Functional materials with superwetting property have been extensively used for wastewater treatment. Here, walnut shell powders (WSPs) were accumulated into a layer to separate oil/water mixtures and adsorb organic dyes, avoiding the complex process involved in the fabrication of traditional super hydrophobic or underwater superoleophobic filtering membranes. By making use of the underwater superoleophobicity and low adhesion to oils, the pre-wetted WSPs layer can be used for gravity driven oil/water separation with ultrahigh separation efficiency. Furthermore, the WSPs exhibited excellent adsorption property to the organic dyes including methylene blue, rhodamine B and crystal violet. Finally, the WSPs are agricultural residue to environment, and using it for water remediation not only is a good way to treat water pollution, but also can reduce the pressure on the environment. We believe that such multifunctional material will be an effective approach for separating oil/water separation and adsorbing organic dyes pollution in practical applications. (C) 2017 Elsevier B.V. All rights reserved.