Theoretical Analysis of the Effect of Nap Charge in Electroflocculation Technology
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Fibre Chemistry, Vol. 52, No. 2, July, 2020 (Russian Original No. 2, March-April, 2020)
THEORETICAL ANALYSIS OF THE EFFECT OF NAP CHARGE IN ELECTROFLOCCULATION TECHNOLOGY O. M. Ivanov, T. A. Anisimova, V. V. Beznosova, and I. A. Kassir
UDC 677.026.4
This paper deals with electroflocculation technology – with the process of nap cover formation from short charged fibers deposited on the warp surface in an electric field. It examines whether there is an optimum nap charge that assures minimum time of nap cover formation with the required density. The answer to this question is based on model for the density of the current generated by the charged moving nap, model of nap charge formation, and understanding of the interrelation of the ultimate nap cover density with the nap charge.
Electroflocculation technology consists in oriented deposition of short charged fibers (nap) on the surface of a material coated with an adhesive agent in a high-intensity electric field between two flat electrodes. Polyamide or polyester fibers chemically treated in a specific way so that they could acquire a charge in the electric field are commonly used as the nap. Since the fibers have a length from 0.5 to 3 mm and a dimeter from 10 to 50 μm, this technology can, in fact, be considered as a variant of electron-ion technology. This approach was developed in monograph [1] and article [2], where equations were derived to calculate the density of the current generated by the charged particles moving between electrodes. The developed model can be used to determine the maximum current density during movement of the charged nap in only one direction, namely, toward the surface of the material being flocculated. The current density constraint is associated with the space charge formed by the nap in the space between the electrodes. The space charge of the nap consists of charges of its fibers occurring between the electrodes at a given point of time. In turn, the nap charge depends not only on the flocculation conditions, but also on the properties of the nap, primarily its electrical resistance, which is specific for each batch of nap. Since the resistance of the nap, i.e., the value of the charge, could vary in quite a wide range, it would be expedient to determine if there is a “best” charge value that is optimum in terms of a specific chosen criterion. Current Density Calculation Model The derived equations for current density measurement are based on several postulates of the theory of electromagnetism: 1. The process occurring between infinite planes: distribution of potential U in the flocculation zone depends only on the coordinate x: ∂U ( x, y , z ) ∂U ( x, y , z ) = 0. = ∂z ∂y
(1)
2. Poisson’s equation applies in the flocculation zone with due regard for p. 1:
∂ 2U ( x) ∂x
2
=−
ρ( x ) , ε0
(2)
where ρ(x) –density of the space charge occurring in the interelectrode space, C/m3; ε0 – dielectric constant, F/m. St. Petersburg State University of Industrial Technologies and Design E-mail: [email protected]. Translated from K
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