Preparation of organic fluids containing Cyanex 302-modified ZnS particles with high loading concentration and their tribological properties

Stable organic fluids containing ZnS nano-particles modified by Cyanex 302 (di-(2,4,4-trimethylpentyl) monothiophosphinic acid) have been prepared directly in gasoline via solvent extraction–precipitation method. The obtained organic fluids were so stable that ZnS particles did not precipitate after keeping at room temperature for more than 6 months when the loading concentration of ZnS was as high as 24.4 g L−1. The ZnS nano-particles were characterized by XRD, TEM, AFM, IR, UV–vis and TG-DTG, respectively, showing that ZnS particles were well modified by Cyanex 302. The obtained ZnS nano-particles could be well dispersed into organic solvents again and the new-formed nano-fluids were also very stable. Moreover, the tribological properties of liquid paraffin (LP) containing obtained ZnS nano-particles were also studied with Optimol SRV oscillating friction and wear tester, showing that such a fluid LP + ZnS has a low friction coefficient.