A Review of Optical and Radiative Properties of Nanoparticle Suspensions: Effects of Particle Stability, Agglomeration, and Sedimentation

Abstract

Nanoparticle suspensions (NPSs) are suspensions of nanosize particles in base fluids in the form of a solid-liquid mixture. They are used extensively in a wide range of industrial and engineering applications, and show considerably different and tunable, physiochemical, thermal, and radiative properties compared to other solutions. It has been demonstrated that added nanoparticles can significantly alter and enhance the optical and radiative properties of the base fluids. There is still a concern about the particle agglomeration and sedimentation behaviors and the long-term stability of NPSs under different conditions, which may limit their potential reliable applications. There is a close relationship between the particle agglomeration and the optical and radiative properties of nanoparticle suspensions. In this review, the relationship between these fundamental properties with the emphasis on the procedural stability of nanoparticle suspensions is explored. Different issues related to the preparation and the characterization of NPSs, their sedimentation, the effects of particle types, sizes on individual, hybrid, and agglomerated nanoparticle suspensions, as well as the effect of pH values, are discussed. Their effects on the optical and spectral radiative properties are also discussed. Simplified analyses are outlined based on dependent-independent scattering demarcation and effective properties of NPSs.