Investigations of the properties of the manganese dioxide suspensions in the presence of guar gum and carboxymethylcellulose

Properties of manganese dioxide suspensions in the presence of two polysaccharides: non-ionic guar gum (GG) and anionic carboxymethylcellulose (CMC) were investigated using NaCl as a background electrolyte. The colloidal stability of MnO₂ suspensions in the presence and absence of these two polymers was measured. It was found that both polymers improve stability of measured suspensions. This fact results from steric stabilization (low polymer concentrations) and depletion stabilization (high polymer concentrations) for MnO₂ particles covered with macromolecules. Next the kinetics of the adsorption of these two polymers on MnO₂ as well as the heats of GG and CMC adsorption processes were measured. The obtained data proved that CMC is adsorbed more effectively on the manganese dioxide surface than guar gum. To obtain more information about the changes of adsorption of these polymers on MnO₂ some factors influencing this process (pH, ionic strength of the background electrolyte) were investigated. The data obtained from the surface charge density and the zeta potential measurements allowed the analysis of the structure of the electric double layer created by polymers on the solid surface.