Dynamic surface tension of flotation deinking systems: from model surfactant mixtures to process waters

The dynamic and equilibrium surface tension of a model deinking system, namely a sodium oleate-C17(PO-EO)n (with n=22, 94) aqueous solution, was interpreted by using a pseudo-single-component approach. The validity of this approach on real deinking systems was verified on process waters sampled during pilot plant runs and a surfactant mass balance was calculated by using dynamic and near equilibrium surface tension measurements. Results obtained at both the pilot plant and laboratory scale were then used to simulate surfactants accumulation in the process waters due to the closure of the water loop and their removal by foam fractionation. Preliminary surface tension measurements in a flotation deinking mill were taken in order to verify, at the industrial scale, the validity of results obtained at the laboratory and pilot plant scale.