Investigation of an improved deinking process of waste paper The influence of surface tension and charge in suspension on ink removal

Significance Statement

The results presented here by the authors of the Leibniz-Institut für Polymerforschung Dresden e.V. were obtained by a cooperation in the frame of a project with the technical University Dresden (Germany) which has big relevance to the paper industry. Recycling of papers by flotation is a very important process. In some countries up to 80% of produced paper will be recycled. And ink removal is one of the most significant challenges in this process. The authors will present an improved concept for ink removal using polymer particles instead of air bubbles. In cooperation with engineers not only the “deinkability score” was measured, but also the properties and interactions between different components such as cellulose, inorganic particles, ink and surfactants in suspension. These interactions are represented by the charge as well as by the dynamic surface tension. A method for determining the content of contamination in process water by tensiometer was developed (DE20111088203). The efficiency of the process, which is also characterized by visual examination of the polymer particles after a deinking step, is strongly influenced by the properties of paper.

Figure Legend: Demonstration of the new deinking process of newspaper in the lab (left); (right) ink is adsorbed on polymer particles such as polypropylene (PP)

Investigation of an improved deinking process of waste paper The influence of surface tension charge in suspension ink removal. Advances in Engineering

 

Journal Reference

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 480, 5 September 2015, Pages 398–404.
Gudrun Petzold, Simona Schwarz
Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, D-01069 Dresden, Germany.

Abstract

“Adsorption deinking” is a new concept for ink removal from suspensions using polymer particles instead of air bubbles (flotation) in a process with high efficiency, concerning the consumption of energy and water. We studied the influence of different papers and inks, of the deinking solution (compared with water), and of the duration of deinking. The process is characterized not only by the colour of polymer particles, but also by the properties in suspension such as charge, turbidity or particle size. Further it is shown, that dynamic surface tension is a useful tool to characterize not only the surfactant in suspension, but also its interaction with other substances (cellulose and ink). The efficiency of adsorption deinking is strongly influenced by the properties in suspension which depend on the type of paper.

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