The solvent is a liquid in which powder of zinc oxide is dissolved to form ions or molecules. This liquid may be hydrochloric acid +water. It zinc oxide reacts (dissolves) to zinc ions. But do you mean, apparently, more. The disperse system comprises the twocomponent : nanoparticles (dispersed phase) and a dispersion medium (solvent). In toluene, stable dispersions of ZnO nanowires were obtained with PEO.