Studies On The Reaction Of L-Cysteine In A Confined Matrix Of Layered Double Hydroxides And Primary Studies On The Catalysis Properties Of Layered Double Hydroxides Films

The amino acid L-cysteine(L-Cys) was intercalated into a MgAl layered double hydroxide(LDH),and its oxidation reaction by hexacyanoferrate(â…¢) (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 L-Cys-LDH quantity,initial Fe(CN)₆^3- concentration 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.Cu/Zn/Al layered double hydroxide(LDH) films were fabricated on the aluminum substrates by using an in-situ growth prodecure.The structure and morphology of the LDH films were investigated by XRD,FT-IR,SEM and XPS.The results show that the hexagonal plate-shaped CuZnAl LDH crystallites grow perpendicularly on substrates.The catalytic properties of the CuZnAl-LDHs were studied by using phenol hydroxylation as a probe reaction.It was found that the CuZnAl-LDHs film catalyst exhibits both higher catalytic activity and selectivity for the reaction compared with the powder catalyst sample.Moreover,a catalytic mechanism was proposed to illustrate the superior catalytic proformances of the CuZnAl-LDHs film catalysts.