Evaluation on dispersion behavior of the aqueous copper nano-suspensions

This paper presents a procedure for preparing a nanofluid which is solid–liquid composite material consisting of solid nanoparticles with sizes typically of 1–100 nm suspended in liquid. By means of the procedure, Cu–H2O nanofluids with and without dispersant were prepared, whose sediment photographs and particle size distribution were given to illustrate the stability and evenness of suspension with dispersant. Aiming at the dispersion of nano-Cu is regarded as the guide of heat transfer enhancement, the dispersion behavior of Cu nanoparticles in water were studied under different pH values, different dispersant types and concentration by the method of zeta potential, absorbency and sedimentation photographs. The results show that zeta potential has good corresponding relation with absorbency, and the higher absolute value of zeta potential and the absorbency are, the better dispersion and stability in system is. The absolute value of zeta potential and the absorbency are higher at pH 9.5. Hexadecyl trimethyl ammonium bromide (CATB) and sodium dodecylbenzenesulfonate (SDBS) can significantly increase the absolute value of zeta potential of particle surfaces by electrostatic repulsions, and polyoxyethylene (10) nonyl phenyl ether (TX-10) can form a thick hydration layer on the particle surfaces by steric interference, which leads to the enhancement of the stability for Cu suspensions. In the 0.1% copper nano-suspensions, the optimizing concentrations for TX-10, CATB, and SDBS are 0.43, 0.05, and 0.07%, respectively, which have the best dispersion results.