Studies on the oxidation reaction of L-cysteine in a confined matrix of layered double hydroxides

The amino acid L-cysteine (L-Cys) was intercalated into a MgAl layered double hydroxide (LDH). and its oxidation reaction by hexacyanoferrate (III) (Fe(CN)(6)(3-)) in the confined region between sheets of LDH has been studied in detail. Based on the measurement results of XRD, Raman and FT-IR, it was found that the interlayer L-Cys was oxidized to cystine by Fe(CN)(6)(3-). Furthermore, the kinetics of this reaction was investigated in batch mode. The influences of initial Fe(CN)(6)(3-) concentration, L-Cys-LDH quantity and reaction temperature on the interlayer oxidation reaction have been studied, respectively. The reaction follows a diffusion-controlled mechanism represented by Crank-Ginstling and Brounshtein kinetic model with the apparent activation energy of 29.93 kJ/mol. Therefore, this layered material may have prospective application as a novel "molecular reactor" for confined chemical reactions. (C) 2009 Elsevier B.V. All rights reserved.