Tinghua Wu

One-step degradation of cellulose to 5-hydroxymethylfurfural in ionic liquid under mild conditions.

One-step conversion of cellulose to HMF (5-hydroxymethylfurfural) has been achieved by using metal chlorides (CrCl3, CuCl2, SnCl4, WCl6) in [BMIM]Cl. The effects of temperature, reaction time, amount of catalysts, and the purity of [BMIM]Cl on the performance have been studied and discussed in detail. More than 63% yield of HMF and 80% yield of TRS (total reducing sugar) were obtained in [BMIM]Cl with CrCl3 at 120 °C under atmospheric pressure. Filter paper and cotton were also used as a source for cellulose degradation to HMF, but only a moderate yield of HMF was obtained (40% for filter paper and 12% for cotton). The reutilization of this system was examined and the reaction mechanism was also discussed.

Oxidative Degradation of Chitosan to the Low Molecular Water-Soluble Chitosan over Peroxotungstate as Chemical Scissors

Low molecular water-soluble chitosan was prepared by the depolymerization of chitosan in the presence of a series of catalysts with active W(O2) sites. Both the peroxo species [W2O3(O2)4]2- and {PO4[WO(O2)2]4}3- showed high efficiency in the degradation of chitosan, indicating that the degradation mechanism did not follow the radical mechanism. That means •OH is not the active species, which has been proven by the fluorescence spectra. H2O2 acted as an oxidant to regenerate the active W(O2) sites in the depolymerization of chitosan. The developed catalyst (TBA)3{PO4[WO(O2)2]4} is recoverable.

A novel protocol for the oxidative degradation of chitosan with hydrogen peroxide catalyzed by peroxomolybdate in aqueous solution

A novel pathway is reported to obtain low molecular weight, water-soluble chitosan (LMWSC) via oxidative degradation of chitosan with a catalyst containing active Mo(O2) sites. H2O2 was found to play a fatal role in the regeneration of Mo(O2). Moreover, (TBA)3{PO4[MoO(O2)2]4} can be recovered and reused four times without loss of reactivity.

The effect of pH value on the synthesis and photocatalytic performance of MnWO4 nanostructure by hydrothermal method

In this study MnWO4 nanocrystals with different morphologies were synthesised by a simple hydrothermal method with MnCl2 · 4H2O and Na2WO4 · 2H2O as source materials. The products were characterised by X-ray powder diffraction, field-emission scanning electron microscopy, Raman spectroscopy and fluorescence spectroscopy. The results reveal that pH value plays an important role in the morphology and phase of samples. A simple reaction mechanism for the formation of MnWO4 was presented. The photodegradation of acetone was employed as a probe reaction to test the photoactivities of the as-prepared samples.