Water-soluble polyelectrolyte in conjunction with membrane systems: modeling and simulation of retention profiles from washing method

Polymer Bulletin - Liquid-phase polymer-based retention (LPR) is a novel technique for eliminating, concentrating and separating pollutants from aqueous effluents. Using the washing method, LPR can...     

Multienzymatic immobilization of laccases on polymeric microspheres: A strategy to expand the maximum catalytic efficiency

Laccase enzymes of were covalently coimmobilized on poly(glycidyl methacrylate) microspheres. The objective of this work was to create a biocatalyst that works efficiently in a wide range of pH. The coimmobilization was performed using two different strategies to compare the most efficient. The results showed that by correctly selecting the enzymes and concentrations involved in the commobilization, it is possible to obtain a biocatalyst that works efficiently at a wide pH range (2.0–7.0). The maximum activity values reached per gram of support for the obtained biocatalyst were 41.90 U (pH 3.0), 40.89 U (pH 4.0), and 39.54 U (pH 6.0). Moreover, the thermal, storage, and mechanical stabilities were improved compared to the free and single-immobilized laccases. It was concluded that enzymatic coimmobilization is an excellent alternative to obtain a robust biocatalyst that works in a wide pH range, with potential environmental and industrial applications.     

Metal ion extraction behavior of poly([2(methacryloyloxy)ethyl]trimethylammonium chloride-co-acrylic acid) resin

SUMMARY The crosslinked poly([2-(methacryloyloxy)ethyl]trimethyl ammonium chloride-co-acrylic acid) was tested as adsorbent for Cd(II), Hg(II), Zn(II), Pb(II), Cr(III), and U(VI) by batch equilibrium procedure. At pH 5.0 the adsorbent retained 74% (1.865 meq/g) of U(VI) with a maximum capacity of load of 2.7 meq/g (108 mg/g). The resin-U(VI) equilibrium was achieved around of 1 h which is considered adequate for a heterogeneous reaction. It showed a high selectivity for U(VI) respect to all the other metal ions both from competitive and non-competitive conditions. The recovery of the resin was over 65% by H₂SO₄ and Na₂CO₃. Received: 5 April 1999/Revised version: 14 July 1999/Accepted: 27 July 1999     

Poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium): Synthesis,characterization, and its potential application for the removal of metal ions from aqueous solution

In the current study, poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium), poly(VP‐co‐AMPS), was prepared and used for the removal of Cu²⁺, Cd²⁺, and Ni²⁺ ions via a polymer‐enhanced ultrafiltration (PEUF) technique. The copolymer was synthesized by radical polymerization in an aqueous medium with a comonomer feed composition of 50:50 mol %. The molecular structure of the copolymer was elucidated by ATR‐FTIR and ¹H NMR spectroscopy, and the average molecular weight was obtained by GPC. The copolymer composition was determined to be 0.42 for VP and 0.58 for AMPS by ¹H NMR spectroscopy. The copolymer and homopolymers exhibited different retention properties for the metal ions. PAMPS exhibited a high retention capacity for all of the metal ions at both pH values studied. PVP exhibited selectivity for nickel ions. Poly(VP‐co‐AMPS) exhibited a lower retention capacity compared to PAMPS. However, for poly(VP‐co‐AMPS), selectivity for nickel ions was observed, and the retention of copper and cadmium ions increased compared to PVP. The homopolymer mixture containing PAMPS and PVP was inefficient for the retention of the studied metal ions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41272.     

Removal of Cr(VI) by a chelating resin containing N-methyl-d-glucamine

The resin poly[N-(4-vinylbenzyl)-N-methyl-d-glucamine] [P(VbNMDG)] was synthesized and its performance for Cr(VI) removal was studied. This resin presented a very fast kinetic of Cr(VI) sorption following a pseudo-second order. Also, the rate-controlling step of Cr(VI) sorption performed by film diffusion in accordance with infinite solution volume model and reacted layer in accordance with unreacted core model. The column study showed a breakthrough capacity of 12.2 mg Cr/mL-resin, with an elution efficiency of 92 %. Mechanism of sorption could correspond to an electrostatic interaction followed by a complexation reaction.     

Application of design of experiments,response surface methodology and partial least squares regression on nanocomposites synthesis

We present an integral chemometric treatment for characterization and synthesis of low-density poly(ethylene)/organically modified montmorillonite nanocomposites using direct melt processing method, complementing design of experiment (DOE), response surface methodology (RSM) and partial least squares (PLS) regression. A central composite circumscribed DOE was used to study the influence of four processing parameters—concentration of clay (Clay%), concentration of compatibilizer (Comp%), mixing temperature (T _mix) and mixing time (t _mix)—on six nanocomposites properties: interlayer distance, decomposition temperature, melting temperature, Young’s modulus, loss modulus and storage modulus. PLS-regression was used to simultaneously correlate parameters and responses. RSM was used to explore interactions among parameters and predict nanocomposite properties on the experimental region. The six responses were simultaneously PLS-modeled with R ² = 0.768 (p ≤ 0.05) being Clay% and Comp% the most important parameters and t _mix the least influential. Moreover, significant (p ≤ 0.05) and complex interactions among Clay%, Comp% and t _mix were found. A complementary interpretation of score and loading plots, coefficient plots, variable importance plots and response surface plots are explained to show how to find the optimal combination of processing parameters according the desired nanocomposite properties.     

Hydrogels from 2-(dimethylamino)ethylacrylate with 2-acrylamido-2-methyl-1-propanesulfonic acid: synthesis,characterization, and water-sorption properties

A novel series of copolymer hydrogels of 2-(dimethylamino)ethylacrylate (DMAEA)/2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) were prepared by solution free radical polymerization at different feed monomer mol ratios. The monomer reactivity ratios were determined by Kelen–Tüdös method. According to that, the monomer reactivity ratios for poly(DMAEA-co-AMPS) were r₁ = 0.125 and r₂ = 2.85, (r₁ × r₂ = 0.356). The effect of reaction parameters, including the concentration of cross-linking reagent N,N′-methylene-bis-acrylamide (MBA) and initiator ammonium persulfate (APS), the monomer concentration, pH, temperature, salt solutions, and solvent polarity on the water absorption have been also studied. The hydrogels achieved water-absorption values of 430 g of water/g of xerogel for the copolymer 1:2 richest in AMPS moiety. This copolymer is also very stable to the temperature effect. The optimum pH for the copolymers is 7. Aqueous solutions of the copolymers showed lower critical solution temperature behaviour (LCST). The phase transition temperatures of aqueous solutions of these copolymer increased with increasing of hydrophilic AMPS unit content in the copolymers. The glass transition temperature (Tg) of hydrogels showed a decrease by increasing of comonomer DMAEA content.