Use CO2-Triggered switchable water additive to reversibly emulsify and demulsify diesel

In this paper, a practical and environmental friendly method was successfully developed by using CO2-Triggered switchable water additive to reversibly emulsify and demulsify diesel, aims to provide guidance for recovering oil substances in waste oil-based drill cuttings. In this new method, N, N, N', N'-tetramethyl-1, 6-hexanediamine (TMHDA) was a switchable water additive whose aqueous solution can switch the ionic strength by addition and removal CO2. Then it can be used to separate diesel through reversibly emulsification and demulsification. The nuclear magnetic resonance hydrogen spectrum (H-1 NMR) and conductivity demonstrated TMHDA have better switching performance. Then, diesel/naphthenic acid mixtures have been used for modeling the application of recovering oil substances in waste oil-based drill cuttings. When the acid value >= 1.76mg KOH/g (the oil and TMHDA solution were 5 mL), diesel can be emulsified. The material produced by TMHDA and naphthenic acid have a strong surface activity so that the oil/water interfacial tension was less than 0.1 mN.m(-1). The demulsification performance was illustrated by change of the ionic strength, pH and the content of oil in the aqueous phase during the breaking process. Brief provided two optimization strategies of recycling of TMHDA additive. Finally, the possible mechanism of the new method was discussed.