Structurally Functionalized Polyurethane Foam for Elimination of Lead Ions from Drinking Water
Pages 16-25
Nidal Abu-Zahra and Subhashini Gunashekar

DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.01.3

Published: 02 April 2014

Abstract: Polyurethane foams functionalized with Sulfonic acid groups have been found to be strong cation exchangers. This novel property of the foam was used to exchange lead (Pb²⁺) ions from aqueous solutions. Polyurethane foam synthesis is based on addition polymerization of the highly reactive isocyanate (-NCO) groups of an isocyanate with the hydroxyl (–OH) groups of a polyol to form the urethane species. Toluene-2,4-2,6- diisocyanate was reacted with Polypropylene glycol 1200 in 2:1 molar ratio to form a linear pre-polymer. The linear pre-polymer was further polymerized using a chain extender, N, N-bis (2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES). BES also acts as a functional group to exchange Pb²⁺ ions. A set of experiments were designed to study various process parameters. The functionalized polyurethane foam was characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The Pb²⁺ ion exchange capacity was determined using an Inductively Coupled Plasma Mass Spectrometer. The maximum Pb²⁺ ion exchange capacity of the foam was found to be 47 parts per billion per gram (ppb/g) from a 100 parts per billion (ppb) Pb²⁺ solution over a period of 60 minutes. A multistage batch filtration process increased the Pb²⁺ ion removal to 50-54 ppb/3g of foam over a period of 90 minutes.

Study and Characterization of Polyaniline at Various Doping of LiCl wt.% Using Electrical Measurements and XRF Analysis
Pages 188-190
Faten Adel Ismael Chaqmaqchee and Amera Ghareeb Baker

DOI: http://dx.doi.org/10.6000/1929-5995.2015.04.04.1

Published: 12 January 2016

Abstract: Polyaniline PANI samples were synthesized via chemical polymerization method. The mechanism of charge transport in these composites has been studies by measuring the DC conductivity at various lithium chloride LiCl wt.%. It shows that their activation energy decreases with increasing LiCl concentration and thus, the conductivity increases at 15 %wt. In addition, X-ray Fluorescence XRF was used to analysis the elements of PANI regarding to LiCl concentration. The elements positively detected by the XRF are Cl, Kr, SO₃, Al₂O₃, SiO₂, and ZrO₂. The XRF data show a relative systematic error typically independent of the concentration.The accuracy is determined by comparing the XRF data with various LiCl wt.%.

Structure of Crystallizable Polymer Solutions
Pages 142-148
Vitaly J. Klenin and Irina V. Fedusenko

DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.03.1

Published: 20 October 2014

Abstract: Visually transparent solutions of crystallizable polymers in wide concentration and temperature ranges contain supramolecular particles which are fragments of the most perfect crystallites of condensed polymer. Though the fraction of these particles is usually with in 0.001-0.1wt % of the total polymer, their presence in a solution of macromolecules severely affects its physicochemical and technological properties (performance) and complicates (or even does not allow) the application of structurally-sensitive research techniques (e.g. lights cattering, dynamic birefringence, etc.). The parameters of the first-level supramolecular particles (just after visual dissolution) depend on the conditions of dissolution, storage, and the preliminary treatment temperature of the polymer. In wide polymer concentration and temperature ranges, a second level of the supramolecular particles ensemble is formed, with characteristic features of crystallization. From the formation rate of the second-level supramolecular particles, a microliquidus curve for them can be plotted. The paper presents data for the poly (vinyl alcohol) + water system which lack the area of liquid-liquid phase separation. Supramolecular particles parameters (average sizes, numerical and mass-volume concentration) were determined by means of the turbidity spectrum method.

Study of Catalytic Activity of Lipase and Lipase-Chitosan Complexes in Dynamics - Pages 15-20

Anastasia A. Savina, Olga V. Abramova, Lilia S. Garnashevich, Ilia S. Zaitsev, Oksana A. Voronina, Marina S. Tsarkova and Sergei Yu. Zaitsev

DOI: https://doi.org/10.6000/1929-5995.2019.08.03

Published: 31 October 2018

Abstract: Pancreatic porcine lipase (PPL) is the unique enzyme in numerous biochemical processes for human and animals. Stability in time is the critical point for many enzymes in relation to their further applications. The effect of chitosan on the activity of PPL during 2 months was investigated.

Materials and Methods: Potentiometric method was used to study the catalytic activity of enzymes that based on measuring of the potential an electrode immersed in a triacetin (substrate) solution by titration with 0.01 M NaOH. A laboratory pH-stat with combined pH electrode was used for the measurements of this potential in the presence of PPL or PPL-chitosan complexes. Standard experimental conditions: 40 ºC, pH 7.0.

Results: The following PPL activity values (data given in % to the activity of free lipase) vs. time (in 10 min. intervals) were obtained: 100%, 97.4%, 89.9%, 82.9%, 77.9% and 75.9% after 10, 20, 30, 40, 50 and 60 min., respectively. The PPL catalytic activity decreased at about ¼ to ½ of the initial values after 7 or 14 days, 1 or 2 months storage, although there were differences in the decline dynamics. The complex PPL:Chit=50:1 has better stabilizing properties as compared to other complexes; does not strongly inhibit lipase and requires a small amount of carrier (chitosan) for its formation.

Conclusions: The complex PPL:Chit=25:1 is less effective as the PPL:Chit=50:1 complex, but both can be applicable in some industrial processes.

Keywords: Lipase, chitosan, enzyme immobilization, activity, triacetin.

Download