Chemical Methods for the Separation of Copper Oxide Nanoparticles From Colloidal Suspension in Dodecane

Several chemical methods for the separation of nanoparticles from a colloidal mixture in a phase change material (PCM) have been developed and systematically investigated. The phase changing property of the colloidal mixture is used in energy storage applications and the mixture is labeled as the nanostructure enhanced phase change materials (NEPCM). The objective is to investigate viable methods for the separation and reclamation of the nanoparticles from the NEPCM before its disposal after its useful life. The goal is to find, design, test, and evaluate separation methods which are simple, safe, effective, and economical. The specific NEPCM considered in this study is a colloidal mixture of dodecane (C₁₂H₂₆) and CuO nanoparticles of 1–5% mass fraction and 5–15 nm size distribution. The nanoparticles are coated with a surfactant to maintain colloidal stability. Various methods for separating the nanoparticles from the NEPCM are explored. The identified methods are: (i) chemical destabilization of nanoparticle surfactants to facilitate gravitational precipitation, (ii) silica column chromatography, and (iii) adsorption on silica particle surface. These different methods have been pursued, tested, and analyzed; and the results are presented in this article. These methods are found to be highly efficient, simple, safe, and economical.