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Effect of Amphiphilic Cationic Compounds on Calcium Ion Desorption from Lecithin Liposome Membranes. Kinetic Studies and Quantum Chemical Calculations Janina Kuczera3, Henryk Chojnackib, Teresa E. Kral3, Stanislaw Przestalski3 a Department of Physics and Biophysics, Agricultural University, Norwida 25, 50-375 Wroclaw, Poland b Institute of Physical and Theoretical Chemistry, Technical University, Lukasiewicza 2, 50-371 Wroclaw, Poland Z. Naturforsch. 51c, 219-225 (1996); received November 7, 1995/January 3, 1996 Cationic Amphiphiles, Liposomes, Calcium Ion

Abstract

Compounds from the group of cationic surfactants are widely applied in household, industrial, cleaning, disinfectant, cosmetic and pharmaceutical products as their specific properties (antimicrobial, emulsifying, anticorrosion, softening). After use, cationic surfactants are disposed to wastewater-treatment plants and finally with effluent water to surface waters due to their incomplete degradation. Moreover, they can freely circulate in different environmental compartments including living organisms. It becomes indispensable to recognize in more detail behavior, fate and biological effects of cationic surfactants. This analytical problem can be solved with use sensitive and reliable analytical techniques at sample preparation step and final determination step. In recent years, during isolation analytes from environmental samples mainly were used liquid-liquid extraction (LLE) - liquid matrices or solid-liquid extraction (SLE) - solid matrices. This technique involves application of toxic solvents (chloroform), is time-consuming and interferences are co-extracted. Nowadays, in scientific centers are carried out research to replace this traditional technique. So far, the following techniques were applied: solid-phase extraction (SPE) or it modification (HF-LPME) - liquid samples; accelerated solvent extraction (ASE) and supercritical fluid extraction (SFE) - solid samples. During the determination of total content of cationic surface active agents in environmental samples were used a traditional spectrophotometry technique and potentiometric titration technique. But those techniques are susceptible of interferences on analysis results (anionic and non-ionic compounds). The chromatographic technique (liquid chromatography) applied at the final determination step gives possibility to determine individual cationic surfactants in solvent extracts of environmental samples. The LC systems coupled with mass spectrometers are most powerful tools during such analysis.

Adsorption of an anionic polyacrylamide on cellulosic fibers with pre-adsorbed cationic polyelectrolytes Rein Aksberg and Lars Odberg, STFI, Swedish Pulp and Paper Research Institute, Stockholm, Sweden Keywords: Adsorption, Anionic compounds, Polymers, Polyacrylamide, Cationic compounds. SUMMARY: The adsorption of an anionic polyacrylamide (A-PAM) on cellulosic fibers onto which cationic polyelec- trolytes have been pre-adsorbed has been investigated. Two of the cationic polyelectrolytes were copolymers between acrylamide and trimethyl-(3-methacrylamido

Polymer adsorption on cellulosic fibers Lars Wdgberg and Lars Odberg, STFI, Swedish Pulp and Paper Research Institute, Stockholm, Sweden Keywords: Adsorption, Polymers, Cationic compounds, Synthetic polymers, Polyelectrolytes, Cellulose fibers. SUMMARY: This paper attempts to give an overview of the factors that govern the adsorption of water soluble polymers on cellulosic fibers. For non-ionic polymers there have been very few investigations. The results available are discussed in terms of specific interactions between the components of the fibers and

51Nordic Pulp and Paper Research Journal Vol 18 no. 1/2003 KEYWORDS: Adsorption, Cationic compounds, Cellulose fibres, Flocculation and retention aids SUMMARY: The adsorption of cationic polyacrylamide on pulp fibers and the induced fiber flocculation have been measu- red at contact times relevant to the practical application of retention aids. In accordance with the La Mer model for brid- ging flocculation, a maximum in flocculation was found around 50 % surface coverage by the polymer and re-dispersion occu- red above 100 % surface coverage. Furthermore, the

The adsorption of cationic starch on microcrystalline cellulose Henrica G.M. van de Steeg, Arie de Keizer and Bert Chemistry, Wageningen Agricultural University, The Nc Keywords: Adsorption, Cationic compounds, Starch, Mi- crocrystalline cellulose, Amylose, Amylopectin. SUMMARY: The adsorption of cationic potato starch with a moderate degree of substitution, on microcrystalline cellulose was investigated by measuring adsorption iso- therms under different conditions. The equilibrium starch concentration was determined with two methods having a

The effect of filler particle size on the dry-strengthening effect of cationic starch wet-end addition Tom Lindstrom and Tommy Florkn, STFI, Stockholm Keywords: Fine papers, Additives, Wet ends, Cationic compounds, Starch, Fillers, Particle size, Mechanical prop- erties, Optical properties. SUMMARY: The effects of wet-end addition of cationic potato starch on the mechanical and optical properties of papers filled with clay or calcium carbonate (30% filler loading) have been investigated. Experiments were conduct- ed with a series of clays and calcium

The use of cationic starch and colloidal silica to improve the drainage characteristics of kraft pulps Kjell Andersson, Ann Sandstrom, Kerstin Strom and Pavol Barla, Eka AB, Surte, Sweden Keywords: Kraft pulps, Unbleached pulps, Drainage, Addi- tives, Cationic compounds, Starch, Anionic compounds, Silica gel. SUMMARY: Drainage studies on an unbleached kraft pulp (kappa number of 30) have been made with two chemical additives, cationic starch and an anionic retention aid (silica sol). The drainage resistance of the pulp was determined by CSF measurements

Phase behavior of polyanion-polycation aggregates and possibilities of utilization Joachim Kotz, Research Group "Colloid Chemistry" at the University of Potsdam, Teltow-Seehof, Germany Keywords: Polyelectrolytes, Phase diagrams, Flocculation, Ad- 2 ' 2 ' sorption, Cationic compounds, Synthetic polymers, Anionic type compounds, Symplexes. SUMMARY: The formation of polyanion-polycation complex- es is of special interest in pulp and papermaking from the analytical point of view as well as practical relevance in the wet- end of the paper machine. The

Preparation and some properties of the colloidal pitch fraction from a thermomechanical pulp Agne Swerin and Lars Odberg, STFI, Swedish Pulp and Paper Research Institute, Stockholm, Sweden Lars W ~ g b e r g , SCA Research AB, Sundsvall, Sweden Keywords: Pitch, Thermomechanical pulps, Colloids, Elec- trophoresis, Particle size distribution, Cationic compounds, Synthetic polymers. SUMMARY: A method is given for the preparation of a col- loidal pitch fraction from a TMP pulp. The following proper- ties of this pitch fraction have been investigated: size