The interaction between solid surfaces was evaluated by scanning probe microscopy using a colloidal probe. The dispersant provided a repulsive force between the solid surfaces at less than 30 nm. On the other hand, the binder provided a bridging force between the solid surfaces for retraction at less than 500 nm. Because of the complicated nature of the forces acting between the surfaces, the separation distance between ceramic particles (SDP) was calculated. Moreover, the relation between the agglomeration/dispersion of Al₂O₃ particles and the calculated SDP were discussed. As an extension of these results, Al₂O₃ pastes were prepared for tape casting from a viewpoint of the SDP. The tape casting of nanoparticles, which is generally difficult, was successful. On the basis of these fundamental studies applied to environmental functional materials, porous ceramics having oriented pores were prepared by an extrusion method. The obtained porous ceramics demonstrate high capillary action and are used for the relaxation of an urban heat island. Porous ceramics having nano-sized pores were prepared by a slip casting method. The porous filter has CO₂ gas separation ability by using surface diffusion.