Flexographic deinking with electric field technology by destabilization and flotation

Abstract

Every year, millions of tons of paper are diverted from landfills and recycled. Newspaper constitutes a large portion of total paper recycled, providing a cheap source of raw material for the paper industry and helping sustainable forestry. The recycling of newsprint paper involves the separation of ink from the newsprint, which is done either by flotation or washing. Conventional flotation processes for separating ink are not adequate for newsprint printed using flexography printing technique and with water-based ink. The removal of these flexographic water-based inks by washing is a better alternative. However, one drawback of washing is that it has lower yield. In addition, the subsequent wash filtrate is difficult and costly to decontaminate. The overall goal is to develop a combination of processes that can remove ink from a feedstock that contains up to 100% flexographic ink newsprint; in the context of process variables with known effects. In the present work the objectives are to (1) demonstrate that incorporating an electric field into a conventional deinking process improves deinking efficiency, (2) propose a mechanism of how incorporating an electric field helps to improve deinking efficiency, (3) demonstrate that an electric field can decontaminate water containing flexographic inks and identify the mechanism behind electric field clarification of water, and (4) demonstrate that by incorporating electric fields into both the flotation deinking stage and water decontamination, the target deinking efficiency can be achieved.