Efficient Demulsification of Acidic Oil-In-Water Emulsions with Silane-Coupled Modified TiO2 Pillared Montmorillonite

Emulsified pickling waste liquid, derived from cleaning oily hardware, cause serious environmental and ecological issues. In this work, a series of grafted (3-aminopropyl)triethoxysilane (APTES) TiO2 pillared montmorillonite (Mt), Ti-Mt-APTES, are prepared and characterized for their assessment in demulsification of acidic oil-in-water emulsion. After titanium hydrate is introduced through ion exchange, montmorillonite is modified by hydrophobic groups coming from APTES. The Ti-Mt-APTES in acidic oil-in-water emulsion demulsification performance and mechanism are studied. Results show that the prepared Ti-Mt-APTES has favorable demulsification performance. The Ti-Mt-APTES demulsification efficiency (E-D) increased to an upper limit value when the mass ratio of APTES to the prepared TiO2 pillared montmorillonite (Ti-Mt) (R-A/M) was 0.10 g/g, and the 5 h is the optimal continuous stirring time for breaking the acidic oil-in-water emulsion by Ti-Mt-APTES. The E-D increased to 94.8% when 2.5 g/L of Ti-Mt-APTES is added into the acidic oil-in-water emulsion after 5 h. An examination of the demulsification mechanism revealed that amphiphilicity and electrostatic interaction both played vital roles in oil-in-water separation. It is demonstrated that Ti-Mt-APTES is a promising, economical demulsifier for the efficient treatment of acidic oil-in-water emulsions.