Colloidal Stability and Aggregation of Lignocellulosic Materials in Aqueous Suspension: a Review

Aqueous dispersions of lignocellulosic materials have important applications in such fields as papermaking, pharmaceuticals, and preparation of cellulose-based composites. The present review article considers published literature dealing with the ability of cellulose particle dispersions (fiber, fines, nanorods, etc.) to either remain well dispersed or to become agglomerated in response to changes in the composition of the supporting electrolyte solution. In many respects, the colloidal stability and coagulation of lignocellulosics can be understood in terms of well-known concepts, including effects due to osmotic pressure arising from overlapping electrostatic double layers at the charged surfaces. Details of the morphology and surface properties of lignocellulosic materials give rise to a variety of colloidal behaviors that make them unique. Adjustments in aqueous conditions, including the pH, salt ions (type and valence), polymers (charged or uncharged), and surfactants can be used to control the dispersion stability of cellulose, lignin, or wood-extractive materials to serve a variety of applications.