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

• We present a concept for ink removal using polymer particles instead of air bubbles.
• The process is characterized by the properties in suspension.
• Dynamic surface tension can represent possible interactions.
• The efficiency is strongly influenced by the properties of paper.

“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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