Aqueous stability and mobility of C 60 complexed by sodium dodecyl benzene sulfonate surfactant

Surfactant complexation may have significant effects on the environmental behavior of nano-particles. In order to understand the ecological exposure of nano-materials, it is important to determine the stability and mobility of surfactant-complexed nano-materials in aqueous systems. In this study, the aggregation and transport of C-60 complexed by the surfactant sodium dodecyl benzene sulfonate (SDBS) were investigated. It was found that SDBS-complexed C-60 had a.-potential of -49.5 mV under near-neutral pH conditions and remained stable during an aging period of 15 days. It had a critical coagulation concentration of 550 mmol/L for NaCl, which was higher than common natural colloids and many kinds of raw nano-materials, and was comparable to those of many kinds of surface-modified nano-materials. SDBS enhanced the stability of C-60 colloid; however, at the same time, it also enhanced the colloidal particle aggregation rate. Much higher mobility was found for SDBS-complexed C-60 than C-60 colloid. Increase in ionic strength, Ca2+ concentration or Al3+ concentration decreased the mobility. In general, SDBS-complexed C-60 had high stability and mobility. (C) 2015 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V