Macroreticular Polystyrene Resin Research Articles

Synthesis of chemically modified macroreticular resins for the preparation of gold nanoparticles via sorption from aqueous gold solution, and the application of these nanoparticles in catalytic remediation

A new solid-phase support for the preparation of stable gold nanoparticles (AuNPs) was developed, consisting of maleic anhydride and alkyl (C18) vinyl monomer encapsulated into a macroreticular polystyrene resin (Amberlite XAD-2). The maleic anhydride moieties were further modified with either diethylenetriamine (to form the resin RN) or NaOH (to form the resin RCO). The sorption of gold ions from an aqueous gold solution was attempted in a batch process. Gold nanoparticles were immobilized into the pores of both resins by shaking them with aqueous solution containing H[AuCl4] for 1 h at room temperature and then drying them for 24 h at 150 °C to form RN-AuNPs and RCO-AuNPs. The conversion of gold to metallic nanogold was achieved without the use of any external reducing agents. The AuNPs prepared in this manner were characterized by UV–vis spectroscopy and transmission electron microscopy (TEM). The catalytic activity of the prepared nanoparticles in the reduction of 4-nitrophenol was studied, and with the kinetic parameters for this catalyzed reaction were calculated.

Depolymerization and demetallation treatments of asphaltene in vacuum residue

The asphaltene fraction [hexane insoluble (HI)] of a vacuum residue (VR) was treated under ultrasonic irradiation at 40°C in THF or 150°C in 1-methyl naphthalene (1-MN) in the presence of an adsorbent composed of modified macro-reticular polystyrene resin. Such a treatment was found effective to convert the asphaltene into the hexane soluble (HS: maltene) without any hydrogen consumption. 61 and 72% of the HI was converted by the adsorption treatment at 40°C in THF and 150°C in 1-MN, respectively, to HS materials having lower molecular weights. About 65% of the metal contaminants in the original asphaltene remained with the newly formed maltenes after this treatment. Structural analyses of the asphaltene and maltene fractions before and after the treatment suggests decoagulation and/or depolymerization of the asphaltene into maltene, while the porphyrin moiety becomes soluble, being transformed to the maltene fraction. The roles of polar solvent, ultrasonic irradiation, and adsorbent are discussed based on the above results.

Macromolecular material (humic substance) in the water column and sediments

The progress during the past 10–15 years in the studies of organic macromolecules (humic substances, HS) in seawater and sediments is reviewed. The review describes the advances in the characterization of seawater and sedimentary HS, HS formation models, studies on the geochemical role of marine HS, and future research needs. A macroreticular polystyrene resin (e.g. Amberlite XAD-2) has been generally used to isolate seawater HS. The HS isolated from seawater or sediments have been characterized by the analysis of lignin-phenols from CuO degradation, 1H and 13C NMR, stable carbon isotope analysis, pyrolysis-GCMS etc. The major conclusions of these analyses are: (1) seawater HS are essentially aliphatic and thought to be of phytoplankton origin and (2) sedimentary HS also have an aliphatic structure. The formation model of marine (both seawater and sedimentary) HS may be categorized into two groups: small molecular polymerization model which assumes that biopolymers are first degraded to small molecules and then re-polymerize to produce HS; and biopolymer degradation and polymerization model which assumes that HS are mainly or partly composed of refractory biopolymers and reaction products among refractory biopolymers, modified biopolymers, regenerated molecules, and the refractory biopolymers and their modified ones are the basic building blocks of humin (insoluble fraction of HS). However, analytical data are still insufficient to draw the conclusion. The effort to isolate a large amount of seawater HS and characterize both seawater HS and sedimentary HS by chemical and physical methods, which should be done with the active participation of biochemists, is strongly needed to draw the picture of chemical structure of marine HS and to confirm the HS formation models.

Insoluble Lignin Models (3): Preparation of a Polymer-Bound Guaiacylpropanol Model

Abstract Guaiacylpropanol (4), has been attached at the gamma carbon through a benzyl ether linkage to a macroreticular polystyrene resin. The phenolic site of 4 was protected as an allyl ether when coupled to the resin. The amount of lignin model 4 which was attached to the polymer was determined by cleaving the benzyl ether linkage with iodotrimethlsilane (ITS) and quantifying the amount of released guaiacylpropanol. The ITS method was reproducible but not quantitative due to a high model loading (1.29 mmol/g). Both FTIR and 13C-NMR were used to characterize the insoluble model.

Insoluble Lignin Models (2): Preparation, Characterization, and Reactions of A Polymer-Bound β-Aryl Ether Lignin Model

Abstract A unique lignin model dimer, 2-(2-methoxyphenoxy)-1-(3-methoxy-4-hydroxyphenyl)-1,5-pentanediol (8), was attached to a macroreticular polystyrene resin by means of a trityl ether linkage. The extent of model loading was determined by gravimetric analysis and Zeisel methoxyl content. When reacted under simulated kraft pulping conditions, the polymer model, 8-TrP, afforded moderate yields of guaiacol, a fragmentation product. The addition of 29% of p-dioxane or DMSO drastically depressed the yield of guaiacol from 8-TrP. The polymer bound dimer model 8-TrP and monomer model 6-TrP were relatively unstable to the harsh, simulated pulping conditions. Some or all of the observed guaiacol fragmentation product could have come from degradation of polymer-released model.

A regenerable immobilized nadh model IV: Reduction of pyridine‐2‐carbaldehyde by immobilized 1,4‐dihydronicotinamide in the presence of Mg2+ ions

AbstractDihydronicotinamide, anchored to a macroreticular polystyrene resin, reduces pyridine‐2‐carbaldehyde (PCA) in the presence of Mg2+ ions in acetonitrile. The reactions are clean at room temperature, the high rate precluding complications arising from slow side reactions. The influence of Mg2+ concentration on the rate of reduction of PCA by polymer‐bound reagent and BNAH (1‐benzyl‐1,4‐dihydronicotinamide; low‐molar‐mass analog) has been studied. Analysis of the kinetic data showed that of the processes contributing to the overall reduction, the reaction between the reductant and the complexed substrate proceeded at the highest rate. In the polymer‐bound reagent, “site isolation” on the rigid matrix was observed to prevent bimolecular disproportionation of the neighboring dihydronicotinamides. Regeneration of the polymeric reagent was achieved with an efficiency of 98% per cycle.

A regenerable immobilized NADH model III. Reduction of N‐methylacridinium perchlorate by immobilized 1,4‐dihydronicotinamide

AbstractA regenerable dihydropyridine, immobilized on a macroreticular polystyrene resin, reduces the N‐methylacridinium ion. The influence of the polymeric network on this hydride transfer reaction was studied. During the reaction charge was built up in the resin and the transport of substrate was hindered, due to electrostatic repulsion. As a result, the reaction rate decreased as the reduction proceeded. It was observed that the charge accumulation was dependent on the site location. Reutilization of the polymeric reagent for the reduction of the acridinium ion amounted to 93% per cycle and was better than that observed (earlier) for the reduction of the ketone trifluroacetophenone.

A regenerable immobilized NADH model. II. Reduction of α,α,α‐trifluoroacetophenone by immobilized 1,4‐dihydronicotinamide in aprotic solvent

AbstractA regenerable dihydronicotinamide, immobilized on a macroreticular polystyrene resin was used for the reduction of trifluoroacetophenone (TFA) in acetonitrile. Practical reutilization of the polymeric reagent (91% per cycle) was obtained when magnesium perchlorate was added to the reaction of the immobilized dihydropyridine with TFA. A possible explanation of the role of Mg ion in the reaction of benzyldihydronicotinamide and its polymeric analog is presented. This explanation also accounts for the results of other NADH model reactions, described in the literature, and for the role of the Zn ion in the enzyme liver alcohol dehydrogenase (LADH).

High Performance Liquid Chromatography of Low Molecular Weight Proteins on a Non-Ionic Macroreticular Polystyrene Resin

Abstract A high performance liquid chromatography system is presented for analytical and preparative separation of proteins. The method utilizes a macroreticular polystyrene resin having no specific functional groups, and proteins are eluted by the use of linear gradient of acetonitrile (20% −75%, v/v) in 0.1% (v/v) trifluoroacetic acid. In this standard elution system, twenty proteins having a molecular weight of 4,200–58,000 and an iso-electric point of 3.9–11.0 have been chromatographed successfully within 80 min. The method allows a rapid, sensitive, and high resolution separation of relatively low molecular weight proteins, where the isolated proteins can be used for subsequent biochemical determinations.

Isolation of toxic metabolites of Phomopsis leptostromiformis responsible for lupinosis.

Two metabolites of P. leptostromiformis (phomopsins A and B) have been isolated as a crystalline mixture from a culture of the fungus on lupin seed. The mixture has been shown to be capable of inducing lupinosis in sheep and in young rats. Key steps in the isolation were the transfer of the phomopsins from crude aqueous solution to tetrahydrofuran and chromatography on macroreticular polystyrene resin. The bioassays used in monitoring fractions were based on inhibition of cell cultures and the mitosis-arresting effect of the metabolites on liver cells in vivo.

The analytical concentration of humic substances from natural waters

The thermodynamics of the adsorption of humic and fulvic acids on the macroreticular polystyrene resin Amberlite XAD-2 have been investigated with a view to optimizing the conditions for its application to the analytical concentration of these compounds. Under the optimal conditions, recoveries of humic and fulvic acids of above 92 and 75%, respectively, were achieved. It has been shown that these compounds can be fractionated on a molecular weight basis during the desorption stage by serial elution at selected pH values.