Surface charge: a useful equation for estimating the surface charge of pulp fibers.APPLICATION: This equation will help analysts determine the surface charge of pulp fibers from polyelectrolyte pol·y·e·lec·tro·lyte n. An electrolyte, such as a protein or polysaccharide, having a high molecular weight. adsorption data. A method commonly used to measure surface charge is to quantify the polyelectrolyte adsorption capacity of the fibers. What is taken as the surface charge is the apparently linear portion of the adsorption isotherm isotherm, line drawn on a map of a particular region of the earth's surface connecting points of equal temperature; each point reflects one temperature reading or an average of several readings over a period of time. extrapolated to zero polymer concentration. However, the adsorption isotherm does not present a plateau, and the selection of the experimental points from which to draw the straight line can be a source of error. We propose an equation for determining the surface charge that allows the isotherms to be analyzed by a uniform criterion. The main hypothesis on which the model is based concerns the difference between stoichiometric stoi·chi·om·e·try n. 1. Calculation of the quantities of reactants and products in a chemical reaction. 2. The quantitative relationship between reactants and products in a chemical reaction. and partial adsorption. At a low concentration, stoichiometric adsorption takes place. An increase in polymer concentration leads to a rise in the isotherm as a result of a nonstoichiometric adsorption, which can be attributed to conformational changes from a flat form of the polymer to a loops and tails form. The equation demonstrated an excellent fit for isotherm data taken from literature and for our own isotherm data. The equation proposed should prove useful in mills for determining the surface charge of fibers, which is directly related to the fiber bonding capacity. View this paper online at http://www.tappi.org/index.asp?pid=32227&ch=1 Paulina Mocchiutti and Miguel A. Zanuttini are with ITC ITC (Brit) n abbr (= Independent Television Commission) → Fernseh-Aufsichtsgremium ITC n abbr (BRIT) (= Independent Television Commission) → , Institute of Cellulose Technology (Facultad de Ingenieria Quimica, Universidad Nacional del Litoral), Santiago del Estero Santiago del Estero, city (1991 pop. including La Banda 264,273), capital of Santiago del Estero prov., N Argentina. It is a transportation hub of the Argentine Chaco and a commercial center for cattle raised in the region. 2654 - S3000AOJ Santa Fe, Argentina Santa Fe is the capital city of province of Santa Fe, Argentina. It sits in northeastern Argentina, near the junction of the Paraná and Salado rivers. It lies opposite the city of Paraná, to which it is linked by the Hernandarias Subfluvial Tunnel. . Email Zanuttini at mzanutti@fiqus.unl.edu.ar. |
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