The impact of additives found in industrial formulations of TCE on the wettability of sandstone Gavin Harrold a , David N. Lerner b , Stephen A. Leharne a, * a School of Sciences, University of Greenwich, Pembroke, Chatham Maritime, Kent ME4 4TB, UK b Groundwater Protection and Restoration Group, Department of Civil and Structural Engineering, Sheffield University, Mappin St, Sheffield S1 3JD, UK Received 13 July 2004; received in revised form 21 June 2005; accepted 5 July 2005 Available online 15 August 2005 Abstract The wettability of aquifer rocks is a key physical parameter which exerts an important control on the transport, residual trapping, distribution and eventual fate of chlorinated hydrocarbon solvents (CHSs) released into the subsurface. Typically chlorinated solvents are assumed to be non-wetting in water saturated rocks and unconsolidated sediments. However industrially formulated solvent products are often combined with basic additives such as alkylamines to improve their performance; and the mineral surfaces of aquifer rocks and sediments usually possess a range of acid and hydrogen-bonding adsorption sites. The presence of these sites provides a mechanism whereby the basic additives in CHSs can be adsorbed at the solvent phase/solid phase interface. Given the amphiphilic molecular structure of these additives, this may result in changes in the wetting conditions of the solid phase. The aim of this study was therefore to test this conjecture for two classes of additives (alkylamines and quaternary ammonium salts) that are often encountered in industrial solvent formulations. Wettability assessments were made on sandstone cores by means of measurements of spontaneous and forced water drainage and spontaneous and forced water imbibition and through contact angle measurements on a smooth quartz surface. No solvent/additive combination produced solvent wetting conditions, though dodecylamine and octadecylamine significantly reduced the water wetting preference of sandstone which frequently resulted in neutral wetting conditions. The large volume of spontaneous water drainage observed in wettability experiments involving cetyltrimethylammonium bromide and octadecyltrimethylammonium bro- mide, suggested that the sandstone cores in these tests remained strongly water wetting. However 0169-7722/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jconhyd.2005.07.004 * Corresponding author. Tel.: +44 208 331 9565; fax: +44 208 331 9805. E-mail address: s.a.leharne@gre.ac.uk (S.A. Leharne). Journal of Contaminant Hydrology 80 (2005) 1 – 17 www.elsevier.com/locate/jconhyd