Stability of manganese dioxide by guar gum in the absence or presence of surfactants

Stability of the manganese dioxide (MnO₂) suspensions by non-ionic guar gum (GG) in the absence or presence of the surfactants: anionic sodium dodecyl sulphate (SDS), cationic hexadecyltrimethylammonium bromide (CTAB) and non-ionic Triton X-100 (t-octylphenoxypolyethoxyethanol) and their equimolar mixtures (SDS/TX-100; CTAB/TX-100) was measured using turbidity. The obtained results of the manganese dioxide suspensions stability were discussed together with the adsorption data and with the data concerning the thicknesses of the adsorption layers. In order to gain more information about the structure of the electric double layer surface charge density and the zeta potential measurements were performed. The obtained results show that the addition of guar gum to the MnO₂ suspensions increases MnO₂ stability. The larger this increase is, the higher is the concentration of the polymer (concentration range 10–200 ppm). Moreover, the addition of single surfactants also causes the increase in the effectiveness of stabilizing the manganese dioxide suspensions. The reason for that is formation of multilayer complexes between the polymer and the surfactants. In such a system both the adsorption of polymer and the thickness of polymer adsorption layer increase. The greatest increase in the stability of MnO₂/GG suspensions was provided by the mixture of anionic and non-ionic surfactants due to a strong synergistic effect. Also, mixing the polymer and two surfactants reduces the stability of the suspension.