, followed by HNO3 4mol/L, both at 2.1mL/min, led to efficient separation of Mo and Ni.The use of SuperLig® 167 resin to treat the leaching solution enabled an easy and efficient separation of the metals present in the acid leachate into mono-metal solutions (Al in the raffinate, Mo and Ni in the alkaline and acid eluates, respectively) with high yield (99.7%, 100% and 87%, respectively) and purity (99.3%, 99.8% and 98.7%, respectively).

Production of a low‐cost scavenger resin to capture aldehydes and ketones in solutions

ABSTRACTOver the past years, polymer‐supported reagents have been extensively studied and used in various applications. One class of such reagents is called “scavengers,” which can be used to easily eliminate compounds in a solution. The present work describes the production of a resin that can be used for scavenging ketones and aldehydes using low‐cost reagents and simple reaction steps, named here Amb15‐Iso. This resin is obtained by reacting a low‐cost commercial sulfonyl resin, Amberlyst‐15, with isoniazid, a drug used for the treatment of tuberculosis. Acetone and isobutyraldehyde were used as carbonyl compound models. The reactions were monitored in‐line by ATR‐FTIR and results showed that the polarity of the solvent influences the kinetics of the production of the resin and water proved to be the fastest solvent. For the scavenging of acetone and isobutyraldehyde, two factors showed to have an impact in the amount of compounds captured: the polarity of the solvent and the solubility of water in the solvent. The capacity of scavenging acetone in water varied from 0.11 to 0.28 mmol per gram of resin, depending on the initial acetone concentration. The equilibrium of this reaction was modeled and the equilibrium constant was calculated to be 0.63 ± 0.07 L mol−1. The resin was also recycled and tested in a second round of scavenging and results showed that there was not much difference between the new resin and the recycled one, proving that the Amberlyst‐15 could be reused for a second cycle of scavenging. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42291.

Fabrication of partially exfoliated and disordered intercalated cloisite epoxy nanocomposites via in situ polymerization: Mechanical, dynamic mechanical, thermal and barrier properties

Clay minerals, especially montmorillonite (Mt), have emerged as a subject of enormous scientific interest due to their unique atomic structure, high cation exchange capacity, high aspect ratio and large surface area. Clay polymer nanocomposites have established a unique position among technologically important materials because of their extensive and potential applications. Herein we have fabricated cloisite epoxy nanocomposites (CPNs) from diglycidyl ether of bisphenol A (DGEBA) epoxy and modified nanoclay, cloisite 93A using triethylenetetramine (TETA) as a curing agent. The major objective was to examine the static and dynamic mechanical properties and the performance of these CPNs for barrier resistance and thermal stability. Determination of cross link density (CLD) of CPNs by Flory–Rehner equation and activation energy by Coats–Redfern procedure were also a focus of the present study. The cloisite layer exfoliation in CPNs was monitored by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and further corroborated using transmission electron microscopy (TEM). Static mechanical properties of CPN were characterized in terms of tensile and flexural properties. Moreover, dynamic mechanical and thermal properties were evaluated by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) respectively. XRD and TEM revealed that the cloisite distribution in the epoxy matrix is of the partially exfoliated kind at lower level loadings and intercalated at higher loadings. The enhancement of mechanical properties of CPNs was to the level of 15% increase in tensile strength and 23% in flexural strength at very low cloisite loadings. The interfacial interactions brought about by cloisite 93A also benefited the thermomechanical properties to a large extent in the form of improved glass transition temperature and an impressive enhancement in storage modulus. Results based on equilibrium swelling experiments revealed that a maximum of 61% increase in barrier performance was achieved by the addition of 5 phr (per hundred gram of resin) cloisite. CLD measurements demonstrated an 11% increase in CLD at 1 phr cloisite loading. TGA results revealed that cloisite can impart greater thermal stability to pure epoxy. All the properties were correlated with the dispersion state of the cloisite in the epoxy resin matrix.

Exploration of the fundamental equilibrium behaviour of calcium exchange with weak acid cation resins

This study evaluated the complexity of calcium ion exchange with sodium exchanged weak acid cation resin (DOW MAC-3). Exchange equilibria recorded for a range of different solution normalities revealed profiles which were represented by conventional “L” or “H” type isotherms at low values of equilibrium concentration (Ce) of calcium ions, plus a superimposed region of increasing calcium uptake was observed at high Ce values. The loading of calcium ions was determined to be ca. 53.5 to 58.7g/kg of resin when modelling only the sorption curve created at low Ce values, which exhibited a well-defined plateau. The calculated calcium ion loading capacity for DOW MAC-3 resin appeared to correlate with the manufacturer's recommendation. The phenomenon of super equivalent ion exchange (SEIX) was observed when the “driving force” for the exchange process was increased in excess of 2.25mmol calcium ions per gram of resin in the starting solution. This latter event was explained in terms of displacement of sodium ions from sodium hydroxide solution which remained in the resin bead following the initial conversion of the as supplied “H+” exchanged resin sites to the “Na+” version required for softening studies. Evidence for hydrolysis of a small fraction of the sites on the sodium exchanged resin surface was noted. The importance of carefully choosing experimental parameters was discussed especially in relation to application of the Langmuir–Vageler expression. This latter model which compared the ratio of the initial calcium ion concentration in solution to resin mass, versus final equilibrium loading of the calcium ions on the resin; was discovered to be an excellent means of identifying the progress of the calcium–sodium ion exchange process. Moreover, the Langmuir–Vageler model facilitated standardization of various calcium–sodium ion exchange experiments which allowed systematic experimental design.

Cannabis retail purchases in a low-risk market: Purchase size and sex of buyers

Aim To analyse the composition of cannabis retail purchases in a representative sample of purchases made in Christiania, Copenhagen in 2004. Material Transactions (n=1,123) were registered along four variables; type (loose resin or joints), quantum (n=957, grams or number of joints), sex (n=559, female or male) and payment (n=707, notes or coins). Results We found that more than half of all transactions were for joints only. The median transaction quantum was small, at two joints or three grams of resin, valued at DKK 100. Of the resin transactions, 88% were three grams or below. Women made 11% of the purchases. There was no statistically significant difference in the preferences for quantum or type between males and females. Conclusions Buyers prefer joints over loose resin despite the higher price, which is interesting. The small median transactions size is consistent with findings in the international literature. Illicit drug buyers appear to prefer small acquisitions across drugs and social context. The share of purchases made by women is 11%, which is similar to the estimated proportion of women among daily cannabis users. This finding suggests an interesting question for future research. At what point in a cannabis-using career do users purchase their drugs? These findings contribute to the existing research by documenting the proportion of female buyers, and preferences for type and quantum in a sample that is representative of a market and is not based on self-reported purchases.

Optimalisasi Hidrolisis Sukrosa Menggunakan Resin Penukar Kation Tipe Sulfonat

Optimization of sucrose hydrolysis has been investigated by using a sulfonic type cation excange. The aim of investigation are to find out the effect of resin concentration, agitation time and the recycling of resin without ion excange treatment with optimum condition for the effectiveness of resin as catalys in hydrolysis of sucrose 70%. The result, there were obtained that the optimum condition in hirolysis of sucrose occurred at 30 grams of resin and agitation time at 16 hours, the product of sugar invert was 833.810 mg or 1.132%. The recycled of resin without ion treatment on the optimum condition as catalys in hidrolysis sucrose affected to the reduction of resin effectiveness. From Duncan’s test, the best effectiveness recycling of resin without ion treatment on the optimum condition are four time

Integration of ion exchange and electrodeionization as a new approach for the continuous treatment of hexavalent chromium wastewater

Mining and electroplating wastewaters contain many harmful ions, which are discharged into waterways and water bodies and cause significant environmental damage. Hexavalent chromium (Cr(VI)) is an ion that is commonly present in these effluents, which has been proven as toxic to humans. In the present work, continuous ion exchange and electrodeionization are proposed as a new hybrid technology for the effective treatment of Cr(VI) wastewater as well as the recovery of chromium ions. We have systemically studied a strong basic macroreticular anion exchange resin (Amberlite® IRA900) for the removal of Cr(VI). The ion exchange isotherm and kinetics of the resin were determined, showing that the IRA900 anionic ion exchange resin has a high capacity for ion exchange with hexavalent chromium (116mg Cr(VI) per gram of resin). When the anionic resin was combined with a strong acidic macroreticular cation exchange resin (Amberlite® 200C) and employed in continuous electrodeionization, over 98.5% of Cr(VI) was continuously removed from the dilute compartment with an energy consumption of less than 0.07kWh/m3, while Cr(VI) was recovered in the concentrate compartment.

Synthesis and evaluation of different thio-modified cellulose resins for the removal of mercury (II) ion from highly acidic aqueous solutions

Seven different types of thio- and/or amine-modified cellulose resin materials were synthesized and their mercury (II) ion adsorption properties determined. All seven resins showed good mercury (II) adsorption capability in the more neutral pH regions. However, the o-benzenedithiol- and o-aminothiophenol-modified cellulosic resins were found to be very effective in removing mercury (II) ions from strongly acidic media. For example, 93.5-100% mercury (II) ion recoveries from very acid aqueous solutions (nitric acid concentration ranged from 0.1 to 2.0 mol/L) were obtained using the o-benzenedithiol-modified resin while recoveries ranged from ca. 50% to 60% for the o-aminothiophenol-modified resin. An adsorption capacity of 23 mg (as Hg atoms) per gram of resin was observed for the o-benzenedithiol-modified cellulose in the presence of 1.0 mol/L nitric acid. This same resin shows very good selectivity for mercury (II) as only ruthenium (II) also somewhat adsorbed onto it out of 14 other metal ions studied (Ag(+), Al(3+), As(3+), Co(2+), Cd(2+), Cr(3+), Cu(2+), Fe(3+), Mn(2+), Ni(2+), Pt(2+), Pb(2+), Ru(2+), and Zn(2+)).

Solid‐Liquid Extraction of Terbium from Phosphoric Acid Medium using Bifunctional Phosphinic Acid Resin, Tulsion CH‐96

Solid‐liquid extraction of terbium from phosphoric acid medium has been studied using the commercially available macroporous bifunctional phosphinic acid resin, Tulsion CH‐96. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, temperature, loading, elution, regeneration, and recycling. In the wide range of phosphoric acid concentration 0.01–7.8 M the percent extraction of terbium decreases from 98.9% at 0.01 M to 16.0% at 1 M due to an ion‐exchange mechanism and increases to 36% at 7.8 M due to a coordination mechanism. The percent extraction increases with an increase in weight of the resin from 2.7% at 0.05 g to 80.7% at 1.2 g. Under the studied experimental conditions, the loading of Tulsion CH‐96 for terbium was determined to be 3.52 mg per gram of resin. The percent extraction of terbium increases with the increase in temperature, indicating the endothermic nature of the extraction process. Screening of various eluants suggested 1 M (NH4)2CO3 as the best with an efficiency of 99.8%. The extraction behavior of commonly associated metals with terbium such as yttrium, holmium, erbium, dysprosium, ytterbium, and lutetium has been studied as a function of phosphoric acid concentration to determine the separation factors and possible separation.

Use of Chelating Resin YPA4 Micro‐Columns for the On‐Line Preconcentration and Separation of Gold(III), Silver(I), Palladium(II) and Platinum(IV) in Geological and Environmental Samples and Their Determination by Inductively Coupled Plasma‐Atomic Emission Spectrometry

A simple and selective method of flow injection (FI) using a micro‐column packed with chelating resin YPA4 as solid phase extractant was developed for the preconcentration and separation of trace amount of noble metals, Au(III), Ag(I), Pd(II) and Pt(IV), followed by ICP‐AES determination. In HNO3 media, the chelating resin was selective towards Au(III), Ag(I), Pd(II) and Pt(IV), and the analysed ions were readily desorbed quantitatively with 5 ml of 2.5% m/v thiourea. Effects of acidity, sample flow rate and concentration, elution solution and interfering ions on the recovery of the analytes were systematically investigated. Under optimum conditions, the adsorption capacities of YPA4 for Au(III), Ag(I), Pd(II) and Pt(IV) were 67.2, 43.1, 64.8 and 27.6 mg per gram of resin in HNO3 media, respectively. It was found that YPA4 could be used for more than eight runs in HNO3 media without loss of capacity. The proposed method was used for the determination of trace noble metals in geological and environmental samples, and the analytical results obtained were in good agreement with the recommended values.

Synthesis and some sorption properties of anion exchangers with guanidyl ligands

The results of synthesis of anion exchangers with guanidyl end groups are presented in this paper. Reaction of primary amino groups attached to resins with S-methylthiourea gave the anion exchangers with up to 2.6 mmol of ligands per gram of resin. The best anion exchangers with guanidyl ligands are these having porous structure and ligands derived from diethylenetriamine. These exchangers sorb about 45 mg of gold/g from 50 ppm dicyanoaurate solution and more than 100 mg of gold/g from tetrachloroaurate solutions. The anion exchangers with guanidyl ligands are selective towards tetrachloroaurate anions. From AuCl 4 - solution containing also Fe(II), Zn(II), Ni(II) and Cu(II) in 0.1 M HCl they sorb practically tetrachloroaurate anions only. When the ratio of metal ions is higher than amine groups, anion exchangers sorb high amount of metal ion from the acetate solution, for example about 700 mg/g of cobalt.

Colorimetric monitoring of solid-phase aldehydes using 2,4-dinitrophenylhydrazine.

A simple and rapid method to achieve colorimetric monitoring of resin-bound aldehydes, based on ambient temperature reaction with 2,4-dinitrophenylhydrazine (DNPH) in the presence of dilute acid, has been developed as an adjunct to solid-phase organic synthesis and combinatorial chemistry. By this test, the presence of aldehydes is indicated by a red to dark-orange appearance, within a minute. Alternatively, resins that are free of aldehydes or in which aldehyde functions have reacted completely retain their original color. The DNPH test was demonstrated for poly(ethylene glycol)-polystyrene (PEG-PS), aminomethyl polystyrene (AMP), cross-linked ethoxylate acrylate resin (CLEAR), and acryloylated O,O'-bis(2-aminopropyl)poly(ethylene glycol) (PEGA) supports and gave results visible to the naked eye at levels as low as 18 micromol of aldehyde per gram of resin.