Surfactants are largely present in papermaking/recycling processes. They are added intentionally or come with raw materials or process/functional additives. Once they have reached the process, they build-up in the circuits and, depending on their surface activity and concentration, they can have adverse effects on deinking and on the whole papermaking process, such as excessive frothing, depression of ink floatability, and paper sizing/retention difficulties. In this paper, the removal of apparent surface active chemicals (ASAASAASAC) is first evaluated in different flotation deinking mills through mass balances using surface tension measurements and a specific methodology. Mill data show that, in two-stage deinking lines, ASAASAASAC are slightly concentrated in the second stage, contributing to an increase in pulp frothing behavior, in flotation loss, and in some cases to a low ink removal efficiency. Trends observed in deinking mills are then interpreted using experimental data obtained at the laboratory scale in the presence of a model surfactant, and by process simulation. The effect of ASAASAASAC concentration on the efficiency of the flotation deinking process is explained in terms of their effect on particle and water transport sub processes, namely, flotation, entrainment, frothing, and drainage.
The possible role of the Surface Active Substances (SAS) in the airborne transmission of SARS-CoV-2
