Adsorption processes seem to be effective for the recovery of rare metals in the effluent from mines, the removal of water pollutants, the collection of useful resources in sea water, the separation and purification of bioproducts etc., especially at low concentrations. In the practical processes, however, excellent adsorbents from both functional and economical standspoints are essential. The liquid-phase adsorption with silica-containing mixed-oxides in amorphous state is reviewed.