Figure 8: Active surface model: measurements (dots), fitted model (continuous) and model parameters: a: active surface; z: ratio between diffusion layer thickness and initial particle radius; R2: goodness of fit; G=Grinded KCl; U=Ungrinded KCl; NS10=Native Starch 10%; L10=Lignin 10%; L20=Lignin 20%; NS20=Native Starch 20%.