Transport in Hydrophobized Montmorillonite Thin Films

SWy-1 montmorillonite clay treated with short-chain and long-chain aliphatic, aromatic, and aliphatic−aromatic quaternary ammonium compounds (QAC) was investigated. The transport properties of the electroactive probes Fe(CN) 6 3 -, Ru(NH 3 ) 6 3+, and p -benzoquinone have been studied by cyclic voltammetric techniques. Coverage at 3.7% and lower of the cation exchange capacity (CEC) of the clay had little impact on the hydrophobic behavior of the film or on the retention of the probe molecule. At 37% coverage, all of the short-chain QAC behaved similarly and inhibited expansion of the clay-reducing transport of the anion, but had little impact on the cation or neutral aromatic. The long-chain QAC all behaved similarly and disrupted the clay structure such that the water-soluble ionic probes travel in pinholes while the aromatic is retained in hydrophobic domains.