Electroflotation Combined with Flotation Deinking of Flexographic Newsprint

A semicontinuous flotation cell, which incorporates an electrolytic cell, was used to collect inks from newsprint pulp slurry. In general, longer pulping time has an adverse impact on deinking of 100% flexographic old newspaper or newsprint (flexo-ONP) while temperature has a positive impact on deinking. However, the use of electric field improved deinking efficiency—measured by the percent reduction in effective residual ink concentration (ERIC)—by as much as 5% at longer pulping time (25 min compared to 5 min). Higher temperature (40 °C compared to 25 °C) combined with the use of electric field further improved deinking efficiency by 5%. Furthermore, the impact of electric field assisted flotation is discussed in the context of the following variables: alkali charge (sodium hydroxide), float consistency (percent solids in the pulp suspension), surfactant and soap concentration, and the amount of flexo newsprint in a mixture of newspaper (or furnish)−newsprint. Unlike 100% flexo-ONP, the mixture of 48% f...