Dynamics of colloidal pitch adsorption at the solid-liquid interface by surface plasmon resonance

The direct adsorption of pitch onto pulp fibres was found to be a poor strategy for pitch control in papermaking. This is because of the very low chemical affinity of pitch for polysaccharide surfaces. Pitch can be carried by fibres as the low desorption rate might not allow full desorption during papermaking. Pitch has a stronger affinity for pitch covered surfaces than for polysaccharides and first adsorbs as colloids-not as individual fatty/resin acid molecules. Adsorbed pitch particles then serve as nucleation centres for further pitch adsorption. SPR is a suitable analytical technique to quantify the adsorption dynamics of polydisperse colloids at the solid-liquid interface. The low signal response measured for the larger colloid was explained with the bouncing ball mechanism. A fractionation of the polydisperse colloid was observed, with the small particles being eluded first, followed by the bigger one.