Preparation of Cu/montmorillonite-chitosan and its catalytic activity for p-nitrophenol reduction

The Cu/montmorillonite (MT)-chitosan (CS) catalyst was prepared by reduction of Cu2+ adsorbed in MT with sodium borohydride which was modified with CS. The catalyst was characterized with X–ray diffraction and Fourier transform infrared spectrometer, indicating that MT was modified with CS successfully, and the copper particles dispersed uniformly in MT-CS. The activity of Cu/MT-CS composite was investigated for the reduction of p-nitrophenol (4-NP) with excess sodium borohydride at 25 °C. The reusability of Cu/MT-CS composite is poor when CS content in the composite is low. However, the activity of Cu/MT-CS composite is low when CS content in the composite is high. The suitable mass ratio of MT to CS is 30:1. The activity of Cu/MT-CS composite increases with the increasing of copper loading, and the suitable copper loading is 5%. Under the conditions of sodium borohydride to 4-NP molar ratio of 40:1, 0.03 g of 5% Cu/MT-CS, the rate constant can reach 0.604 min−1. The activity of the catalyst can maintain after 9 cycles.